1. Epidemiological map of onchocerciasis in Nyagak-Bondo Focus
ONCHOCERCIASIS TRANSMISSION CONTINUES IN NYAGAK-BONDO FOCUS OF NORTHWESTERN UGANDA AFTER 18 YEARS OF ANNUAL DISTRIBUTION OF IVERMECTIN
Moses N Katabarwa1, Tom Lakwo2, Peace Habomugisha3, Stella Agunyu3, Edson Byamukama3, Ephraim Tukesiga4, Dickson Unoba 5, Patrick Dramuke6 Frank Walsh7 and Frank Richards1
1 The Carter Center, Atlanta, USA, 2Ministry of Health, Uganda, 3The Carter Center, Uganda, 4Kabarole District Health service, 5Nebbi District Health service, 6Zombo District Health service,
and 7United Kingdom
#611
Abstract No: 2428
Background
Results
Conclusions and Recommendations
Follow up mf rates in adults (2011) range is 3.4%-40%, and 4/7 communities still above 20%, a threshold for mass treatment after 18 yrs of a single annual dose of ivermectin.
Follow up mf rates in children (2011) range is %, and 6/7 communities with at least 8% implying continuing transmission.
63.6% (2333) crabs were infested with larvae stages of S.neavei.
Transmission is continuing, and mass treatment should continue.
Uganda Onchocerciasis Elimination Expert Advisory Committee (UOEEAC) recommended launching of twice yearly treatment with ivermectin.
Nyagak-Bondo focus covers Zombo District and parts of Nebbi and Arua districts of West Nile Region.
The focus borders DRC, and River Nyagak, R. Ora and Agoi are main systems.
The vector is S.neavei breeding in the middle reaches of the above systems.
Annual mass treatment commenced in 1993.
As the policy in Africa begin to shift from control to elimination, impact assessment results of North region becomes key in the debate for selection of effective policies and tools against onchocerciasis.
Eligible Population covered in Nyagak-Bondo Focus from
Epidemiological map of onchocerciasis in Nyagak-Bondo Focus
Katabarwa M, Eyamba A, Habomugisha P, Lakwo T, Ekobo S, Kamgno J, Kuete T, Ndyomugyenyi R, Onapa A, Salifou M, Ntep M, Richards FO (2008). After a decade of annual dose mass ivermectin treatment in Cameroon and Uganda, onchocerciasis transmission continues. Trop Med Int Health. 13(9):
Diawara L, Traoré MO, Badji A, Bissan Y, Doumbia K, Goita SF, Konaté L, Mounkoro K, Sarr MD, Seck AF, Toé L, Tourée S, Remme (2009). Feasibility of onchocerciasis elimination with ivermectin treatment in endemic foci in Africa: first evidence from studies in Mali and Senegal. PLoS Negl Trop Dis, 3(7):e497.
Katabarwa MN, Eyamba A, Chouaibou M, Enyong P, Kuété T, Yaya S, Yougouda A, Baldiagaï J, Madi K, Andze GO, Richards F (2010). Does onchocerciasis transmission take place in hypoendemic areas? a study from the North Region of Cameroon. Trop Med Int Health. 15(5):
Katabarwa M N, Eyamba A, Nwane P, Enyong P, Yaya, Baldiagaï J, Madi K, Yougouda A, Andze G.O, and Richards F (2011). Seventeen years of annual distribution of ivermectin has not interrupted onchocerciasis transmission in North Region, Cameroon. Am. J. Trop. Med. Hyg., 85(6), 1041–1049
References
Adults microfilariae (mf) prevalence
Objectives of the study
to assess the impact of a single dose of ivermectin just before mass treatment of 2011,on the prevalence of microfilaria (mf) and nodule prevalence in adults and children.
to assess the level of crab infestation with larval stages of S.neavei in the follow up study.
to assess the infection rates in S.neavei.
to determine whether an annual dose of ivermectin has eliminated transmission of onchocerciasis after 18 years.
Microfilariae (mf) prevalence – Children < 10 years old
Examining a crab
A Crab Trap
Methods
The present study followed up ( in 2011) the baseline surveys of 1993 on parasitological, and added in the follow up study, entomological surveys (i.e crab infestation and infective rates).
Consent was obtained: Only persons who approved and signed consent forms were examined (parents approved for children).
The study was approved by Emory IRB as “non-research, and classified as routine program monitoring.
Crab infestation with larval stages of S. neavei
Acknowledgements
Parasitological
The skin was cleaned with alcohol, and sterilized needle, and a new surgical blade was used per individual in order to avoid disease transmission.
Skin snip in normal saline solution was observed under microscope after hrs.
Entomological
Three Simulium vector fly collections points were established in April 2011.
The black flies collected were preserved for PCR analysis.
Crabs were captured and analysed for larval stages of S.neavei
Ministry of health and district health services personnel are acknowledged for ensuring annually distribution of ivermectin since 1993, and conducting necessary surveys in affected communities. Without the support of these communities, good treatment coverages and results from the surveys would not have been possible. Merck & Co/Mectizan Donation program are acknowledged for ensuring availability of free ivermectin annually. Also acknowledged are CBM/Kuluva Hospital that provided financial assistance to Arua District, while the Lions Clubs International Foundation/Uganda Lions Clubs, African Programme For Onchocerciasis Control (APOC) provided financial assistance. The River Blindness Foundation, Mr. John Moores and The Carter center are also acknowledged for providing financial, managerial, and technical assistance.
S. neavei collection
Monthly S. neavei collection in Nyagak-Bondo focus began in April, 2011 and will continue for at least 12 months. Analysis will be done with PCR.