Biology subjects

Laudisoit, A.

Publications and source records attributed to Laudisoit, A..

3 recordsLinked to original sources

bioRxiv2022

Identification of the onchocerciasis vector in the Kakoi-Koda focus of the Democratic Republic of Congo

BackgroundThe objective of this study was to characterise the vector in a small hyper-endemic focus of onchocerciasis (the Kakoi-Koda focus) which has recently been discovered on the western slopes of the rift valley above Lake Albert. Methodology/Principal FindingsAquatic stages of blackflies were collected by hand from streams and rivers, and anthropophilic adult females were collected by human landing catches. Using a combination of morphotaxonomy and DNA barcoding, the blackflies collected biting humans within the focus were identified as Simulium dentulosum and S. vorax, which were also found breeding in local streams and rivers. Simulium damnosum s.l., S. neavei and S. albivirgulatum were not found (except for a single site in 2009 where crabs were carrying S. neavei). Anthropophilic specimens from the focus were screened for Onchocerca DNA using discriminant qualitative real-time triplex PCR. One specimen of S. vorax was positive for Onchocerca volvulus in the body, and out of 155 S. dentulosum, 30% and 11% were infected and infective (respectively). Conclusions/SignificanceSimulium dentulosum currently appears to be the main vector of human onchocerciasis within the Kakoi-Koda focus, and S. vorax may be a secondary vector. It remains possible that S. neavei was the main (or only) vector in the past having now become rare as a result of the removal of tree-cover and land-use changes. Simulium vorax has previously been shown to support the development of O. volvulus in the laboratory, but this is the first time that S. dentulosum has been implicated as a vector of onchocerciasis, and this raises the possibility that other blackfly species which are not generally considered to be anthropophilic vectors might become vectors under suitable conditions. Because S. dentulosum is not a vector in endemic areas surrounding the Kakoi-Koda focus, it is probable that the Kakoi-Koda focus is significantly isolated. AUTHOR SUMMARYRiver blindness (=onchocerciasis) is a severely debilitating disease caused by the nematode parasite Onchocerca volvulus, and in Africa it is known to be transmitted from person to person by blood-sucking blackflies (Diptera: Simuliidae) of the Simulium damnosum complex, the S. neavei group and (rarely) by S. albivirgulatum. Using classical morphological characteristics and DNA analysis we have unexpectedly identified the vector blackfly as S. dentulosum (and possibly S. vorax) in a small endemic area (the Kakoi-Koda focus) which has been recently discovered on the western slopes of the rift valley in the Democratic Republic of Congo above Lake Albert. In the surrounding endemic areas, the vectors are S. damnosum complex and/or S. neavei (as normally expected), and because S. dentulosum is not a vector in these surrounding areas, it follows that this focus is entomologically isolated from immigrant blackfly species which might otherwise have carried new infections into the Kakoi-Koda focus (and vice-versa). This is of local importance, because it makes elimination of the parasite easier, but our findings have wider significance across Africa, because they raise the possibility that under the right conditions, other common and widely-distributed blackfly species might unexpectedly become man-biters and significant vectors.

ecology↗

bioRxiv2020

Unravelling the evolutionary relationships of hepaciviruses within and across rodent hosts

Hepatitis C virus (HCV; genus Hepacivirus) represents a major public health problem, infecting about 3 % of the human population ({+/-} 185,000,000 people). Because no plausible animal reservoir carrying closely related hepaciviruses has been identified, the zoonotic origins of HCV still remain elusive. Motivated by recent findings of divergent hepaciviruses in rodents and a plausible African origin of HCV genotypes, we have screened a comprehensive collection of small mammals samples from seven sub-Saharan African countries. Out of 4,303 samples screened, 80 were found positive for the presence of hepaciviruses in 29 different host species. We here report 56 novel genomes that considerably increase the diversity of three divergent rodent hepacivirus lineages, which previously were almost exclusively represented by New World and European hepaciviruses. Further-more, we provide undisputable evidence for hepacivirus co-infections in rodents, which remarkably, we exclusively but repeatedly found in four sampled species of brush-furred mice. We also point at hepacivirus co-infections indirectly in different animal hosts by demonstrating evidence for recombination within specific host lineages. Our study considerably expands the available hepacivirus genomic data and elucidates the relatively deep evolutionary history that these pathogens have in rodents compared to other mammalian hosts. Overall, our results emphasize the importance of rodents as a potential hepacivirus reservoir and as models for investigating HCV infection dynamics.

evolutionary biology↗

bioRxiv2020

Coronavirus surveillance in Congo basin wildlife detects RNA of multiple species circulating in bats and rodents

Coronaviruses play an important role as pathogens of humans and animals, and the emergence of epidemics like SARS, MERS and COVID-19 is closely linked to zoonotic transmission events primarily from wild animals. Bats have been found to be an important source of coronaviruses with some of them having the potential to infect humans, with other animals serving as intermediate or alternate hosts or reservoirs. Host diversity may be an important contributor to viral diversity and thus the potential for zoonotic events. To date, limited research has been done in Africa on this topic, in particular in the Congo Basin despite frequent contact between humans and wildlife in this region. We sampled and, using consensus coronavirus PCR-primers, tested 3,561 wild animals for coronavirus RNA. The focus was on bats (38%), rodents (38%), and primates (23%) that posed an elevated risk for contact with people, and we found coronavirus RNA in 121 animals, of which all but two were bats. Depending on the taxonomic family, bats were significantly more likely to be coronavirus RNA-positive when sampled either in the wet (Pteropodidae and Rhinolophidae) or dry season (Hipposideridae, Miniopteridae, Molossidae, and Vespertilionidae). The detected RNA sequences correspond to 15 Alpha- and 6 Beta-coronaviruses, with some of them being very similar (>95% nucleotide identities) to known coronaviruses and others being more unique and potentially representing novel viruses. In seven of the bats, we detected RNA most closely related to sequences of the human common cold coronaviruses 229E or NL63 (>80% nucleotide identities). The findings highlight the potential for coronavirus spillover, especially in regions with a high diversity of bats and close human contact, and reinforces the need for ongoing surveillance.

microbiology↗