Biting behaviour and infectivity of Simulium damnosum complex with Onchocerca parasite in Alabameta, Osun State, Southwestern, Nigeria

Abstract

A longitudinal study was carried out to investigate species composition, seasonal abundance, parity and transmission potential of Simulium damnosum complex in Alabameta community in Osun State, Southwestern, Nigeria. Adult Simulium damnosum complex were collected along Owena River, Alabameta, by two dark complexioned vector collectors from 07:00hr to 18:00hr weekly using collecting tubes from November 2014 to April 2015. The flies were morphologically identified and dissected for the purpose of detecting Onchocerca parasite using dissecting microscope. The Monthly Biting Rate (MBR) of flies was determined using World Health Organization standard formula. A total of four hundred and forty flies were collected during the study period with all of them identified as forest species of Simulium damnosum complex. There was significant variation in monthly collection of the flies with the month of November having the highest number of flies (194) (44%) while the month of April recorded the lowest number of flies (31) (7%) (p<0.05). The morning biting peak (09hr - 11hr) (137) was higher than the evening biting peak (15hr -17hr) (64) (p<0.05) while nulliparous flies (294) (67%) were more abundant than the parous flies (146) (33%) (p<0.05). There was absence of infection (zero infectivity) of the flies (p<0.05). The zero infectivity in the flies may plausibly indicate the possibility of zero transmission of Onchocerca parasite in the community which if sustained over a period of time may signify the possibility of onchocerciasis elimination. Also, the presence of forest species of the flies reduces the risk of resident’s intense exposure to blinding savannah strain of onchocerciasis.

Status of Onchocerciasis Elimination in Gabon and Challenges: A Systematic Review

“…Moreover, the maximum density of black flies was observed during the wet rather than the dry season. This is consistent with observations made in Nigeria [46], supported by the fact that increased rainfall will favor the breeding of black flies [48]. Thus, the result of the density showed that the daily bite rate was very high in this forest area of Mahouya (506.6 bites/man/day) compared to those observed in the Sudanian-Cameroonian savannah region (195 flies/person/day) and the rainforest (100 flies/person/day) [44].…”

“…Thus, after one year of capture in the Mahouya village, 30,397 black flies were collected. The number of Diptera reported in the single study carried out in Gabon was higher than those reported from Galabat (8202 flies) in Sudan [ 45 ] and Alabameta, Osum State in Nigeria (440 black flies) [ 46 ]. However, this was lower than Abu-Hamed’s reported number (39,394 flies) [ 45 ].…”

Black flies and Onchocerciasis: Knowledge, attitude and practices among inhabitants of Alabameta, Osun State, Southwestern, Nigeria

“…Among the filarial nematodes, the public health significance of Onchocerca volvulus cannot be overemphasized being the causative organism of the dreadful and debilitating disease onchocerciasis [ 1 ]. O .…”

Species diversity and daily infestation patterns of Haematophagus flies in cattle farms at Tanah Bumbu District, South Kalimantan Province, Indonesia

“…These flies can attack and suck human blood, so they have the potential to transmit diseases from animals to humans (Keita et al 2020;Rochon et al 2021). Blood-sucking flies have a greater potential to transmit the disease because apart from carrying pathogens to external parts of the body, flies can also transmit pathogens contained within their bodies, such as Trypanosoma, Mansonella, Onchocerca worms, Toscana viruses, and others (Baldacchino et al 2013;Es-Sette et al 2014;Ta-Tang et al 2018;Busari et al 2021). The negative impact caused by blood-sucking flies is very significant from an economic point of view, with reduced livestock productivity and threats to public health (Narladkar 2018;Libera et al 2022).…”