Viral and bacterial diseases in amphibians
Hemmingway, Valentine, Brunner, Jesse, Speare, Rick, and Berger, Lee (2009) Viral and bacterial diseases in amphibians. In: Heatwole, Harold, and Wilkinson, John W., (eds.) Amphibian Decline: diseases, parasites, maladies and pollution. Amphiban Biology, 8 . Surrey Beatty & Sons, Australia, pp. 2963-2985.
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At least six groups of viruses have been reported to affect amphibians, including caliciviruses, herpesviruses, and iridoviruses (Johnson and Wellehan 2005). Only ranaviruses are known to cause widespread mass mortality and have been studied in detail; hence a review of this group of viruses forms the majority of this chapter. Various strains of ranavirus are found worldwide and some appear to have spread recently (Hyatt et al. 2000). Indicative of the broad host range of ranaviruses and their potentially devastating effects, ranaviral disease was listed by the World Organization for Animal Health (OIE) as an internationally notifiable disease in 2008. Although their impacts on populations of declining species are a concern, there is currently no evidence that they have caused permanent declines or extinctions (Daszak et al. 2003). Nevertheless, because of their potential impacts on naive populations, as well as on species that are facing multiple threats, it is important that the risk of spreading these pathogens is minimized (Cunningham et al. 2007a).
There have been few investigations into other amphibian viruses. Apart from Frog Erythrocytic Virus (FEV), their impact on wild populations has not been studied. Lucke tumor herpesvirus has been well described, but the other viruses found associated with disease in amphibians have been reported in single papers with little or no experimental work. Their significance as pathogens of amphibians is therefore largely unknown. In addition other viruses, not reviewed here, such as arboviruses (including West Nile Virus), retroviruses and an adenovirus, can infect frogs but their pathogenicity to amphibians is low or unknown (Densmore and Green 2007).
There are no substantiated reports of bacteria causing outbreaks in wild frogs, and cases of bacterial disease were rare during large surveys for disease in the United States and Australia (Berger 2001; Green et al. 2002). Bacterial diseases, including septicaemia, are associated with significant mortality in captivity and are associated with poor husbandry. For details on prevention, management and treatment of bacterial diseases in captivity see Wright and Whitaker (2001). Zoonotic bacteria carried by wild and captive amphibians with minimal effect on themselves, but which are potential risk to humans (e.g., Salmonella and Leptospira), are not included in the present review.
|Item Type:||Book Chapter (Research - B1)|
|Date Deposited:||19 May 2010 00:16|
|FoR Codes:||06 BIOLOGICAL SCIENCES > 0608 Zoology > 060899 Zoology not elsewhere classified @ 100%|
|SEO Codes:||96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960499 Control of Pests, Diseases and Exotic Species not elsewhere classified @ 100%|