A cross sectional study of dengue virus infection in febrile patients presumptively diagnosed of malaria in Maiduguri and Jos plateau, Nigeria

BACKGROUND: In Nigeria, where malaria is endemic, greater than 70% of febrile illnesses are treated presumptively as malaria, often without a laboratory evaluation for other possible causes of fever. This cross-sectional study evaluated the presence of dengue virus infection in febrile patients, presumptively diagnosed of malaria infections in the clinic. METHODOLOGY: Blood samples were collected from 529 febrile patients (246 in Jos and 283 in Maiduguri) attending the general outpatient clinics of the Jos University Teaching Hospital (JUTH) and the University of Maiduguri Teaching Hospital (UMTH) and tested for anti-dengue immunoglobulin M (IgM) and immunoglobulin G (IgG), as well as anti-non-structural protein (NS1) by ELISA. The samples were also evaluated for presence of P. falciparum malaria parasites by microscopic examination of Giemsa-stained blood smears. RESULTS: The prevalence of confirmed, highly suggestive and probable dengue virus infections categorized in relation to duration of illness since onset of fever were 2.3%, 5.5% and 1.5% respectively, while the prevalence of anti-flavivirus IgG and IgM seropositivity was 11.7%. In a total of 117 (22.1%) patients (32 in Jos, 85 in Maiduguri), malaria parasites were detected by blood smear microscopy, out of which 7 (6%) also had a positively confirmed, highly suggestive or probable dengue test result. CONCLUSION: Although the high cross-reactivity of anti-flavivirus antibodies should be taken into account in the interpretation of the seroprevalence data, our findings suggest a significant presence of dengue virus in this environment, some of which may otherwise be misdiagnosed as malaria. These findings are strong enough to recommend serological screening for anti-dengue virus titer and NS1 antigen for all febrile patients, as part of fever diagnostic protocols in tropical regions. Given the prevalence of dengue virus infections, there is also a need for a dengue control program and public education to prevent outbreaks and occurrence of severe dengue complications.