WNV Antibodies in Wild Birds, Morocco | CDC EID

EID Journal Home > Volume 15, Number 10–October 2009

Volume 15, Number 10–October 2009
Dispatch
West Nile Virus Antibodies in Wild Birds, Morocco, 2008
Jordi Figuerola, Riad E. Baouab, Ramon Soriguer, Ouafaa Fassi-Fihri, Francisco Llorente, and Miguel Angel Jímenez-Clavero
Author affiliations: Consejo Superior de Investigaciones Científicas, Seville, Spain (J. Figuerola, R. Soriguer); Université Mohammed V, Rabat, Morocco (R.E. Baouab); Institut Agronomique et Vétérinaire Hassan II, Rabat (O.Fassi-Fihri); and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Valdeolmos, Spain (F. Llorente, M.A. Jímenez-Clavero)

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Abstract
To determine circulation of West Nile virus (WNV) during nonepidemic times, we serosurveyed wild birds of Morocco in 2008. We found antibodies against WNV in 12 (3.5%) birds, against Usutu virus in 1 (0.3%), and against both in 2 (0.6%). High WNV prevalence among juvenile birds suggests local virus circulation among resident birds.

In the Mediterranean basin, West Nile virus (WNV) causes sporadic disease outbreaks, which usually affect a low number of humans and animals, after which long periods without virus circulation occur. This pattern has occurred in France (outbreaks in 2000, 2003, 2004, and 2006), Italy (1998 and 2008), Algeria (1994), Tunisia (1997 and 2003), Morocco (1996 and 2003), Romania (1996–2000), and Israel (1998–2000) (1; www.oie.int/wahis/public.php?page=home). This finding has led to the hypothesis that the virus is absent from Europe and North Africa and periodically seeded into different places by infected migratory birds. An alternative hypothesis is that the virus can remain silent, circulating in a sylvatic enzootic bird–mosquito cycle and only under appropriate conditions causing new outbreaks in humans and horses (2). To test these 2 hypotheses, research under nonepidemic conditions is needed.

During the summer of 1996, WNV outbreaks caused the death of 42 horses and 1 human (3); during 2003, a total of 5 horses died from WNV infection (4). To determine circulation of the virus during a nonepidemic year, we conducted a serosurvey of wild birds in Morocco in 2008.

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WNV Antibodies in Wild Birds, Morocco | CDC EID