Slaughterhouse facilities in developing nations: sanitation and hygiene practices, microbial contaminants and sustainable management system

Abstract

Poor personal and environmental hygiene and sanitary conditions of abattoirs in developing countries in sub-Saharan Africa have been implicated in the occurrence and spread of foodborne diseases. This focused review aims to evaluate the sanitation and hygiene practices of slaughterhouses in selected sub-Saharan African countries as well as the microbial (bacterial) contaminants associated with these slaughterhouses. Pathogenic microorganisms of public health importance have been associated with these slaughterhouses due to poor hygiene conditions, non-formal occupational health and safety training, and poor knowledge of workers as well as substandard infrastructures and crude tools in these facilities. Put together, these conditions enable the growth, survival, transmission, and proliferation of foodborne pathogens such as bacteria, parasites, and viruses. To address this issue, there is a need to assess the poor environmental and personal hygiene of butchers and other abattoir workers, the inaccessibility of potable water, waste management practices, and the lack of appropriate infrastructure and technology, which have been identified as some of the enabling factors for bacteria, fungi, and viruses. Sustainable strategies should include instituting regulations that are backed by law.

Introduction

Countries with low human development index (i.e., low life expectancy, educational outcomes, and per capita income) and characterized by an industrially developing and underdeveloped base are referred to as developing countries and are mostly found in parts of the Global South like sub-Saharan Africa, Latin America, the Caribbean, and South Asia (Erinle et al., 2021). According to the World Bank Group (2022), the over 40 countries in sub-Saharan Africa has a population of 1.17 billion (in 2021) with a growth rate of 2.6% and a 35.1% poverty rate as at 2019, 7.7% unemployment rate, life expectancy of 62 years as at 2020 and GDP per capita and growth rate of US$1656 and in 4.1% in 2021. One of the challenges exacerbating the current predicaments of developing countries in sub-Saharan Africa is non-communicable and infectious foodborne diseases because of their poor food handling and sanitation practices, dietary issues, and weak or non-existing regulatory systems (Gebremedhin and Bekele, 2021; Omotosho et al., 2016; Vaughan et al. 2016).

Poor food handling practices, preparation, packaging, and overall knowledge about food quality regulations as well as limited financial resources for investment in safer equipment have worsened the problems (Chime et al., 2016; Evivie et al., 2020; Ikhajiagbe et al., 2021a, 2021b; Odeyemi 2016; Ogwu 2019a, 2019b, 2019c; Ogwu et al. 2019a). Foods of animal origin are more likely to be hazardous than others and are regarded as high-risk foods. This is because food from animal sources is more susceptible to spoilage due to microbial infestation and/or enzymatic and oxidative processes. Since microbes cause spoilage in foods, especially those of animal origin, the principles of food hygiene are vital. The total attributes and perception of food as acceptable by a consumer is the focus of food quality. On the other hand, food safety issues are embedded into the food chain and are associated with microbial and chemical characteristics as well as personal and hygiene properties of the key players within the food system between the farm and plate. Therefore, to prevent foodborne illnesses and non-communicable diseases associated with food from slaughterhouses especially in developing counties it is pertinent to promote collaboration and medical supervision of all the stakeholders (Fung et al., 2018). Currently, the safety of food from slaughterhouses is threatened by foodborne pathogens and chemical contaminants due to unhealthy practices (Borchers et al., 2010). These are capable of resulting in teratogenic, immunotoxic, genotoxic, nephrotoxic, estrogenic, cardiotoxic, neurotoxic, and other developmental effects in a region that is already threatened with other sustainability issues connected to their economic and political systems. This is a clear example of “mixture toxicology” as presented in Borchers et al. (2010) i.e., the complex interactions and exposure to and between harmful chemicals, and this will require an integrated approach to address it.

In many developing countries, for example, in Nigeria, the slaughtering of animals is done in an unregulated manner. Thus, the process is carried out while setting aside the standards set in place by regulatory authorities such as the Food and Agriculture Organisation of the United Nations (FAO), the World Health Organisation (WHO), and national agencies peculiar to Nigeria. According to the Registrar of the Veterinary Council of Nigeria, there are only three standard abattoirs in the country, located in Lagos, Borno, and Nassarawa states (Daily Post, 2015). This implies that the remaining 33 states and the Federal Capital Territory have substandard slaughterhouses. These substandard abattoirs are operated using traditional methods that are characterized by rudimentary equipment and poor handling processes. A similar scenario has been reported in western Kenya by Cook et al. (2017), who opined that the current working conditions in slaughterhouses were not in line with the recommendations of the Meat Control Act of Kenya. Similarly, countries like Ghana (Annan-Prah et al. 2012), Eastern D.R. Congo (Babe et al., 2018), Cameroon (Afolabi et al., 2014), Bamako, Mali (Brahima et al., 2022), have been reported to observe similar high risks from hygiene compromise in slaughterhouses, leading to high levels of meat contamination.

Meat is an important constituent of meals in households in urban and rural areas in many countries (Kigigha et al., 2015a). There is a rising trend in meat consumption and demand within the Global South where most developing countries are situated. This may be due to ongoing urbanization, population growth, health benefits, and changing economic status. Delgado (2022, 2003) reported that developing nations consume one-third of the meat and one-quarter of the milk consumed in developed parts of the world. Globally, meat consumption has been growing since the industrial revolution and agricultural intensification despite the attendant environmental and biodiversity risks (Erinle et al., 2021; González et al., 2020; Omoigui et al., 2016; Osawaru et al., 2013a, 2013b, 2013c, 2013d, 2013e; Salter 2018). In a study carried out by Laskowski et al. (2018), based on the “Nutritive Value for Foods and Meat published by Kunachowicz et al. (2017), they examined energy and nutrient intake from 22 nutrients in meat, meat products, and seafood and observed that over 50% of the nutrients are from vitamin B12 and niacin; 40–50% are from cholesterol, protein, and vitamin D; 30–40% of monounsaturated fatty acids, thiamin, zinc, total fat, and saturated fatty acids; and 20–30% for vitamin B6, riboflavin, phosphorus, iron, vitamin A, polyunsaturated fatty acids and sodium. Also, these constitute the major nutrients found in meat and seafood.

Microbial contamination of meat in developing countries is unavoidable during slaughtering and processing (Annan-Prah et al., 2012; Babe et al., 2018). This is because contamination can occur when raw meat comes in contact with pathogenic microorganisms. Disease-causing microbes have been variously described to be ubiquitous i.e., found everywhere and such have been reported in different environmental components including air (Izah et al., 2021a; Seiyaboh et al., 2020a;), water (both surface and ground water) (Agedah et al., 2015; Ben-Eledo et al., 2017; Izah et al., 2021b; Nwizugbo et al., 2023; Seiyaboh and Izah, 2017; Seiyaboh et al., 2020b, 2020c, 2017), soil (Ikhajiagbe and Ogwu 2020; Kerfahi et al. 2019; Ogwu and Osawaru 2015; Ogwu et al. 2019b, 2019c, 2019d; Richard et al., 2020; Song et al. 2019), in waste waters (Ohimain et al., 2012, 2013b), in food including palm oil (Izah and Ohimain, 2016; Ohimain et al., 2013a; Omorotionmwan et al. 2019; Seiyaboh et al., 2018), fruits (Chime et al., 2018; Evivie et al., 2019; Ikhajiagbe et al. 2021a, 2021b; 2022; Izah et al., 2015a, 2016a; Ogwu 2020; 2023; Ogwu et al. 2013, 2016a, 2016b), food and drinks (Izah et al., 2015b, 2016b; Kigigha et al., 2018; Ogwu and Osawaru, 2022; 2023; Osawaru and Ogwu 2020), toasted meat (Kigigha et al., 2015a), cassava flake (Kigigha et al., 2015b), snacks such as puff-puff (Kigigha et al., 2017), etc. Slaughterhouses in developing and underdeveloped countries are the sites where meat is prepared and cut into pieces before shipping to processers and processing units for packaging, marketers, and consumers. Therefore, potential and actual microbial contamination in slaughterhouses during slaughtering is a public health and safety problem that can affect the economic value and shelf life of the meat (Diyantoro and Wardhana, 2019). Stunning, skinning, evisceration, bleeding, hanging, rinsing and washing, cutting, and deboning are some common activities that characterize slaughterhouses in developing countries (Bersisa et al., 2019). Several studies have reported that meat from developing countries is known to harbor toxins, as well as contain antibiotic-resistant genes of foodborne bacteria like Staphylococcus and the like (Anthony, 2012; Babe et al., 2018; Okoli et al., 2018). According to the Global Panel on Agriculture and Food Systems for Nutrition (2016), foodborne disease is responsible for an estimated 2.3 million death in developing countries per year and is a sustainable development challenge.

According to Ayalew et al. (2015), the sanitary conditions and hygiene practices in many abattoirs are poor, making them reservoirs and growth media for microorganisms when in contact with meat. This poses a serious threat to public health as food-borne illnesses and diseases can arise after the consumption of meat from such abattoirs. Therefore, unhygienic processed, slaughtered, and processed meat could be a vehicle for disease outbreaks. Food-borne diseases could arise from the consumption of poorly cooked meat slaughtered in an unhygienic environment. The clinical symptoms and severity of the disease are associated with the causative agent of the disease. Generally, the severity of food-borne diseases can be high, especially for children under the age of five and the elderly, as well as immunocompromised individuals.

In many developing countries, not many meat handlers, especially the abattoir workers, are aware of the role of microbial contaminants found in meat slaughtered in unhygienic conditions. To improve the general hygiene practices and prevent possible disease outbreaks from abattoirs in these countries, it is therefore important to evaluate the condition of the abattoir and provide relevant background information that will aid in the intervention processes. Therefore, the goal of this focused review is to evaluate the sanitation and hygiene practices of slaughterhouses in selected sub-Saharan African countries as well as the microbial (bacterial) contaminants associated with these slaughterhouses. The review concludes by suggesting a sustainable management system for abattoirs in some developing countries of the global South, particularly, those with similar socio-economic backgrounds.

Methodology and organization

This comprehensive review is written as a narrative assessment of slaughterhouse facilities and practices in developing countries. Using related keywords (like “abattoir”, “slaughterhouse”, “developing countries”, Slaughter facilities”, “meat quality and safety”, “sub-Saharan Africa”, and “meat preparation practices”), a systematic search was conducted to gather primary literature from a wide range of databases, including Africa Index, Medicus, CABI Global, NCBI, Health, Scopus, Web of Science, Embase, PubMed, and Google Scholar. The primary literature gathered (articles, books, reports) was subjected to a quality check using the Critical Appraisal Tool (i.e., an organized checklist that enables methodological quality assessment). The resultant literature from the quality checks was used to address the state of slaughterhouse facilities in developing countries from Sub-Saharan Africa, assessing their sanitation and hygiene practices, microbial contaminations, and sustainable management systems. The work is organized into four sections, with each section comprehensively reviewing critical thematic areas.

The first section addresses the characteristics of slaughterhouses. In developing countries discussing food (meat) quality and safety, physical features of slaughterhouses in developing countries, public and environmental health concerns, and waste management strategies. The second section is on animal slaughtering practices in developing countries and environmental hygiene, human health, and ethical considerations. In this section practices like lairage, stunning, slaughtering and bleeding, skinning and dehairing, evisceration, chilling, and others are discussed. The third section is the high point of this review wherein the focus is on the hygiene and sanitation quality of slaughterhouses in developing countries. It highlights environmental and personal hygiene issues as well as some contaminants that have been reported from these slaughterhouses. The fourth section provides some recommendations for the sustainable management of slaughterhouses and slaughterhouse practices in the Global South.

Characteristics of slaughterhouses in developing countries and the associated risks

In most sub-Saharan African Countries, slaughterhouses and abattoirs have been indicated as sites for microbial contaminants due to poor hygiene practices (Ahouandjnou et al., 2015; Kyayesimira et al., 2020; Mpundu et al., 2019). Broadly, the FAO (1985) recognizes three types of slaughterhouses in developing countries which are modern slaughterhouses, old slaughterhouses, slaughter slabs, or makeshift premises. While old slaughterhouses and slaughter slabs are informal makeshift facilities that operate on a pay-as-you-need basis, modern slaughterhouses are similar to facilities found in developed countries but are found few and far between in developing countries because of their costly design and equipment requirements. According to Ayoade and Olayioye (2016), many developing countries in sub-Saharan Africa operate three main types of abattoir systems—the line slaughter system, the slaughter slab system, and the batch system. The most commonly found are the slaughter slabs operated by the municipal and local government authorities (Adeyemo, 2002) as stipulated by the 4th schedule of the 1999 Constitution of the Federal Republic of Nigeria (Nwanta et al., 2008). Slaughter slabs require a license to operate and use and provide slaughterers with slabs and space for dressing and packaging meat. In the batch system slaughter facility in developing countries, animals are processed in or near abandoned buildings on floors that are either bare or has corrugated roofing sheet placed on them. The batch type of slaughter facility does not require a license to use or operate and adheres to few or no regulations. The line system of slaughterhouses is a well-organized facility with up-to-date equipment that conforms to regulations outlined in World Health Organization guidelines as presented in Eriksen (1999).

The types of slaughterhouses can be further categorized into three based on their sizes, number of animals processed daily, proximity to urban centers, and whether the meat from the properties is for consumption or transported out to distant markets (Cook et al., 2017). In Category A abattoirs, over 40 animals are processed daily and products can be distributed all over the country, Category B processes between 6 and 39 animals daily and may supply the meat product within local governments, counties, regions, and states while Category C slaughterhouses process five or fewer animals per day and are mainly supplied for direct residential consumption and local markets. This categorization is supported by legislation like the Meat Control Act of Kenya (Cook et al., 2017). It is important to note that slaughterhouses in developing countries rarely operate on a 24-h schedule. They open at dawn and close around midday when meat and meat products are shipped out of the facility. Slaughterhouses may also be considered formal when recognized by a constituted authority or informal when run independently of official procedures in developing countries.

Slaughter slabs are typically well-built and, to some extent, conform to WHO guidelines; however, over time, these facilities become dilapidated due to poor maintenance, become overcrowded, and experience a decline in attendance from the appropriate authorities (Adeyemo, 2002; Nwanta et al., 2008). Even at the point of entry to most slaughterhouses in developing countries, one could easily notice the obvious signs of a failed or dysfunctional system (Timothy, 2020). This includes deteriorated slaughtering and processing facilities, where unhygienic practices are the norm (Adetunji and Awosanya, 2011), a lack of quality regulation from relevant authorities (Nwanta et al., 2008), leading to the production of unsafe and impaired meat quality (Gurmu and Gebretinsae, 2013; Lawan et al., 2013) that is not fit for human consumption (Fasanmi et al., 2010). Basic structural facilities in slaughterhouses in developing countries are presented in Table 1.

Table 1.

Type of structures used in slaughterhouses in developing countries and their frequency

Type of structure	Frequency	Characteristics
Roof	None to rarely present	Zinc, aluminum, asbestos
Floor	Complete or partially completed	Wooden, tiles, iron, stones, cement/concrete or grass/plant leaves
Walls and fence	None to rarely present	Bricks or wooden
Electricity	None	Part of the grid or off grid through power generator or solar panels
Gate and door	None to rarely present	Metal or wooden gates

The layout of slaughterhouses in developing countries rarely considers environmental and human hygiene needs. Therefore, critical public health and environmental concerns are associated with the large-scale slaughtering of animals (Ayoade and Olayioye, 2016), poor access to potable water (Ayoade and Olayioye, 2016), poor environmental hygiene, and lack of ante mortem inspection of animals before slaughtering (Nwanta et al., 2008; Ogwu and Oladeji 2014), purchase of animals for slaughter by individuals who may cover up defects to avoid financial loss, and non-compliance and enforcement of laws regarding animal welfare and meat safety (Omotosho et al., 2016) are some of the deterrents to the production of wholesome meat. There is also no proper sewage or refuse disposal systems (Timothy, 2020). Environmental hazards and health risks of inhabitants living near abattoirs in Ibadan, Oyo State, were reported for 570 participants in neighbourhoods within 300, 600, and 900 m of the selected abattoirs throughout the state. Moreover, slaughterhouse waste is typically discharged into flowing rivers or the run-off gutters of nearby buildings, polluting drinking water sources (surface and groundwater) and producing odour pollution (Timothy, 2020). In some cases, these waste products are piled behind the slaughterhouse, thereby, creating a breeding ground for vectors of diseases like mosquitoes.

Poor waste management is to blame for the environmental and health concerns associated with abattoirs, according to studies conducted in Nigeria (Seiyaboh and Izah, 2017). Residents’ health and the environment, in general, have been jeopardized or endangered as a result of the dangers. This is because animal waste such as blood, bones, intestinal contents, tissues, hides, and skin is strewn around the abattoirs in massive quantities (Timothy, 2020). Abattoirs in sub-Saharan Africa pose several health risks, including inappropriate abattoir planning; illegal abattoirs; unskilled slaughterhouse workers; and butchers who are unaware of sanitary principles. Poor waste management always attracts vectors, especially the housefly, to the vicinity. The offensive odour causes devaluation of properties in the area and makes the area unattractive for residents. Studies have shown that methane gas can be produced from animal dung or waste. When the wastes are dumped in an environment, an anaerobic condition may set in, allowing methane-producing microbes that are found in the wastes to lead to the production of methane gas, which is one of the major gases that cause the greenhouse effect.

Animal slaughtering practices

In slaughterhouses, hygiene i.e., conditions and practices that promote safety and good health which incorporate all elements like environmental, personal, and co-workers is key to ensuring the safety of meat produced. By extension, this is connected to occupation or industrial health or medicine and safety, which is seek to understand how best to detect, monitor, evaluate, and control risk at or originating from a workplace (Copello et al., 2015; Guillemin 2006; Swaminathan 2014). According to Omotosho et al. (2016), slaughtering methods depend on the equipment available and training received by the abattoir personnel and can impact the quality of meat, and the main principle of hygiene in abattoirs is the separation of “clean” and “dirty” operations. The purpose of this is to avoid cross-contamination. Cross-contamination as defined by Bartz et al. (2010) is the direct or indirect transfer of microorganisms from utensils, raw materials, food handlers, objects, or surfaces to food. According to the Meat Inspectors’ Manual of South Africa (2015), the layout of the abattoir must be in a way that all processes move in a particular direction without the cross-flow of products i.e., live animals get in from one end—“dirty” and leave from the other end “clean” as dressed carcasses (FAO, 2016a, 2016b).

The “dirty” area also called the pre-evisceration area, is designated for activities including livestock entrance; lairage for holding animals’ antemortem inspection; stunning; bleeding area; storage for by-products (fat, blood), inedible parts (like horns, hooves, bones), condemned products; store rooms and washing facilities (Meat Inspectors’ Manual of South Africa, 2015). While the “clean” area also known as the post-evisceration area is designed and more restricted in terms of accessibility for abattoir personnel. It includes areas for separating the different components of an animal under hygienic settings to prevent cross-contamination, post-mortem inspection, and chilling- to ensure product quality and optimal shelf life; dispatch facilities; laboratory facilities and washing facilities accessible to only workers in the clean area (Meat Inspectors’ Manual of South Africa, 2015).

The type of practice adopted in slaughterhouses within developing countries depends on the following –

1. Type of animal (whether domesticated or wild). The most common domesticated animals processed in slaughterhouses in developing countries are cows, turkeys, ducks, goats, rabbits, pigs, chickens, and sheep while the wild ones include crocodiles, antelopes, porcupines, snakes, etc.

2. Ethical and religious considerations (halal or non-halal). This depends on the dominant religion in the developing country or the part of it where the slaughterhouse is located.

3. Legislative requirements, especially in the design, location, and practices.

4. Material needs are connected to the types of animals i.e., if the animal has feathers, hair, or none, and requires water, fireplace, or not.

5. Destination of the meat i.e., nearness to where the meat will be taken to after processing in the slaughterhouse. This will determine whether it will be chilled, smoked and dried, fresh, or combined.

6. Meat products and meat parts required

7. Available resources (like water and power).

It is worth stating that not all meat animals consumed or found in the retail centers or on dinner tables were slaughtered in slaughterhouses in developing countries but all food animals can be slaughtered in these abattoirs. More so, the rates differ between and among the food animals depending on different factors like the urgency of needs, space requirements, and country. From a young age, some residents of developing countries are taught how to slaughter animals like chickens and continue this practice in their resident. Some common slaughter practices in developing countries include:

Lairage

Lairage is an important aspect of the operations that take place at the abattoir. The lairage is characterized by a large space for the reception of the animals transported to the abattoir (Meat Inspectors’ Manual of South Africa, 2015), drinking water for the animals, spraying system for cleaning purposes for the animals before they enter the slaughterhouse and the facility which should be made of concrete and sloping towards the drains (FAO, 2016a, 2016b). But unfortunately, the space in most abattoirs in developing countries is grossly inadequate.

Stunning

Stunning is usually carried out before the slaughtering of the animal to ease the pain. Hence, it is a process of immobilizing or rendering an animal unconscious before killing the animal. Most abattoirs in Ghana, Nigeria, and Eastern D.R. Congo, do not carry out this activity (Anthony, 2012; Babe et al., 2018). Stunning can be through electrical or gas. Electrical stunning is only practiced in a few developing countries where electric supply is constant or near contact while gas stunning is becoming increasingly popular in developing countries in other parts of the world like Asia and the Caribbean.

Slaughtering and bleeding

Slaughtering is done immediately after stunning while the animal is still unconscious. It is usually carried out using a sterile knife. According to the FAO (2016a, 2016b), Ofosu-Korateng (2014), all animals must be hoisted vertically with their heads down for faster bleeding as this decreases the risk of the carcass being contaminated, and the blood if not intended for use should be drained separately and not allowed to drain into the wastewater. This is very expedient because according to Chukwu et al. (2011), the highest pollution load of abattoir effluents is blood followed by fat and blood has the highest chemical oxygen demand (COD) as one of the major dissolved pollutants in abattoir wastewater. For example, in Nigeria this procedure is rarely put into consideration; the common practice is cutting the neck of the animal with a knife while collecting as much blood with a bucket.

Skinning/dehairing

According to the FAO (2016a, 2016b), skinning and dehairing must be carried out in a separate area, and the unskinned carcass must never enter the clean area but must be hygienically transferred immediately to the clean area for evisceration. For improved cleanliness, hoists should be used during the skinning and dehairing process but where hoists are not available; the carcasses must be kept above the floor level. The skinning of the animals is mostly carried out using non-sterilised knives and unprotected hands and dehairing is done using condemned tires, plastic, and kerosene; thereby predisposing the consumers to chemical constituents of the choice of material used for the dehairing processes.

Evisceration

This is a very critical stage, as it is the point of highest contamination if strict hygiene conditions are not followed, especially during the removal of the viscera (Baird et al., 2006), hence care should be taken to prevent the extent of contamination FAO (2016a, 2016b). According to Ntanga (2014), the main aim of effective slaughter is protecting the essentially sterile muscles of the carcass from being contaminated by the gastrointestinal tract (GIT), therefore care must be taken to avoid damaging the viscera (FAO, 2016a, 2016b) and all visceral processing must be done in an area that will prevent direct or aerosol contamination (Baird et al., 2006). Edible organs must be carefully removed hygienically and stored, and waste must be rapidly removed from the floor. All hand tools must be sterilized before and between activities. The evisceration processes in abattoirs in developing countries are mostly not mindful of these procedures as everything is done together and bring a risk of cross-contamination from the butchers to the viscera and then to the carcasses.

Chilling

According to Baird et al., (2006), chilling should begin within 1 h of the bleeding of the carcass or otherwise be halved or quartered and distributed for sale immediately (FAO, 2016a, 2016b). There must be sufficient space and capacity for chilling all meat produced and a constant temperature must be maintained at all times for all products (FAO, 2016a, 2016b; Harris and Savell, 2009). There is no registered public abattoir in some developing countries like Nigeria, Togo, and Burkina Faso with facilities for chilling as carcasses are usually sold immediately after butchering with no preservative measure taken.

Cutting/deboning

Care must be taken to minimise contamination of the meat when cutting and deboning carcasses, this must be done on regularly cleaned surfaces or preferably hanging. After this, the meat must be in clean containers exclusively used for meat (FAO, 2016a, 2016b). With little or no clear separation for “clean” and “dirty” areas in Nigerian, Angola, and Benin abattoirs, cutting and deboning are done together with other processes as is the case with the evisceration process.

Packaging

According to the FAO (2016a, 2016b), meat must be packaged before retail with material that is clean and approved for food packaging and the packaging should be in a way that will prevent contamination of the meat. At this point, dispatch of the meat can be done. However, this process is not in practice in most developing countries in sub-Saharan Africa unlike in South Asia. Here, the meat after the dressing is transported in large sacks or plastic bowls and sometimes dropped in vehicles with a thin sheet of nylon covering them. This gives room for flies to perch on them and contaminate them, cross-contamination from the hands of the butchers, the storage medium, the hands of the transporters, and the vehicles themselves to the meat.

Hygiene and sanitation quality in slaughterhouses in developing countries

The United States Centre for Disease Control and Prevention (CDC) in 2016 stated that hygiene is a behaviour, attitude, or disposition that can improve cleanliness and lead to good health. This involves the practice of keeping oneself and the surroundings clean, especially to avoid the spread of preventable diseases. According to the FAO (2016a, 2016b), hygiene involves well-planned and controlled cleaning and sanitation programmes. Therefore, proper hygiene involves personal and environmental hygiene processes because only one of these cannot adequately contribute to achieving the goal of hygiene. In slaughterhouses, hygiene is of paramount importance as poor hygiene and sanitation practices, weak food safety laws and regulatory practices are some of the major causes of foodborne diseases (Haileselassie et al., 2013; Lee et al., 2017) spread of vectors.

Basic sanitation materials are needed in slaughterhouses and a snapshot of their frequency of occurrence in developing countries broadly and in particular sub-Saharan Africa is presented in Table 2. The rarity and scarcity of these materials contribute to the numerous sanitation challenges experienced in slaughterhouses in developing countries.

Table 2.

Some basic sanitation materials needed in slaughterhouses and their frequency of occurrence in developing countries

Sanitation materials needed	Frequency in developing countries
Toilet	None to rarely present
Piped water	None to rarely present
Personal protective gears	Optional worn by workers
Toilet	None to rarely present
Cleaning area	None to rarely present
Waste disposal facility	None to rarely present
Personal hygiene materials and products	None to rarely present

Meat is consumed as a delicacy in different parts of the world because of their rich protein content (Adzitey et al., 2010). As part of the daily meal constituents in homes, consumers expect to buy meat that is safe and wholesome but the biochemical composition of meat makes it favourable for the growth of microorganisms. This process begins in the abattoir where the meat is produced and is enhanced by its poor sanitary conditions. According to Nwanta et al. (2008) and Oloruntoba et al. (2014), the management of abattoirs and slaughter slab leaves much to be desired, particularly in compliance with the standard practice of sanitation and meat inspection as the basis for sound public health standards. The inadequacy of slaughtering and processing facilities in abattoirs are drivers of the practices by the workers, ignorance, the lax attitude shown by some butchers towards modernization and change, the lack of sewage and waste disposal systems, inadequate potable water supply which leads to pollution of the slaughter slabs by blood and faecal matter, infestation by flies, rodents, and birds and the heaps of waste constitute environmental pollution and public health hazards.

Environmental hygiene

This involves all precautions and processes implemented to prevent the infestation of the abattoir. According to FAO (2016a, 2016b), the major principles of environmental hygiene in the abattoir include;

• Proper Fencing An abattoir must have an intact fence at all times that is in contact with the ground and high enough to prevent the access of the public, unauthorized people, dogs, and other stray animals. Unfortunately, most of the abattoirs in many cities do not have intact fences as most are dilapidated as such people and animals stray into the area constituting a nuisance.

• Pest control A good structural design and construction can hinder the entry of pests considering it is not possible to completely prevent their entry. Pests must be controlled to prevent contamination by their entry into storage facilities, slaughter slabs, and other production areas. Pests include all insects, rodents, and birds. The majority of the abattoirs lack pest control facilities. In many areas, pests including birds and rodents mostly rats are seen within the vicinity. These pests can be carriers of certain disease-causative agents which could be transferred to humans when contaminated meat is consumed when it has not been properly cooked.

• Waste disposal Wastes segregation into solid and liquid in the abattoirs is crucial for proper disposal. Liquid waste constitutes the highest form of waste, as 80–85% of the water intake in abattoir results in effluents, which contain fat, faecal matter, urine, and paunch contents typically with a high organic load that adds a substantial amount of suspended material in the wastewater (Meat Inspectors’ Manual of South Africa, 2015). According to FAO (2016a, 2016b), diversion of abattoir effluents into existing water bodies is the easiest method of disposal but because of preventing contamination of water sources safe disposal methods must be adopted which include:

  • Separation of blood Blood can easily coagulate and block drains if allowed to flow into the drains, blood should therefore be collected and used for purposes such as stock feed for fertilizer production and constituents of human food, for example, sausages were given that the use of blood is allowed by religious and cultural norms.
  • Screening of solids Vertical sieves should be placed in drains to trap solids such as meat trimmings, hair, bones, hooves, and horns.
  • Trapping of grease Grease traps should also be fixed in drains as melted fat or pieces of fatty tissues are always part of abattoir effluents, when trapped the fats solidify which then rise to the surface and can then be removed.

The final effluent can then be disposed of properly by incineration, anaerobic digestion, oxidation dams, or deep burial (Meat Inspectors’ Manual of South Africa, 2015). But these procedures are rarely carried out in many abattoirs in developing countries. Rather they are discharged into the nearby surface water in the coastal region, and the environment in upland areas.

Personal hygiene

Personal hygiene of food handlers is of paramount importance because as the key element in hygiene if efforts are not made to deliver safe products to consumers, foodborne pathogens or spoilage-causing bacteria may be transmitted or carried to surfaces and meat by the workers (FAO, 2016a, 2016b; Meat Inspectors’ Manual of South Africa, 2015). Every butcher has a role to play in ensuring good personal hygiene standards in the abattoir, they must undergo medical examinations to determine their physical fitness and their health status to ensure that transmissible diseases are not transmitted from them to the consumers through the food in the event of them suffering from any communicable diseases; butchers with sores and blisters on their hands and arms must not handle edible meat (Meat Inspectors’ Manual of South Africa, 2015). Many of the abattoir workers rarely undergo a medical examination to ascertain their health condition except when they cannot work conveniently.

Hand-washing

Hand washing is one of the most important aspects of personal hygiene; frequent and thorough hand washing practices can reduce food contamination, and therefore it is important for sufficient water supply to be on the ground in hand washing facilities (FAO, 2016a, 2016b). Before commencing the day’s work, after using the toilet, touching money, dirty objects, and material, and after eating and smoking, scratching the hair or skin, changing or putting on clothes, and nose picking, workers must wash their hands as there is a higher risk of microbial contamination which can be transmitted to food after such activities. Hand washing facilities must therefore be available, especially in the restroom and the working area (FAO, 2016a, 2016b). Some of the abattoirs lack access to adequate water supply thereby the workers are bound to compromise on hand-washing practices, most of the workers often clean their hands and some of their working tools on their aprons and vests.

Working clothes and other personal protective wears

According to the FAO (2016a, 2016b), clothes do not protect the worker against contamination but rather protect the meat against contamination from the workers. In the working area, working clothes used must be exclusive to slaughter activities, where possible workers must not go from clean to unclean areas without changing work clothes and washing their hands and the use of different coloured overalls should be adopted to identify the workers in different areas (Meat Inspectors’ Manual of South Africa, 2015). According to the Meat Inspectors’ Manual of South Africa (2015), FAO (2016a, 2016b), human hair and beard are contaminated with bacteria and the prevention of these bacteria from contaminating food involves covering the hair and beard with clean coverings. The protection of hands against cuts and the transfer of microorganisms from the hands is crucial in maintaining certain hygiene standards; the use of gloves protects the meat against contamination and should be made of rubber or plastic. In some abattoirs, it was observed that some of the butchers keep full-grown beards without little and most times no adequate covering thereby making the meats susceptible to contamination by microbes.

Personal working equipment

Personal working tools such as knives, cutlasses, machetes, and sharpening tools of butchers used during skinning and evisceration must be thoroughly washed and sterilised, especially the handle and the point where the blade and handle meet (Meat Inspectors’ Manual of South Africa, 2015). Cleaning of hand tools should be done continuously during work hours and also at the end of the day’s work. Again, in sub-Saharan Africa, most of the abattoir workers lack adequate knowledge of diseases caused by microbes, and the importance of the sterility of their tools, they are mostly concerned with contamination caused by physical contaminants such as sand and other debris on the working tools.

Bacterial contaminants of slaughterhouse and processing equipment

The diversity of bacteria that have been reported from slaughterhouses in selected countries from sub–Saharan Africa is presented in Table 3. Assessment of the microbial quality of meat can be used as an indicator of how the animal slaughtering method has been handled to control or avoid contamination. It also indicates the hygienic quality of the meat (Bersisa et al., 2019; Tafida et al., 2013). Therefore, a high bacterial load of meat could be a result of poor abattoir facilities, handling of carcasses, and hygienic conditions. The microbiological quality or condition of the meat is mostly dependent on the animal's health status before slaughtering and the processing methods in conjunction with the hygienic conditions of the environment (Oluwafemi et al., 2013; Rombout and Nout, 1994). Table 4 reveals selected reports of studies on the prevalence of pathogenic bacteria, sources, and recommendations.

Table 3.

Diversity of bacteria that have been reported from slaughterhouses in in selected countries from sub Saharan Africa

Location of slaughterhouse	Part of the slaughter evaluated in the slaughterhouse	Bacteria species reported	Source
Abuja FCT, Nigeria	Water	Escherichia coli, Facal streptococcus and Fecal coliforms	Nafarnda et al. (2012)
Agege and Odo, Lagos State, Nigeria	Effluent	Bacillus spp., Clostridium welchii (C. perfringes), Pseudomonas aeruginosa, Vibrio spp., Lactobacillus plantarum and Micrococcus luteus	Adesemoye et al. (2006)
Akure, Ondo State, Nigeria	Floor, tables, knives, clothes, waste dump, wastewater and meat	Bacillus pumilus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Corynebacterium xerosis, Proteus Vulgaris, Nitrococcus mobilis, Aeromonos hydrophila, and Sarcina flava	Adegunloye (2013)
Bamako, Mali	Slaughtering room	Salmonella	Sacko et al. (2022)
Benin City, Edo State, Nigeria	Wastewater	Pseudomonas aeruginosa, Bacillus spp., Alcaligens spp., Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella spp., Escherichia coli, Serratia spp. And Micrococcus spp.	Akinnibosun and Ayejuyoni (2015)
Bukavu urban slaughterhouses, South Kivu, Congo D.R	Carcass	Staphylococcus aureus, Salmonella ssp., E. coli, coliforms and other Enterobacteriaceae	Babe et al. (2018)
Cotonou/Porto-Novo, Benin	Carcass	Salmonella	Ahouandjnou et al. (2015)
Ekiti State, Nigeria	Wastewater	Pseudomonas aeruginosa, Bacillus anthracis, Bacillus polmyxa, Staphylococcus epidermidis, Bacillus subtilis, Klebsiella pneumonia, Escherichia coli, and Vibrio spp.	Temidayo et al. (2021)
Ghana	Meat sample	Escherichia coli	Annan-Prah et al. (2012)
Kigali city, Rwanda	Meat sample	Escherichia coli	Niyonzima et al. (2013)
Lusaka, Zambia	Meat sample	Escherichia coli and Salmonella	Mpundu et al. (2019)
Nagelle town, Ethiopia	Meat sample	Staphylococcus aureus, E. coli and Salmonella spp.	Hassen et al. (2021)
Owerri, Imo State, Nigeria	Floor, hand, knives and tables, neck, loin and flank	Staphylococcus aureus, Escherichia coli Salmonella spp.	Uzoigwe et al. (2021)
Port-Harcourt, River State, Nigeria	Knife swab, wash up, Table swab and water	Clostridium spp., Staphylococcus spp., Bacillus spp. and Escherichia coli	Azuonwu et al. (2019)
Uganda	Carcass, tools, protective clothing and hands of meat handlers	Staphylococcus aureus	Kyayesimira et al. (2020)
Dar-es-Salaam, Tanzania	Serum samples	Leptospira hardjo, L. tarassovi, L. bataviae, L. pomona	Swai and Schoonman (2012)

Table 4.

Selected reports of studies on the prevalence of pathogenic bacteria, source and recommendations

Location of slaughterhouse	Study focus	Bacteria prevalence	Indicated source of contamination/recommendation	Source
Bamako, Mali	To assess the impact of slaughter practices on the prevalence of Salmonella poultry carcasses in slaughterhouses	The percentage of Salmonella observed in category A slaughterhouse (poor hygiene) (15.97%) is high compared to that of category B (better hygiene) (7.29%)	Non-application of basic hygiene rules in slaughterhouses promotes contamination. Recommends the application of good slaughtering practices	Sacko et al. (2022)
Bukavu urban slaughterhouses, South Kivu, Congo D.R-	To assess the current hygienic quality level of fresh beef slaughtered in Elakat, Ciriri, Bagira slaughterhouses	Elakat slaughterhouse: CFU/10 g of meat Escherichia coli (134), Staphylococcus aureus (91), Salmonella typhimurium (240), Salmonella enterica (283) Ciriri slaughterhouse: CFU/10 g of meat E. coli (160), Pseudomonas aeruginosa (220), S. aureus (240), Salmonella enterica (120), Bagira slaughterhouse: CFU/10 g of meat, Escherichia coli (100), Pseudomonas aeruginosa (140), Staphylococcus aureus (180), Salmonella enterica (146)	The bacteria loads observed represent a great danger of food poisoning to consumers, hence the need to implement an effective program against beef contamination, veal and respect for hygiene breeding farm, slaughterhouses, slaughter procedures, method of handling meat, and transport to the sale to consumer	Babe et al. (2018)
Cotonou/Porto-Novo,	To assess the microbiological quality of cattle carcasses in the slaughterhouses of Cotonou/Porto-Novo	Salmonella and Enteric bacteria	The study demonstrated the critical non hygienic status of the slaughterhouses of Cotonou/Porto-Novo	Ahouandjnou et al. (2015)
Nagelle town, Ethiopia	To identify of the major source of bacterial contamination at abattoirs and butcheries	S. aureus (2.76), E. coli (2.81)	The meat was heavily contaminated with the high incidence of bacterial pathogen at the Abattoirs, which vary in decreasing order from person hand, environment, cutting board and knife respectively	Hassen et al. (2021)
Kigali city, Rwanda	To assess the bacteriological contamination of beef meat in a commercial abattoir at slaughtering stages, during transportation from the abattoir to butcheries and during marketing in Kigali City	Total coliforms ranged from 3.1 to 4.7 log cfu/g E. coli ranged from 0.8 to 3.0 log cfu/g	Contamination level were found to be high during slaughtering, marketing and transportation in Kigali City	Niyonzima et al. (2013)
Uganda	To determine the hygienic practices and microbial quality risk among meat handlers (MH) in SME slaughterhouses and butcheries	Total viable counts (TVC) − 4.76 log 10 cfu/cm2 to 7.90 log 10 cfu/cm2 Total coliform counts (TCC) ranged from 1.42 log 10 cfu/cm2 to 3.05 log 10 cfu/cm2 E. coli ranged from 0.68 log 10 cfu/cm2 to 1.06 log 10 cfu/cm2 Staphylococcus aureus ranged from 3.25 log 10 cfu/cm2 to 4.84 log 10 cfu/cm2	Ugandan slaughterhouses and butcheries are not hygienic and hence not up to standard. Hygienic handling of carcasses after slaughter is critical in preventing contamination and ensuring meat safety in informal meat trading sectors in Uganda	Kyayesimira et al. (2020)

Also, some of these parasitic diseases are meat-borne like Listeria monocytogenes, and the poor sanitation practices and prevailing environment encourage their spread (Huang et al. 2021; Oh et al., 2016). The study by Chiaramonte et al. (2009) also showed a synergistic interaction between gastrointestinal microbes like E. coli and meat-borne ones like Lactobacillus sakei leading to increased survival, colonization, mutation, and disease incidence. Meat contact surfaces which include butcher garments, hands, cutting knife, tables, weighing scales, buckets, slaughterhouses, plastic cans, wheelbarrows, and meat transporters serves as sources of contamination of meats (Eruteya et al., 2014; Faleke et al., 2017). Without an adequate sanitary system, the slaughterhouse environment could be a potential source of microbial contamination (Bersisa et al., 2019; Okoli et al., 2006; Oluwafemi et al., 2013). Hence, the potential human health risk can be assessed by the analysis of bacterial loads in the meat (Bersisa et al., 2019; Sofos, 2008). Some bacterial populations and diversities found in Nigeria, sub–Saharan Africa are shown in Tables 2 and 5.

Table 5.

Population of bacteria found in abattoir in Nigeria

Total viable bacteria (cfu/g)	Total Enterobacteriaceae bacteria counts (cfu/g)			Location/state	References
	Salmonella spp.	Staphylococcus aureus	Escherichia coli
19	–	6	7	Akure/Ondo State	Adegunloye (2013)
6.84 × 104	9	25	24	Owerri/Imo State	Uzoigwe et al. (2021)
6.3 × 106	–	4 × 106	2 × 102	Osogbo/Osun State	Adesiji et al. (2011)
7.3 × 104	–	16	40	Port-Harcourt/River State	Azuonwu et al. (2019)
84	16	30	48	Ibadan/Oyo State	Adesokan et al. (2021)
25	–	9	2	Owo/Ondo State	Egberi et al. (2016)
46	4	2	19	Abakaliki/Ebonyi State	Iroha et al. (2011)

Some microorganisms in animal wastes or meat include; Escherichia coli, Pseudomonas aeruginosa, Giardia lamblia, Bacillus anthracis, Campylobacter spp., Bacillus polmyxa, Yersinia enterocolitica, Staphylococcus epidermidis, Cryptosporidium parvum, Bacillus subtilis, Salmonella spp., Klebsiella pneumonia and rotaviruses (Jackson et al., 1998). These pathogenic organisms can multiply to millions and billions/g of faeces, which can infect humans through contact with animals or their wastes, contaminated air, swimming and consuming animal wastes contaminated water and food, exposure vectors (flies and rodents) (Armand-Lefevre et al., 2005; Schlech et al., 2005). In Indonesia, Soepranianondo et al. (2019) in a study to assess microbial load and antibiotics in meat from slaughterhouses reported the presence of Escherichia coli, Staphylococcus aureus, and Salmonella species in the proportion of 32.5%, 20.0% and 2.5% of their positive samples. However, their results implicate a low presence of antibiotic residue in the meat from the slaughterhouses. The same group of foodborne microorganisms was reported in a different study on slaughterhouses and butcher shops in Ethiopia by Bersisa et al. (2019) in addition to Klebsiella species, Proteus species, and Shigella species. In Morocco, Bahir et al. (2022) found a similar group of microorganisms in addition to Pseudomonas aeruginosa. In all of these studies, Escherichia coli was the most predominant isolate. These microorganisms in addition to Listeria monocytogenes, Campylobacter species, Shigella species, and Clostridium perfingens are considered the most foodborne pathogens. Others are yeast, mold, and some viruses, which are also known to cause food-related illnesses. According to Diyantoro and Wardhana (2019), animal carcasses for consumption can be contaminated via contact with parts like human and animal skin and hair, limbs, stomach, gut contents, bile, blood, and excretory materials as well as the clothes and hands of slaughterhouse workers and their equipment and water.

Meat contamination with pathogenic microorganisms makes up the utmost human and environmental health concern as stated in previous literature (Cohen et al., 2007). In Nigeria, the meat production processes and monitoring policies are not properly structured. Slaughterhouses have become pollution and infection breeding sources that attract wild and domestic animals and rodents because of the poor facilities (Adeyemo, 2002), since abattoirs generate huge quantities of wash water, solid wastes, and process effluents made up of suspended solids, organic matter, and other contaminants which are produced during various stages of production (Eze et al., 2013). In abattoirs, Borch and Arinder (2002) reported that microorganisms can either come from the live animals or from the environment that harbours them, in addition to this cross-contamination from the hands and skin of humans are major sources of microbial contamination. The most common source of bacteria contaminants includes:

Live animals

Bacteria are present on the skin, fleece, and hooves of animals that have been deposited there either by direct contact with faeces or indirectly from the farm environment, lairage, or vehicles used for transportation. The gastrointestinal tract of all animals carries a large number of bacteria usually excreted in faecal matter and these bacteria are non-pathogenic in livestock, it is assumed that the potential to carry pathogenic organisms is in all animals (Meat Industry Guide, 2015).

Water

According to Adetunji and Awosanya (2011), Daniyan and Unwuchiola (2002), Fasanmi et al. (2010), water used for abattoir processes is important in meat hygiene as it plays a major role in increasing or decreasing microbial meat contamination. Water is used in maintaining the environment, washing contact surfaces, carcasses; blood from the meat, and the hands and equipment of workers, if the water is contaminated, all processes will be prone to higher levels of microbial contamination.

Unhygienic practices

Poor personal hygiene such as hand washing practices, and the use of contaminated equipment and tables can serve as points of meat contamination during slaughtering (Fasanmi et al., 2010; Gurmu and Gebretinsae, 2013). According to Daniyan and Unwuchiola (2002), each slaughtering procedure provides the opportunity for microbial contamination from the exterior surfaces, utensils, equipment, and most importantly, from the gastrointestinal tract. Cutting of carcasses also involves the use of utensils and equipment and transfers microorganisms to the cut surfaces by cross-contamination.

Poor sanitation

Poor sanitary conditions have a direct effect on the abattoir standard, proper sanitation can efficiently reduce the microbial burden on all work areas and equipment (Daniyan and Unwuchiola, 2002; Gurmu and Gebretinsae, 2013).

Carcasses

According to the Meat Industry Guide (2015), Sethulekshmi and Nanu (2009), bacteria from the gastrointestinal tract may be transferred from one carcass to another during slaughtering processes and this transfer may be by direct contact or through cross-contamination by the workers, equipment, water, aerosols, and surfaces.

Other factors

According to Adeyemo et al. (2009), for fear of running at a loss, butchers slaughter diseased animals before they die, subsequently, the diseased animals and healthy ones are slaughtered near the effect being the spread of the disease and the contamination of the facility, hands of the workers, clothes and healthy meat.

Sustainable management strategies of slaughterhouses practices in developing countries

It is important to state that slaughterhouses are best located in the fringes of cities (urban or suburban) as well as in rural centers and very far from built and residential environments and unconnected to environmental matrices like water. In developing countries, environmental problems associated with abattoirs or slaughterhouses are numerous and challenging. Various disease conditions as a result of poor sewage or waste disposal facilities or systems, eating and drinking contaminated food and water, poor control of vectors such as flies and rodents, and other deleterious environmental conditions which brings about negative sanitary conditions and public health concerns (Adonu et al., 2017). Indubitably, these pose threats to both humans and the physical environment. Hence, the critical issue in most slaughterhouses is proper hygiene maintenance and standard sanitary practices. Therefore, sustainable management strategies for slaughterhouses in Nigeria cannot be overemphasized. An abattoir is an establishment that generates solid, liquid, and gaseous wastes. It is a designated establishment duly registered and approved by the government or other controlling agencies for approving slaughtering methods, processing, inspection, proper preservation, and storage of meat for consumption. Abattoirs are expected to maintain a high standard of hygienic practices and safety procedures that function effectively for the welfare of humans in society (Adonu et al., 2017). Some of the common features and general unsanitary practices in Nigerian abattoirs are; draining the blood of slaughtered animals into surrounding areas and in most cases, such blood is collected for the production of blood meal and animal feed; a practice that can potentially serve as a means of vehicle for infection to the handler and the consumer if not done with optimum precautions (Oruonye, 2015). Intestinal contents are heaped within premises, composted, and washed into surrounding areas. This practice will tamper with the environmental microbiota as pathogenic strains and mutated strains of microbes that may have acquired drug-resistant genes through plasmid transfer; transduction or natural selections are released into the environment (Abiola, 1995).

Bones are burnt or crushed into animal feeds. The burning generates heavy smoke and stench thereby polluting the entire environment (Oruonye, 2015). Waste tissues are burned and disposed of in depressions within the premises. The inadequate management of waste generated from abattoirs across the country constitutes a huge health risk to the human population as this affects the quality of air, portable water, and aquatic life (Adeyemi and Adeyemo, 2007). Pathogenic microorganisms have been isolated from both effluents and abattoir solid waste (Elder et al., 2000). These poor hygienic practices at slaughterhouses have resulted in meat contamination by several disease etiologies (Haileselassie et al., 2013; Kebede et al., 2016; Thomas et al., 2016). Slaughter slabs are not adequately washed and cleaned between slaughter rounds and within each round, as there is an inadequate supply of water, thus causing contamination of several batches of meat per incidence (Fasanmi et al., 2017; Oruonye, 2015).

Operations of abattoirs are not environmentally friendly and pose serious health and environmental challenges to the residents. Hence, the following Sustainable management strategies are recommended; most abattoirs in developing countries should be upgraded with modern abattoir infrastructures and facilities for hygienic slaughtering, handling, storage, and selling of meat to consumers to forestall infestation of meat by flies and other vectors that affect human health. All abattoir premises should be interlocked and construction of standard drainages for abattoir wastewater channelling. Adequate underground reservoirs should be constructed as a panacea for the prevention of land/premises of the abattoir from becoming muddy or polluted with wastewater. Pollution of air should be controlled if possible be avoided by ensuring that used tires are not burnt and used as means of roasting slaughtered animals or removing hides. This is harmful to both humans and the environment (Ekpo, 2019).

Lairage and waste disposal equipment should be provided; all types of waste should be treated before discharge into any media of the environment to avoid the pollution of such medium or media. Modern waste management practices which involve waste reduction, reuse, and recycling should be adopted whereby animal wastes such as bones, horns, skin, hides, and blood are integrated and used respectively as by-products in other sectors of the economy. Various Local Government Area Councils should be proactive in the monitoring of operations of the abattoir by carrying out routine inspections including animal and meat supervision and general sanitary inspection of the abattoir as well as ensuring maximum compliance with the global requirements and sanitary regulations and standards governing abattoir operations. Sensitization of stakeholders through environmental education on the implications of poor waste management of abattoirs for workers and residents should be compulsory in all slaughterhouses in Nigeria (Ekpo, 2019). Abattoirs should be equipped with potable water and electricity and linked with an uncongested road or rail network. It should provide access to services of both public and private transport companies as well as open to people who supply various types of labour and services (Adonu et al., 2017). Obnoxious odours, dust, smoke, and wastes emanating from these facilities should be effectively controlled to avoid outbreaks of epidemics.

In conclusion, with the recent wave of health-related issues around the world, particularly from foodborne pathogens, which can be prevented through proper hygiene, there is a need for proper hand washing, and personal and environmental hygiene in slaughterhouse facilities in developing countries. It is also pertinent to expedient measures to curb or at the very least reduce to the barest minimum the spread of already existing preventable infectious diseases, especially through the faeco-oral route, as it accounts for high morbidity and mortality. The standards employed by slaughterhouse workers need to be improved upon to foster proper hygiene and sanitation as these are indicators for good health and wellbeing. A common index implicated in the contamination of meat and meat products from slaughterhouses in developing countries is poor hygiene and sanitation practices as well as the low educational level of workers. Food safety authorities in developing countries must improve environmental hygiene as well as personal hygiene of slaughterhouse workers to limit microbial contamination of meat and meat products and ensure public safety (Okoli et al. 2018). Generally, food of animal origin should be monitored to avoid contamination. There is a need to institute stringent monitoring and supervisory processes that should include physical, chemical, and biological quality assessments by agencies like the Inter-Ministerial Committee on Food Safety and the National Food Safety Management Committee in the case of Nigeria and related agencies in other developing countries. This is necessary because diverse microorganisms and microbial communities characterize the digestive tracts, hides, and feces of healthy animals among other reasons (Diyantoro and Wardhana, 2019). In the past decades, there have been several health issues such as infectious and communicable diseases in developing countries due to the emergence and reemergence of foodborne pathogens (Ajuwon et al., 2021; Ishola et al., 2016; Odeyemi and Bamidele, 2016). Hence, the need for paradigm shifts away from current practices. Also, the consumption of raw, unprocessed meat and meat products from slaughterhouses should be discouraged in developing countries.

Author contributions

The article idea was conceived by KO and SI, KO and OO wrote the first manuscript draft. SI and OI prepared all the tables and figures. MO wrote the final manuscript. All the authors read and approved the final draft.

Funding

Not applicable.

Data availability

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Nomenclature

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Declarations

Conflict of interest

The authors declare no conflicts of interest.