Entomological Coinfections of Arboviruses Dengue and Chikungunya Viruses along the Coastline of Kenya

Abstract

Arthropod-borne disease outbreaks as a result of pathogen influx including arboviruses transmitted by strains of Aedes species occur periodically in varying spots in Kenya. However, there has been paucity of documented information on the Aedes species involved in transmission of different haplotypes of arboviruses. This study assessed for concomitant infection of arboviruses in different vectors. Aedes species were sampled by Bio gent sentinel trap. Mosquitoes were stunned at 4°C for 5 minutes; sorted according to site, species and sex. RNA was extracted using Trizole®. cDNA was generated using one step real time PCR. Proportions of vectors and arboviruses were analyzed by R-statistics. A total of 37, 220 mosquitoes of Aedes species were analyzed. Vectors were: Aedes aegypti formosus (23,265=62.5%), Aedes aegypti aegypti (4,931=13.2%), Aedes mcintoshi (3,557=9.56%), Aedes ochraceus (2,156=5.79%), Aedes pembaensis (2,049=5.51%), Aedes tricholabis (487=1.31%), Aedes albicosta (415=1.11%), Aedes fulgens (200=0.54%) and Aedes fryeri (160=0.43%). Dengue virus (DENV) had highest entomological infections at 79% (n=1910) while Chikungunya (CHIKV) at 21%. DENV-2 had the highest frequency at 54%, while DENV-4 with the least frequency at 6%. Only ECSA genotype of CHIKV was present. Concomitant infections of arboviral haplotypes in different clades of Aedes species occur along the coastal region. Aedes aegypti aegypti is incubates all serotypes of DENV and genotype of CHIK viruses thus the major vectors of arboviruses. This information is important as it gives knowledge on areas at high risk for arboviral disease outbreaks. Consecutively, up scaled survey and implementation of control and prevention measures taken appropriately.

Mosquitoes of Etiological Concern in Kenya and Possible Control Strategies

“…Aedes aegypti and A. albopictus of African and Asian origins, respectively, are globally known for their invasive nature and role in transmitting viruses that cause chikungunya, dengue fever, yellow fever, Zika, and encephalitis [32]. The success of these species in virus transmission has been attributed to three mechanisms: interaction of vector and the host, transovarial transmission, and sexual mating [28,33].…”

“…An important species is A. ochraceus which is highly distributed in the arid regions of north-eastern Kenya and linked to the spread of Rift Valley fever virus (RVFV), NDUV, Bunyamwera virus (BUNV), Babanki virus (BBKV), Sindbis virus (SNBV), and Semliki Forest virus (SMFV) in the region [4,11,34,35,36,37,38]. Additionally, this species has also been reported to be associated with RVFV, dengue virus (DENV), and chikungunya virus (CHKV) in coastal counties (Kwale, Kilifi, Mombasa, Lamu) [11,33,39], and some parts of in the western region [22]. Aedes mcintoshi and A. sudanensis are also important arbovirus vectors occasionally reported in coastal and north-eastern regions [4,11,14,22,33,36,40], while A. circumluteolus have been reported in Busia and Garissa counties [4,22,36].…”

“…Additionally, this species has also been reported to be associated with RVFV, dengue virus (DENV), and chikungunya virus (CHKV) in coastal counties (Kwale, Kilifi, Mombasa, Lamu) [11,33,39], and some parts of in the western region [22]. Aedes mcintoshi and A. sudanensis are also important arbovirus vectors occasionally reported in coastal and north-eastern regions [4,11,14,22,33,36,40], while A. circumluteolus have been reported in Busia and Garissa counties [4,22,36]. Other Aedes secondary vectors of arboviruses such as: A. tricholabis [4,33], A. Albicosta [33], A. fulgens [33], A. fryeri [33], A. pembaensis [33], and A. Luridus [4] have been identified in various parts of the country and mostly along the Kenyan coastline.…”

“…Aedes aegypti , the principal vector of dengue, chikungunya, and other emerging arboviruses is also widely distributed in Kenya [4,33,44] but not uniformly, with more occurrence being recorded in the lowlands [22]. It exists in two forms that were found coexisting sympatrically in Rabai, along the coast of Kenya [45]: the domestic, light-colored A. aegypti aegypti and the sylvatic form, A. aegypti formosus, which is dark in color [45,46].…”

Dengue virus infection in Aedes mosquitoes at the interface of human-livestock-wildlife ecosystem in Kilosa District, Morogoro, Tanzania.

“…Previous studies in Kilosa and the neighbouring Kilombero district have reported a high prevalence of DENV among febrile children seeking health care from hospitals [10,12]. This indicates the possibility of transmission of DENV infection in the ecosystem from mosquito to human and livestock [26-28] hence chance of co-infections in mosquitoes as reported by Ngala [29]. Circulation of DENV has also been recently reported among residents of the neighbouring Kilombero District [12] and elsewhere in Tanzania [9].…”