Movement of animals vectors and intermediate hosts

Migrating birds can move potential human pathogens into new regions, as has been shown with West Nile virus and H5N1 influenza A (avian) virus (Rappole et al., 2000; Chen et al., 2005; Liu et al., 2005). Much movement of animals (live, dead, parts) is orchestrated by humans, sometimes with disastrous consequences. The importation of wild animals from Ghana that were then housed with wild-caught prairie dogs from the United States led to an outbreak of monkeypox (a disease previously known to exist only in Africa) in the Midwest (Reed et al., 2004). Hunting of bushmeat, as local populations seek a source of protein and as logging roads make trade easier, threatens some wild animal species. Killing and butchering wild animals also puts people at risk for becoming infected with pathogens in animals (Wolfe et al., 2005). The global market in bushmeat has grown. A report from the UK Department of Environment, Food and Rural Affairs estimated that 11,600 tons of illegal bushmeat were smuggled into the UK in 2003 (Daily Telegraph, 5 September 2004; main.jhtml). Shipments included monkey, rat, bat, gorilla, camel, and elephant. Consumption is on the increase outside of Asia, Africa, and South America as immigrant populations expand in Europe, North America, and other areas.

Illegal trade may also be a source of imported pathogens. Two Crested Hawk-Eagles were confiscated in Brussels after being carried from Thailand via Vienna in hand luggage placed in an overhead storage bin on airplanes. Although the birds did not appear ill, both were found to be infected with highly pathogenic H5N1 virus (van Borm et al., 2005).

Mosquitoes are regularly carried on commercial flights and ships, and can be introduced into new regions where they may be able to survive and become established locally (Sutherst, 2004). Depending on the local environment and opportunities, they may be able to transmit tropical infections to humans. During the period 1969 through August 1999, 12 countries reported 89 cases of confirmed or probable cases of "airport malaria" - instances when an infected mosquito was transported by plane from a malaria-endemic region to an area without malaria and survived long enough to transmit malaria to a local resident. Most countries were in Europe, but the US, Australia, and Israel also reported cases (Muentener et al., 1999; Gratz et al., 2000).

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