TY - JOUR
T1 - Impact of ivermectin and vector control on onchocerciasis transmission in Togo
T2 - Assessing the empirical evidence on trends in infection and entomological indicators
AU - Vinkeles Melchers, Natalie V.S.
AU - Agoro, Sibabi
AU - Togbey, Kwamy
AU - Padjoudoum, Koffi
AU - Telou, Ibrahim Gado
AU - Karabou, Potchoziou
AU - Djatho, Touka
AU - Datagni, Michel
AU - Dorkenoo, Ameyo Monique
AU - Kassankogno, Yao
AU - Bronzan, Rachel
AU - Stolk, Wilma A.
N1 - Publisher Copyright:
© 2024 Vinkeles Melchers et al.
PY - 2024/7/22
Y1 - 2024/7/22
N2 - Background:The World Health Organization’s 2021–2030 Road Map for Neglected Tropical Diseases boosted global commitment towards the elimination of onchocerciasis, but the timeline to elimination will vary strongly between countries in Africa. To assess progress towards elimination in the Republic of Togo, we reviewed the history of control and time trends in infection. Methodology/Principal findings: We collated all available programmatic, entomological, and epidemiological data since the initiation of the Onchocerciasis Control Programme (OCP) in Togo through different data sources. We then visualised data trends over time, to assess the impact of interventions on infection and transmission levels. Vector control was initiated by OCP from 1977 (northern and central parts of Togo) or 1988 (southern regions) up to 2002 (most areas) or 2007 (“spe-cial intervention zones” [SIZ], parts of Northern and Central Togo). Between 1988 and 1991, Togo initiated ivermectin mass drug administration (MDA) in eligible communities. The impact of vector control was high in most river basins, resulting in low annual biting rates and annual transmission potential declining to very low levels; the impact was lower in river basins designated as SIZ. Repeated, longitudinal ivermectin mass treatments have overall strongly reduced onchocerciasis transmission in Togo. Epidemiological surveys performed between 2014 and 2017 showed that the prevalence of skin microfilariae (mf) and anti-OV16 IgG4 antibodies had declined to low levels in several districts of the Centrale, Pla-teaux, and Maritime region. Yet, relatively high mf prevalences (between 5.0% and 32.7%) were still found in other districts during the same period, particularly along the Kéran, Mô and Ôti river basins (SIZ areas).Conclusions/Significance: Trends in infection prevalence and intensity show that onchocerciasis levels have dropped greatly over time in most areas. This demonstrates the large impact of long-term and wide-scale interventions, and suggest that several districts of Togo are approaching elimination.
AB - Background:The World Health Organization’s 2021–2030 Road Map for Neglected Tropical Diseases boosted global commitment towards the elimination of onchocerciasis, but the timeline to elimination will vary strongly between countries in Africa. To assess progress towards elimination in the Republic of Togo, we reviewed the history of control and time trends in infection. Methodology/Principal findings: We collated all available programmatic, entomological, and epidemiological data since the initiation of the Onchocerciasis Control Programme (OCP) in Togo through different data sources. We then visualised data trends over time, to assess the impact of interventions on infection and transmission levels. Vector control was initiated by OCP from 1977 (northern and central parts of Togo) or 1988 (southern regions) up to 2002 (most areas) or 2007 (“spe-cial intervention zones” [SIZ], parts of Northern and Central Togo). Between 1988 and 1991, Togo initiated ivermectin mass drug administration (MDA) in eligible communities. The impact of vector control was high in most river basins, resulting in low annual biting rates and annual transmission potential declining to very low levels; the impact was lower in river basins designated as SIZ. Repeated, longitudinal ivermectin mass treatments have overall strongly reduced onchocerciasis transmission in Togo. Epidemiological surveys performed between 2014 and 2017 showed that the prevalence of skin microfilariae (mf) and anti-OV16 IgG4 antibodies had declined to low levels in several districts of the Centrale, Pla-teaux, and Maritime region. Yet, relatively high mf prevalences (between 5.0% and 32.7%) were still found in other districts during the same period, particularly along the Kéran, Mô and Ôti river basins (SIZ areas).Conclusions/Significance: Trends in infection prevalence and intensity show that onchocerciasis levels have dropped greatly over time in most areas. This demonstrates the large impact of long-term and wide-scale interventions, and suggest that several districts of Togo are approaching elimination.
UR - http://www.scopus.com/inward/record.url?scp=85200522603&partnerID=8YFLogxK
U2 - 10.1371/journal.pntd.0012312
DO - 10.1371/journal.pntd.0012312
M3 - Article
C2 - 39038058
AN - SCOPUS:85200522603
SN - 1935-2727
VL - 18
JO - PLoS Neglected Tropical Diseases
JF - PLoS Neglected Tropical Diseases
IS - 7
M1 - e0012312
ER -