Genetic characterization of West Nile Virus strains during neuroinvasives infection outbreak in Tunisia, 2018

Abstract

West Nile Virus (WNV) is a vector-borne flavivirus mainly transmitted by Culex mosquitoes in sylvatic cycles involving birds, as amplifying host, and bird-feeding mosquitoes, as vectors (Jourdain et al., 2007;Turell, 2012; Vázquezet al., 2011). Humans and equines are considered as incidental dead-end hosts (Mcvey et al., 2015).WNV was first isolated from a febrile woman in 1937 in Uganda (Smithburn et al., 1940); nowadays, it is recognized as one of the most widespread arbovirus worldwide with major public health concerns. Related infections have been reported in Africa, Middle East,

Epidemiology of West Nile virus in Africa: An underestimated threat

“…Following the introduction of WNV-L1 in the New World, a huge number of sequences have been obtained overtime [ 3 , 14 , 20 ]. Interestingly, phylogenetic analysis demonstrated that the strain PaH001 isolated in Tunisia in 1997 roots the tree of WNV-L1 circulating in North America [ 14 , 21 ]. Furthermore, phylogenetic and genetic distance studies evidenced that the Tunisian strain PaH001 is closely related to a group of highly conserved viruses collected in America and Israel between 1998 and 2000, suggesting that viruses circulating in the Middle East / North Africa are related to those circulating in North America [ 14 ].…”

“…Several WNV outbreaks in humans were registered in the African continent starting from the 1950s [ 2 , 13 , 21 , 34 , 41 , 44 , 46 , 49 , 104 – 106 ]. Neurological cases and fatalities related to WNV-L2 were reported in South Africa (1976, 1980, 1984) while in the Mediterranean basin, hundreds of cases of encephalitis and deaths related to WNV-L1 (clade A) were registered in Tunisia between 1997 and 2018 (1997, 2003, 2007, 2010, 2011, 2012, 2016, 2018) [ 21 , 41 , 44 , 104 , 107 ]. In addition, WNV-L1 human infections were recorded for the first time in the 1994 and 1996 in Algeria and Morocco, respectively [ 44 , 82 , 105 ].…”

“…A possible introduction of WNV-L1 in Europe from Morocco is also suspected: the closest ancestor of the European strains could be a Moroccan strain which appears to be closely genetically related to French and Italian isolates (France: 2000(France: , 2006Italy: 1998Italy: , 2008 [3]. Up to date, WNV-L1 has been reported in the following African countries: Algeria, Central African Republic, Egypt, Co ˆte d'Ivoire, Kenya, Morocco, Tunisia, Senegal, and South Africa [1,2,14,15,18,19,[21][22][23].…”

Which Plagues are Coming Next?

“…WNV is now considered endemic in the US with as many as 47 US states reporting WNV cases each year [38]. Although the incidence of WNV has increased throughout the decades, most human WNV infection are asymptomatic [39]. About 1% of infected individuals experience severe neuroinvasive disease such as meningitis, encephalitis, and flaccid paralysis [39,40].…”

“…Although the incidence of WNV has increased throughout the decades, most human WNV infection are asymptomatic [39]. About 1% of infected individuals experience severe neuroinvasive disease such as meningitis, encephalitis, and flaccid paralysis [39,40]. The movement of migratory birds in addition to the local movement of sedentary birds are hypothesized to contribute to the global distribution of WNV [38].…”