Avian Cholera in Waterfowl in Saskatchewan, Spring 1977

Abstract

Avian cholera was diagnosed in lesser snow geese (Anser c. caerulescens), Ross' geese (Anser rossii) and individuals of several other waterfowl species in a small area of south-western Saskatchewan over a 1 month period during the 1977 spring migration. Approximately 250 dead birds were found. This is apparently the first time avian cholera has been reported in migrating waterfowl in Canada. The site of the mortality was midway between the wintering and nesting areas of the two principal species, and the significance of the occurrence of the disease this far north is discussed.

Behaviour of Australian rainforest stream frogs may affect the transmission of chytridiomycosis

“…The formation of aggregations by host populations promotes contact between individuals, and in many other host -pathogen systems it is positively correlated with both the prevalence and intensity of contact-transmitted parasites (Anderson & May 1979, Hoogland 1979, Brown & Brown 1986, Coté & Poulin 1995, Ezenwa 2004. Outbreaks of disease are also most commonly observed in aggregations of individuals (Vermeer 1969, Wobeser et al 1979). In contrast, predominantly solitary or non-social species such as L. lesueuri and L. genimaculata will come into direct contact almost exclusively for reproduction, and it is likely that, for these species, most instances of direct transmission occur at this time (Loehle 1995).…”

Avian Cholera in Waterfowl: The Role of Lesser Snow and Ross's Geese as Disease Carriers in the Playa Lakes Region

“…Although P. multocida isolates have been recovered previously from wild waterfowl (see Botzler, 1991;Wobeser, 1992), only Samuel et al (1997) determined the serotypes of the isolates and demonstrated that the isolates were virulent. Samuel et al (1997) reported recovering only a single P. multocida serotype 1 isolate from oral swabs of more than 3,400 adult snow geese (Samuel et al, 1999b).…”

“…Since that time, the disease has been reported in wild birds from all flyways and has become the most important infectious disease affecting North American waterfowl (Friend, 1999). Avian cholera outbreaks occur almost annually as acute outbreaks at waterfowl concentration areas in the Central Valley of California, the Rainwater Basin of Nebraska, areas of Texas and Minnesota, and western Canada (Wobeser et al, 1982;Botzler, 1991) and in snow goose (Chen caerulescens caerulescens) breeding colonies (Samuel et al, 1999a). In addition, chronic transmission and infection might occur year-round in some snow goose populations (Samuel et al, 1999b).…”

“…Serologic samples obtained from snow geese at breeding colonies on Wrangel Island (Russia) and at Banks Island (Canada) when avian cholera outbreaks did not occur indicated that birds had been recently (within 3-4 mo) infected with P. multocida and survived infection (Samuel et al, 1999b). These summer outbreaks in colonial nesting species might help maintain the disease cycle through carrier birds (Botzler, 1991;Wobeser, 1992;Samuel et al, 1999b). Although serologic techniques might be useful in assessing recent infection from P. multocida (Samuel et al, 1999b), they only suggest that wild birds that survive infection could retain bacteria and become potential carriers of P. multocida, which could be transmitted later to susceptible birds.…”

“…Previous investigators have suspected that lesser snow and Ross's geese (Chen rossii) (light geese) could be the primary source of P. multocida because outbreaks have been associated with their movement and distribution patterns (Wobeser et al, 1979(Wobeser et al, , 1982Brand, 1984;Samuel et al, 2001), they suffer outbreaks and chronic mortality every year (Mensik and Samuel 1995), outbreaks that might perpetuate the disease cycle occur in snow goose breeding areas (Samuel et al, 1999a), and the magnitude of mortality in other species has been associated with snow goose mortality. This evidence suggests that snow and Ross's geese, and possibly other species, could serve as a reservoir for P. multocida.…”