**Abstract**

Understanding and detecting diseases of amphibians has become vitally important in conservation and ecological studies and prevent and biosecurity a determinant priority in experimental farms, mainly when related with academic and research activities. Ranavirus belongs to the family Iridoviridae, and causes an emergent infectious disease that affects different species, especially fish, reptiles and amphibians, with a significant contribution to the decline of the population. In amphibian systems, Ranaviruses transmission can occur between vertebrate classes through direct contact, by scavenging or through virus particles persisting in the environment. Subclinical infected individuals may serve as reservoirs in the most susceptible anura species. Humans play a significant role in this emergent disease and biosecurity measures are determinant to prevent the introduction of these viruses, either in commercial or experimental farms. A Biosafety Plan is a fundamental tool in the Ranaviruses prevention and include educational and training programs, relevant to the mission of a Higher Education Institution.

**Keywords:** amphibians, biosafety plan, infectious diseases, Ranavirus, surveillance

### **1. Introduction**

Emerging infectious diseases are currently a threat to the conservation of global biodiversity [1]. Amphibian diseases linked to declining of amphibian populations, are a constant threat to endangered species, and are frequently a hazard in ranaculture facilities [2]. Many factors have been implicated in these declines in the wild, including introduced predators, increased ultraviolet-B radiation, chemical contaminants, habitat destruction and degradation, and emerging diseases [3]. Amphibians are susceptible to a variety of pathogens, including internal and external parasites, bacteria, fungi, and viruses. Understanding and detecting diseases of amphibians has become vitally important in conservation and ecological studies [2].

Changes in environmental conditions can be a potential driver of emerging infectious diseases [4]. Environmental influence affects the population susceptibility, with seasonal variation in response to climate (temperature) alterations, moisture availability, and their interactions' in amphibian behavior [1]. In fact, pathogens are favored for warmer ambient temperatures, that provide ideal conditions for propagation [4, 5].

The causes of the population decline are complex, but it is clear that infectious agents, either directly, or following environmentally-induced immune suppression, play an important role in this process [6, 7]. Each of the three major life stages of amphibians (embryos, larvae, and adults) has distinct diseases [2] and at least six groups of viruses have been reported to affect amphibians, including iridoviruses, herpesviruses, and arboviruses.

Some infectious diseases of amphibians share similar pathological signs; thus, their detection, recognition, and correct diagnosis can be a challenge [2, 8]. A group of viruses belonging to the genus Ranavirus are amphibian pathogens, globally distributed, with higher morbidity and mass mortality [2, 8–11]. Ranaviruses infect at least 175 species across 52 families of ectothermic vertebrates, as fish, amphibians, and reptiles, and cause systemic diseases, compromising multiple internal organs [4–6, 12–14]. They are the second most common infectious cause of mortality in amphibians worldwide, after the fungus Batrachochytrium dendrobatidis [5], with a relevant impact in the population decline. As indicative of the ranaviruses host range and their potentially negative effects, ranaviral disease was listed by the World Organization for Animal Health (OIE) as an internationally notifiable disease [2, 8, 9, 15, 16]. Ranavirus is associated with amphibian die-offs, like many other diseases it generally does not lead to the extinction of the host [17].

Ranaviruses may function as a novel or endemic pathogen, associated with the movement of infected amphibians by humans. The infectious process involves genetics, environmental factors (pollution, temperature and other stressors) and inherent biological characteristics of the host (age, life stage, physiological aspects) that directly affect immune competence. Anthropogenic stressors also may facilitate emergence, compromising the imune system [2, 18]. Additionally, subclinical infected hosts may serve as reservoirs for more susceptible amphibian species [18].

Several authors have noted that commercial exchange of live amphibians for food, pets, and laboratory animals may be adversely influencing wild populations by direct harvesting or through the spread of disease [19, 20]. To supplement the higher demand for frogs, and to counteract the effects of over-harvesting, some countries have introduced frog farming.

Dissemination is facilitated by contact with infected individuals or contaminated water as well as inherent behaviors of amphibians such as necrophagy and cannibalism [21]. Measures that prevent or minimize the possibility of introducing potentially pathogenic infectious agents, either wild or captive amphibians, are crucial [22]. Managing ranaviral disease in captive facilities is more straightforward than in natural populations. Isolation of positive individuals and disinfection of animal enclosures are important initial steps, but similar to wild populations, it is essential to minimize possible stressors and maintain proper biosafety procedures to prevent cross contamination [23].

Vertebrate iridoviruses, specifically members of the genus Ranavirus, have become a significant cause of disease in ectothermic animals, and that from a virological, commercial and ecological point of view deserve additional study [6]. The aim of this chapter is to introduce common amphibian diseases outlining value biosafety measures in a frog farm, with production, experimentation, and research purposes, as well as academic activities, inserted in a Higher Education Institution.
