ZELLER HG; Interscience Conference on Antimicrobial Agents and Chemotherapy (43rd: 2003: Chicago, Ill.).
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2003 Sep 14-17; 43: abstract no. 1768.
Institut Pasteur - UBIVE, Lyon, France.
West Nile (WN) virus is an arbovirus transmitted by mosquitoes, belonging to the Japanese encephalitis group within the Flavivirus genus and Flaviviridae family. It was originally isolated in 1937 from the blood of a febrile woman in the West Nile district in Uganda. The cycle of transmission of the virus was studied in the 1950's in Egypt; it involves birds as amplifying hosts with no apparent illness, and mosquitoes as vectors. The role of ticks as vectors is also suspected. The geographic distribution includes Africa, the Middle East, India, Australia and Southern/Eastern Europe. Humans and horses are considered as accidental dead-end hosts. Most of the cases are non symptomatic or the disease is considered as a minor flue-like illness. However some cases of encephalitis and fatalities were reported in humans in Israel in 1957, in France in 1962 both in humans and horses, or in India in children. Since the last ten years, several outbreaks are reported with fatal encephalitis cases mainly among elderly people in the Mediterranean basin and Eastern Europe: Algeria (1994), Romania (1996), Tunisia (1997), Russia (1999), Israel (2000). Epizootics in horses were described in Morocco (1996), Italy (1998) and France (2000). Phylogenetic studies have shown two main lineages among the identified WN strains. Strains from lineage I are circulating in Africa, India, Australia and are responsible for the outbreaks in Europe and in the Mediterranean basin. Strains from lineage II are circulating only in Sub Saharan Africa and Madagascar. In 1997-1998, in Israel, WN viral strains were isolated from migrating stork and domestic birds (geese) with clinical symptoms of encephalitis, paralysis and death. Similar viral strain suddenly emerged in New York during the summer 1999 killing various species of birds along with cases with fatalities in humans. The virus is now well established in the New World and the bird mortality is a key indicator for WN surveillance. In contrast, unusual mortality in birds was not noticed in Europe during the last outbreaks.West Nile viral activity was reported in France in 2001 and 2002 at a very low extend in monitored sentinel birds in the Camargue area without clinical cases in horses or humans. In Romania and Russia, a few encephalitis cases in humans are reported each year. Appropriate surveillance may reveal the presence of the virus in different locations in Europe but the occurrence of outbreaks still remains unpredictable. Further studies on the genetic susceptibility of the hosts and on the competence of potential mosquitoes vectors are needed.
Publication Types:
Keywords:
- Africa
- Africa South of the Sahara
- Africa, Northern
- Aged
- Algeria
- Animals
- Australia
- Birds
- Child
- Culicidae
- Disease Outbreaks
- Egypt
- Europe
- Europe, Eastern
- Female
- France
- Horses
- Humans
- India
- Israel
- Italy
- Madagascar
- Mediterranean Sea
- Middle East
- Morocco
- New York
- Romania
- Russia
- Tunisia
- Uganda
- West Nile virus
Other ID:
UI: 102266499
From Meeting Abstracts