Dengue fever is the most common arboviral infection worldwide. Its epidemiology in Africa is not yet fully understood due to the lack of awareness, the presence of other dengue-like febrile diseases, and insufficient laboratory capabilities. This paper reports on the import of dengue virus serotype 2 case from Côte d'Ivoire to Senegal in West Africa. Phylogenetic analysis based on full-length genome sequence revealed that the isolate clustered with strains of cosmopolitan genotypes from the Burkina Faso outbreak in 2016 and those from the ongoing dengue fever outbreak in Côte d'Ivoire. This suggests a possible spread of strains from the Burkina Faso outbreak to other West African countries including Côte d'Ivoire and Senegal.

Dengue fever is a major public health problem in the world, because it is especially endemic in the tropical and subtropical areas. Arbovirus infection is less well documented in African countries. We aimed to assess the distribution of patients in the dengue epidemic and the seroprevalence of different serotypes of the circulating dengue virus. A retrospective study included analyses of human blood samples sent to the National Reference Laboratory for diagnosis during dengue infection outbreak. Samples were screened by IgM capture ELISA (MAC-ELISA) or by RT-PCR. Of the 2,849 serum samples from suspected dengue cases, 2,297 (80.6%) were from Abidjan. The seroprevalence of dengue was (15.1%) during this epidemic. The seroprevalence of dengue virus serotypes in cocirculation was predominated by DENV-2 with 189 cases (6.6%), followed by DENV-3 77 cases (2.7%), and DENV-1 14 cases (0.5%). The seroprevalence in children was 8.7% compared to 19.0% in adults. The age group of 16 to less than 45 years accounted for 54.0% of total positive cases. In addition, positive peak was observed in July (28.3%) and Abidjan East was the most affected locality. The increasing trend of serotypes of the dengue virus cocirculation suggests that Abidjan is becoming a hyperendemic state from an endemic one.

Lassa fever has not been reported in Côte d’Ivoire. We performed a retrospective analysis of human serum samples collected in Côte d’Ivoire in the dry seasons (January–April) during 2015–2018. We identified a fatal human case of Lassa fever in the Bangolo District of western Côte d’Ivoire during 2015.