Lymphatic filariasis control in Tanga Region, Tanzania: status after eight rounds of mass drug administration.
BACKGROUND
Lymphatic filariasis (LF) control started in Tanga Region of Tanzania in 2004, with annual ivermectin/albendazole mass drug administration (MDA). Since then, the current project has monitored the effect in communities and schools in rural areas of Tanga District. In 2013, after 8 rounds of MDA, spot check surveys were added in the other 7 districts of Tanga Region, to assess the regional LF status.


METHODS
LF vector and transmission surveillance, and human cross sectional surveys in communities and schools, continued in Tanga District as previously reported. In each of the other 7 districts, 2-3 spot check sites were selected and about 200 schoolchildren were examined for circulating filarial antigens (CFA). At 1-2 of the sites in each district, additional about 200 community volunteers were examined for CFA and chronic LF disease, and the CFA positives were re-examined for microfilariae (mf).


RESULTS
The downward trend in LF transmission and human infection previously reported for Tanga District continued, with prevalences after MDA 8 reaching 15.5% and 3.5% for CFA and mf in communities (decrease by 75.5% and 89.6% from baseline) and 2.3% for CFA in schoolchildren (decrease by 90.9% from baseline). Surprisingly, the prevalence of chronic LF morbidity after MDA 8 was less than half of baseline records. No infective vector mosquitoes were detected after MDA 7. Spot checks in the other districts after MDA 8 showed relatively high LF burdens in the coastal districts. LF burdens gradually decreased when moving to districts further inland and with higher altitudes.


CONCLUSIONS
LF was still widespread in many parts of Tanga Region after MDA 8, in particular in the coastal areas. This calls for intensified control, which should include increased MDA treatment coverage, strengthening of bed net usage, and more male focus in LF health information dissemination. The low LF burdens observed in some inland districts suggest that MDA in these could be stepped down to provide more resources for upscale of control in the coastal areas. Monitoring should continue to guide the programme to ensure that the current major achievements will ultimately lead to successful LF elimination.
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark. pesi@sund.ku.dk.
Paul E
PE
Simonsen
National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza, Tanzania. yahyaathman@yahoo.com.
Yahya A
YA
Derua
RTI International, Global Health Division, Dar es Salaam, Tanzania. smagesa@hotmail.com.
Stephen M
SM
Magesa
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark. empe@sund.ku.dk.
Erling M
EM
Pedersen
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, 1870, Frederiksberg C, Denmark. asstensgaard@snm.ku.dk.|Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen Ø, Denmark. asstensgaard@snm.ku.dk.
Anna-Sofie
AS
Stensgaard
National Institute for Medical Research, P.O. Box 9653, Dar es Salaam, Tanzania. mwelentuli@gmail.com.
Mwelecele N
MN
Malecela
National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza, Tanzania. wnkisinza@gmail.com.
William N
WN
Kisinza
D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage*; D002648:Child; D003140:Communicable Disease Control / Q000379:methods*; D009033:Culicidae / Q000469:parasitology; D004605:Elephantiasis, Filarial / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007303:Insect Vectors / Q000469:parasitology; D008297:Male; D012424:Rural Population; D013636:Tanzania / Q000453:epidemiology; D014958:Wuchereria bancrofti / Q000302:isolation & purification / Q000502:physiology
D000871:Anthelmintics