Onchocerca spp.

Hendy, Adam, Krit, Meryam, Pfarr, Kenneth, Laemmer, Christine, Witte, Jacobus De, Nwane, Philippe, Kamgno, Joseph, Nana-Djeunga, Hugues C., Boussinesq, Michel, Dujardin, Jean-Claude, Post, Rory, Colebunders, Robert, O’Neill, Sarah, Enyong, Peter & Njamnshi, Alfred K., 2021, ONCHOCERCA VOLVULUS transmission in the Mbam valley of Cameroon following 16 years of annual community-directed treatment with ivermectin, and the description of a new cytotype of SIMULIUM SQUAMOSUM, Parasites & Vectors (563) 14 (1), pp. 1-14 : 9

Onchocerca spp. transmission intensity as assessed by pool screening

Onchocerca volvulus was the predominant species developing to infective stages in S. damnosum s.l. (106/434 head pools), and while O. ochengi was present in the area (7/417 body pools), only 1/434 head pools were positive for infection. Pool screening revealed estimated infection rates in blackfly heads at Bayomen (0.10%), Nyamongo I (0.33%), and Egona II (0.13%), similar to the percentage of infective (L3H) flies encountered by dissection during the study at these sites (0.13%, 0.36%, and 0.13%, respectively) ( Fig. 7 ). However, 4/15 pools containing 1453 black flies were positive at Ondouano, 7.9 km from the riverside, despite parasites being absent from the 489 flies dissected at this site.

Figures

Fig. 7 Results of pool screening showing maximum likelihood estimate of the percentage of S.damnosum s.l. possessing L3 larvae in their heads (±95% CI) based on black flies collected over the 12-month sampling period.The number above the bar denotes the maximum likelihood point estimate for each site