Dengue virus (DENV) is arthropod-borne virus that is prevalent in tropical and sub-tropical regions. Main vectors for the virus are mosquitoes of the Aedes genus, including Aedes egypti and Aedes albopictus [1, 2]. DENV belong to the family Flaviviridae, genus Flavivirus. The virus has a positive-sense, enveloped, single-stranded RNA genome of approximately 11 kb in length which have been categorised into four serotypes, DENV 1–4. DENV 2 reported to cause the most epidemics followed by DENV 1[3, 4, 5].
In recent year’s DENV have caught worldwide attention because of increase in the frequency of major epidemics . Globally, 50–100 million DENV infections occur annually, accounting for 20,000–70,000 deaths per year. An estimated 2.5 billion people are at risk of infection. Dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) account for about 250,000–500,000 cases each year. Children under 5 years of age are mainly affected. In hyperendemic Asian countries, 22–292 per 1,000 children are infected each year [6, 7, 8]. Dengue epidemics have been reported in African countries since 19th century and all four DENV serotypes have been isolated [3, 9]. The recent outbreak of DENV in Sub-Saharan Africa ascertain that febrile illnesses are now becoming the next threat to the population living in malaria endemic areas . Early 2013, outbreak of dengue was reported in Somalia and Kenya where majority of cases were found in the Indian Ocean Coastal town of Mombasa. Most recently, outbreak was reported in Dar es Salaam, Tanzania. In 2014 dengue outbreak, a total of 2,129 suspected case and 1,018 confirmed cases were reported, where as in 2019 outbreak about 3,000 suspected cases with 71.4% confirmed cases and 2 deaths were reported [11, 12].
Many cases of DENV infections in most of the hospitals in Sub-Saharan Africa remain undiagnosed due to lack of accurate diagnostic technique. Every so often febrile illness are treated as presumptive malaria without proper laboratory diagnosis [3, 13, 14]. The clinical manifestation of DENV infections may be confused with those caused by chikungunya fever and other febrile illness, but unlike chikungunya and other febrile illness, DENV infections is associated with DHF and DSS .
Virus culture is often regarded as gold standard method for laboratory diagnosis of DENV but is time consuming and must be performed under biosafety level 3 conditions. Viral culture is rarely done in routine clinical diagnosis as these facilities are not widely available [1, 16]. Serological diagnosis based on capture IgM and IgG ELISA are reliable can only detect IgM around 5 days from the onset of illness and in addition strong antibody cross-reactivity occurs among members of the family which may confuse interpretation of the results [1, 17, 18].
To date, polymerase chain reaction (PCR) methods have been suggested as appropriate laboratory diagnostic technique of DENV infections [1, 14]. Real-time reverse transcriptase PCR (RT-PCR) has been developed as an accurate diagnostic technique at an early stage of infection of several arboviruses. Advantages of Real time RT-PCR over other diagnostic methods including, higher sensitivity, higher specificity and rapidity [2, 16, 19, 20]. The aim of this study was to optimize real-time RT-PCR for detection of DENV infections by using rapid and simple nucleic acid extraction method.