First Report of Sylvatic DENV-2-Associated Dengue Hemorrhagic Fever in West Africa

Abstract

Dengue virus (DENV) circulates in human and sylvatic cycles. Sylvatic strains are both ecologically and evolutionarily distinct from endemic viruses. Although sylvatic dengue cycles occur in West African countries and Malaysia, only a few cases of mild human disease caused by sylvatic strains and one single case of dengue hemorrhagic fever in Malaysia have been reported. Here we report a case of dengue hemorrhagic fever (DHF) with thrombocytopenia (13000/µl), a raised hematocrit (32% above baseline) and mucosal bleeding in a 27-year-old male returning to Spain in November 2009 after visiting his home country Guinea Bissau. Sylvatic DENV-2 West African lineage was isolated from blood and sera. This is the first case of DHF associated with sylvatic DENV-2 in Africa and the second case worldwide of DHF caused by a sylvatic strain.

Dengue Outbreak in Mombasa City, Kenya, 2013–2014: Entomologic Investigations

“…The distribution of dengue vectors and several other factors including rapid population growth, unplanned urbanization, and increased international travel increase the risk of dengue transmission [16]. Indeed, over the past 5 decades, dengue cases have been reported in many countries in sub-Saharan Africa [10] including European travelers returning from Tanzania, Zanzibar, the Comoros, Benin, Cape Verde, Gunea Bisau and Senegal [17–20] and the 2011–2013 outbreaks in Angola and Kenya [21,22]. This apparent emergence of DENV in most of Africa might be due to increased awareness of the disease, availability of better diagnostic tests, and improved access to specialized laboratory facilities [23].…”

Viral kinetics of primary dengue virus infection in non-human primates: A systematic review and individual pooled analysis

“…These sylvatic viruses are ancestral to the four serotypes of DENV that are currently transmitted between humans by domestic and peridomestic Aedes [7]. Populations living in areas surrounding sylvatic hotspots of DENV transmission are at risk of infection [8, 9] from a transmission process that is poorly understood [10]. Importantly, it has recently been discovered that sylvatic DENV infection in humans can produce the most severe manifestation of dengue disease – dengue hemorrhagic fever [8, 9].…”

“…Populations living in areas surrounding sylvatic hotspots of DENV transmission are at risk of infection [8, 9] from a transmission process that is poorly understood [10]. Importantly, it has recently been discovered that sylvatic DENV infection in humans can produce the most severe manifestation of dengue disease – dengue hemorrhagic fever [8, 9]. In the light of recent advances in DENV vaccines [11, 12], sylvatic reservoirs may play a key role in maintaining transmission over long time scales and may continue to expose human populations to new, genetically distinct viruses after human endemic transmission is controlled [7].…”

Genetic and phenotypic characterization of sylvatic dengue virus type 4 strains

“…Both species bite humans, resulting in potential transmission of sylvatic DENV to humans. Indeed, several reports have now documented spillover of sylvatic DENV, resulting in infection of individual humans or small outbreaks (Cardosa et al, 2009; Carey et al, 1971; Franco et al, 2011; Monlun et al, 1992; Saluzzo et al, 1986a; Saluzzo et al, 1986b; Vasilakis et al, 2008c). Currently it is not possible to distinguish sylvatic and human DENV infections with antibody-based assays, and thus sylvatic DENV infections may frequently be misclassified as human DENV.…”

“…Currently it is not possible to distinguish sylvatic and human DENV infections with antibody-based assays, and thus sylvatic DENV infections may frequently be misclassified as human DENV. Nonetheless two recent reports from Southeast Asia (Cardosa et al, 2009) and West Africa (Franco et al, 2011) reveal that sylvatic DENV infections can result in severe disease.…”