First Evidence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Hong Kong Amphibian Trade

Abstract

The emerging infectious amphibian diseases caused by amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranaviruses are responsible for global amphibian population declines and extinctions. Although likely to have been spread by a variety of activities, transcontinental dispersal appears closely associated with the international trade in live amphibians. The territory of Hong Kong reports frequent, high volume trade in amphibians, and yet the presence of Bd and ranavirus have not previously been detected in either traded or free-ranging amphibians. In 2012, a prospective surveillance project was conducted to investigate the presence of these pathogens in commercial shipments of live amphibians exported from Hong Kong International Airport. Analysis of skin (Bd) and cloacal (ranavirus) swabs by quantitative PCR detected pathogen presence in 31/265 (11.7%) and in 105/185 (56.8%) of amphibians, respectively. In addition, the water in which animals were transported tested positive for Bd, demonstrating the risk of pathogen pollution by the disposal of untreated wastewater. It is uncertain whether Bd and ranavirus remain contained within Hong Kong’s trade sector, or if native amphibians have already been exposed. Rapid response efforts are now urgently needed to determine current pathogen distribution in Hong Kong, evaluate potential trade-associated exposure to free-ranging amphibians, and identify opportunities to prevent disease establishment.

Distribution and Host Range of Ranaviruses

“…Schloegel et al ( 2009 ) found that 8.5 % of amphibians imported into the USA at three major port Allender), and ( f ) infected green striped tree dragon ( Japalura splendida ) with ranavirus-associated dermatitis in Germany (credit = Helge Behncke) cities were infected with ranavirus. Similarly, Kolby et al ( 2014 ) found over 50 % of amphibians exported via Hong Kong International Airport were infected with ranavirus. Reptiles infected with ranaviruses also have been discovered in internationally traded animals (Hyatt et al 2002 ;Stöhr et al 2013bStöhr et al , 2015.…”

“…For example, barred tiger salamander ( Ambystoma mavortium ) larvae are sold as fi shing bait in the southwestern USA, and as many as 100 % have been shown to be infected with the ranavirus, Ambystoma tigrinum virus (ATV; Picco and Collins 2008 ;Brunner et al 2015 ). Amphibian ranaviruses have been found in animals that are traded over international borders for a variety of reasons, including human consumption and the pet trade (Schloegel et al 2009 ;Kolby et al 2014 ). Schloegel et al ( 2009 ) found that 8.5 % of amphibians imported into the USA at three major port Allender), and ( f ) infected green striped tree dragon ( Japalura splendida ) with ranavirus-associated dermatitis in Germany (credit = Helge Behncke) cities were infected with ranavirus.…”

“…If novel strains of ranaviruses are introduced into naïve populations, experimental evidence suggests that there could be devastating effects (e.g., Pearman et al 2004 ;Storfer et al 2007 ;Hoverman et al 2010 ). With the trade in animals being truly global and ranaviruses accompanying them (e.g., Schloegel et al 2009 ;Kolby et al 2014 ), it is important to understand what ranaviruses are being transported and where they end up.…”

Pathogenic fungus in feral populations of the invasive North American bullfrog in Argentina

“…The chytrid fungus Batrachochytrium dendrobatidis (Bd) (Chytridiomycetes: Ryzophydiales) (2) has been recognized as responsible for mass mortalities or population extinctions of numerous anuran species in different continents (e.g., 3,4,5 and citations therein). There is evidence that legal and illegal trade in amphibians as pets, food and for bio-control is one of the reasons for the spread of Bd (6,7,8,9).…”

Design and Analysis of Ranavirus Studies: Surveillance and Assessing Risk

“…The World Organization for Animal Health (OIE) lists ranaviruses that infect amphibians as notifiable pathogens, meaning that a subsample of amphibians that are involved in international trade should be verified ranavirus negative prior to shipment (Schloegel et al 2010). Currently, these regulations are not being enforced in most countries (Kolby et al 2014). The procedures we outline below are based on principles and recommendations of the OIE (Vose 2000;OIE 2014), with examples of how they can be applied to parts of an IRA for the introduction of a ranavirus into an uninfected area.…”