Predominant prevalence of Ranavirus in southern Brazil, a region with widespread occurrence of the amphibian chytrid

Author(s)

Ruggeri, J. ; Pontes, M. R. ; Ribeiro, L. P. ; Gendreau, K. L. ; Sousa, R. L. M. ; Toledo, L. F.

• Document type: Journal article
• Source: ANIMAL CONSERVATION; v. N/A, p. 12-pg., 2023-10-05.

Abstract

Emerging infectious diseases are a major cause of amphibian declines worldwide. Two of these diseases are amphibian chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd) and a viral disease caused by different ranaviruses (Rv). Whereas Bd is known to be widespread in Brazil, Rv was only recently detected in natural habitats. We therefore investigated the co-occurrence of Bd and Rv in wild tadpoles in the southern Brazilian Atlantic Forest from 21 ponds. Because infection by Bd might cause immune suppression in the host, we hypothesized that tadpoles infected with Bd would be more prone to infection with Rv than Bd-free individuals, hence presenting higher Rv loads. Surprisingly, co-infection was rare (less than 6% of the sampled specimens), and we did not find evidence that Bd would facilitate Rv infection. On the other hand, we detected Rv in 38% of tadpoles (125 out of 324), representing twice the prevalence of Bd in the same populations. We tested the influence of biotic and abiotic factors on infection by each pathogen on tadpoles, and we detected a positive relationship between forest cover and infection by Rv, whereas no relationship was found for Bd infection. Based on the putatively low rate of co-infection and high prevalence of Rv in wild anuran populations, we advocate for the inclusion of Rv screening and monitoring in addition to Bd in conservation-oriented amphibian surveys. Only surveying both diseases will provide a complete picture of amphibian disease-related declines. (AU)

• FAPESP's process: 18/23622-0 - Implications of national and international bullfrog trade in spread and tolerance acquired to chytrid fungus and conservation measures of anurans
• Grantee: Luisa de Pontes Ribeiro
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 16/25358-3 - The chytrid fungus: from its origins to its consequences
• Grantee: Luis Felipe de Toledo Ramos Pereira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/01917-6 - Interaction between the chytrid Batrachochytrium dendrobatidis and the Ranavirus in anuran assemblages from the Southern Atlantic forest
• Grantee: Joice Ruggeri Gomes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 20/00099-0 - The chytrid fungus and ranavirus in species of the genus Melanophryniscus (Anura: Bufonidae)
• Grantee: Mariana Retuci Pontes
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/50741-7 - Diversity and conservation of Brazilian amphibians
• Grantee: Célio Fernando Baptista Haddad
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 19/18335-5 - Passive air transportation of an amphibian lethal pathogen in high elevation sites: practical applications for protected areas conservation in the State of São Paulo
• Grantee: Luis Felipe de Toledo Ramos Pereira
• Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants