0432 - Post-Treatment Surveillance for Onchocerciasis in Plateau and Nasarawa, Nigeria: evidence for elimination of transmission

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Post-Treatment Surveillance for Onchocerciasis in Plateau and Nasarawa, Nigeria: evidence for elimination of transmission

Author Block: Abel Eigege¹, Barminas Kahansim¹, Kenrick Nwodu¹, Yohana Sambo¹, John Umaru¹, Bulus Mancha¹, Solomon Adelamo¹, Jonathan Kadimbo², Jacob Danboyi³, Hayward Mafuyai⁴, Nse Akpan⁵, Joel Akilah⁵, Michael Igbe⁵, Lindsay Rakers⁶, Emily Griswold⁶, Thomas R. Unnasch⁷, Bertram E. Nwoke⁸, Emmanuel S. Miri¹, Gregory S. Noland⁶, Frank O. Richards^{6 1}The Carter Center, Nigeria, Jos, Plateau State, Nigeria, ²Plateau State Ministry of Health, Jos, Nigeria, ³Nasarawa State Ministry of Health, Lafia, Nigeria, ⁴University of Jos, Jos, Nigeria, ⁵Federal Ministry of Health, Abuja, Nigeria, ⁶The Carter Center, Atlanta, GA, United States, ⁷University of South Florida, Tampa, FL, United States, ⁸Imo State University, Owerri, Nigeria
Nigeria has 480 onchocerciasis-endemic districts or local government areas (LGAs), of which 12 (2.5%) are in Plateau and Nasarawa States. In 2017 these two states were the first in the country to interrupt transmission and stop mass drug administration (MDA) for onchocerciasis after 8 – 26 years of MDA with ivermectin in the 12 hyper-/meso-endemic LGAs and ivermectin-albendazole treatment for LF in 18 other LGAs non-endemic or hypo-endemic for onchocerciasis. A three-year post-treatment surveillance (PTS) entomological evaluation, required to declare transmission elimination, was completed in 2019-2020 transmission season per WHO and National Onchocerciasis Elimination Committee (NOEC) guidelines. Entomology collections for Simulium damnosum s.l. blackflies were carried out from mid-June through October 2019 and 2020 in 42 sites (21 sites per state) in formerly hyper-/meso-endemic areas. Collections were from known high risk LGAs as well as hypo-endemic LGAs bordering with other endemic Nigerian states. Blackflies were tested for the presence of L3 infective-stage Onchocerca volvulus by O-150 polymerase chain reaction. In Nasarawa State, results from 93 pools comprised of 7925 flies found 0 positive pools (0%, 95% confidence interval [CI] 0% - 0.024%). In Plateau State, 89 pools comprised of 7368 flies resulted in 0 positive (0%, 95% CI 0% - 0.026%). These results meet the 2016 WHO entomological criteria for elimination of transmission infectivity threshold of less than 0.05% (<1/2000). Other PTS activities included tracking and treating immigrants and internally displaced persons (IDPs), and health educating the communities. A total of 21,994 immigrants and IDPs were tracked and treated with ivermectin in the border villages as well as those in identified camps. Health education messages were disseminated through radio jingles, posters and face-to-face contact by community-directed drug distributors. Pending approval of the NOEC, these results indicate Plateau and Nasarawa states could be the first to eliminate onchocerciasis transmission in Nigeria.

Disclosures: A. Eigege: None.