Integrated Transmission Assessment Surveys (iTAS) of Lymphatic Filariasis and Onchocerciasis in Cross River, Taraba and Yobe States Nigeria.

Abstract Background: Integrated Transmission Assessment Surveys (iTAS) has been recommended for evaluation of transmission of both lymphatic filariasis and onchocerciasis, as the prevalence of both diseases move toward their respective elimination targets in Nigeria. Therefore, iTAS was conducted between May and December 2017 in five local government areas also known as implementing units (IU) in Cross River, Taraba and Yobe States of Nigeria. Methods: TAS comprises of two phases: The Pre-iTAS and the iTAS. Three states (Cross-Rivers, Taraba and Yobe) comprising of 5 LGAs and 20 communities that have completed 5 rounds of combined treatment with ivermectin and albendazole for LF and 12 rounds of ivermectin were selected for the study. For the Pre-iTAS, Filariasis Test Strip (FTS) and Biplex rapid diagnostic test (Ov16/Wb123 RDT) were used to test 2000 children from age 5-9 for onchocerciasis and 300 persons aged 10 years and above for LF. For the iTAS, only LGAs where all sampled communities during the Pre-iTAS were with less than 2% antigenemia prevalence for LF was selected.Results: Four out of the five LGAs passed the pre-iTAS except Ikom LGA which had an antigenemia prevalence of more than 2%. A total of 11531 school-aged children were tested for LF and onchocerciasis across the four LGAs. Bade tested 2,873, Bekwara 2,622, Gashaka 3,026 and Karim Lamido 3,010 from 148 schools. For LF prevalence, zero prevalence was recorded for Bade and Karim Lamido while Bekwara and Gashaka recorded 0.19% and 0.23% respectively using FTS. The same was not recorded using Ov16/Wb123 biplex as Bade, Bekwara, Gashaka and Karim Lamido recorded 0.03%, 0.53%, 0.43% and 0.03% respectively. For onchocerciasis prevalence, Bade and Karim Lamido recorded zero prevalence while Bekwara, Gashaka recorded 3.09% and 1.75% respectively.Conclusion: This study has provided additional information on the current burden of onchocerciasis and lymphatic filariasis (LF) in the 4 IUs sampled where MAM for both infections has been ongoing for years. The study identifies that LF-MAM can be safely stopped in all 4 of the studied IUs. However, MAM for onchocerciasis needs to continue, although this may pose a challenge for LF surveillance. Based on the preliminary results from all four sites, this study has fulfilled the primary objective of determining the programmatic feasibility of an integrated transmission assessment survey (iTAS), to be used to simultaneously assess onchocerciasis and LF prevalence in areas co-endemic for the two infections that have completed the recommended treatment for one or both infections, and to make decisions on how to proceed.