2003: Birds, Migration and Emerging Zoonoses: West Nile Virus, Lyme Disease,

1: Clin Med Res. 2003 Jan;1(1):5-12. Related Articles, Links


Birds, Migration and Emerging Zoonoses: West Nile Virus, Lyme Disease,
Influenza A and Enteropathogens.

Reed KD, Meece JK, Henkel JS, Shukla SK.

Clinical Research Center, Marshfield Medical Research Foundation,
Marshfield, Wisconsin.

Wild birds are important to public health because they carry emerging
zoonotic pathogens, either as a reservoir host or by dispersing
infected arthropod vectors. In addition, bird migration provides a
mechanism for the establishment of new endemic foci of disease at great
distances from where an infection was acquired. Birds are central to
the epidemiology of West Nile virus (WNV) because they are the main
amplifying host of the virus in nature. The initial spread of WNV in
the U.S. along the eastern seaboard coincided with a major bird
migration corridor. The subsequent rapid movement of the virus inland
could have been facilitated by the elliptical migration routes used by
many songbirds. A number of bird species can be infected with Borrelia
burgdorferi, the etiologic agent of Lyme disease, but most are not
competent to transmit the infection to Ixodes ticks. The major role
birds play in the geographic expansion of Lyme disease is as dispersers
of B. burgdorferi-infected ticks. Aquatic waterfowl are asymptomatic
carriers of essentially all hemagglutinin and neuraminidase
combinations of influenza A virus. Avian influenza strains do not
usually replicate well in humans, but they can undergo genetic
reassortment with human strains that co-infect pigs. This can result in
new strains with a marked increase in virulence for humans. Wild birds
can acquire enteropathogens, such as Salmonella and Campylobacter spp.,
by feeding on raw sewage and garbage, and can spread these agents to
humans directly or by contaminating commercial poultry operations.
Conversely, wild birds can acquire drug-resistant enteropathogens from
farms and spread these strains along migration routes. Birds contribute
to the global spread of emerging infectious diseases in a manner
analogous to humans traveling on aircraft. A better understanding of
avian migration patterns and infectious diseases of birds would be
useful in helping to predict future outbreaks of infections due to
emerging zoonotic pathogens.

PMID: 15931279 [PubMed - as supplied by publisher]

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