Isolation of west nile and sindbis viruses from mosquitoes collected in the Nile Valley of Egypt during an outbreak of Rift Valley fever.
As part of an evaluation of potential vectors of arboviruses during a Rift Valley fever (RVF) outbreak in the Nile Valley of Egypt in August 1993, we collected mosquitoes in villages with known RVF viral activity. Mosquitoes were sorted to species, pooled, and processed for virus isolation both by intracerebral inoculation into suckling mice and by inoculation into cell culture. A total of 33 virus isolates was made from 36,024 mosquitoes. Viruses were initially identified by indirect fluorescent antibody testing and consisted of 30 flaviviruses (all members of the Japanese encephalitis complex, most probably West Nile [WN] virus) and three alphaviruses (all members of western equine encephalitis complex, most probably Sindbis). The identity of selected viruses was confirmed by reverse transcriptase-polymerase chain reaction and sequencing. Culex antennatus (Becker) and Culex perexiguus Theobald accounted for five (17%) and 23 (77%) of the WN virus isolations, respectively. Despite isolation of viruses from 32 pools of mosquitoes (both WN and Sindbis viruses were isolated from a single pool), RVF virus was not isolated from these mosquitoes, even though most of them are known competent vectors collected during an ongoing RVF outbreak. Thus, it should be remembered, that even during a known arbovirus outbreak, other arboviruses may still be circulating and causing disease.
Turell
Michael J
MJ
Virology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA. michael.turell@det.amedd.army.mil
Morrill
John C
JC
Rossi
Cynthia A
CA
Gad
Adel M
AM
Cope
Stanton E
SE
Clements
Tamara L
TL
Arthur
Ray R
RR
Wasieloski
Leonard P
LP
Dohm
David J
DJ
Nash
Denise
D
Hassan
Mosaad M
MM
Hassan
Ali N
AN
Morsy
Zakaria S
ZS
Presley
Steven M
SM
D000818:Animals; D000852:Anopheles / Q000821:virology*; D003465:Culex / Q000821:virology*; D009033:Culicidae / Q000821:virology; D004279:DNA, Viral / Q000032:analysis; D004196:Disease Outbreaks; D004534:Egypt / Q000453:epidemiology; D051379:Mice; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012295:Rift Valley Fever / Q000453:epidemiology* / Q000821:virology; D012845:Sindbis Virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D014902:West Nile virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*
D004279:DNA, Viral