Dataset Information

A household serosurvey to estimate the magnitude of a dengue outbreak in Mombasa, Kenya, 2013.

ABSTRACT: Dengue appears to be endemic in Africa with a number of reported outbreaks. In February 2013, several individuals with dengue-like illnesses and negative malaria blood smears were identified in Mombasa, Kenya. Dengue was laboratory confirmed and an investigation was conducted to estimate the magnitude of local transmission including a serologic survey to determine incident dengue virus (DENV) infections. Consenting household members provided serum and were questioned regarding exposures and medical history. RT-PCR was used to identify current DENV infections and IgM anti-DENV ELISA to identify recent infections. Of 1,500 participants from 701 households, 210 (13%) had evidence of current or recent DENV infection. Among those infected, 93 (44%) reported fever in the past month. Most (68, 73%) febrile infected participants were seen by a clinician and all but one of 32 participants who reportedly received a diagnosis were clinically diagnosed as having malaria. Having open windows at night (OR = 2.3; CI: 1.1-4.8), not using daily mosquito repellent (OR = 1.6; CI: 1.0-2.8), and recent travel outside of Kenya (OR = 2.5; CI: 1.1-5.4) were associated with increased risk of DENV infection. This survey provided a robust measure of incident DENV infections in a setting where cases were often unrecognized and misdiagnosed.

SUBMITTER: Ellis EM

PROVIDER: S-EPMC4414477 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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A household serosurvey to estimate the magnitude of a dengue outbreak in Mombasa, Kenya, 2013.

Ellis Esther M EM Neatherlin John C JC Delorey Mark M Ochieng Melvin M Mohamed Abdinoor Haji AH Mogeni Daniel Ondari DO Hunsperger Elizabeth E Patta Shem S Gikunju Stella S Waiboic Lilian L Fields Barry B Ofula Victor V Konongoi Samson Limbaso SL Torres-Velasquez Brenda B Marano Nina N Sang Rosemary R Margolis Harold S HS Montgomery Joel M JM Tomashek Kay M KM

PLoS neglected tropical diseases 20150429 4

Dengue appears to be endemic in Africa with a number of reported outbreaks. In February 2013, several individuals with dengue-like illnesses and negative malaria blood smears were identified in Mombasa, Kenya. Dengue was laboratory confirmed and an investigation was conducted to estimate the magnitude of local transmission including a serologic survey to determine incident dengue virus (DENV) infections. Consenting household members provided serum and were questioned regarding exposures and medi ...[more]

PMID: 25923210

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Project description:Between late 2017 and mid-2018, a chikungunya fever outbreak occurred in Mombasa, Kenya that followed an earlier outbreak in mid-2016 in Mandera County on the border with Somalia. Using targeted Next Generation Sequencing, we obtained genomes from clinical samples collected during the 2017/2018 Mombasa outbreak. We compared data from the 2016 Mandera outbreak with the 2017/2018 Mombasa outbreak, and found that both had the Aedes aegypti adapting mutations, E1:K211E and E2:V264A. Further to the above two mutations, 11 of 15 CHIKV genomes from the Mombasa outbreak showed a novel triple mutation signature of E1:V80A, E1:T82I and E1:V84D. These novel mutations are estimated to have arisen in Mombasa by mid-2017 (2017.58, 95% HPD: 2017.23, 2017.84). The MRCA for the Mombasa outbreak genomes is estimated to have been present in early 2017 (2017.22, 95% HPD: 2016.68, 2017.63). Interestingly some of the earliest genomes from the Mombasa outbreak lacked the E1:V80A, E1:T82I and E1:V84D substitutions. Previous laboratory experiments have indicated that a substitution at position E1:80 in the CHIKV genome may lead to increased CHIKV transmissibility by Ae. albopictus. Genbank investigation of all available CHIKV genomes revealed that E1:V80A was not present; therefore, our data constitutes the first report of the E1:V80A mutation occurring in nature. To date, chikungunya outbreaks in the Northern and Western Hemispheres have occurred in Ae. aegypti inhabited tropical regions. Notwithstanding, it has been suggested that an Ae. albopictus adaptable ECSA or IOL strain could easily be introduced in these regions leading to a new wave of outbreaks. Our data on the recent Mombasa CHIKV outbreak has shown that a potential Ae. albopictus adapting mutation may be evolving within the East African region. It is even more worrisome that there exists potential for emergence of a CHIKV strain more adapted to efficient transmission by both Ae. albopictus and Ae.aegypti simultaneously. In view of the present data and history of chikungunya outbreaks, pandemic potential for such a strain is now a likely possibility in the future. Thus, continued surveillance of chikungunya backed by molecular epidemiologic capacity should be sustained to understand the evolving public health threat and inform prevention and control measures including the ongoing vaccine development efforts.

Project description:BackgroundChikungunya virus is an alphavirus, primarily transmitted by Aedes aegypti and Ae. albopictus. In late 2017-2018, an outbreak of chikungunya occurred in Mombasa county, Kenya, and investigations were conducted to establish associated entomological risk factors.MethodsHomes were stratified and water-filled containers inspected for immature Ae. aegypti, and larval indices were calculated. Adult mosquitoes were collected in the same homesteads using BG-Sentinel and CDC light traps and screened for chikungunya virus. Experiments were also conducted to determine the ability of Culex quinquefasciatus to transmit chikungunya virus.ResultsOne hundred thirty-one houses and 1637 containers were inspected; 48 and 128 of them, respectively, were positive for immature Ae. aegypti, with the house index (36.60), container index (7.82) and Breteau index (97.71) recorded. Jerry cans (n = 1232; 72.26%) and clay pots (n = 2; 0.12%) were the most and least inspected containers, respectively, while drums, the second most commonly sampled (n = 249; 15.21%), were highly positive (65.63%) and productive (60%). Tires and jerry cans demonstrated the highest and lowest breeding preference ratios, 11.36 and 0.2, respectively. Over 6900 adult mosquitoes were collected and identified into 15 species comprising Cx. quinquefasciatus (n = 4492; 65.04%), Aedes vittatus (n = 1137; 16.46%) and Ae. aegypti (n = 911; 13.19%) and 2 species groups. Simpson's dominance and Shannon-Wiener diversity indices of 0.4388 and 1.1942 were recorded, respectively. Chikungunya virus was isolated from pools of Ae. aegypti (1) and Cx. quinquefasciatus (4), two of which were males. Minimum infection rates of 3.0 and 0.8 were observed for female Ae. aegypti and Cx. quinquefasciatus, respectively. Between 25 and 31.3% of exposed mosquitoes became infected with CHIKV 7, 14 and 21 days post-exposure. For the experimentally infected Cx. quinquefasciatus mosquitoes, between 13 and 40% had the virus disseminated, with 100% transmission being observed among those with disseminated infection.ConclusionsThese results demonstrated high risk of chikungunya transmission for residents in the sampled areas of Mombasa. Transmission data confirmed the probable role played by Cx. quinquefasciatus in the outbreak while the role of Ae. vittatus in the transmission of chikungunya virus remains unknown.

Project description:BackgroundAedes aegypti and Aedes albopictus play a fundamental role in transmission of dengue virus to humans. A single infected Aedes mosquito is capable to act as a reservoir/amplifier host for dengue virus and may cause epidemics via horizontal and vertical modes of dengue virus (DENV) transmission. The present and future dengue development can be clarified by understanding the elements which help the dissemination of dengue transmission. The current study deals with molecular surveillance of dengue in addition to ecological and social context of 2013 dengue epidemics in Swat, Pakistan.MethodsHerein, we reported dengue vectors surveillance in domestic and peridomistic containers in public and private places in 7 dengue epidemic-prone sites in District Swat, Pakistan from July to November 2013. Using the Flaviviruses genus-specific reverse transcriptase (RT) semi nested-PCR assay, we screened blood samples (N = 500) of dengue positive patients, 150 adult mosquito pools and 25 larval pools.ResultsThe 34 adult and 7 larval mosquito pools were found positive. The adult positive pools comprised 30 pools of Ae. aegypti and 4 pools of Ae. albopictus, while among the 7 larval pools, 5 pools of Ae. aegypti and 2 pools of Ae. albopictus were positive. The detected putative genomes of dengue virus were of DENV-2 (35% in 14 mosquito pools & 39% in serum) and DENV-3 (65% in 27 mosquito pools & 61% in serum). The higher vector density and dengue transmission rate was recorded in July and August (due to favorable conditions for vector growth). About 37% of Ae. aegpti and 34% Ae. albopictus mosquitoes were collected from stagnant water in drums, followed by drinking water tanks (23% & 26%), tires (20% & 18%) and discarded containers (10% & 6%). Among the surveyed areas, Saidu was heavily affected (26%) by dengue followed by Kanju (20% and Landikas (12%). The maximum infection was observed in the age group of <15 (40%) followed by 15-45 (35%) and >45 (25%) years and was more in males (55.3%) as compare to females (44.7%). The increase in vector mosquito density and the subsequent viral transmission was determined by a complex interplay of ecological, biological and social factors.ConclusionThe suitable environmental conditions and discriminable role of Aedes through trans-ovarial transmission of DENV is indispensable in the recent geographic increase of dengue in Pakistan. Climate change affects the survival and dispersion of vectors as well as the transmission rates of dengue. Control of Aedes mosquitoes (vectors) and elimination of breeding sources must be emphasized and prioritized. Such actions may not only reduce the risk of dengue transmission during epidemics, but also minimize the chances of dengue viruses establishment in new (non endemic) areas of the region.

Dataset Information

A household serosurvey to estimate the magnitude of a dengue outbreak in Mombasa, Kenya, 2013.

Publications

A household serosurvey to estimate the magnitude of a dengue outbreak in Mombasa, Kenya, 2013.

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