|
|
Letter
Human West Nile Virus, France
Pascal Del Giudice,*
Isabel Schuffenecker,† Fréderic Vandenbos,* Evelyne Counillon,* and Hervé
Zeller†
*Hôpital Bonnet, Fréjus, France; and †Institut Pasteur, Lyon, France
Suggested
citation for this article
To the Editor: West Nile virus (WNV) is a mosquito-transmitted
flavivirus, widely distributed in Africa, the Middle East, Asia, and southern
Europe. Since the 1990s, its geographic distribution has expanded and
caused epidemics of meningoencephalitis (1). Recently
introduced into the United States, it expanded rapidly from New York throughout
the country and caused illness in 9,862 human patients in 2003 (2).
In France, the first reported WNV outbreak that affected horses and humans
occurred during the summer of 1962 in the Camargue region (1).
After 1965, no human or equine WNV infections were reported until September
2000, when a large outbreak of equine encephalitis occurred in France
(3). No human cases were reported at that time. In September
2003, a human living in Fréjus (Département du Var, southeastern France)
was diagnosed with acute WNV infection in Nice University Hospital. At
the same time, an equine case was diagnosed 20 km from the patient’s home;
consequently, public health authorities initiated a retrospective study
of patients hospitalized in the French Mediterranean region in which viral
meningoencephalitis was suspected. We report four human cases from Fréjus
Hospital.
Twenty patients who had been hospitalized at some time from August 1
to October 15, 2003, for febrile meningitis, encephalitis, or polyradiculoneuritis
were screened. Four patients in whom cerebrospinal fluid (CSF) analysis
indicated a viral cause were included. In addition, serum samples from
two patients who had experienced flulike symptoms with exanthema during
the same period were tested further. Serologic diagnosis of acute WNV
infection was based on immunoglobulin (Ig) M-capture and direct IgG enzyme-linked
immunosorbent assay followed by 80% plaque reduction neutralization titer
(PRNT80) by using the France 2000 WNV strain (3).
Patient 1, 46 years old, and patient 2, 25 years old, had a flulike syndrome
with maculopapular exanthema; WNV seroconversion was seen on a pair of
sera collected on days 3 and 16 for patient 1, and days 3 and 12 for patient
2, after onset of fever. Patients 3 and 4 had meningoencephalitis with
maculopapular exanthema. In patient 3, a fourfold increase in WNV neutralizing
antibodies was seen in serum samples on 2 consecutive days (days 3 and
15 after onset of fever). In patient 4, WNV IgM antibodies were detected
in CSF (day 4 after onset of fever), and neutralizing antibodies (titer
= 160) were reported in a serum specimen on day 75. Attempts to detect
WNV RNA by reverse transcription–polymerase chain reaction, or to isolate
the virus from serum specimens in patients 1 and 2 and CSF in patient
4, were negative because of the low level and short duration of WNV viremia
(4). All patients recovered.
On the basis of serologic results, we describe the first human clinical
WNV infections in France since 1964 (5). The four patients
lived in the same city, had not traveled, and had an onset of their illness
during the last week of August 2003. Of note, four clinical infections
were identified, but many more WNV subclinical and asymptomatic infections
likely occurred simultaneously.
After the reemergence of WNV in horses in the Camargue region in 2000,
surveillance on sentinel birds (ducks and chickens) showed a low circulation
of WNV in 2001 and 2002 in this area. Meanwhile, no clinical human or
equine cases were detected. During the summer of 2003, WNV reemerged in
humans 200 km east of Camargue, in the Département du Var, along the Mediterranean
coast. A study conducted on French blood donors from September to November
2000 showed low titers of WNV neutralizing antibodies in two donors originating
from the Département du Var (6). However, to date, no
clinical human cases have been reported in this area.
WNV must be considered as a causative agent of meningitis, encephalitis,
and polyradiculoneuritis during summer and early fall in southern France.
Given the capacity of WNV to cause large outbreaks, the surveillance will
be extended to the entire Mediterranean coastal area.
Acknowledgments
We thank Mireille
Grelier and Pierre Dellamonica for helpful discussion and Séverine Murri
for excellent technical assistance.
References
- Murgue B, Zeller H, Deubel V. The ecology and epidemiology
of West Nile virus in Africa, Europe and Asia. In: Mackenzie JS, Barrett
ADT, Deubel V, editors. New York: Springer; 2002. p. 195–221.
- West Nile Virus Statistics, Surveillance, and Control [monograph on
the Internet]. Centers for Disease Control and Prevention [cited 2004
Jul 30]. Available from www.cdc.gov/ncidod/dvbid/westnile/surv&controlCaseCount03_detailed.htm
- Murgue B, Murri S, Zientara S, Durand B, Durand JP, Zeller H. West
Nile virus outbreak in horses, southern France, 2000: the return after
35 years. Emerg Infect Dis. 2001;7:692–6.
- Lanciotti RS, Kerst AJ, Nasci RS, Godsey MS, Mitchell CJ, Savage HM,
et al. Rapid
detection of West Nile virus from human clinical specimens, field-collected
mosquitoes, and avian samples by a TaqMan reverse transcription-PCR
assay. J Clin Microbiol. 2000;38:4066–71.
- Hannoun C, Panthier R, Mouchet J, Ezouan JP. Isolement en France du
virus West Nile à partir de malades et du vecteur Culex modestus
Ficalbi. Comptes-Rendus Académie Sciences Paris. 1964;259:4170–2.
- Charrel RN, de Lamballerie X, Durand JP, Gallian P, Attoui H, Biagini
P, et al. Prevalence
of antibody against West Nile virus in volunteer blood donors living
in southeastern France. Transfusion. 2001;41:1320–1.
Suggested citation
for this article:
Del Giudice P, Schuffenecker
I, Vandenbos F, Evelyne C, Zeller H. Human West Nile virus, France [letter].
Emerg Infect Dis [serial on the Internet]. 2004 Oct [date cited].
Available from: http://www.cdc.gov/ncidod/EID/vol10no10/03-1021.htm
|
