Abstract
BackgroundDengue fever, a mosquito-borne disease, is associated with illness of varying severity in countries in the tropics and sub tropics. Dengue cases continue to be detected more frequently and its geographic range continues to expand. We report the largest documented laboratory confirmed circulation of dengue virus in parts of Kenya since 1982.MethodsFrom September 2011 to December 2014, 868 samples from febrile patients were received from hospitals in Nairobi, northern and coastal Kenya. The immunoglobulin M enzyme linked immunosorbent assay (IgM ELISA) was used to test for the presence of IgM antibodies against dengue, yellow fever, West Nile and Zika. Reverse transcription polymerase chain reaction (RT-PCR) utilizing flavivirus family, yellow fever, West Nile, consensus and sero type dengue primers were used to detect acute arbovirus infections and determine the infecting serotypes. Representative samples of PCR positive samples for each of the three dengue serotypes detected were sequenced to confirm circulation of the various dengue serotypes.ResultsForty percent (345/868) of the samples tested positive for dengue by either IgM ELISA (14.6 %) or by RT-PCR (25.1 %). Three dengue serotypes 1–3 (DENV1-3) were detected by serotype specific RT-PCR and sequencing with their numbers varying from year to year and by region. The overall predominant serotype detected from 2011–2014 was DENV1 accounting for 44 % (96/218) of all the serotypes detected, followed by DENV2 accounting for 38.5 % (84/218) and then DENV3 which accounted for 17.4 % (38/218). Yellow fever, West Nile and Zika was not detected in any of the samples tested.ConclusionFrom 2011–2014 serotypes 1, 2 and 3 were detected in the Northern and Coastal parts of Kenya. This confirmed the occurrence of cases and active circulation of dengue in parts of Kenya. These results have documented three circulating serotypes and highlight the need for the establishment of active dengue surveillance to continuously detect cases, circulating serotypes, and determine dengue fever disease burden in the country and region.
Highlights
Dengue fever, a mosquito-borne disease, is associated with illness of varying severity in countries in the tropics and sub tropics
Serotypes detected varied by year and region with DENV1 accounting for 44 % (96/218) of the three serotypes detected followed by DENV2 at 38.5 % (84/218) and DENV3 17.% (38/218) detected in both the northern and coastal regions of Kenya (Fig. 2)
Lack of awareness of dengue among health workers, erratic treatment seeking behavior among populations, presence of symptomatically similar illnesses like malaria and typhoid, low case fatality rates, limited availability appropriate diagnostic systems, and under reporting by existing public health systems all contribute to under recognition of dengue in the continent [1, 26]. Results during this 4 year period were able to detect multiple dengue serotypes and helped to provide clear evidence of active dengue transmission and identified serotypes circulating in parts of northeastern and coastal Kenya
Summary
A mosquito-borne disease, is associated with illness of varying severity in countries in the tropics and sub tropics. Dengue fever is regarded as the most important reemerging mosquito-borne disease globally and is endemic in more than 125 countries worldwide [1]. It is an acute systemic viral illness that manifests with varying degrees of severity ranging from a mild febrile illness to severe hemorrhagic presentations, dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). It is estimated that 96 million apparent dengue infections occurred worldwide in 2010 with most of these being reported in Asia, which bore 70 % of the global burden while Africa bore 16 % of the global burden. There are more than 390 million cases annually, of which 294 million maybe in apparent infections not detected by the public health system [4]
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