Zoonoses and sapronoses of wild birds in the urban ecosystem

Public Health Significance of Urban Pests Birds 259 258 and respiratory tract disorders in birds, or more often subclinical and asymptomatic infections. Cryptosporidium oocysts were found in faeces and cloacal specimens of gulls herring gulls and black-headed gulls in Scotland Smith et al., 1993, and Cryptosporidium baileyi has been detected very frequently in black-headed gulls 28–100 chicks positive in the Czech Republic; respiratory cryptosporidiosis was also diagnosed in several young gulls Pavlásek, 1993. However, no cryptosporidial infections of people have been reported as attributable to, or directly associated with, urban birds.

8.3. Zoonoses and sapronoses of wild birds in the urban ecosystem

Although zoonoses of avian origin remain relatively infrequent Cooper, 1990, many of the agents considered here see Table 8.1 have been found to cause sporadic human cases or epidemics of corresponding zoonoses and sapronoses in urban areas, while others, though already established as associated with urban birds, have not yet been reported to cause infections in people attributable to, or directly caused by, urban birds. Nonetheless, vigilance is necessary, as the incidence of disease might be significantly underreported, and there might be a number of undiagnosed cases. Pathogens significantly associated with wild and feral birds in urban areas are, for example: • mosquito-borne SLEV several epidemics in North American cities; • WNV epidemics with hundreds of patients in Bucharest, 1996–1997; in Volgograd, 1999–2000; and in United States cities, 1999–2006; • Chlamydophila psittaci at least 500 cases of ornithosis acquired from feral pigeons have been reported in the world since 1966; • Borrelia burgdorferi s.l. blackbirds in urban parks are carriers of infected ticks and are amplifying hosts of the agent; • Campylobacter jejuni; • enterotoxigenic Escherichia coli; • Salmonella enterica, particularly serovars Typhimurium and Enteritidis; • Cryptococcus neoformans pigeon droppings can be the microhabitat for the growth of the yeast-like fungus at urban gathering places of feral pigeons, such as church belfries, old buildings and squares; and • Histoplasma capsulatum hundreds of human cases of histoplasmosis acquired near com- munal roosts of blackbirds and starlings in North American city parks. The ability of some fungi less so of certain bacteria to grow in avian excreta and nests is remarkable. These pathogens assimilate uric acid and other low-molecular-weight Table 8.1. Important human microbial pathogens associated with wild birds Agent Arthropod Avian association Human disease Geographic Avian disease vector with the agent No. of cases a area St. Louis encephalitis flavivirus Mosquito Principal hosts NDC b Americas None West Nile flavivirus Mosquito Principal hosts NDC b Worldwide Encephalitis some strains TBE flavivirus complex Ixodes tick Occasional hosts, NDCc Europe, Asia Occasional tick carriers e.g., in the grouse Chlamydophila psittaci None Principal hosts About 500 Worldwide Ornithosis Coxiella burnetii Argasid tick Occasional hosts 5 Worldwide None Borrelia burgdorferi sensu lato Ixodes tick Occasional hosts, NDCc N. America, None tick carriers Eurasia Campylobacter jejuni None Principal hosts About 60 Worldwide Campylobacterosis in juveniles Escherichia coli enteropathogenic None Occasional hosts – Worldwide None Salmonella enterica None Occasional hosts Tens Worldwide Salmonellosis Yersinia pseudotuberculosis None Occasional hosts – Worldwide Pseudotuberculosis Listeria monocytogenes None Occasional hosts – Eurasia, Asia Listeriosis Erysipelothrix rhusiopathiae None Occasional hosts – Worldwide Erysipelas Mycobacterium avium None Principal hosts – Worldwide Tuberculosis Mycobacterium xenopi None Occasional hosts Tens Worldwide Mycobacteriosis Candida albicans None Hosts, lessors – Worldwide Candidosis Candida parapsilosis None Hosts, lessors 12 Worldwide None Cryptococcus neoformans None Lessors, occasional hosts Tens Worldwide None Histoplasma capsulatum None Lessors About 1000 Americas None Toxoplasma gondii None Occasional hosts Several Worldwide Toxoplasmosis a Reported human disease cases or epidemics directly associated with urban birds or their habitats. b The number of cases acquired directly from urban wild birds has yet been described, but the birds can serve as amplifying hosts that contribute to the circulation of the agent in urban areas. c The number of cases acquired directly from birds has been described, but wild birds can serve as carriers of infected preimaginal ixodid ticks and can thus contribute to the circulation of the agent in urban areas. Notes. NDC: no direct cases; –: no data or no detailed reports. Source: Prepared by the author from numerous sources, all of them present in the reference list. ceptible to T. gondii when infected with it experimentally. For instance, pigeons inocu- lated with T. gondii have shown distinct clinical abnormalities Biancifiori et al., 1986. Infected birds, such as pigeons, are less mobile and more susceptible to predation by cats which, as a definite host, could transmit the disease to other mammals, including human beings. On several occasions, pigeons were found to be the source of human toxoplas- mosis Orlandella Coppola, 1969; Neto Levi, 1970.

8.2.4.4. Cryptosporidiidae

Cryptosporidium is an enteric intracellular coccidian parasite that causes gastrointestinal Public Health Significance of Urban Pests Birds 261 260 8.4. Management implications 8.4.1. Benchmarks