Surveillance of lymphatic filariasis (SOLF) and the impact of annual Ivermectine-Albendazole mass treatment on LF prevalence in Kyela District
SOLF is generating prevalence data for lymphatic filariasis in Southwest Tanzania. Lymphatic Filariasis (LF) is a mosquito-transmitted disease which is found throughout the tropics. In Tanzania, six million people have debilitating manifestations of the disease. Eradication programs are conducted throughout the country. In the Mbeya district they commenced 2009 giving the opportunity to create pre-treatment prevalence data and also monitoring the success rate of the control program.
The SOLF study is conducted within the framework of the EMINI survey, an EU funded project which started in 2005 and is still ongoing. In the EMINI survey 10% of all households in selected sites are visited. Typical clinical manifestations of lymphatic filariasis were reported from one area of the EMINI study, Kyela, a town close to the lake Nyasa. Efforts are undertaken by the “Global Alliance to Eliminate Lymphatic Filariasis”, to eradicate the disease using repeated once annual mass drug treatment with a two drug combination of Albendazole and Ivermectine. In Southwest Tanzania, the campaign for eradication of LF started in Nov 2009. Mapping of the prevalence of different regions as well as evaluation of treatment is needed for the success of the programme.
The analysis of frozen samples from the EMINI cohort, which were collected before the government programme commenced, creats a first overview over the prevalence of LF infection in this area. A commercially available ELISA (TropBio® Og4C3 serum ELISA, Townsville, Australia) which detects the circulating filarial antigen (CFA) is used to test sera. CFA is secreted by fully developed worms of W. Bancrofti and can be found at similar levels during day and night. Antigen levels reflect the worm burden and have been previously used to monitor the efficacy of lymphatic filariasis elimination programs. 100 µl of sera are used for the ELISA.
Analysis of samples after the treatment will give valuable information about the treatment success of the governmental mass drug administration.
NIMR-MMRC: Lucas Maganga (site principal investigator), Petra Clowes (study coordinator), Anthony Nsojo (EMINI laboratory), Joseph Mabuye (EMINI laboratory), Neema Mgeni (EMINI laboratory)
NIMR-Tukuyu: Akili Kalinga (collaborator for Filariasis program)
NIMR Tanga: Williams Makunde (collaborator for Filariasis program)
University Bonn: Achim Hoerauf (collaborator Filariasis program)
LMU: Inge Kroidl (principal investigator), Michael Hoelscher
Part 1 of the study was conducted in 2009/2010. 1000 sera from EMINI participants from the Kyela area which were taken before the government program commenced were tested with the TropBio ELISA. Overall we demonstrated circulating filarial antigen in 24.7 % of the analyzed samples. These are unevenly distributed, ranging from 1.3% in young children to 44% in adults above 35 years of age. The prevalence also differed among the different sub-villages in Kylea. For example, prevalence was below 15% in Kati and Kilombero but above 30% in Busale and Mpanda.
Out of the 1000 participants 15 were identified with clinical manifestations of the disease. Six participants with hydrocele were transferred to the government program for further treatment. Seven participants with elephantiasis received additional supportive treatment.
Its planned to revisit the 1000 participants 6 months after the current drug administration to collect information about the participation in the MDA program and to collect blood samples to measure circulating filarial antigen (CFA). The visit is planned for March 2011.
The project is funded by the Bundesministerium für Bildung und Forschung (BmBF) under the supportnumber: 01KA0904.
NIMR-Mbeya Medical research Center , Mbeya Tanzania
NIMR-Tukuyu Medical Research Station
NIMR Tanga Medical Research Centre
The Division of Infectious Diseases and Tropical Medicine, Medical Center of the University of Munich (LMU), Germany
Poster presentation at the NIMR 24th Annual Joint Scientific Conference in Arusha, Tanzania; 16th -18th March 2010