Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species

Garnham, James I; Bower, Deborah; Stockwell, Michelle P; Pickett, Evan J; Pollard, Carla J; Clulow, John; Mahony, Michael J

doi:10.3354/dao03628

Author(s)

Garnham, James I

Bower, Deborah

Stockwell, Michelle P

Pickett, Evan J

Pollard, Carla J

Clulow, John

Mahony, Michael J

Publication Date

2022

Abstract

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis, which is a primary driver for amphibian population declines and extinctions worldwide. For highly susceptible species, such as the green and golden bell frog Litoria aurea, large numbers of Bd-related mortalities are thought to occur during the colder season (winter), when low temperatures favour the growth of the pathogen. However, extant L. aurea populations are persisting with Bd. We measured Bd prevalence and infection levels of wild L. aurea using capture-mark-recapture and radio-tracking methods. Using this information, we sought to determine host and environmental correlates of Bd prevalence and infection load. Mean ± SE infection load was higher in frogs sampled in autumn (431.5 ± 310.4 genomic equivalents; GE) and winter (1147.5 ± 735.8 GE), compared to spring (21.8 ± 19.3 GE) and summer (0.9 ± 0.8 GE). Furthermore, prevalence of Bd infection in L. aurea was highest in winter (43.6%; 95% CI 33.1-54.7%) and lowest in summer (11.2%; 95% CI 6.8-17.9%). Both prevalence and infection load decreased with increasing temperature. Seven frogs cleared their fungal infection during the coolest months when Bd prevalence was highest; however, these clearances were not permanent, as 5 frogs became infected again. Understanding the factors that allow amphibians to clear their Bd infections when temperatures are optimal for Bd growth presents the potential for manipulating such factors and provides an important step in future research.

Citation

Diseases of Aquatic Organisms, v.148, p. 1-11

ISSN

1616-1580

0177-5103

Pubmed ID

35142293

Link

https://hdl.handle.net/1959.11/52556

Language

en

Publisher

Inter-Research

Title

Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species

Type of document

Journal Article

Entity Type

Publication

Author(s)	Garnham, James I Bower, Deborah Stockwell, Michelle P Pickett, Evan J Pollard, Carla J Clulow, John Mahony, Michael J
Publication Date	2022
Abstract	<p>The amphibian chytrid fungus <i>Batrachochytrium dendrobatidis</i> (<i>Bd</i>) causes the disease chytridiomycosis, which is a primary driver for amphibian population declines and extinctions worldwide. For highly susceptible species, such as the green and golden bell frog <i>Litoria aurea</i>, large numbers of <i>Bd</i>-related mortalities are thought to occur during the colder season (winter), when low temperatures favour the growth of the pathogen. However, extant <i>L. aurea</i> populations are persisting with <i>Bd</i>. We measured <i>Bd</i> prevalence and infection levels of wild <i>L. aurea</i> using capture-mark-recapture and radio-tracking methods. Using this information, we sought to determine host and environmental correlates of <i>Bd</i> prevalence and infection load. Mean ± SE infection load was higher in frogs sampled in autumn (431.5 ± 310.4 genomic equivalents; GE) and winter (1147.5 ± 735.8 GE), compared to spring (21.8 ± 19.3 GE) and summer (0.9 ± 0.8 GE). Furthermore, prevalence of <i>Bd</i> infection in <i>L. aurea</i> was highest in winter (43.6%; 95% CI 33.1-54.7%) and lowest in summer (11.2%; 95% CI 6.8-17.9%). Both prevalence and infection load decreased with increasing temperature. Seven frogs cleared their fungal infection during the coolest months when <i>Bd</i> prevalence was highest; however, these clearances were not permanent, as 5 frogs became infected again. Understanding the factors that allow amphibians to clear their <i>Bd</i> infections when temperatures are optimal for <i>Bd</i> growth presents the potential for manipulating such factors and provides an important step in future research.</p>
Citation	Diseases of Aquatic Organisms, v.148, p. 1-11
ISSN	1616-1580 0177-5103
Pubmed ID	35142293
Link	https://hdl.handle.net/1959.11/52556
Language	en
Publisher	Inter-Research
Title	Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species
Type of document	Journal Article
Entity Type	Publication

Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species

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