Onchocerciasis in Ecuador, 1980?1986: Epidemiological evaluation of the disease in the Esmeraldas Province

Abstract

An increase in both the prevalence (68.3%) and intensity of infection (106.2%) occurred in the Ecuadorian onchocercal focus during the 6 year period, 1980 to 1986. In 1986, a higher prevalence of infection was noted in males (53.6%) than females (33.1%), but a greater rate of increase of infection over the 6 years was seen in females than males (75.7% vs 61.9% respectively). In all endemic areas, the Chachi race had a higher prevalence of infection as well as higher increase rate of infection than the Black. In the hyperendemic and hypoendemic areas the highest increase of infection was seen in the Chachi female and Chachi male respectively. The prevalence of infection in 1986 was greater than that in 1980 for all ages, with the greatest increase of infection in the 1-4 year age groups. There was an average increase of 106.2% in the microfilarial skin density with an increase seen in all age groups. A higher microfilariae density increase was seen in the hypoendemic (100.0%) than the hyperendemic (66.5%) areas. The Blacks showed a greater microfilarial density increase than the Chachi (155.1% vs 70.7% respectively) with the Black female showing the highest increase (117.6%) in the hyperendemic area and the Black male showing the highest (155.6%) in the hypoendemic area. Along the Rio Cayapas, high microfilarial densities were found in 3 major areas on the river, a reflection of man-vector exposure.

RANTES in onchocerciasis: changes with ivermectin treatment

“…The study was performed in an O. volvulus-hyperendemic area in Esmeraldas Province in Ecuador [26]. Twenty-two inhabitants were recruited from the community of Tigre along the River Cayapas.…”

Onchocerciasis in Ecuador: changes in prevalence of ocular lesions in Onchocerca volvulus infected individuals over the period 1980-1990

“…The most plausible explanation for these epidemiological changes lies with the increased disease transmission which is likely to have occurred over the same period. There is substantial evidence that both prevalence and intensity of infection in the hyperendemic area has been increasing over the period 1980 to 1990 (Guderian et al 1989, Guderian & Shelley 1992. Over the period 1980 to 1986, the prevalence of infection in the hyperendemic area increased from 63.9% to 93.7% in the Chachi and from 62.3% to 78.8% in Blacks and the intensity increased from 26.3 to 43.8 mf/ mg in both racial groups (Guderian et al 1989).…”

“…Study population -The study was performed in the hyperendemic area of the rain forest focus of onchocerciasis in the Santiago River Basin of Esmeraldas Province (Guderian et al 1989). The communities living in this area included both indigenous Amerindian (Chachi tribe) and Black (of African descent) communities.…”

“…The evolution of ocular onchocerciasis in the Esmeraldas focus in Ecuador is of particular interest in the light of the increases in infection prevalence and dermal microfilarial counts which have been documented over the period between 1980 and 1990 (Guderian et al 1989, Guderian & Shelley 1992. This report examines secular trends in prevalence rates of onchocercal ocular lesions over the same period to determine if ocular disease has remained static or evolved in parallel with these epidemiological changes.…”

Immunoglobulin kappa chain allotypes (KM) in onchocerciasis.

“…The difference in the clinical expression of onchocerciasis between Afro-Ecuadorians and the Amerindians (11)(12)(13), and its association with the HLA complex (14,15), suggest the involvement of genetic factors in susceptibility to this infection. In addition, the local and systemic immune mechanisms are clearly implicated in the Onchocerca-induced tissue damage (16 (17).…”