Abstract
The present study evaluated the efficacy of albendazole in treating soil-transmitted helminth infections among school children aged 6 to 15 years in three districts of Central Tigray, Ethiopia. A total of 1020 elementary school children were screened from three schools using Kato-Katz and microscopic detection techniques. Of these, 35.2% (359/1020) of children were infected with one or more soil-transmitted helminths and were treated with 400 mg albendazole. The efficacy of the drug was assessed by measuring the percentage reduction in helminth egg counts using Kato-Katz. Albendazole was most effective against hookworm, with overall 94.1% egg reduction rates (ERRs), 3 weeks post-treatment followed by A. lumbricoides and T. trichiura, with overall ERRs of 83.9% and 31%, respectively. Analysis of factors affecting albendazole treatment success revealed that the age of respondents, source of drinking water, and infection intensity at baseline were significant predictors of treatment success. School children 6–8 years old showed higher ERRs, while those using stream water for drinking purposes and with multiple parasite infections at baseline had lower probability of ERRs. These findings demonstrate the varying efficacy of albendazole across different STH infections and geographical locations, calling a more refined research to enhance treatment approaches for A. lumbricoides and T. trichiura. This study underscores the need for context-specific therapeutic intervention to enhance treatment success in endemic areas.
Keywords: Albendazole, Efficacy, Infection, Soil-transmitted helminths
Introduction
Human beings have been affected by helminth parasites since ancient times in human history. The ova of intestinal helminths may be identified in the mummified feces of humans dating back thousands of years (Hotez et al. 2008). Soil-transmitted helminth (STH) infections caused by hookworms, A. lumbricoides and T. trichiura, are still implicated with significant public health risks globally, particularly in low- and middle-developing countries (Eze et al. 2020). They are prevalent burdens primarily affecting children, resulting in physical and intellectual disabilities including malnutrition, retarded growth, metal deficits, and a high incidence of anemia (Assefa et al. 2024). STH infections are widespread in Sub-Saharan African countries (Olusola 2013), like Ethiopia; school-aged children are the most vulnerable because they are highly exposed to contaminated soil, limited sanitation, and scarcity of availability of clean washing and drinking water (Adeyeba and Akinlabi 2002; de Silva et al. 2003).
Globally, almost 1.45 billion people are infected with A. lumbricoides, 1.3 billion with hookworms, and 1.05 billion with T. trichiura (Mathewos et al. 2014). About 300 million of these infections cause severe morbidity, which is linked to heaviest worm burdens and accounts for 150,000 deaths annually (Montresor et al. 2002).
In Ethiopia, where helminth infections are prevalent, albendazole remains a critical medication commonly prescribed for widespread treatment of STH infections, especially in school-aged children because of its efficacy and safety profile (Assefa et al. 2024). It is among the drugs which have a distinct broad-spectrum effect (Horton 2000). Although a 400 mg oral single dose of albendazole works well against some of soil-transmitted helminth infections (Keiser and Utzinger 2008; Olsen et al. 2009), it has a varied effect based on severity of the illness, parasite species, and dosage (Assefa et al. 2024).
Reports on the efficacy of a single-dose albendazole on intestinal helminth infections have been increasing progressively in multiple sites in Ethiopia, revealing a low efficacy of albendazole for some parasites (Gebreyesus et al. 2024; Legesse et al. 2004; Sisay et al. 2024). Therefore, robust information regarding the efficacy of albendazole is required to resolve the discrepancy and influence stakeholders to reconsider the anti-helminthic therapeutic approach. Furthermore, studies related to the evaluation of the efficacy of this chemotherapy are limited or nonexistent in Tigray, Northern Ethiopia. The study was conducted across three different locations (Adiet, Aksum, and Adwa) in Central Tigray, with unknown use of anti-helminthic drug pressure histories as well as efficacy of albendazole. Therefore, this study aims to evaluate the efficacy of albendazole currently in use, against STHs in Central Tigray, Northern Ethiopia. It seeks to identify predictors of treatment outcomes that could provide insights into effective strategies to improve helminth eradication programs in the region.
Materials and methods
The study area
This study was conducted in selected primary schools in Central Tigray, Northern Ethiopia. The study area is characterized by its diverse geographical features, including urban and rural societies, with scarcity of access to clean water for washing and drinking, as well as public healthcare services. There are schools with large class sizes and a lack of sanitation and hygiene facilities for the students.
Study design and period
A cross-sectional experimental study was conducted from February to June 2016 at Adiet (Debregenet Elemetary School), Axum (Bazien Elementary School) and Adwa (Maytsadk Elementary School), Central Tigray, Northern Ethiopia.
Study population
This study targeted school children aged 6–15 years from three primary schools within the selected region. The school children were selected using a random sampling method to ensure adequate representative sample. Informed consent was obtained from parents or guardians of participants of this study.
Sample size and sampling technique
The required sample size was calculated using the formula (Adugna et al. 2007) for a single population proportion. Research studies reported that STH infection prevalence in the study area (Central Tigray) is 38.5% (Dejenie and Petros 2009) and estimation of effects is taken with 95% confidence interval. The sample size (n) of the study would be 876 based on the formula in Hotez and others (Hotez et al. 2008). However, the ultimate sample size was determined to be 1020; the design effect was considered to enable multistage sampling procedures (i.e., to decrease error resulting from the sampling procedure). Before the start of the study, three districts from Central Tigray were specifically chosen based on transportation accessibility. Based on the total number of primary school students enrolled during the study period, the sample size was then distributed proportionately among the districts, schools, and class sections. Enrollment lists of students served as the sampling frame. Lastly, a systematic random sampling technique was used to choose study participants.
Inclusion and exclusion criteria
Inclusion criteria
Children aged 6–15 years and those attending school during the study period were included in the study. Additionally, randomly chosen school-aged children in the selected schools who consented to submit the necessary sociodemographic information and a stool sample were included, as were participants and their guardians who signed informed consent.
Exclusion criteria
Children who had taken an anti-helminthic drug within the past 3 months prior to data collection and those who were unable to provide a sufficient stool sample were excluded. They were also excluded if they were very sick or if their caregiver could not provide their information. Children who refused to participate in the study were also excluded.
Data collection methods
Data were collected using the following techniques:
Parasitological examinations
Pretreatment (baseline) assessment
Stool samples were collected from each child for parasitological analysis after providing sufficient instruction on how to collect stool samples. The stool samples were examined for STH infections using the Kato-Katz technique for the detection of eggs of hookworms, A. lumbricoides and T. trichiura as indicated in a previous study (Crompton and World Health 2006). The leftover stool specimens were preserved in 10% formalin and analyzed using a concentration method. The prepared slides were sent to Aksum University for microscopic analysis, allowing for additional verification and quality assurance. Positive samples were quantified as eggs per gram of stool to assess the intensity of the infection. Prevalence was calculated based on the ratio of infections relative to the total population examined. The intensity of infection was determined by the number of eggs per gram of feces (epg). The assessment of egg count for hookworm was conducted within 1 h following the collection of stool samples and the preparation of Kato slides. The laboratory examination of the slides for additional helminths took place within a week of stool collection. The total number of eggs identified was then multiplied by 24 to determine the quantity of eggs per gram of feces.
Treatment procedure and post-treatment assessment
The school children who tested positive for at least one type of soil-transmitted helminth infection were prepared for treatment. Subsequently, the students were notified of the treatment date by their teachers and received a single dose of 400 mg albendazole, administered according to their height, in alignment with the guidelines set forth by the World Health Organization (Montresor et al. 2005). The treatment process was strictly supervised by a health professional to ensure drug adherence. At the commencement of the treatment, all children were questioned regarding their receipt of any anti-helminthic medications within the preceding 3 months, as well as their age, which needed to fall between 6 and 15 years. In accordance with WHO guidelines, a follow-up stool sample was taken from STH-infected study participants 21 days post-treatment to evaluate the effectiveness of albendazole (World Health Organization 2013). Fecal samples were collected for efficacy determination. The efficacy of the drug was assessed by measuring the percentage reduction in egg counts. The level of infection was evaluated for the parasites and quantified as epg of feces for each individual.
Sociodemographic and environmental factors
A structured questionnaire was prepared and provided to the school children and their parents/guardians to collect data on gender, age, source of water, study districts, and other sociodemographic factors.
Statistical analysis
Descriptive statistics was used to summarize sociodemographic data, infection rates, and treatment efficacy. The efficacy of the treatment was evaluated for each STH species based on the fecal egg counts. The fecal egg count reduction rate was calculated by comparing the mean fecal egg counts before and after the intervention. One-way ANOVA was used to identify associations between sociodemographic baseline characteristics and egg reduction rates of STH infections. Additionally, linear regression analysis was conducted to identify predictors of treatment outcomes. Data analysis was performed using IBM SPSS version 22; a 95% confidence interval (CI) and p-values less than 0.05 were considered statistically significant.
Ethics approval and consent to participate
Prior to the commencement of the study, ethical approval was obtained from the Ethical Review Committee of Aksum University, College of Health Sciences and the Comprehensive Specialized Hospital. The committee issued a letter of authorization, and additional letters of support were secured from the educational bureau, and the health offices of Adiet, Axum, and Adwa districts. Participants, along with their parents or guardians, were informed about the study’s objectives. Written, informed consent was obtained from the parents or legal guardians of the children. The confidentiality of the data was strictly maintained. Children diagnosed with STH infections received treatment following national guidelines and the standards outlined in the Declaration of Helsinki.
Results
Sociodemographic and baseline characteristics
A total of 1020 school children were screened for hookworm, A. lumbricoides and T. trichiura in the study. Among the 1020 school children from the three sites, only 1007 appropriately submitted fresh stool samples (98.73 response rates). A total of 359 school children, aged between 6 and 15 years, were found to be infected with at least one type of STH parasite and subsequently participated in this study. Of the participants, 211 (58.8%) were male, and majority (88.0%) were above the age of nine (Table 1).
Table 1.
Sociodemographic and baseline characteristics of the study participants
| Variables | Category | Number | Percent | |
|---|---|---|---|---|
| Sex | Male | 211 | 58.8 | |
| Female | 148 | 41.2 | ||
| Age groups (years) | 6–8 | 183 | 51.0 | |
| 9–11 | 133 | 37.0 | ||
| > 11 | 43 | 12.0 | ||
| Source of water | Pipe | 91 | 25.3 | |
| Well | 127 | 35.4 | ||
| Stream | 141 | 39.3 | ||
| Number of STH infections at baseline | Single infection | 241 | 67.1 | |
| Double infection | 86 | 24.0 | ||
| Triple infection | 32 | 8.9 | ||
| Study districts | Adiet | 183 | 51.0 | |
| Aksum | 76 | 21.1 | ||
| Adwa | 100 | 27.9 | ||
|
Hookworm (n = 196) |
Infection intensity | Light intensity | 184 | 93.9 |
| Moderate intensity | 12 | 6.1 | ||
| Heavy intensity | 0 | 0.0 | ||
| A. lumbricoides (n = 192) | Infection intensity | Light intensity | 154 | 80.2 |
| Moderate intensity | 24 | 12.5 | ||
| Heavy intensity | 14 | 7.3 | ||
| T. trichiura (n = 126) | Infection intensity | Light intensity | 113 | 89.7 |
| Moderate intensity | 13 | 10.3 | ||
| Heavy intensity | 0 | 0.0 | ||
A little over one-third (39.3%) of the participants who were infected reported using stream water as their source. The majority of these participants (67.1%) experienced a single infection, while the remainder had double infections (24.0%) and triple infections (8.9%) at the initial assessment. Nearly half (51.0%) of the infected school children were located in Adiet district, with the remaining participants distributed between Aksum (21.1%) and Adwa (27.9%). Among the infections, 196 participants were found to be infected with hookworm (38.1%), followed closely by A. lumbricoides (37.4%) and T. trichiura (24.5%). According to World Health Organization (WHO), species-specific infection intensity categories are light infection (1–4999 epg for A. lumbricoides, 1–999 epg for T. trichiura, 1–1999 epg for hookworms), moderate infection (5000–49,999 epg for A. lumbricoides, 1000–9999 epg for T. trichiura, 2000–3999 epg for hookworms), and heavy infection (≥ 50,000 epg for A. lumbricoides, ≥ 10,000 epg for T. trichiura, ≥ 4000 epg for hookworms) (Alemu et al. 2022). The majority of infected children exhibited light infection intensity, with 93.9% for hookworm, 80.2% for A. lumbricoides, and 89.7% for T. trichiura. The prevalence of moderate infections among school children was 6.1% for hookworm, 12.5% for A. lumbricoides, and 10.3% for T. trichiura. Notably, there were no cases of heavy infection for hookworm and T. trichiura; however, 7.3% of the school children were found to have heavy infection intensity (Table 1).
Egg reduction rates
Table 2 shows the results of the efficacy of albendazole against various infection levels of the different helminths found in this study. Albendazole was found to be highly effective against hookworm but it was not effective against A. lumbricoides and T. trichiura in children given a single 400 mg dose.
Table 2.
Pre-and post‐treatment intensity of infection for hookworm, A. lumbricoides and T. trichiura, among school children in Central Tigray, Northern Ethiopia
| Study district | Parasite species | Total n | Arithmetic mean (epg) | WHO threshold for ERR | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pretreatment | Post-treatment | ERR (%) | ||||||||
| Adiet | Hookworm | 113 | 868.4 | 24.6 | 97.2 | ≥ 90 | ||||
| A. lumbricoides | 93 | 1432.3 | 156.0 | 89.1 | ≥ 95 | |||||
| T. trichiura | 62 | 62.7 | 45.5 | 27.5 | ≥ 50 | |||||
| Aksum | Hookworm | 30 | 676.4 | 88.2 | 87.0 | ≥ 90 | ||||
| A. lumbricoides | 50 | 1224.5 | 298.8 | 75.6 | ≥ 95 | |||||
| T. trichiura | 26 | 46.2 | 27.6 | 40.4 | ≥ 50 | |||||
| Adwa | Hookworm | 53 | 896.6 | 16.7 | 98.1 | ≥ 90 | ||||
| A. lumbricoides | 49 | 1023.9 | 132.3 | 87.1 | ≥ 95 | |||||
| T. trichiura | 38 | 58.5 | 43.7 | 25.2 | ≥ 50 | |||||
| Overall data | ||||||||||
| Parasite species | Total n | Weighted mean pretreatment | Weighted mean post-treatment | Overall ERR (%) | ||||||
| Hookworm | 196 | 847.2 | 32.2 | 96.2 | ||||||
| A. lumbricoides | 192 | 1274.0 | 187.2 | 85.2 | ||||||
| T. trichiura | 126 | 58.0 | 41.24 | 28.9 | ||||||
ERR egg reduction rate, epg egg per gram
The egg reduction rate for hookworm was notably high across all districts, with an overall ERR of 96.2%. The drug albendazole showed an egg reduction rate of 87.0% in Aksum, which is slightly lower than the two other districts. For A. lumbricoides, egg reduction rates were moderate, with 89.1% in Adiet, 75.6% in Aksum, and 87.1% in Adwa with 85.2% overall ERR, suggesting that even if treatment was somewhat effective, it did not meet the WHO threshold (≥ 95%). T. trichiura showed significantly lower egg reduction rates particularly in Adwa (25.2%) and Aksum (40.4%) with an overall ERR of 28.9%, indicating ineffective albendazoletherapy with below the WHO recommended standard of ≥ 50% (Table 2).
Parameters associated to treatment success
The factors associated with the egg reduction rates (ERRs) for the three parasite infections at week three are detailed in Table 3. The ERRs for hookworm infection exhibited a significant association with the baseline sociodemographic characteristics of the participants, specifically source of water (p < 0.001), number of soil-transmitted helminth infections (p = 0.001), and study districts (p = 0.004). In contrast, sex, age groups, and pretreatment infection intensity did not show any significant relationship with the ERRs of the three parasite infections (p > 0.05). Similarly, the ERR for A. lumbricoides was also significantly associated with the age group of study participants, source of water, number of soil-transmitted helminth infections, and pretreatment infection intensity, in which the higher age groups (≥ 11 years), children with stream as a source of water, children with triple infections, and those with moderate and heavy baseline infection intensity had a lower ERRs than the other categories (p < 0.05). In the same token, the ERRs for T. trichiura infection was associated with the age group of study participants, source of water, number of soil-transmitted helminth infections, and study districts. That is, lower ERRs were observed in participants with higher age groups (≥ 11 years), with stream as a source of water and those with triple infections (Table 3).
Table 3.
Factors associated with ERRs for each STH infections of post-treatment of single-dose albendazole using ANOVA
| Variables | Category | Hookworm | A. lumbricoides | T. trichiura | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total n | ERR (%) | F statistics | p-value | Total n | ERR (%) | F statistics | p-value | Total n | ERR (%) | F statistics | p-value | ||
| Sex | Male | 117 | 93.8 | 1.85 | 0.18 | 110 | 80.7 | 0.45 | 0.51 | 72 | 72.5 | 0.63 | 0.43 |
| Female | 79 | 89.3 | 82 | 78.1 | 54 | 68.8 | |||||||
| Age groups (years) | 6–8 | 99 | 94.9 | 0.42 | 0.66 | 95 | 85.5 | 42.71 | < 0.001 | 66 | 82.2 | 58.39 | < 0.001 |
| 9–11 | 64 | 95.1 | 77 | 72.2 | 52 | 44.6 | |||||||
| > 11 | 33 | 91.2 | 20 | 51 | 8 | 42.9 | |||||||
| Source of water | Pipe | 104 | 98.2 | 19.23 | < 0.001 | 83 | 97.1 | 35.12 | < 0.001 | 37 | 78.3 | 29.4 | < 0.001 |
| Well | 55 | 93.8 | 66 | 71.6 | 53 | 63.7 | |||||||
| Stream | 34 | 85.5 | 41 | 59.4 | 34 | 38.9 | |||||||
| Number of STH infections at baseline | Single infection | 96 | 99.4 | 8.27 | 0.001 | 102 | 86.2 | 10.14 | < 0.001 | 47 | 75.4 | 14.93 | < 0.001 |
| Double infection | 68 | 94.8 | 58 | 75.4 | 47 | 64.5 | |||||||
| Triple infection | 32 | 90 | 32 | 69 | 32 | 42.3 | |||||||
| Pretreatment infection intensity | Light | 184 | 96.2 | 0.01 | 0.99 | 154 | 87.2 | 3.84 | 0.025 | 113 | 60.0 | 0.62 | 0.54 |
| Moderate | 12 | 96.3 | 24 | 78.5 | 13 | 67.2 | |||||||
| Heavy | 0 | - | 14 | 71.7 | 0 | - | |||||||
| Study districts | Adiet | 113 | 97.2 | 5.63 | 0.004 | 93 | 89.1 | 2.12 | 0.13 | 62 | 27.4 | 4.57 | 0.01 |
| Aksum | 30 | 87.0 | 50 | 75.6 | 26 | 40.37 | |||||||
| Adwa | 53 | 98.1 | 49 | 87.1 | 38 | 25.2 | |||||||
ERR- egg reduction rate STH- soil transmitted helminths
Table 4 presents the predictors of treatment efficacy at 21 days after albendazole administration for three different STHs. Treatment efficacy is evaluated by egg reduction rate (ERR%) and we analyzed different factors including age groups, source of drinking water, number of STH infections at baseline, and pretreatment infection intensity.
Table 4.
Predictors of treatment success at week three of albendazole administration
| Hookworm | |||||||
|---|---|---|---|---|---|---|---|
| Predictors | Category | ERR (%) | Estimate (β) | SE | 95% CI | p-value | |
| Age groups (years) | 6–8 (Ref.) | 94.9 | 0 | - | - | - | |
| 9–11 | 95.1 | + 0.2 | 2.5 | (− 4.7, 5.1) | 0.94 | ||
| > 11 | 91.2 | − 3.7 | 3.1 | (− 9.7, 2.3) | 0.22 | ||
| Source of water | Pipe (Ref.) | 98.2 | 0 | - | - | - | |
| Well | 93.8 | − 4.4 | 2.3 | (− 8.9, 0.11) | 0.05 | ||
| Stream | 85.5 | − 12.7 | 3.5 | (− 19.5, − 5.9) | < 0.001 | ||
| Number of STH infections at baseline | Single infection (Ref.) | 99.4 | 0 | - | - | - | |
| Double infection | 94.8 | − 4.6 | 2.1 | (− 8.7, − 0.5) | 0.03 | ||
| Triple infection | 90 | − 9.4 | 2.9 | (− 15.0, − 3.8) | 0.002 | ||
| Pretreatment infection intensity | Light (Ref.) | 96.2 | 0 | - | - | - | |
| Moderate | 96.3 | + 0.1 | 4.1 | (− 7.9, 8.1) | 0.98 | ||
| Heavy | - | - | - | - | - | ||
| Ascarislumbricoides | |||||||
| Age groups (years) | 6–8 (Ref.) | 85.5 | 0 | - | - | - | |
| 9–11 | 72.2 | − 13.30 | 3.1 | (− 19.3, − 7.3) | 0.002 | ||
| > 11 | 51 | − 34.50 | 5.2 | (− 44.7, − 24.7) | < 0.001 | ||
| Source of water | Pipe (Ref.) | 97.1 | 0 | - | - | - | |
| Well | 71.6 | − 25.50 | 3.8 | (− 33.0, − 18.0) | < 0.001 | ||
| Stream | 59.4 | − 34.7 | 4.5 | (− 46.5, − 28.9) | < 0.001 | ||
| Number of STH infections at baseline | Single infection (Ref.) | 86.2 | 0 | - | - | - | |
| Double infection | 75.4 | − 10.80 | 3.2 | (− 17.1, − 4.5) | 0.014 | ||
| Triple infection | 69 | − 17.2 | 4.0 | (− 25.0, − 9.4) | 0.002 | ||
| Pretreatment infection intensity | Light (Ref.) | 87.2 | 0 | - | - | - | |
| Moderate | 78.5 | − 8.7 | 3.4 | (− 15.2, − 2.0) | 0.01 | ||
| Heavy | 71.7 | − 15.6 | 5.1 | (− 25.5, − 5.5) | 0.003 | ||
| Trichiristrichiura | |||||||
| Age groups (years) | 6–8 (Ref.) | 82.2 | 0 | - | - | - | |
| 9–11 | 44.6 | − 36.7 | 4.4 | (− 45.6, − 27.8) | < 0.001 | ||
| > 11 | 42.9 | − 38.3 | 6.1 | (− 50.0, − 26.6) | < 0.001 | ||
| Source of water | Pipe (Ref.) | 78.3 | 0 | - | - | - | |
| Well | 63.7 | − 14.5 | 4.3 | (− 22.8, − 6.2) | 0.001 | ||
| Stream | 38.9 | − 38.4 | 5.2 | (− 48.6, − 28.2) | < 0.001 | ||
| Number of STH infections at baseline | Single infection (Ref.) | 75.4 | 0 | - | - | - | |
| Double infection | 64.5 | − 10.8 | 4.0 | (− 18.7, − 3.0) | 0.005 | ||
| Triple infection | 42.3 | − 33.0 | 5.7 | (− 44.1, − 21.9) | < 0.001 | ||
| Pretreatment infection intensity | Light (Ref.) | 60.0 | 0 | - | - | - | |
| Moderate | 67.23 | + 7.1 | 6.4 | (− 5.4, − 19.6) | 0.25 | ||
| Heavy | - | - | - | - | - | ||
SE standard error, CI confidence interval
For hookworm, age had no significant effect on egg reduction rates across the participant groups, with generally high albendazole efficacy across the three age groups, with ERR% above 90. However, individuals using pipe water as a source for drinking had the highest ERR (98.2%), while those using well and especially stream as source of drinking water showed significantly lower ERRs (93.8% and 85.5% respectively, p < 0.001 significance level in stream water user group). In addition, individuals with multiple infections had reduced treatment success compared to single STH infection, with statistically significant difference in ERR (94.8%, p < 0.03 for double infection and 90.0%, p < 0.002 for triple infection). Pretreatment intensity did not significantly affect hookworm treatment efficacy (Table 4).
In contrast, for A. lumbricoides and T. trichiura, age group, water source, number of parasite infections at baseline, and pretreatment infection intensity showed significant associations with albendazole treatment success as revealed in ERRs. Younger age groups (6–8 years) showed notably higher ERR compared to older children, with the oldest age group (> 11 years) exhibiting the lowest ERR. Both STHs displayed stark differences in egg reduction rates based on drinking water source. Individuals using pipe water for drinking had a significantly higher ERR, while individuals who used well and streams as a source of water had remarkably lower ERRs, with children using stream water showing the lowest treatment response (< 60% for A. lumbricoides and < 40% for T. trichiura). Similarly, having multiple parasite infections or heavier infection intensity at baseline is associated with reduced ERRs. The present findings suggest that age, poor water source, increased parasite infection burden, and baseline infection intensity negatively impact albendazole efficacy for A. lumbricoides and T. trichiura than for hookworm (Table 4).
Discussion
The present study evaluated the effectiveness of albendazole in treating soil-transmitted helminth infections, employing Kato-Katz and microscopic techniques. The efficacy of anti-helminthic drug is compromised by resistance, posing challenges to the management of helminth infestations. Accordingly, in case where decreased efficacy noted or the preventive chemotherapy program has been conducted for more than 4 years consecutively, the WHO recommends evaluating the effectiveness of anti-helminthic drugs used for preventive chemotherapy (World Health 2013).
The overall prevalence of intestinal helminth infections was 35.65%, with specific rates of 51.0% in Adiet, 21.1% in Aksum, and 27.9% in Adwa. These figures are relatively higher than previous reports for A. lumbricoides and T. trichiura, yet lower in comparison to hookworm infections observed among school children in Asendabo town, and Wondo-Genet area of Southern Ethiopia (Demissie et al. 2008). This variation may be attributed to the differing sociodemographic conditions of the populations residing in these areas, which can determine the distribution and prevalence of these geohelminths.
Analysis of efficacy of albendazole exhibited marked differences in treatment success across parasite species and study district. It demonstrated high treatment efficacy against hookworm, with commendable egg reduction rates of 97.17% and 98.14% in Adiet and Adwa, satisfying WHO efficacy threshold. This is in line with the previous study conducted in Dembia (Northwestern Ethiopia), revealing a higher egg reduction rates of a single dose of albendasole against hookworm infection (Assefa et al. 2024). Another study in rural Bahir Dar (Northwest Ethiopia) reported low efficacy of albendazole against hookworm (Hailu et al. 2018), which contradicts our result. This difference may be due to low sample size taken in the study compared to the sample size in the present study.
However, our findings revealed that albendazole demonstrated a reduced efficacy against A. lumbricoides. This is consistent with other studies suggesting that current albendazole treatments have a limited effect against A. lumbricoides (Gebreyesus et al. 2024; Sisay et al. 2024). Similarly, single dose of albendazole also exhibited low ERRs across all the study districts (with ERR as low as 25.17% in Adwa). These finding are consistent with previous studies that reported a notably reduced efficacy of single-dose albendazole against T. trichiura, with levels below the WHO thresholds (Gebreyesus et al. 2024; Sisay et al. 2024) possibly due to parasite species–specific drug sensitivity or emerging drug resistance. Current studies have suggested that although albendazole remains the crucial treatment for soil-transmitted helminth infections, its efficacy varies depending on factors such as co-infections, geographical location, and the type of soil-transmitted helminth species. For instance, the study conducted in Southern Ethiopia on school children indicated that multiple infections of soil-transmitted helminths were correlated with higher re-infection rates post-treatment (Gebreyesus et al. 2024). These observed geographical differences in ERRs highlight that local social or environmental factors, including variation in sanitation, water source, and community health conditions, remarkably influence treatment success.
The factors that influence efficacy of a single-dose albendazole were multifactorial and largely consistent across the three soil-transmitted helminth infections. The age group of the participating school children was a crucial predictor of ERRs for A. lumbricoides and T. trichiura. Younger children showed better treatment success than those above 11 years. These age-related efficacy differences might be explained by behavioral factors such as increased re-infection risks among older school children, variations in drug metabolism, or adherences in post-treatment personal hygiene. Source of drinking water was associated to different ERRs for hookworm and A. lumbricoides, highlighting possible environmental health problems in the study areas affecting parasite treatment outcomes. Furthermore, pretreatment intensity and the number of concurrent infections at the baseline are essential predictors of treatment success; higher parasite burdens and multiple infections predicted lower ERRs. These effects may suggest the synergistic or antagonistic interactions among concurrent infections and higher infection intensity that exceed the efficacy standard of single-dose albendazole. The results imply that taking these predictors into account targeted interventions to improve the efficacy of albendazole treatment against the three soil-transmitted parasite diseases in target population.
Given that some areas did not meet the WHO thresholds for certain soil-transmitted helminths such as A. lumbricoides and T. trichiura, scholars have called for alternative therapeutic strategies or combination therapies to improve treatment outcomes (Grolimund et al. 2022; Sisay et al. 2024). A literature indicated that efficacy of albendazole, in particular, against A. lumbricoides and T. trichiura, may be enhanced by dual or co-administration together with fatty acid foods (Kim et al. 2023; Grolimund et al. 2022).
The WHO has planned aggressive goals to eliminate soil-transmitted helminths that impose public health burden by 2030, which calls for practical treatment approaches that satisfy the established benchmarks, such as ≥ 90 ERR for hookworm parasite (Assefa et al. 2024; Truscott et al. 2017). The finding from this research underscores that while an improvement has been recorded in treating hookworm infection, a challenge remains for A. lumbricoides and T. trichiura, urging immediate attention in order to enhance treatment outcomes.
This study has several limitations. We used the Kato-Kasz technique to identify and count the eggs of the three STH infections, which may have resulted in underestimation of infections. Furthermore, we did not perform molecular diagnostic techniques to confirm drug resistance. Additionally, the study was cross-sectional with only a 3-week treatment follow-up, which may limit the capability of capturing long-term drug efficacy and potential re-infection patterns. These limitations will be addressed in our future researches to provide more reliable insights.
Conclusion
This study reveals a complex landscape of soil-transmitted helminth infection treatment outcomes across various districts, highlighting significant treatment successes with hookworm but showing persistent challenges with A. lumbricoides and T. trichiura infections with reduced efficacy. Addressing these issues will be vital to enhance public health outcomes associated to soil-transmitted helminth infections in affected regions. Furthermore, the predictors identified in this study offer important insights into enhancing albendazole treatment strategies for soil-transmitted helminth infections. Future studies should focus on investigating alternative treatment strategies and identifying predictive factors to achieve the goal of eliminating soil-transmitted helminth infections by 2030.
Acknowledgements
We would like to acknowledge the Zonal and district Health and Education Bureau for their support in conducting this research. We thanks the school children, parents/guardians, teachers, and school principals from the three schools for their participation and assistance. We also acknowledge the support from Aksum University laboratory professionals and directors.
Author contributions
Y.T.D. conceived the study. Y.T.D., M.T., M.T, T.T.and H.K.A. designed and conducted data collection. Y.T.D., M.T. and M.T. conducted analysis and interpretation of results. Y.T.D., T.T. and H.K.A. wrote the manuscript. All authors read and approved the final manuscript.
Data availability
No datasets were generated or analysed during the current study.
Declarations
Ethics approval and consent to participate
The study received ethical approval from Aksum University, College of Health Sciences and Comprehensive Specialized Hospital Ethics Review Committee (IRB number: IRB064/2016) in Ethiopia. Consent was also obtained from children and parents/guardians for the collected information and sample analysis.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
- Adeyeba OA, Akinlabi AL (2002) Intestinal parasitic infections among school children in a rural community, Southwest Nigeria. Niger J Parasitol 23:11–18 [Google Scholar]
- Adugna S, Kebede Y, Moges F, Tiruneh M (2007) Efficacy of mebendazole and albendazole for Ascaris lumbricoides and hookworm infections in an area with long time exposure for antihelminthes, Northwest Ethiopia. Ethiop Med J 45(3):301–306 [PubMed] [Google Scholar]
- Alemu Y, Degefa T, Bajiro M, Teshome G (2022) Prevalence and intensity of soil-transmitted helminths infection among individuals in model and non-model households, South West Ethiopia: a comparative cross-sectional community based study. PLoS ONE 17(10):e0276137. 10.1371/journal.pone.0276137 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Assefa A, et al. (2024) Efficacy of 400 mg albendazole against soil-transmitted helminthes among Salgy Primary School Children, Dembia district, Northwest Ethiopia, 2020. "Uncontrolled experimental study". Health science reports 7(4):e2041 10.1002/hsr2.2041
- Crompton DWT, World Health O (2006) Preventive chemotherapy in human helminthiasis : coordinated use of anthelminthic drugs in control interventions : a manual for health professionals and programme managers. World Health Organization, Geneva [Google Scholar]
- de Silva NR, Brooker S, Hotez PJ, Montresor A, Engels D, Savioli L (2003) Soil-transmitted helminth infections: updating the global picture. Trends Parasitol 19(12):547–551. 10.1016/j.pt.2003.10.002 [DOI] [PubMed] [Google Scholar]
- Dejenie T, Petros B (2009) Irrigation practices and intestinal helminth infections in Southern and Central Zones of Tigray. Ethiop J Health Dev 23:10.4314/ejhd.v23i1.44837 [Google Scholar]
- Demissie F, Petros B, Kebede A (2008) Hookworm species distribution among school children in Asendabo Town, Jimma Zone, South West Ethiopia. Ethiopian journal of health sciences 18
- Eze P, Agu UJ, Aniebo CL, Agu SA, Lawani LO (2020) Perception and attitudinal factors contributing to periodic deworming of preschool children in an urban slum, Nigeria. BMC Public Health 20(1):1839. 10.1186/s12889-020-09958-x [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gebreyesus TD et al (2024) Reduced efficacy of single-dose albendazole against Ascaris lumbricoides, and Trichuris trichiura, and high reinfection rate after cure among school children in southern Ethiopia: a prospective cohort study. Infect Dis Poverty 13(1):8. 10.1186/s40249-024-01176-6 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Grolimund CM, Bärenbold O, Utzinger J, Keiser J, Vounatsou P (2022) Modeling the effect of different drugs and treatment regimen for hookworm on cure and egg reduction rates taking into account diagnostic error. PLoS Negl Trop Dis 16(10):e0010810. 10.1371/journal.pntd.0010810 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hailu T, Abera B, Mulu W, Alemu M, Yizengaw E, Genanew A (2018) Efficacy of single dose albendazole and praziquantel drugs among helminth-infected school children at rural Bahir Dar, northwest Ethiopia. Trop Doct 48(4):270–272. 10.1177/0049475518786835 [DOI] [PubMed] [Google Scholar]
- Horton J (2000) Albendazole: a review of anthelmintic efficacy and safety in humans. Parasitology 121(Suppl):S113–S132. 10.1017/s0031182000007290 [DOI] [PubMed] [Google Scholar]
- Hotez PJ, Brindley PJ, Bethony JM, King CH, Pearce EJ, Jacobson J (2008) Helminth infections: the great neglected tropical diseases. J Clin Invest 118(4):1311–1321. 10.1172/jci34261 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keiser J, Utzinger J (2008) Efficacy of current drugs against soil-transmitted helminth infections: systematic review and meta-analysis. JAMA 299(16):1937–1948. 10.1001/jama.299.16.1937 [DOI] [PubMed] [Google Scholar]
- Kim ES et al (2023) The impact of dual- versus single-dosing and fatty food co-administration on albendazole efficacy against hookworm among children in Mayuge district, Uganda: Results from a 2x2 factorial randomised controlled trial. PLoS Negl Trop Dis 17(7):e0011439. 10.1371/journal.pntd.0011439 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Legesse M, Erko B, Medhin G (2004) Comparative efficacy of albendazole and three brands of mebendazole in the treatment of ascariasis and trichuriasis. East Afr Med J 81(3):134–138. 10.4314/eamj.v81i3.9142 [DOI] [PubMed] [Google Scholar]
- Mathewos B et al (2014) Current status of soil transmitted helminths and Schistosoma mansoni infection among children in two primary schools in North Gondar, Northwest Ethiopia: a cross sectional study. BMC Res Notes 7(1):88. 10.1186/1756-0500-7-88 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Montresor A, Crompton DWT, Gyorkos TW, Savioli L, World Health O, Montresor A (2002) Helminth control in school-age children : a guide for managers of control programmes. World Health Organization, Geneva [Google Scholar]
- Montresor A et al (2005) The WHO dose pole for the administration of praziquantel is also accurate in non-African populations. Trans R Soc Trop Med Hyg 99(1):78–81. 10.1016/j.trstmh.2004.06.006 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Olsen A, Namwanje H, Nejsum P, Roepstorff A, Thamsborg SM (2009) Albendazole and mebendazole have low efficacy against Trichuristrichiura in school-age children in Kabale District, Uganda. Trans R Soc Trop Med Hyg 103(5):443–446. 10.1016/j.trstmh.2008.12.010 [DOI] [PubMed] [Google Scholar]
- Olusola O (2013) Terminating the neglect of neglected tropical diseases in Africa. Journal of Medical Microbiology and Diagnosis. 10.4172/2161-0703.1000e118
- Sisay M, Damtie D, Hailu T (2024) Efficacy of albendazole against soil-transmitted helminth infections in Ethiopia: a systematic review and meta-analysis. Sci Rep 14(1):21970. 10.1038/s41598-024-71308-3 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Truscott JE et al (2017) Identifying optimal threshold statistics for elimination of hookworm using a stochastic simulation model. Parasit Vectors 10(1):321. 10.1186/s13071-017-2256-8 [DOI] [PMC free article] [PubMed] [Google Scholar]
- World Health O (2013) Assessing the efficacy of anthelminthic drugs against schistosomiasis and soil-transmitted helminthiases. World Health Organization, Geneva [Google Scholar]
Associated Data
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Data Availability Statement
No datasets were generated or analysed during the current study.