Date of Award

January 2023

Document Type


Degree Name

Medical Doctor (MD)



First Advisor

Michael Cappello


Background: Soil-transmitted helminthiases (STH) are amongst the most common diseases of poverty worldwide despite mass deworming campaigns. However, widespread use of benzimidazole anthelminthics in these campaigns has been associated with variable efficacy against three of the most common STHs, thus raising concerns regarding emerging resistance. Albendazole, in particular, has been shown to be least effective against Trichuris trichiura.

Methods: Our aim was to determine baseline prevalence and intensity of STH infections in rural school children living in Retalhuleu, Guatemala, and to evaluate the efficacy of single dose albendazole in infected children. We conducted a cross-sectional study with 557 children ages 4-16 from seven different high-risk schools. Household surveys were distributed to parents and anthropometric were collected from participants to identify risk factors associated with infection. Pre-treatment stool samples were examined via Kato Katz fecal microscopy. Participants found to be infected were treated with a single dose of 400mg albendazole and re-examined 10-20 days following treatment.

Results: The overall prevalence rate of any STH infection was 22.6% (116/557), with Trichuris (20.8%) being more prevalent than Ascaris (5.9%). No hookworm was visualized in any sample. The majority of infections were light to moderate intensity. The overall cure rate following administration of single-dose albendazole (400 mg) was 93.3% (28/30) for Ascaris and 19.8% (22/111) for Trichuris. Community-wide fecal egg reduction rates (ERR) were 99.9% and 50.8% for Ascaris and Trichuris, respectively. Associated risk factors for infection included gender, poor sanitation and nutritional status. Medication response was positively associated with students who had fasted for more than 6 hours prior to treatment.

Conclusions: Our findings support the need for continued monitoring of treatment efficacy in at-risk communities with frequent exposure to benzimidazole anthelminthics. Interventions in these communities should consider encouraging fasting prior to deworming in order to enhance medication benefits. Further studies are needed to identify appropriate dosing of albendazole and evaluate other alternatives in communities with low treatment response.


This thesis is restricted to Yale network users only. It will be made publicly available on 07/24/2024