Human and entomologic investigations of chikungunya outbreak in Mandera, Northeastern Kenya, 2016

Abstract

Chikungunya is a reemerging vector borne pathogen associated with severe morbidity in affected populations. Lamu, along the Kenyan coast was affected by a major chikungunya outbreak in 2004. Twelve years later, we report on entomologic investigations and laboratory confirmed chikungunya cases in northeastern Kenya. Patient blood samples were received at the Kenya Medical Research Institute (KEMRI) viral hemorrhagic fever laboratory and the immunoglobulin M enzyme linked immunosorbent assay (IgM ELISA) was used to test for the presence of IgM antibodies against chikungunya and dengue. Reverse transcription polymerase chain reaction (RT-PCR) utilizing flavivirus, alphavirus and chikungunya specific primers were used to detect acute infections and representative PCR positive samples sequenced to confirm the circulating strain. Immature mosquitoes were collected from water-holding containers indoors and outdoors in the affected areas in northeastern Kenya. A total of 189 human samples were tested; 126 from Kenya and 63 from Somalia. 52.9% (100/189) tested positive for Chikungunya virus (CHIKV) by either IgM ELISA or RT-PCR. Sequence analysis of selected samples revealed that the virus was closely related to that from China (2010). 29% (55/189) of the samples, almost all from northeastern Kenya or with a history of travel to northern Kenya, tested positive for dengue IgM antibodies. Entomologic risk assessment revealed high house, container and Breteau indices of, 14.5, 41.9 and 17.1% respectively. Underground water storage tanks were the most abundant, 30.1%, of which 77.4% were infested with Aedes aegypti mosquitoes. These findings confirm the presence of active chikungunya infections in the northeastern parts of Kenya. The detection of dengue IgM antibodies concurrently with chikungunya virus circulation emphasizes on the need for improved surveillance systems and diagnostic algorithms with the capacity to capture multiple causes of arbovirus infections as these two viruses share common vectors and eco-systems. In addition sustained entomological surveillance and vector control programs targeting most productive containers are needed to monitor changes in vector densities, for early detection of the viruses and initiate vector control efforts to prevent possible outbreaks.

Community-based sero-prevalence of chikungunya and yellow fever in the South Omo Valley of Southern Ethiopia

“…reservoirs for CHIKV and for many other arboviruses. The proximity of the present study area to Kenya, a country reported the occurrence of CHIKV infection [14][15][16]20] could have resulted in an increased sero-prevalence of CHIK in the present study area since migration and travel of people across the border inferring the likelihood of transmission of this virus.…”

“…CHIK outbreaks have been reported from many African countries including Uganda [13], Kenya [14][15][16], Sudan [17] and Tanzania [18]. Despite the proximity of Ethiopia to these countries, and migration of people across the border between Ethiopia and contingent countries as well as the existence of the potential mosquito vectors (Aedes bromeliae and Aedes aegypti) responsible for transmitting CHIKV in the study area [9], and the repeatedly occurrence of CHIK outbreaks in Kenya [14-16, 19, 20], either health facility or community-based survey of CHIKV infection has not been conducted in the present study area.…”

Epidemiological and Entomological Investigation of Chikungunya Fever Outbreak, in Serdang Bedagai District, North Sumatera Province, Indonesia, 2013

“…This activity needs unrelenting contribution from the whole of affected communities (4,24). High numbers of disposable water containers has been shown to be a risk in other chikungunya outbreaks in another countries and in Indonesia as well, as it increases breeding sites for Aedes (6,12,16,25,(29)(30)(31)(32).…”

Arboviruses in the East African Community partner states: a review of medically important mosquito-borne Arboviruses

“…The legend shows the country names and their year of accession into the EAC in bracket. Non-human primates, humans [115,149,192,[195][196][197][200][201][202] Ndumu During this time there were more than 20 known arboviruses including the Yellow fever virus which were unrelated to the virus, hence it was named Bunyamwera [30,31]. The virus has spread across many regions over the past decades and remains an important virus due to its ability to cause human diseases.…”

“…taylori and Ae. cordellieri in South Africa and non-human primates [192,201,202]. Outbreaks of CHIKV have occurred across the globe [1] since the first outbreak in Tanzania.…”