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Clin Infect Dis. 2020 Mar 24. pii: ciaa318. doi: 10.1093/cid/ciaa318. [Epub ahead of print]

Serological Evaluation of Onchocerciasis and Lymphatic Filariasis Elimination in the Bakoye and Falémé foci, Mali.

Author information

1
Lymphatic Filariasis Research Unit, International Center of Excellence in Research, Faculty of Medicine and Odontostomatology, Point G, Bamako, Mali.
2
Global Health Institute, University of Antwerp, Antwerp, Belgium.
3
Centre National d'Appui à la lutte contre la Maladie (CNAM), Bamako, Mali.
4
Programme National de Lutte contre l'Onchocercose, Bamako, Mali.
5
Programme National d'Elimination de la Filariose Lymphatique, Bamako, Mali.
6
Faculty of Geography and History, Bamako, Mali.
7
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
8
Department of Pathobiology and Population Sciences and London Centre for Neglected Tropical Disease Research, Royal Veterinary College, Hatfield, UK.
9
Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, MRC Centre for Global Infectious Disease Analysis, Imperial College London, UK.

Abstract

BACKGROUND:

In Mali, ivermectin-based onchocerciasis elimination from the Bakoye and Falémé foci, reported in 2009-2012, was a beacon leading to policy shifting from morbidity control to elimination of transmission (EOT). These foci are also endemic for lymphatic filariasis (LF). In 2007-2016 mass ivermectin plus albendazole administration was implemented. We report Ov16 (onchocerciasis) and Wb123 (LF) seroprevalence after 24-25 years of treatment to evaluate if onchocerciasis EOT and LF elimination as a public health problem (EPHP) have been achieved.

METHODS:

The SD Bioline Onchocerciasis/LF IgG4 biplex rapid diagnostic test (RDT) was used in 2,186 children aged 3-10 years in 13 villages (plus two hamlets) in Bakoye, and 2,270 children in 15 villages (plus one hamlet) in Falémé. In Bakoye, all-age serosurveys were conducted in three historically hyperendemic villages, testing 1,867 individuals aged 3-78 years.

RESULTS:

In Bakoye, IgG4 seropositivity was 0.27% (95%CI=0.13-0.60%) for both Ov16 and Wb123 antigens. In Falémé, Ov16 and Wb123 seroprevalence was, respectively, 0.04% (95%CI=0.01-0.25%) and 0.09% (95%CI=0.02-0.32%). Ov16-seropositive children were from historically meso- and hyperendemic villages. Ov16 positivity was <2% in those ≤14 years, increasing to 16% in those ≥40 years. Wb123 seropositivity was <2% in those ≤39 years, reaching 3% in those ≥40 years.

CONCLUSIONS:

Notwithstanding uncertainty in the biplex RDT sensitivity, Ov16 and Wb123 seroprevalence among children in Bakoye and Falémé appears consistent with EOT (onchocerciasis) and EPHP (LF) since stopping treatment in 2016. The few Ov16-seropositive children should be skin-snip PCR tested and followed up.

KEYWORDS:

Mali; elimination; lymphatic filariasis; onchocerciasis; serological monitoring

PMID:
32206773
DOI:
10.1093/cid/ciaa318

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