The effect of repeated half-yearly diethylcarbamazine mass treatment on wuchereria bancrofti infection and transmission in two East African communities with different levels of endemicity
Date
2004Author
SIMONSEN, PAUL E.
MEYROWITSCH, DAN W.
MUKOKO, DUNSTAN A.
PEDERSEN, ERLING M.
MALECELA-LAZARO, MWELE N.
RWEGOSHORA, RWEHUMBIZA T.
OUMA, JOHN H.
MASESE, NAFTAL
Jaoko Walter G.
MICHAEL, EDWIN
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
The effect of repeated half-yearly mass treatment with diethylcarbamazine (DEC, 6 mg/kg body weight)
on infection and transmission of Wuchereria bancrofti was assessed and compared in communities with high and low
endemicity in eastern Africa, with pretreatment microfilaria (mf) and circulating filarial antigen (CFA) prevalences of
29.4% and 53.2% in the high endemicity community and 3.1% and 18.7% in the low endemicity community, respectively.
Human infection was monitored by repeated cross-sectional surveys, and transmission by weekly light trap collection of
vector mosquitoes in selected houses in each community. Treatments resulted in a progressive decrease in microfilaremia
and circulating antigenemia in both communities, with relative reductions being considerably higher for mf than for
CFA. Among pretreatment mf-positive individuals, more than 60% were diagnosed as mf negative and mean mf
intensities were reduced by 99% in both communities after two treatment rounds. In contrast, only moderate reductions
were seen in circulating antigenemia among pretreatment CFA-positive individuals, with mean intensities still being
24−39% of pretreatment values after two treatment rounds. Among the pretreatment mf/CFA-positive individuals,
clearance to a CFA-negative status was negligible. Complete CFA clearance was only observed among pretreatment
CFA-positive but mf negative individuals who also had much lower initial mean CFA levels than the mf-positive
individuals. After treatment, the intensity of transmission decreased in the high-endemicity community, but this appeared
mainly to be a consequence of a drought-induced reduction in vector density rather than to reduced mf load in
the human population, since the proportion of mosquitoes carrying infective larvae was not reduced. No change in
transmission or mosquito infectivity was observed after treatment in the low-endemicity community. Implications of
these observations for the control of Bancroftian filariasis are discussed.
URI
http://www.ncbi.nlm.nih.gov/pubmed/14971700http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/10159
Citation
The American Society of Tropical Medicine and HygieneCollections
- Faculty of Health Sciences (FHS) [10387]