Monitoring migrant groups as a post-validation surveillance approach to contain the potential reemergence of lymphatic filariasis in Togo

• Published in: Parasites & vectors 2021-03, Vol.14 (1), p.134-134, Article 134
• Main Authors: Dorkenoo, Monique Ameyo, Tchankoni, Martin Kouame, Yehadji, Degninou, Yakpa, Kossi, Tchalim, Mawèké, Sossou, Efoe, Bronzan, Rachel, Ekouevi, Didier Koumavi
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Algorithms; Animals; Antigens; Child; Child, Preschool; Community; Cross-Sectional Studies; Demographics; Demography; Disease; Economics; Elephantiasis; Elephantiasis, Filarial - drug therapy; Elephantiasis, Filarial - epidemiology; Epidemiological Monitoring; Female; Filariasis; Filaricides - therapeutic use; Health aspects; Health surveillance; Humans; Identification; Infant; Infant, Newborn; Infections; Laboratories; Labour; Local communities; Lymphatic filariasis; Male; Mass Drug Administration; Methods; Middle Aged; Migrants; Migrants group; Monitoring; Post-validation surveillance; Prevalence; Public Health; Refugees; Reintroduction; Risk; Risk factors; Seasonal employment; Sentinel health events; Sociodemographics; Statistics; Surveillance; Togo; Togo - epidemiology; Transients and Migrants - statistics & numerical data; Tropical diseases; Vector-borne diseases; Wuchereria bancrofti - isolation & purification; Young Adult
• ISSN: 1756-3305; 1756-3305
• DOI: 10.1186/s13071-021-04644-2

In March 2017, Togo was declared the first country in sub-Saharan Africa to eliminate lymphatic filariasis as a public health problem, but post-validation surveillance has been lacking. In some areas of the country, migrant groups from neighboring countries that are still endemic for LF pose a risk of reintroduction of LF to Togo. The objective of this study was to identify the risk posed by migrant groups by measuring their prevalence of LF infection and investigating any positive case using Togo's case investigation algorithm to prevent resurgence of LF and sustain Togo's elimination success. A cross-sectional study was conducted in 2018 in the northernmost region of the country. Three migrant populations were identified: (i) nomadic Peuhls, (ii) Togolese members of local communities who migrate annually to neighboring countries for seasonal labor, and (iii) refugees from Ghana who came to Togo because of a communal conflict in Ghana. A questionnaire was designed to collect data on demographics and history of LF and MDA; all participants were tested for circulating filariasis antigen (CFA) using the filariasis test strip (FTS). Any CFA-positive case was confirmed with nocturnal microfilaremia. Refugees, seasonal economic migrants and nomadic Peuhls represented 42.1%, 31.4% and 26.5% of the study participants, respectively. The overall prevalence of CFA was 4.2% (58/1391) with the highest prevalence in the nomadic Peuhl group (11.9%), but only one of them (0.07%) was confirmed positive with nocturnal microfilaremia. Using the case investigation algorithm, no other positive case was identified in the positive case's surroundings. This study demonstrates that nomadic Peuhls, with a CFA prevalence of 11.9%, pose a potential risk for reintroduction of LF into Togo while Ghanaian refugees and seasonal economic migrants do not appear to pose a significant risk. Periodic monitoring of migrants, especially the nomadic Peuhl population, is a potential post-validation surveillance approach that could be used to promptly detect any LF cluster that may arise.