Impact of single annual treatment and four-monthly treatment for hookworm and Ascaris lumbricoides, and factors associated with residual infection among Kenyan school children.
BACKGROUND
School-based deworming is widely implemented in various countries to reduce the burden of soil-transmitted helminths (STHs), however, the frequency of drug administration varies in different settings. In this study, we compared the impact of a single annual treatment and 4-monthly treatment over a follow-up among Kenyan school children, and investigated the factors associated with residual infection.


METHODS
We performed a secondary analysis of data from a randomized trial investigating whether deworming for STHs alters risk of acquiring malaria. Children received either a single treatment or 4-monthly albendazole treatments were followed longitudinally from February 2014 to October 2014. The relative impact of treatment and factors associated with residual infections were investigated using mixed-effects regression models. Predisposition to infection was assessed based on Spearman's rank and Kendall's Tau correlation coefficients.


RESULTS
In the 4-monthly treatment group, the proportion of children infected with hookworm decreased from 59.9 to 5.7%, while Ascaris lumbricoides infections dropped from 55.7 to 6.2%. In the single treatment group, hookworm infections decreased over the same time period from 58.7 to 18.3% (12.6% absolute difference in reduction, 95% CI: 8.9-16.3%), and A. lumbricoides from 56.7 to 23.3% (17.1% absolute difference in reduction, 95% CI: 13.1-21.1%). There was strong evidence for predisposition to both STH types. Residual hookworm infection among children on 4-monthly treatment were associated with male sex and baseline nutritional status, whereas A. lumbricoides infection was associated with individual and school-level infection at baseline, latrine cleanliness at schools.


CONCLUSIONS
This study found that 4-monthly treatment w more effective than single annual treatment. Repeated treatments led to dramatic reductions in the intensities of STHs, but did not completely clear infections among school children in Kenya, a presumed reflection of reinfection in a setting where there is ongoing transmission.
School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda. stellakepha2005@yahoo.com.
Stella
S
Kepha
Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya.
Charles S
CS
Mwandawiro
London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK.
Roy M
RM
Anderson
London School of Hygiene and Tropical Medicine, London, UK.
Rachel L
RL
Pullan
School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda.
Fred
F
Nuwaha
London School of Hygiene and Tropical Medicine, London, UK.
Jorge
J
Cano
Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya.
Sammy M
SM
Njenga
Centre for Global Health Research, KEMRI, Kisumu, Kenya.
Maurice R
MR
Odiere
London School of Hygiene and Tropical Medicine, London, UK.
Elizabeth
E
Allen
London School of Hygiene and Tropical Medicine, London, UK.|KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya.
Simon J
SJ
Brooker
London School of Hygiene and Tropical Medicine, London, UK.
Birgit
B
Nikolay
D000293:Adolescent; D015766:Albendazole / Q000008:administration & dosage; D000723:Ancylostomatoidea / Q000187:drug effects; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage*; D001196:Ascariasis / Q000188:drug therapy* / Q000453:epidemiology*; D017164:Ascaris lumbricoides / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D005260:Female; D006725:Hookworm Infections / Q000188:drug therapy* / Q000453:epidemiology*; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D012574:Schools; D013334:Students; D016896:Treatment Outcome
D000871:Anthelmintics; D015766:Albendazole
Albendazole; Kenya; School children; School-based deworming; Soil-transmitted helminths