Abstract
BackgroundIn veterinary parasitology samples are often pooled for a rapid assessment of infection intensity and drug efficacy. Currently, studies evaluating this strategy in large-scale drug administration programs to control human soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and hookworm), are absent. Therefore, we developed and evaluated a pooling strategy to assess intensity of STH infections and drug efficacy.Methods/Principal FindingsStool samples from 840 children attending 14 primary schools in Jimma, Ethiopia were pooled (pool sizes of 10, 20, and 60) to evaluate the infection intensity of STHs. In addition, the efficacy of a single dose of mebendazole (500 mg) in terms of fecal egg count reduction (FECR; synonym of egg reduction rate) was evaluated in 600 children from two of these schools. Individual and pooled samples were examined with the McMaster egg counting method. For each of the three STHs, we found a significant positive correlation between mean fecal egg counts (FECs) of individual stool samples and FEC of pooled stool samples, ranging from 0.62 to 0.98. Only for A. lumbricoides was any significant difference in mean FEC of the individual and pooled samples found. For this STH species, pools of 60 samples resulted in significantly higher FECs. FECR for the different number of samples pooled was comparable in all pool sizes, except for hookworm. For this parasite, pools of 10 and 60 samples provided significantly higher FECR results.Conclusion/SignificanceThis study highlights that pooling stool samples holds promise as a strategy for rapidly assessing infection intensity and efficacy of administered drugs in programs to control human STHs. However, further research is required to determine when and how pooling of stool samples can be cost-effectively applied along a control program, and to verify whether this approach is also applicable to other NTDs.
Highlights
The soil-transmitted helminths (STHs) Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species, Necator americanus and Ancylostoma duodenale, cause the highest burden among all neglected tropical diseases (NTDs), with school-aged children and pregnant women being at highest risk [1,2,3].Preventive chemotherapy (PC) programs, in which albendazole (400 mg) or mebendazole (500 mg) administered in a single dose are the principal means of control of soiltransmitted helminths (STHs) infections in schoolaged children, has recently received increased political and scientific attention [4,5]
Health care decision makers have a limited repertoire of strategies for a rapid assessment of infection intensity and for checking of drug resistance development
We verified whether examination of pooled stool samples provide estimates of intestinal worm infection intensity and drug efficacy comparable to those obtained by examination of individual stool samples
Summary
The soil-transmitted helminths (STHs) Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species, Necator americanus and Ancylostoma duodenale, cause the highest burden among all neglected tropical diseases (NTDs), with school-aged children and pregnant women being at highest risk [1,2,3].Preventive chemotherapy (PC) programs, in which albendazole (400 mg) or mebendazole (500 mg) administered in a single dose are the principal means of control of STH infections in schoolaged children, has recently received increased political and scientific attention [4,5]. The World Health Organization (WHO) has devised a roadmap to guide implementation of the policies and strategies set out in a global plan to combat NTDs (period 2008–2015), and more than 70 pharmaceutical companies, governments, and global health organizations committed to supporting this roadmap [6] in the London Declaration on NTDs in January 2012 by sustaining or expanding drug donation programs [7]. In veterinary parasitology samples are often pooled for a rapid assessment of infection intensity and drug efficacy Studies evaluating this strategy in large-scale drug administration programs to control human soiltransmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and hookworm), are absent. We developed and evaluated a pooling strategy to assess intensity of STH infections and drug efficacy
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