Alphaviruses Detected in Mosquitoes in the North-Eastern Regions of South Africa, 2014 to 2018.

The prevalence and distribution of African alphaviruses such as chikungunya have increased in recent years. Therefore, a better understanding of the local distribution of alphaviruses in vectors across the African continent is important. Here, entomological surveillance was performed from 2014 to 2018 at selected sites in north-eastern parts of South Africa where alphaviruses have been identified during outbreaks in humans and animals in the past. Mosquitoes were collected using a net, CDC-light, and BG-traps. An alphavirus genus-specific nested RT-PCR was used for screening, and positive pools were confirmed by sequencing and phylogenetic analysis. We collected 64,603 mosquitoes from 11 genera, of which 39,035 females were tested. Overall, 1462 mosquito pools were tested, of which 21 were positive for alphaviruses. Sindbis (61.9%, N = 13) and Middelburg (28.6%, N = 6) viruses were the most prevalent. Ndumu virus was detected in two pools (9.5%, N = 2). No chikungunya positive pools were identified. Arboviral activity was concentrated in peri-urban, rural, and conservation areas. A range of Culicidae species, including Culex univittatus, Cx. pipiens s.l., Aedes durbanensis, and the Ae. dentatus group, were identified as potential vectors. These findings confirm the active circulation and distribution of alphaviruses in regions where human or animal infections were identified in South Africa.

First confirmed occurrence of the yellow fever virus and dengue virus vector Aedes (Stegomyia) luteocephalus (Newstead, 1907) in Mozambique.

BACKGROUND: Mozambique, same as many other tropical countries, is at high risk of arthropod-borne virus (arbovirus) diseases and recently two dengue virus (DENV) outbreaks occurred in the northern part of the country. The occurrence of some important vector species, such as Aedes (Stegomyia) aegypti (Linnaeus) and Ae. (Stg.) albopictus (Skuse), besides several other sylvatic vectors, have been reported in the country, which may indicate that the transmission of some arboviruses of public health importance may involve multiple-vector systems. Therefore, knowing the occurrence and distribution of existing and the new important vectors species, is crucial for devising systematic transmission surveillance and vector control approaches. The aim of this study was to map the occurrence and distribution of mosquito species with potential for transmitting arboviruses of human and veterinary relevance in Niassa Province, Northern Mozambique. METHODS: Field entomological surveys were undertaken in April 2016 in Lago District, Niassa Province, northern Mozambique. Breeding sites of mosquitoes were inspected and immature stages were collected and reared into adult. Mosquitoes in the adult stages were morphologically identified using taxonomic keys. Morphological identification of Aedes (Stegomyia) luteocephalus (Newstead) were later confirmed using dissected male genitalia and molecular based on the phylogenetic analyses of the sequenced barcode (cox1 mtDNA) gene. RESULTS: A total of 92 mosquito larvae collected developed into adults. Of these, 16 (17.39%) were morphologically identified as Ae. luteocephalus. The remaining specimens belonged to Ae. (Stg.) aegypti (n = 4, 4.35%), Ae. (Aedimorphus) vittatus (n = 24, 26.09%), Anopheles garnhami (n = 1, 1.09%), Culex (Culiciomyia) nebulosus (n = 28, 30.43%), Eretmapodites subsimplicipes (n = 18, 19.57%) and Toxorhynchites brevipalpis (n = 1, 1.09%), taxa already known to the country. Male genitalia and phylogenetic analyses confirmed the identity of Ae. luteocephalus specimens collected in this study. CONCLUSIONS: To our knowledge, this is the first detection of Ae. luteocephalus in Mozambican territory, a vector species of yellow fever virus (YFV), Zika virus (ZIKV) and dengue virus (DENV) in Africa. Further studies are encouraged to investigate the role of Ae. luteocephalus in the transmission of arboviral diseases in Mozambique.

First confirmed occurrence of the yellow fever virus and dengue virus vector Aedes (Stegomyia) luteocephalus (Newstead, 1907) in Mozambique

Mozambique, same as many other tropical countries, is at high risk of arthropod-borne virus (arbovirus) diseases and recently two dengue virus (DENV) outbreaks occurred in the northern part of the country. The occurrence of some important vector species, such as Aedes (Stegomyia) aegypti (Linnaeus) and Ae. (Stg.) albopictus (Skuse), besides several other sylvatic vectors, have been reported in the country, which may indicate that the transmission of some arboviruses of public health importance may involve multiple-vector systems. Therefore, knowing the occurrence and distribution of existing and the new important vectors species, is crucial for devising systematic transmission surveillance and vector control approaches. The aim of this study was to map the occurrence and distribution of mosquito species with potential for transmitting arboviruses of human and veterinary relevance in Niassa Province, Northern Mozambique.

Mosquito surveys and West Nile virus screening in two different areas of southern Portugal, 2004-2007.

Longitudinal mosquito surveys were carried out in southern Portugal from 2004 to 2007, in a wetland area (Comporta, District of Setúbal) and around the perimeter of a dam irrigation plant that created the largest artificial lake in Europe, 250 km(2) (Alqueva, Districts of Evora and Beja). Our aim was to study the diversity, abundance, and seasonal dynamics of mosquitoes, comparing these two different areas, to screen mosquitoes for West Nile Virus (WNV), an arboviral agent already detected in Portugal, because these areas are populated with abundant avian fauna. Monthly collections of adult mosquitoes were carried out by Centers for Disease Control light-traps with CO(2) and by indoor resting collections. Mosquitoes were identified and screened for arboviruses by reverse transcriptase (RT)-polymerase chain reaction directed toward amplification of a 217-bp fragment of the NS5 gene. Mosquito peak densities were observed in July-August in Comporta and May-June, with a plateau in July-October, in Alqueva. However, densities were far higher in Comporta area (220,821 specimens) than in Alqueva area (9442 specimens), with a clear difference in species distribution, as in Comporta the predominant species was Culex theileri (85%), followed by Aedes caspius (6%), Anopheles atroparvus (4%), and Culex pipiens sensu latu (s.l.) (3%), whereas in Alqueva the predominant species was Cx. pipiens s.l. (56%), followed by An. atroparvus (18%), Cx. theileri (14%), and Culiseta longiareolata (9%). Female mosquitoes (8842 in 175 pools) of the species Ae. caspius, An. atroparvus, Culex mimeticus, Cx. pipiens Sensu latu (s.l.), Cx. theileri, and Culex univittatus were screened and found to be negative for WNV genomic RNA. Although there was no detection of WNV sequences in mosquitoes, vigilance should continue as the circulation of virus has been previously detected more than once in Portugal, in humans, animals, and mosquitoes, and in other surrounding Mediterranean countries.