The First Confirmed Elimination of an Onchocerciasis Focus in Africa: Abu Hamed, Sudan

Abstract

Abstract. Mass treatment with ivermectin for onchocerciasis was stopped in 2012 in Abu Hamed, an isolated focus on the River Nile in northern Sudan. A 3-year posttreatment surveillance (PTS) ensued, at the end of which an evaluation was conducted in 2015 following the current World Health Organization guidelines for verification of onchocerciasis elimination. Vector black flies were collected from sentinel breeding sites and finger-prick bloodspots were collected from children ≤ 10 years of age resident in 35 communities within the focus. Polymerase chain reaction (PCR) screening of 19,191 flies from four sites for the O-150 parasite-specific marker found no flies carrying Onchocerca volvulus larvae (0%, 95% upper confidence limit [UCL] = 0.16), and serological testing of 5,266 children identified only one Ov16 seropositive child (0.019%, 95% UCL = 0.074); whose skin snips were negative when tested by O-150 PCR assay. These results indicate that for the first time in Africa, onchocerciasis elimination has been verified after a successful PTS in Abu Hamed.Onchocerciasis or river blindness is a major tropical disease currently endemic in Venezuela, Brazil, Yemen, and importantly in 31 African countries where 99% of the estimated 123 million individuals at risk reside.

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

“…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.…”

Socioeconomic impacts of elimination of Onchocerciasis in Abu-Hamed focus, northern Sudan: lessons after elimination

“…The fact that Abu Hamed is the most remote focus of Onchocerciasis in the north worldwide with a very limited opportunity of re-establishment of the infection after the elimination (26). This situation provided us with an extraordinary opportunity to study the socioeconomic impacts of the elimination of Onchocerciasis in Abu Hamed focus.…”

“…Comprehensive surveys showed low level of transmission in 2007 (24), and complete interruption of the disease transmission in 2011 that was officially declared by the Sudan government in 2012 (15,25). Following WHO guidelines and after a 3-year post-treatment surveillance, the elimination of Abu Hamed focus was officially declared in 2015 (26).…”

“…Information on the social and economic impacts of Onchocerciasis elimination are required to assess and evaluate the success and guide the redevelopment of the focus population (26). The present study was designed to investigate the socio-economic impacts of Onchocerciasis on Abu-Hamed populations and assess the social changes in their lives after the elimination of the disease.…”

Onchocerciasis Elimination from Africa: One Step in Northern Sudan

“…The technical procedures and the corresponding cutoff values to signify transmission interruption included the following: 1) screening pools of black flies by polymerase chain reaction for the DNA repeat sequence Ov150; minimal elimination value is < 1/2,000 Ov150-positive flies and 2) serologic screening of school-aged children < 10 years of age for immunoglobulin G4 antibodies to the Ov16 antigen; elimination value is antibody prevalence < 0.1%. In this issue of the American Journal of Tropical Medicine and Hygiene , Zarroug and others6 describe results of a 3-year post-MDA treatment survey that confirm elimination of O. volvulus transmission by these criteria in Abu Hamed, a geographically isolated endemic focus in northern Sudan inhabited by approximately 120,000 people. Of the 5,266 children tested for Ov16 antibody, one 9-year-old child was positive.…”