Serosurveillance to Monitor Onchocerciasis Elimination: The Ugandan Experience

Abstract

Abstract. Uganda is the only African country whose onchocerciasis elimination program uses a two-pronged approach of vector control and mass drug distribution. The Ugandan program relies heavily upon the use of serosurveys of children to monitor progress toward elimination. The program has tested over 39,000 individuals from 11 foci for Onchocerca volvulus exposure, using the Ov16 ELISA test. The data show that the Ov16 ELISA is a useful operational tool to monitor onchocerciasis transmission interruption in Africa at the World Health Organization (WHO) recommended threshold of 0.1% in children. The Ugandan experience has also resulted in a re-examination of the statistical methods used to estimate the boundary of the upper 95% confidence interval for the WHO prevalence threshold when all samples tested are negative. This has resulted in the development of Bayesian and hypergeometric statistical methods that reduce the number of individuals who must be tested to meet the WHO criterion.

Evaluation of an OV-16 IgG4 Enzyme-Linked Immunosorbent Assay in Humans and Its Application to Determine the Dynamics of Antibody Responses in a Non-Human Primate Model of Onchocerca volvulus Infection

“…2,3 Annual and biannual ivermectin (IVM) mass drug administrations (MDAs) have been shown to interrupt transmission in several American and African foci, and four countries have been verified to be free of onchocerciasis. 1,[4][5][6][7][8][9][10][11][12][13] Elimination efforts have been challenged by inadequate treatment coverage, migration, and recrudescence of infections in areas of suspended treatment. Previous monitoring efforts have relied on the detection of mf in skin snips taken from the iliac crest.…”

“…22 The anti OV-16 ELISA has been used to evaluate the status of disease transmission in the Americas 6,7,23 and some parts of Africa. 10,11,24 A good understanding of the temporal evolution of the host immune response to O. volvulus infection is needed to be able to use OV-16 for monitoring onchocerciasis control and elimination efforts. The present study reports the refinement of an ELISA method using a panel of human serum specimens from onchocerciasis-endemic areas in Africa and from individuals with a variety of non-OV parasitic infections.…”

Expanding the MDx toolbox for filarial diagnosis and surveillance

“…When antibody is used, enhanced specificity is often achieved by assessment of IgG4 rather than total IgG [13]. The current tool to assess O. volvulus infection in the population is based on IgG4 responses to the Ov-16 antigen [16], and a test is now commercially available (the Alere SD Bioline Onchocerciasis IgG4 test, Alere, USA). To determine if interruption of transmission or possible recrudescence has occurred in MDA control communities, the test is used to screen children who act as sentinels for recent infection (http://apps.who.int/iris/handle/10665/ 66889).…”

One Hundred Years After Its Discovery in Guatemala by Rodolfo Robles, Onchocerca volvulus Transmission Has Been Eliminated from the Central Endemic Zone

“…The eluted solution was run in duplicate in a standard Ov-16 ELISA as previously described. 19,23 Any positive results were repeated before being reported as positive. The IgG4 based ELISA as configured in the Guatemala laboratory has a sensitivity of 67% and a specificity of 100% and performs equally well on sera and filter paper DBSs (Vitaliano Cama, CDC, personal communication).…”