West Nile Virus Surveillance using Sentinel Birds

Abstract

Captive and free‐ranging birds have been used for decades as living sentinels in arbovirus surveillance programs. This review summarizes information relevant to selecting sentinel bird species for use in surveillance of West Nile (WN) virus. Although experience using avian sentinels for WN virus surveillance is limited, sentinels should be useful for both detecting and monitoring WN virus transmission; however, sentinel bird surveillance systems have yet to be adequately tested for use with the North American strain of WN virus. Captive chickens are typically used for arbovirus surveillance, but other captive species may be used as well. Serosurvey and experimental infection data suggest that both chickens and pigeons show promise as useful captive sentinels; both species were naturally exposed during the epizootics in New York City, 1999‐2000, and both species develop antibodies after infection without becoming highly infectious to Culex pipiens vectors. Wild bird species that should be targeted for use as free‐ranging sentinels include house sparrows and pigeons. The ideal wild bird should be determined locally on the basis of seroprevalence studies. Interpreting serological data generated from studies using free‐ranging sentinel birds is complex, however. Sentinel bird monitoring sites should be selected in enzootic transmission foci. Several years of observation may be required for selection of effective sentinel monitoring sites.

Limited pathogenicity of Usutu virus for the domestic chicken (Gallus domesticus)

“…However, natural infection via mosquitoes might result in a slightly different outcome. Nonetheless, looking at the experimental resistance of chickens to WNV, which is also proven under natural conditions (Komar, 2001), it is highly likely that the result of this 1,2,3,4,5,7 1,2,3,4,5,7 3,5,7 Á/ 6 Positive,7 d.p.i. 1,2,3,4,5 ,7 1,2,3,4,5,7 3,5,7 Á/ 7 Negative,10 d.p.i.…”

“…In the case of these viruses, and also some alphaviruses, however, chickens develop reliable and robust viraemias and seroconversions (Maguire & Miles, 1965;Campbell & Hore, 1975;Calisher et al ., 1986;Reisen et al ., 1994;Komar et al ., 2001), which allow the use of chickens in vector competence studies and monitoring programmes for virus activity (Morris et al ., 1994;Komar, 2001;Broom et al ., 2002a;Blackmore et al ., 2003;Reisen et al ., 2004;Quirin et al ., 2004). Contrary to these findings, experimental USUV infection only inconsistently led to viraemia and seroconversion.…”

Evaluation of a West Nile virus surveillance and early warning system in Greece, based on domestic pigeons

“…Four categories of birds have been used for WNV surveillance; dead wild birds, trapped wild birds, captive sentinel birds, or domestic sentinel birds [22]. In the USA the value of using WNV-infected dead birds as an indicator of increased WNV disease risk has been demonstrated in several studies [23][24][25].…”

“…Sentinel chicken -based WNV surveillance systems have provided evidence of WNV transmission several weeks before the occurrence of human cases [29]. Moreover, pigeons have already been identified as potential sentinel birds [22]. Consequently, active surveillance of domestic birds has been used successfully in America and Europe for their early warning capacity [30][31][32][33][34][35].…”

“…An ideal sentinel bird is a species that is susceptible to infection, is resistant to disease, develops a detectable immune response rapidly, is maintained easily, presents negligible health risks to handlers, does not contribute to local pathogen transmission cycles and seroconverts to the target pathogen prior to the onset of disease outbreaks in the community [22]. Chickens and pigeons develop low-level WNV viremia [27] and are maintained easily in captivity, making them ideal sentinel species [28].…”