Abstract. We report the elimination of Onchocerca volvulus transmission from the Central Endemic Zone (CEZ) of onchocerciasis in Guatemala, the largest focus of this disease in the Americas and the first to be discovered in this hemisphere by Rodolfo Robles Valverde in 1915. Mass drug administration (MDA) with ivermectin was launched in 1988, with semiannual MDA coverage reaching at least 85% of the eligible population in > 95% of treatment rounds during the 12-year period, 2000-2011. Serial parasitological testing to monitor MDA impact in sentinel villages showed a decrease in microfilaria skin prevalence from 70% to 0%, and polymerase chain reaction (PCR)-based entomological assessments of the principal vector Simulium ochraceum s.l. showed transmission interruption by 2007. These assessments, together with a 2010 serological survey in children 9-69 months of age that showed Ov16 IgG4 antibody prevalence to be < 0.1%, meeting World Health Organization (WHO) guidelines for stopping MDA, and treatment was halted after 2011. After 3 years an entomological assessment showed no evidence of vector infection or recrudescence of transmission. In 2015, 100 years after the discovery of its presence, the Ministry of Health of Guatemala declared onchocerciasis transmission as having been eliminated from the CEZ. INTRODUCTION Human onchocerciasis (river blindness) is caused byOnchocerca volvulus, a tissue-dwelling filarial nematode transmitted by certain species of the genus Simulium.1 Adult male and female worms form fibrous, often palpable, subcutaneous onchocercomas ("nodules"), in which fertilized female worms produce microfilariae (mf). The mf leave the nodule and reside in the dermis. They may also enter the eyes. Human disease results largely from death of the mf, which results in inflammation, itching, visual impairment, and blindness. The Simulium ("black fly") vectors breed in rapidly flowing rivers and streams and become infected when they ingest mf during a blood meal; in competent black fly species, mf develop into third stage larvae that can infect humans when the vector takes a subsequent blood meal. There are no important animal reservoirs of O. volvulus to maintain the transmission cycle independent of the human population itself. Human onchocerciasis is thought to have originated in Africa when Onchocerca species in ungulates adapted to man; the parasite is believed to have been brought to the Americas through the Atlantic slave trade.3 Transmission was only focally established in the Americas, in contrast to the extensive transmission zones that exist in Africa. In the Americas, due to a limited distribution of competent vectors, transmission zones ("foci") are small and sharply delimited geographically, and are generally maintained by high vector biting rates. Before control measures were implemented, there were 13 foci in six countries in Latin America (Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela), with an overall human population at risk in 2013 of just over 500,000 persons. 4Guatemala...

BackgroundMass drug administration (MDA) with ivermectin for onchocerciasis was provided in Guatemala’s Central Endemic Zone (CEZ) over a 24 year period (1988–2011). Elimination of Onchocerca volvulus transmission was declared in 2015 after a three year post MDA surveillance period (2012–2014) showed no evidence of recrudescence. The purpose of the present study was to evaluate the knowledge, attitudes and practices (KAP) towards onchocerciasis and ivermectin among residents in the post endemic CEZ. A major interest in this study was to determine what community residents thought about the end of the ivermectin MDA program.Methodology/Principal FindingsA total of 148 interviews were conducted in November 2014 in four formerly hyperendemic communities using a standard questionnaire on smart phones. The majority (69%) of respondents knew that the MDA program had ended because the disease was no longer present in their communities, but a slight majority (53%) was personally unsure that onchocerciasis had really been eliminated. Sixty-three percent wanted to continue to receive ivermectin because of this uncertainty, or because ivermectin is effective against intestinal worms. Eighty-nine percent of respondents said that they would seek medical attention immediately if a family member had symptoms of onchocerciasis (especially the presence of a nodule), which is a finding very important for ongoing surveillance.Conclusions/SignificanceMany respondents wanted to continue receive ivermectin and more than half did not believe onchocerciasis had been eliminated. The ministry of health outreach services should be prepared to address ongoing concerns about onchocerciasis in the post endemic CEZ.