Epidemic West Nile Virus Encephalitis in Tunisia

Abstract

West Nile fever (WNF) is a mosquito-borne flavivirus infection. It is epidemic in Africa and Asia. In autumn 1997, a WNF epidemic occurred in the Sfax area (southeastern Tunisia). Fifty-seven patients were hospitalized with aseptic meningitis and/or encephalitis. Search for specific anti-West Nile virus (WNV) antibodies in serum and cerebrospinal fluid (CSF) was performed using an ELISA test. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the WNV genome in CSF and brain specimens. Recent central nervous system (CNS) infection by WNV was confirmed in 30 patients, probable infection in 17 and it was excluded in 10. In the confirmed subgroup, patients with encephalitis were older than those with meningitis. CSF showed pleocytosis, high protein (47%) and normal glucose levels. Brain computed tomography-scan (CT-scan) and magnetic resonance imaging (MRI) were normal. RT-PCR disclosed WNV genome in the CSF in two cases and in a brain specimen in one. Three patients died rapidly, the remaining cases had favorable prognosis. Autopsy was performed in two cases and showed nonspecific lesions of encephalitis. No viral inclusions were seen with light microscopy. Seropositivity rate in patients’ proxies for WNV was 23.4%. Prognosis of CNS involvement during WNF seemed to be poor in older patients. This is the first WNV encephalitis epidemic report in the Sfax area of Tunisia.

Seroprevalence of West Nile Virus in Ghana

“…Since the discovery of the first isolate of WNV in Uganda in 1937, few outbreaks of West Nile disease were reported between 1988 and 2003 in African countries such as the Sudan (8,24), the Democratic Republic of Congo (19), and Tunisia (1,9), but to our knowledge none occurred in West Africa. Few viral isolates in humans, mosquitoes, and domestic animals were reported in 1958-1998 from Kenya, WANG ET AL.…”

Mapping the Serological Prevalence Rate of West Nile fever in Equids, Tunisia

“…In Tunisia, two major outbreaks of WNF were reported in humans. At the fall of 1997, a total of 173 human cases of meningoencephalitis were recorded, with 8 deaths (Triki et al., ; Feki et al., ). In 2003, WNV infections were confirmed in 21 patients with neurological signs, including 3 fatal cases (Hachfi et al., ).…”

“…An entomological survey conducted in Tunisia after the WNF epidemic of 1997 (Feki et al., ) showed the abundance of Culex and Aedes species, potential vectors of WNV in Tunisia (El Ghoul, ). Culex pipiens was abundant including in urban areas (Feki et al., ): it is an opportunistic mosquito, feeding on birds and mammals. Therefore, it might play the role of bridge species between birds and mammals.…”

Prevalence of IgM and IgG antibodies to West Nile virus among blood donors in an affected area of north-eastern Italy, summer 2009

“…The largest European outbreak occurred in 1996 in Bucharest, Romania [10]. In the Mediterranean area, the first outbreak of human encephalitis was identified in the Camargue, France, in 1962 [11], followed by other epidemics in the 1990s involving a relatively high number of human cases in Algeria [8], Tunisia [12] and Israel [13,14]. In the past few years, cases of WNV encephalitis have also been reported in the Volgograd region in Russia [15], in Hungary [16] and Romania [17], and very recently in Greece [18].…”