A cross-sectional survey on the seroprevalence of dengue fever in febrile patients attending health facilities in Cross River State, Nigeria

BACKGROUND: In Nigeria, recent reports suggest that dengue viruses could be a major cause of acute fevers. We sought to make a cross-sectional estimate of the prevalence of current and previous dengue infections in patients presenting with fever to healthcare centres in Cross River State Nigeria. METHODOLOGY/PRINCIPAL FINDINGS: This cross-sectional health facility survey recruited persons with temperature ≥38°C. Dengue virus immunoglobulin M (IgM)/immunoglobulin G (IgG) antibody testing using Onsite Duo dengue Ag-IgG/IgM lateral flow immunoassay cassettes was done. Samples which tested positive were further confirmed using the RecombiLISA dengue IgM and IgG enzyme linked immunosorbent assay kits and classified into primary and secondary dengue infection. Malaria testing was carried out using microscopy. Between 4 January 2017 and 24 August 2017 a total of 420 participants were sampled across 11 health centres. The mean age was 34 (range = 1–99), 63% were female, 49% reported sleeping under a treated mosquito net in the past week and 44% reported taking an antimalarial prior to seeking care. The mean number of days fever was present prior to seeking care was 8, and many of the participants presented with symptoms indicative of respiratory or urinary tract infections. Testing indicated that 6% (95% CI: 2, 13; n = 24) had either a primary or secondary dengue infection with or without co-existing malaria, while 4% (95% CI: 2, 9; n = 16) had either a primary or secondary dengue infection without co-existing malaria. 52% (95% CI: 46, 58; n = 218) had a malaria infection with or without any dengue infection, and 50% (95% CI: 44, 57; n = 210) had a malaria infection without any dengue infection. CONCLUSION: Our study confirms the presence of dengue at not insignificant levels in patients attending health centres with fever in this south eastern province of Nigeria. These data highlight the danger of the common presumption in this setting that fever is due to malaria. Surveillance for dengue is vital in this setting.