Update on the biology and ecology of Culicoides species in the South-West region of Cameroon with implications on the transmission of Mansonella perstans

Abstract

Background Culicoides (Diptera; Ceratoponidae) are tiny, stout, blood-sucking flies with a near worldwide distribution. When present, they are often considered a biting nuisance but in addition, they are involved in the transmission of pathogens to humans, domestic and wild animals. Data on Culicoides species in the South-West region of Cameroon dates back to the 1950s. Over the decades, ecological transformation due to agriculture and deforestation may have affected the population dynamics of Culicoides and therefore our study provides an update of their bio-ecology in the region. Furthermore, the role of various Culicoides species in the transmission of parasitic filariae of the genus Mansonella remains inconclusive in this region. This study was designed to address these unknown issues and expand on current scientific knowledge. Results Eight species of Culicoides ( C. bedfordi , C. inornatipennis , C. fulvithorax , C. grahamii , C. imicola , C. milnei , C. neavei and C. kumbaensis ) were collected using light traps and human baits. Culicoides grahamii was the most abundant species, followed closely by C. milnei . Three species ( C. milnei , C. grahamii and C. inornatipennis ) were common in all observed larval development sites. Only four species ( C. inornatipennis , C. fulvithorax , C. grahamii and C. milnei ) were collected on humans. Anthropophilic species were more abundant ( P < 0.001) in the evening (4–7 pm) when compared to the morning collections (6–9 am). After overnight fly collections using a drop trap with a human microfilaremic donor, C. milnei emerged as the potential host for transmitting Mansonella perstans . Substantial heterogeneity was observed between the trap visiting cycles of the various species ( P < 0.001). The biting cycle of the main vector, C. milnei , showed two peaks (10–11 pm and 4–5 am), the highest being 10–11 pm. Conclusions The Culicoides fauna of the South-West region of Cameroon has not changed significantly since the 1950s. Culicoides milnei was demonstrated to be the major vector of M. perstans in this part of Cameroon. It is essentially a nocturnal species which peaks in abundance bet...

Filariasis and transfusion‐associated risk: a literature review

“…All three Mansonella species, M. perstans, M. ozzardi and M. streptocerc a , are transmitted via biting midges of the genus Culicoides [13, 30]; M. ozzardi may also be transmitted by black flies of the genus Similium . Both M. perstans and M. ozzardi may overlap in the Caribbean and Latin America [9–12, 31] (Table 1), whereby morphological approaches to diagnosis (i.e.…”

Climate predictors and climate change projections for avian haemosporidian prevalence in Mexico

“…Ceratopogonid insects show high ecological flexibility and tolerate temperature ranges from 4 to 30°C (Sprygin et al ., 2014). Several species acting as haemosporidian vectors can breed in animal excrements, the rotting fruit of cacti and other vegetation detritus (Wanji et al ., 2019). All these conditions are available in our study sites from San Luis Potosí, covering the physiographic region of the Mexican Plateau.…”

Characterising co-infections with Plasmodium spp., Mansonella perstans or Loa loa in asymptomatic children, adults and elderly people living on Bioko Island using nucleic acids extracted from malaria rapid diagnostic tests

“…The higher parasite density, as expressed by the qPCR's Cq values, of M. perstans infection found in rural areas on the East coast of Bioko Island might reflect the distribution or abundance of the vector and its active transmission in those areas. The vector Culicoides presence is more likely associated to aquatic environments, banana and plantain stems [9] that might describe the environmental characteristics of rural areas in Bioko Island. Entomological monitoring for the presence of these vectors would be justified to improve the understanding of the geographic patterns observed and inform control interventions.…”

“…In areas where different filarial nematodes are co-endemic, misclassification of mf by microscopy can be problematic [8,9]. Therefore, molecular methods have been developed to improve filarial nematode detection [10] and qPCR-based molecular techniques have shown higher sensitivity to detect low parasite density infections, and to discriminate between different filarial nematode species [8].…”