Thereaputic efficacy of single dose Albendazole against Ascaris lumbricoides, prevalence of re-infection, and its associated factors among school children at Northwest Ethiopia: an open-label trial study

Abstract

Background

Despite extensive implementation of albendazole (ALB) mass drug administration to reduce Ascaris lumbricoides among school childrens, it remains a major chilhood health concern which needs close monitoring of ALB efficacy. Additionally, ALB donot prevent re-infection, and determinat for re-infection needs investigation. Thus, the study aimed to evaluate an efficacy of ALB against A.lumbricoides, re-infection rate, and their risk factors among school age childern (SAC) at Northwest Ethiopia.

Methods

An open-label trial study was conducted at Chuahit Primary School from June to September 2023. A total of 415 SAC were recruited using convenient sampling techniques. Nearly 2 g of stool were collected and screened using direct wet-mount and Keto-katz (KK) techniques at baseline. Of these, 50 school children who tested positive for A. lumbricoides were treated with a single dose (400 mg) of ALB. A cure and egg reduction rates were evaluated within 2–3 weeks post-treatment using KK techinque. Addtionally, reinfection rate of A.lumbricoides was assessed 3 months after ALB treatment by formal-ether concentration techinque. Pre-tested, semi-structured questionnaire was used to collect sciodemographic, and risk factors of re-infection. Data were entered into Epi-data (version 4.6) and exported to STATA (version 14) for analysis. Descriptive statistics, paired t-tests, bivariate and multivariate logistic regression model were performed. A P-value < 0.05 with a 95% CI was considered as significant value.

Result

In this study, the cure and egg reduction rates of a single dose of ALB against A.lumbricoides were found to be 92.3% [95% CI: 87.5%–97.2%] and 96.7% [95% CI: 87.8%-100%], respectively. Of the 46 school children considered for assessing the re-infection rate, about 34.7% [21.8% − 47.6%] were found to have been re-infected. Poor latrine utilization [AOR = 5.52; 95% CI: 1.07–28.5, P = 0.004] and finger nail trimming practice [AOR = 0.064; 95% CI: 0.009–0.42, P = 0.041] were significantly associated with A. lumbricoides re-infection.

Conclusion

Efficacy of single-dose ALB (400 mg) was within WHO satisfactory level against A. lumbricoides although a high re-infection rate was observed in the study area. This underscores the importance of promoting proper hygiene practice like regular fingernail trimming and toilet utilization strategies, alongside sustained MDA campaigns with ALB (400 mg) to achieve disease elimination goals.

Trial registration

This trial is retrospectively registered at www.pactr.org (number PACTR202407793260730) on July 16, 2024.

Introduction

Ascaris lumbricoides (A. lumbricoides), often known as roundworm, is the largest soil-transmitted helminth (STHs) parasite belonging to the class nematode [1]. Natural transmission occurs through fecal-oral route, involving the ingestion of embryonated eggs via contaminated hands, water, and food sources [2–4]. It is utmost responsible for the majority of STH infections, posing significant public health challenges mainly among socioeconomically disadvantaged populations [5]. Of this, school age children (SAC) are the most vulnerable segment of population, bearing a substantial and lion-share burden worldwide [6, 7]. A global epidemiological report shows that South America, the Caribbean region, Asia, and sub-Saharan Africa(SSA) are the most common areas of ascariasis [8]. Ethiopia, including our study setting, is also facing unwavering problems [9, 10]. This is often linked to low socioeconomic standards, poor personal and environmental sanitation, high open-field defection habits, and poor waste brass practice including schools [7].

A. lumbricoides induces biological, mechanical, and exploitative effects in infected children, leading to impairment in the digestion and absorption of functional micro and macro nutrients and may result in malnutrition [11]. This often proceeds to acute and/or prolonged clinical outcomes of anemia, compromised immune systems, mortality, growth retardation, and cognitive impairment, which often result in poor school performance and absenteeism [12–14].Abdominal discomfort, loss of appetite, vomiting, diarrhoea, constipation, abnormal abdominal sounds, and Loeffler syndrome are some defining clinical features [15, 16]. However, these features are non-specific and require laboratory methods. Direct wet-mount, formal ether concentration, and Kato-Katz (KK) techniques are widely used methods for establishing precise diagnosis [17]. Of these, KK is further used for detection and quantification of moderate to heavey infection enabling accurate monitoring of drug efficacy [17].

Currently, World Health Organization (WHO) uses benzimidazole mass drug administration (MDA) for risk groups including school and preschool age children (PSAC) to limit ascariasis severity and transmission intensity [18]. The frequency of drug administration is determined by prevalence of STHs in target population [18, 19]. Albendazole (ALB) is most frequently used anthelminthic for MDA in the Ethiopia. In Kenya, Ethiopia, and other countries, prevalence rates of ascariasis have dropped compared to baseline surveys [20].

The 2021 WHO road map for neglected tropical disease(NTD) sets the goal of reducing infections to levels where they no longer pose a public health concern, by achieving at least 75% MDA coverage across 96 countries [21]. The ongoing 2030 NTD elimnation roadmap integrates MDA with water, sanitation and hyigen (WASH) practice as basic elements in controling ascariasis and its re-infection.recognizing reinfection as obstacle for achivment goals [20].

In addition, the Ethiopian Ministry of Health (EMoH) and the WHO in collaboration started deworming campaigns that treated 7.8 million SAC with estimated treatment coverage 71.0% − 91.6% [21, 22].

Despite the implementation of periodic large-scale MDA for the last two decades, many endemic countries, including Ethiopia, did not achieve the WHO target of STH elimination and remained major public health problems [23, 24].This might be partly due to large-scale adoption and blanket usage of ALB might place strong selective pressure on parasites and swiftly led to the emergence of resistant parasite strains [25]. Studies conducted in Brazil, Haiti, Kenya, and Panama demonstrated the presence of single nucleotide polymorphisms (SNPs) in the beta-tubline gene, indicating the predictive potential in the emergency of resistance to ALB [26]. There has been report of reduced ALB efficacy observed in African regions, including Ethiopia [27, 28]. Besides, in cases of suspected treatment failure or when ALB is in use for 4 or more years, the WHO recommends monitoring the efficacy of anthelminthic drugs. Moreover, recent studies reported contradictory findings on the efficacy of ALB [27, 29],due to a lack of sufficient global surveillance systems in place to monitor the efficacy of ALB or the emergence of ALB resistance [30]. In contrast, although the drug can eliminate the parasite, reinfection can occur as early as 2 months after treatment [31, 32]. The intensity of infection can revert to pre-treatment levels after 12 months complet post albedazole highly linked with presence of poor hygien practice and wast management system [33, 34]. This greatly contributes to the persistence of transmission [35] and also implies the inadequacy of MDA alone for elimination [36].

Periodic ALB drug efficacy and re infection rate assessments are vital for resistance detection, reduction of transmission, deployment, and implementation of alternative timely mitigation strategies, including regimen changes, use of combination drugs, and appropriate dose adjustment. Additionally, identifying and targeting transmission reservoirs and specific factors associated with reinfection can guide activities to reduce exposure and designing targeted interventions for sustainable control. Thus, this study aimed to evaluate the therapeutic efficacy of a single-dose ALB (400 mg) against A. lumbricoides, re-infection and factors associated with re-infection among school children in northwest Ethiopia.

Methods and materials

Study design, period, and settings

An open-label trial study was conducted from June to September 2023 at Chuahit Primary School in Dembiya district Northwest Ethiopia. This district found in Amhara region 789 km away from Addis Ababa (capital city [37]. The district comprises 59,382 households, averaging 4.56 persons per household, with 23.6% lacking a properly constructed slab for their latrine [38]. The district is served by 10 health centers and 40 health posts, including Chuahit Health Centre, equipped with a routine laboratory [39]. Health extension workers and other health professionals engaged in providing health education at schools, community and at health centers about STHs including ascariasis and provide MDA. Yet ongoing transmission of A.lumbricoides is observed in the district with prevalence of 41.3% despite prolonged deworming implementations [40].

Study population and eligibility criteria

All SAC with microscopically confirmed A. lumbricoides mono- infection and fulfill eligibility criteria were included in this study. Being 7 to 14 years old with no history of anti-helminthic drug usage with the last 6 months before study period and willing to provide required stool samples at baseline, after 2–3 weeks (for efficacy evaluation), and 3rd months (for re-infection assessment) of post ALB treatment were eligiblity criteria at baseline. Whereas for drug efficacy evaluation, children who unable to bring parents/legal guardians to the school, who have a history of major systemic illnesses, malnutrition, and GIT diseases, take anti-inflammatory and antibiotics during study period, who vomited ALB with 4 h, experienced diarrhoea, severe allergic reaction to ALB, and were infected with other intestinal parasite than A. lumbricoides and co-infected with A. lumbricoides were excluded from the study. For re-infection assessment, children who remain positive after 14–21 days ALB administration and were absent at the time of visit were excluded from the study. Medical history in anti-helminthic drug usage and general health status of SAC participant was obtained from local health extension worker and legal guardian/parents’ interview.

Sample size determination and sampling technique

For this study, intended sample size was determined according to the 2013 WHO anthelminthic efficacy assessment guideline [41]. This guideline specified a minimum of 50 parasitologically confirmed positive individuals for each targeted parasite to assess the drug’s efficacy. Therefore, our study included 50 patients infected with A. lumbricoides to evaluate the efficacy of ALB. To reach this minimum required number, the number to be screened was estimated based on the prevalence in the study area, with a recent estimate of A. lumbricoides prevalence at P = 41.6% [40]. Additionally, 80% compliance rate was considered, and 10% of the calculated sample size was added to account for possible loss to follow-up and total sample size was 150. However, due to the inadequacy of the total calculated sample size, 415 SAC were screened for A. lumbricoides infection until the desired sample size was achieved. Study participants were selected using a convenient sampling (Fig. 1).

Fig. 1.

Flowcharts that show initial enrollment of eligible children for the study

Operational definition

• Schoolchildren: refers to children between 7 and 14 years old [42].

• Cure rate: refers to the proportion of infected individuals who are treated with a single dose of ALB (400 mg) and achieve complete elimination of parasites (became egg-free 14-21days post treatment) from their body using KK.

• Egg reduction rates (ERRs): the relative reduction in fecal egg counts after the administration of a single dose of ALB(400 mg) compared with baseline eggs count by using KK [43]. Albendazole efficacy: Satisfactory (ERR ≥ 95%), doubtful (95 > ERR ≥ 85ERR), and reduced (ERR < 85) [12].

• Infection intensity: light if microscopy eggs count range from 1 to 4,999 per gramme of stool, moderate if egg count ranges 5,000 to 49,999, and heavy if egg count equals to or exceeding 50,000 eggs per gram [44].

• Reinfection: Children positive at baseline who were treated successfully and achieved complete elimination of the parasite from their body after 14–21 days and became positive on the 12th week of ALB treatment.

Stool sample collection and laboratory methods

After receiving written permission from the school director to recruit the children, the researcher collected demographic data by interviewing the children. Then, approximately 2 g of fresh stool specimens were collected from each participant in clean, dry, and leak-proof containers labelled with unique identification numbers. This was performed at three different time points: baseline survey, 14–21 days, and 12 weeks after treatment at the school. Additionally, children who brought an insufficient stool sample were asked to provide another sample. Besides, diarrhic stool sample was not used for our trial and so disposed at the school public latrine. Adequately collected stool sample was promptly transported to the nearby Chuahit Health Centre laboratory within an hour for examination.

Baseline parasitological survey and wet mount technique

In this study, we received written informed consent from parents or guardians of the patients, and stool samples were collected, subjected to a saline wet-mount microscopic technique to screen for parasitologically eligible children. A droplet of physiological saline solution (0.85% NaCl) was dispensed onto a slide. Thus, a small amount of stool (2 mg) was applied to the saline solution and mixed thoroughly using an applicator stick. A standard smear was made, the slide was covered with a cover slip, and the slides were examined under 10 and 40 objective lenses. The prepared slides were examined at the Chuahit Health Centre. Microscopically positive samples for A. lumbricoides were further subjected to the KK technique for egg quantification.

Baseline Kato –Katz thick smear method

Considering the WHO recommendations, the KK diagnostic technique was implemented for diagnosing and quantifying the parasite egg per gramme of stool in this study [45, 46]. The remaining faces were pressed through a mesh screen to remove large particles. A portion of the sieved sample was then transferred to the template hole on a slide. After filling the hole, the template was removed, and the remaining sample (approximately 41.7 mg) was covered with a special wet-able cellophane cover slip soaked in glycerin containing aqueous malachite green. The preparation was left to stand at room temperature. The prepared slides were examined at the University of Gondar Comprehensive Specialized Hospital (UoGCSH) Parasitology Unit within 1 day. Subsequently, the principal investigator and other laboratory technologists observed the slides and counted the eggs. Finally, the mean count of the KK slide was multiplied by the correction factor [23] to obtain Egg per gramme (EPG).

Risk factors and health-related data in children with confirmed A. lumbricoide infection

Initially, a pretested, semi-structured questionnaire was prepared in English. It was then translated into the local mother tongue language (Amharic) and finally back into English. The questionnaire included sociodemographic information, behavioral and environmental factors, and other health-related data. Children confirmed to have A. lumbricoides brought their parents or guardians to the school. Written informed consent was obtained from the parents or guardians of the patients before proceeding. Data collectors then conducted face-to-face interviews with them under careful supervision of the principal investigator.

Administration of single dose(400 mg) albendazole

Each A. lumbricoide positive child who fulfilled all the necessary eligibility criteria received a biscuit, followed by a single 400 mg dose of ALB (ALDAZ Batch №: FDM5M101 Mfg 12/21 date and expire date 11/24) purchased from local pharmacy, administered through direct observation by trained nurse (BSc) at school. Each child was closely monitored for approximately 4 h for the occurrence of any possible adverse effects. Although the children remained at school and engaged in their regular activities, they were instructed to immediately report any side effects to a member of the investigation team.

Follow–up KK survey and ALB efficacy

Treated children were revisited after14-21 days of post-treatment and requested to provide a second stool sample. An identical laboratory methodology employed during the initial surveys was replicated in the follow-up examination (KK technique). Children who failed to provide a specimen on the follow-up day underwent assessment 1 or 2 days after that. At this time point, participants who vomited within 4 h after drug administration or participants with diarrhoea were excluded.

Reinfection rate after 3 months of ALB treatment

Children who were A. lumbricoides positive at baseline and achieved cure within 14–21 days post ALB treatment underwent retesting after 3 months. The re-infection rate was evaluated using the formol ether concentration technique. Approximately 2 mg of stool sample was collected for the third time and 0.5 mg of sample was mixed, emulsified with 10 ml of 10% formalin. The 7 ml of emulsion was filtered by fine gauze within funnel into a conical test tube and 3 ml of ethyl acetate was added, shaken, and centrifuged at 1500 rpm for 2 min. The top three layers were decanted, prepared smear from sediment and examined for A. lumbercoid using 10X and 40 X objective at Chuahit health center.

Study outcome measures

Faecal egg reduction rate (ERR) and cure rate (CR) were used to measure the therapeutic efficacy status of the ALB after14–21 days post-treatment. ERR is considered as the primary outcome measure, while CR was regarded as a secondary outcome measure.

Quality control and management

Data collectors were trained; and regular supervision was performed. To ensure the quality of the questionnaire, the English version of the questionnaire was translated into the participant’s language (Amharic language). Before data collection, the questionnaire was pre-tested with 5% of the total sample size among parents residing in Jangua kebele to check the accuracy of the responses and language clarity. Any ambiguous questions were corrected, and additional response categories were added based on the pretest findings. Quality control was ensured using standard controls for the working equipment and reagents. The quality of normal saline, glycerol, malachite green, ethyl acetate, and formalin was ensured by checking expired dates for stock, using positive and negative controls. During stool sample collection, children were instructed to avoid possible contamination with soil, urine, and water.

Before administering the drug, its expiration date and storage conditions were verified. In order to ensure the accuracy of the egg counts conducted by the laboratory technicians, quality control was performed by rereading 10% randomly selected slides from each laboratory technician by a senior laboratory technologist. Slides showing a discrepancy in the egg count per gramme of stool of more than 10% and more than four eggs, the laboratory technologists re-read the slide until a consensus was reached. The results of each test were recorded, transcribed, and reviewed.

Data processing and analysis

Data were checked for completeness, coded, and entered to Epi-data (version 7.2) and exported to STATA (version 17) software for analysis. Descriptive statics like frequency, mean, and standard deviations were used to express the baseline characteristics of the study participants. ERR and CR were used to assess therapeutic efficacy. The arithmetic mean (AM) was used to express ERR. The paired sample t-test was used to estimate the ERR and 95% CI using the mean EPG at baseline and follow-up data of treated participants. Pearson’s chi-square test was used to determine the association of study variables. Bivariate logistic regression was performed to identify factors associated with A. lumbricoide re-infections. All variables with P-value < 0.25 were considered for multivariate regression. A P-value 0.05 was considered statistically significant.

Ethical approval and consideration

Ethical clearance was obtained from the Ethical Review Committee of School of Biomedical and Laboratory Science, University of Gondar with protocol number of SBLS/5115/. A supportive letter and permission were obtained from Chuahit district office and school director. We received informed consent from the child-parent or legal guardian and verbal assent from children and those who vomited the drug, remained infected after 14–21 days of ALB treatment, reinfected after 3 months, and affected by other intestinal parasite were linked to nearby health center for appropriate treatment.

Result

Initial screening and study participants enrolment

A total of 415 school children were requested to provide stool samples upon study initiation to determine their parasitological eligibility. Among them, 376 (90.6%) children provided sufficient stool specimens for initial screening of SAC for A. lumbricoides. Using saline wet-mount 26.8% (101/376) of children were found to have microscopically confirmed A. lumbricoides infection, however only 22.80% (72/376) were parasitologically eligible participants (A. lumbricoides mono- infected) and subjected to KK. The remaining 3.84% of children were co-infected with other common intestinal helminths. Of confirmed, A. lumbricoides mono infection, 72 study participants received the single dose (400 mg) of ALB under direct observation at school. Then, with a one-week time frame in 14–21 days of post treatment, only 52 participants provided all the required follow-up data sets and were considered for the final efficacy evaluation (Fig. 1).

Baseline characteristics of the participants

A total of 52 SACs were included in the final efficacy analysis. Of these, females accounted for 57.7% (29/52) and 42.3% (23/52) of the respondents were males. The mean age of SAC was 9.9 ± 1.7 years (mean ± SD) (Table 1). Regarding the intensity of infection expressed in terms of the EPG, the majority of children had a light intensity of infection of 55.7%(Fig. 2).

Table 1.

Demographic characteristics of study participants at Chuahit, Northwest Ethiopia

Variable	Category	Frequency	Percentage
Sex	Male	23	42.3%
	Female	29	57.7%
Age	7–10	36	69.2%
	11–14	16	30.8%

Fig. 2.

Variable intensity of infection among SAC enrolled for assessment of single dose ALB efficacy at Chuahit, northwest Ethiopia

Therapeutic efficacy of albendazole at a single dose against A. lumbricoides infection

In this study, only 4 of 52 children who had microscopically confirmed A. lumbricoides infection at baseline remained infected 14–21 days post-treatment. The majority, 48 of the infected children were get cured. Besides, a reduction in parasite egg count was observed in terms of the arithmetic mean from 8718.1 to 282 EPG after 14–21 days treatment. Based on these findings, the overall therapeutic efficacy of ALB in terms of cure rate (CR) and egg reduction rate (ERR) was found to be 92.3% [95% CI: 87.5%–97.2%] and 96.7% [95% CI: 87.8%-100%], respectively.

Re-infection rate of A. lumbricoides among SAC treated with single dose albendazole

In this study we have assessed the reinfection rate of A. lumbricoides after 3 months of single dose ALB treatment. Out of 52 children finally included for efficacy study, only 46 participants were found to be eligible for reinfection assessment while 6 children were excluded from the study with specific reasons (Fig. 1). Among 46 initially cured participants,16 of 46 were found to be infected again and the reinfection of A. lumbricoides was found to be [34.7%, 95% CI: 21.8% − 47.6%].

Factors associated with A. lumbricoides re-infection among school age childern

In this study, bivariate logistic regression analysis was performed to identify factors associated with re-infection of A. lumbricoide after 3 months, as shown in (Table 2). Factors including latrine utilization (COR: 0.09, 95% CI: 0.01–0.49), hand washing with soap after defecation (COR: 4.22, 95% CI: 1.15–15.5), and finger nail trimming practice (COR: 3.81, 95% CI: 1.04–13.83) yielded P-values < 0.25 and were subsequently entered into multivariable analysis.

Table 2.

Bivariable logistic regression analysis of factors associated with Ascaris lumbricoides re-infection among school children in Chuahit, Northwest Ethiopia

Variables	Category	Ascaris lumbricoide reinfection			COR (95%CI)	P-value
		No. of RI		No. of NRI
Age (years)	7–10	12	23		1	0.900
	11–14	7	4		1.09(0.26–4.49)
Sex	Female	8	17		1	0.666
	Male	8	13		1.30(0.38–4.41)
Fathers’ occupation	Government employee	3	2		4.5(0.61–32.69)	0.137
	Farmer	7	21		1
	Merchant	6	7		2.57(0.64–10.28)
Residency	Rural	4	5		1	0.500
	Urban	12	25		0.6(0.136–2.64)
Mothers’ education	Illiterate	11	20		1	0.577 0.941 0.576
	Primary school	2	6		0.60(0.10–3.52)
	Secondary school	1	2		0.90(0.07–11.19)
	Collage and above	2	2		1.81(0.22–14.75)
No. of siblings	0–1	1	1		1	0.550 1.000
	2–3	10	24		0.41(0.023–7.33)
	≥ 4	5	5		1 (0.04–20.82)
Nail trimming practice	Yes	2	18		1	0.043 *
	No	14	12		3.81(1.04–13.83)
Shoes wearing	Every time	11	22		1	0.743
	Sometimes	5	8		1.25(0.33–4.73)
Hand washing with soap before a meal	Every time	1	1		1	0.598 0.711
	Sometimes	13	24		2.15(0.12–37.19)
	Never	2	1		0.50(0.01–19.56)
Hand washing with soap after defecation	Yes	7	23		1	0.030*
	No	9	7		4.22(1.15–15.5)
Drinking water source	Home pipe	6	10		1	0.479 0.899
	Public pipe	5	14		0.59(0.14–2.50)
	Pit water	5	6		1.11(0.21- 5.61)
Latrine availability	Yes	5	19		1	0.005*
	No	11	11		0.09(0.01–0.49)

No.: Numbers; RI: re-infection; NRI: not re-infection; COR: crude odds ratio; CI: confidence interval; 1.: reference; *: significant association at P < 0.25

Based on multivariate logistic regression, latrine utilization (AOR = 5.52; 95% CI: 1.07–28.5, P = 0.004) and finger nail trimming practice (AOR = 0.064; 95% CI: 0.009–0.42, P = 0.041) were identified as independent risk factors for A. lumbricoide re-infection among SAC (Table 3).

Table 3.

Multivariable logistic regression analysis of factors associated with Ascaris lumbricoides re-infection among school children in Chuahit, Northwest Ethiopia

Variables	Category	A. lumbricoide reinfection			AOR (95% CI)	P-value
		No. of RIs	No. of NRIs
Nail trimming practice	Yes	2		18	1	0.041 *
	No	14		12	5.52 (1.07–28.52)
Handwashing with soap after defecation	Yes	7		23	1 0.08 (0.81–22.45)	0.087
	No	9		7
Latrine utilization practice	Yes	5		19	1	0.004*
	No	11		11	0.06 (0.01–0.42)

No.: Numbers; RI: re-infection; NRI: not re-infection; AOR: adjusted odds ratio; CI: confidence interval; 1 reference; *: significant association at P < 0.05

Discussion

In Ethiopia where ascariasis remains a substantial public health problem, both individual-and community-based interevention strategy heavily relys on oral single dose(400 mg) ALB thereapy [47, 48]. However, different studies conducted in effciacy of the ALB revealed reduced efficacy of ALB in both livestock and human infected with soil transmiited helminthic infection [25, 27, 29],requires a close efficacy monitoring platform. Besides, ALB cannot prevent re-infection and childern expirences a largest reinfection rate after short time of complet prior treatment [31, 32]. Thus, studing thereaputic efficacy of ALB against A.lumbricoides, magnitude of re-infection, and its risk factors looks utmost important in order to draw confident clinical decision, rejecting unwanted roamers on the thereaputic status ALB or starting to search for alternative thearpy.

In this study, administration of a single dose (400 mg) of ALB resulted in a significant reduction of parasite load in terms of egg per gram(EPG) from the baseline measurement of 8718.1EPG to 282 EPG with an overall ERR in terms of AM; 96.7%). This substantial reduction in the intensity of infection strongly supports the primary aim of preventive chemotherapy administration to affected segments of the population. Furthermore, according to the WHO anthelminic efficacy classification criteria, the efficacy of ALB for the treatment of ascariasis in our study relies with satisfactory level (ERR exceeds the threshold of ERR ≥ 95%) [43]. Unlike the ERR efficacy status, the CR of a single dose of 400 mg of ALB proved its unsatisfactory fecal egg clearance rate among treated individuals with a curative status of CR of 92.3%. Considering that the CR against A.lumbricoides infection is comparatively low when compared to the WHO threshold level.

In the present study, the therapeutic outcome of a single dose ALB for treating ascariasis in terms of CR is in line with a study reported in South Africa, western province Rwanda, and in some parts of Ethiopia like Axum and Adiet, with an estimated CR ranges from 92.2% to 97.2% [29, 49–51]. Whereas, in terms of ERR, it was also supported by studies reported in South Africa, Nigeria, western province Rwanda, and in some parts of Ethiopia like Axum, Adwa, and Adiet, with an estimated ERR ranged from 94.3%-99.7% [49–52].

On the other hand, the present study also revealed the higher therapeutic efficacy of a single dose of ALB against A. lumbricoides than the study conducted in India with a CR of 55.5% -70.8% [53, 54] and ERRs of 81.4% [53],in Huyu district Rwanda of CR 69.9% and ERRs of 75.4% [27] and Adwa Ethiopia CR87.4% [42].This inconsistent result may be related to the variations in the length of the parasitological survey following treatment, participant’s baseline infection intensity, and study participants in association with previous anthelmintic exposure status, diagnostic techniques used, diet, and geographical location.

For instance, in previous studies conducted in India and Huyu district, Rwanda, the length of follow-up survey after treatment was between 10 and 14 days and 7–10 days, respectively. In contrast, in the current study extended the survey period to 14–21 days. Recent articles highlight the importance of this extended period, as Ascaris worm expulsion kinetics and egg output suggest waiting at least 14 days after ALB treatment before conducting follow-up egg counts [55]. Sampling before this point may lead to bias in ERR estimation due to the release of residual eggs from degenerating worms and only 20% of worms being expelled between days 7 and 10 post-treatment. Sequential analysis revealed a poor ERR (89.4%) on day 7 but a 100% ERR at days 14 and 21 post-treatment [55].

Another reason for the observed discrepancy might be Rwanda being categorized as a high-drug-pressure area, whereas Ethiopia is classified as a low-drug-pressure area [56–58].The extensive drug usage and high level of drug pressure in Rwanda could exert strong selective pressure on parasites, making preventive chemotherapy (PC) programmes highly vulnerable to the development of anthelmintic resistance (AR) [25, 59].

Moreover, the study carried out in Rwanda applied mini FLOTAC procedures, which have high sensitivity for helminth detection [60], whereas the current study used a single KK technique. KK is known to have low sensitivity to light intensity helminth infections [61].Study carried out in India utilized the Stoll diagnostic technique [62, 63].

Finally, studies conducted in both Rwanda and India showed that the drug was administered without consuming fatty meals. However, in this study, a single dose of (400 mg) of ALB was administered after the biscuit. This is because when ALB is administered with a fatty meal, the active metabolite reaches plasma concentrations of 425–1,592 ng/ml and its absorption increases five-fold [64, 65] high absorption ensures adequate bioavailablity to target parasites in the body might incrseased drug effectiveness [66].

In this study, magnitude of re-infection using formal-ether concentration was found to be 34.7% with a 95%CI: 21.8% − 47.6%) within the three months after treatment, indicating that SAC targeted treatment against ascariass is not effective in preventing ongoing transmission of the parasite with in communities but only reduces clinical complication [67]. This often lead to the development of drug resistance due to frequent intake of anti-helminthics, while hindering the success of ongoing STH elimination goals [68].

Although re-infection is frequent after treatment, intensity of infection is ususally light, which needs more senstive formal -ether concetration techinques [69, 70]. The role of ether in the techinque is enhancing parasite egg detection rate through extraction of fecal debrise to top layer or degisition of fat component which hide parasite ova detection under microsocpe [70]. Additionally, centrifugations step is vital in incrseasing the concetration of parasite from large volume of samples unlike to that of KK [71]. Our magnitude finding aligns with similar study that have been reported in Chencha district, Ethiopia (23.1%) [72]. Incontrast, the current finding is lower compared with the studies conducted in China (75.8%) [73]. The varation may be due to the degree of endemicity across community which affect the post-treatment reinfection patterns of A.lumbricoides [31], meaning in China, the pre-treatment prevalence of A.lumbricoides was 93.3% [73], but in our study, the baseline prevalence was 23%, and with 12 months of prior treatment, the prevalence of ascariasis tended to return to beyond pre-treatment levels [33, 34]. In the present study, the post-treatment reinfection rate was conducted with a time frame of slightly less than 1 month as compared with reports from china.

In relation to associated factors, this study found that fingernail trimming and latrine utilizations were significant factors for A. lumbricoides reinfection among school children. This suggests that reliance solely on preventive chemotherapy may be insufficient for effective elimination. It is crucial to implement a comprehensive and integrated approach. In this study, children who engage in fingernail trimming were associated with a 93.6% reduction in the risk of A. lumbricoides reinfection compared with those who do not. This finding is supported by a study conducted in northern Ethiopia, which reported that 49% of intestinal parasite reinfection rates decrease with weekly nail clipping [74]. The possible reason behind that association could be underneath fingernails, dirt may harbour various parasite stages, and it might be consumed by sucking one’s thumb or chewing one’s nails [75].

Furthermore, individuals without access to a latrine were 5.52 times more likely to be reinfected by A. lumbricoides than those with access. Similar results were reported in a study conducted in Malaysia [76] and the Chencha district of Ethiopia [72]. The possible reason could be the enormous quantity of eggs (200,000 to 1,000,000) per day, capable of enduring harsh environments, released into the environment due to open defecation [16, 77]. If left in the open, these eggs can be carried by flies, fluids (water), fingers, and fields, infecting another person through the faecal-oral route [78].

Strength and limitation of the study

The use of a single KK stool specimen from each participant might underestimate detection rate might pushed to intra- and inter-specimen variation of egg output, and might failed to cover various ALB brands, was considered as a limitation of the study. Moreover, the sample size used to assess the reinfection rate and factors associated with reinfection was small to draw strong conclusion.

Conclusion

Based on our findings, the efficacy of ALB against A. lumbricoides was satisfactory in terms of ERR according to the WHO threshold. However, achieving complete egg clearance, as indicated by the Cure Rate (CR), remains a concern. Additionally, a significant number of re-infection cases occurring 3 months after successive treatment suggest that elimination and control efforts are being challenged by various factors. Factors such as lack of latrine utilization and inadequate nail trimming practice seems to contribute significantly to high reinfection rates. This implies that preventive chemotherapy alone is insufficient for the elimination of such cases.

Recommendation

We highly recommend a continued emphasis on mass drug-administration with a single dose of albendazole (400 mg) to combat A.lumbricoides. However, the study also highlights the persistent challenge of reinfection. To address the ongoing risk of re-infection, it is crucial to consider additional measures, such as promoting proper hygiene practices, including regular fingernail trimming practice, increase latrine utilization, and multi sectorial intervention strategies. Furthermore, future research should utilize sensitive diagnostic tools, double kk slide at baseline and follow-up 1, KK should be used for reinfection assessment with large sample size to estimate the actual burden of reinfection. Sustainable anti-helminthic drug efficacy evaluations that cover various drug brands are essential to achieve long-term success in controlling and preventing A. lumbricoide in the community.

Abbreviations

ALB

Albendazole

AOR

Adjusted Odds Ratio

CI

Confidence Interval`

COR

Crude Odds Ratio

CR

Cure Rate

EPG

Eggs per Gramme

ERR

Egg Reduction Rate

FECT

Formol ether Concentration Technique

FECR

Faecal Egg Count Reduction

KK

Kato-Katz

MDA

Mass Drug Administration

PSAC

Pre School-Age Children

SAC

School-Age Children

SC

School Children

STH

Soil-Transmitted Helminthes

WHO

World Health Organization

Author contributions

HM: Conceptualization and design of study, study protocol development, data collections, Data curation, MT, TE, AS: Supervision of data collection, formal analysis, Data interpretation and writing original draft manuscript: YT, DMB, BBT, ZYA, AA: Methodology, Review and editing of manuscript: NC, TG, AAA, EC: Idea conceptions, Review and editing of manuscript. All authors have read and approved the final manuscript.

Funding

No specific funding was provided for this study.

Data availability

The datasets used in this study are available from the corresponding author upon reasonable request.

Declarations

Ethical approval and consent to participate

Ethical clearance was received from Ethical review committee (ERC) of school of Biomedical and Laboratory science, university of Gondar. Additionally, support letters were collected from the Chuahit district health center and primary school. Moreover, written and oral assents were received from the parents or legal guardians of all children.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.