The use of singleplex and nested PCR to detect Batrachochytrium dendrobatidis in free-living frogs

Many microorganisms are able to cause diseases in amphibians, and in the past few years one of the most reported has been Batrachochytrium dendrobatidis. This fungus was first reported in Brazil in 2005; following this, other reports were made in specimens deposited in museum collections, captive and free-living frogs. The aim of this study was to compare singleplex and nested-PCR techniques to detect B. dendrobatidis in free-living and apparently healthy adult frogs from the Brazilian Atlantic Forest. The sample collection area was a protected government park, with no general entrance permitted and no management of the animals there. Swabs were taken from the skin of 107 animals without macroscopic lesions and they were maintained in ethanol p.a. Fungal DNA was extracted and identification of B. dendrobatidis was performed using singleplex and nested-PCR techniques, employing specific primers sequences. B. dendrobatidis was detected in 61/107 (57%) and 18/107 (17%) animals, respectively by nested and singleplex-PCR. Nested-PCR was statistically more sensible than the conventional for the detection of B. dendrobatidis (Chi-square = 37.1; α = 1%) and the agreement between both techniques was considered just fair (Kappa = 0.27). The high prevalence obtained confirms that these fungi occur in free-living frogs from the Brazilian Atlantic Forest with no macroscopic lesions, characterizing the state of asymptomatic carrier. We concluded that the nested-PCR technique, due to its ease of execution and reproducibility, can be recommended as one of the alternatives in epidemiological surveys to detect B. dendrobatidis in healthy free-living frog populations.(AU)

Chytridiomycosis: a Devastating Emerging Fungal Disease of Amphibians

Amphibians have suffered the most striking declines among all vertebrates. Infectious diseases are one of the causes and Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd) is considered the most concerning one. This emerging infectious disease infects a broad variety of amphibians and is considered responsible for numerous declines and extinctions of these animals. Bd has been reported all over the world including Brazil in captive and free living species of amphibians. The origin of this pan-epizootic is unkown. Major histopathological findings include epidermal hyperkeratosis, hyperplasia, and focal necrosis of epidermal cells. The cause of death may be by disruption of ion equilibrium. The chytrid infection may be diagnosed with methods such as histopathology, immunohistochemistry, electron microscopy, conventional PCR, real-time PCR, and nested PCR. The most used treatment is daily baths of itraconazole at 0.01% for five minutes during 11 days. This has been successfully used to treat chytridiomycosis in a few amphibian species. Disinfection protocols are essential for the management of chytridiomycosis in captivity and in the wild. This is an important disease to be studied in Brazil due to the devastating effects that it can cause in amphibians populations.(AU)

Chytridiomycosis: a devastating emerging fungal disease of amphibians

Amphibians have suffered the most striking declines among all vertebrates. Infectious diseases are one of the causes and Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd) is considered the most concerning one. This emerging infectious disease infects a broad variety of amphibians and is considered responsible for numerous declines and extinctions of these animals. Bd has been reported all over the world including Brazil in captive and free living species of amphibians. The origin of this pan-epizootic is unkown. Major histopathological findings include epidermal hyperkeratosis, hyperplasia, and focal necrosis of epidermal cells. The cause of death may be by disruption of ion equilibrium. The chytrid infection may be diagnosed with methods such as histopathology, immunohistochemistry, electron microscopy, conventional PCR, real-time PCR, and nested PCR. The most used treatment is daily baths of itraconazole at 0.01% for five minutes during 11 days. This has been successfully used to treat chytridiomycosis in a few amphibian species. Disinfection protocols are essential for the management of chytridiomycosis in captivity and in the wild. This is an important disease to be studied in Brazil due to the devastating effects that it can cause in amphibians populations.