Download Did the world wide amphibian emerging infectious disease originate

Amphibian Fungal
Disease Dynamics
Chytridiomycosis fungus
dynamics in wildlife
Gabriela Rios-Sotelo
Vance Vredenburg Lab
San Francisco State University
Amphibian
diversity
Emerging disease
Emerging disease
Global amphibian declines
• Number 1 most threatened vertebrate
• 1/3 (32%) of amphibians are threatened species
• May be on the brink of a sixth mass extinction
• Many reasons for declines
• Recently…
INFECTIOUS DISEASE
Chytridiomycosis (chytrid)
 Largest
disease-caused loss of species in
history
 200 species already driven to extinction
 Fungal pathogen specific to amphibians
 Transmitted by aquatic zoospores
 Infects keratin layers of amphibian skin
 Thickened skin leading to blocked
osmotic regulation and electrolyte
transport
Skerratt et al 2007; Voyles et al 2009
Batrachocytrium
dendrobatidis(Bd) lifecycle
Chytrid Dynamics
Many questions…
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



Where did this disease originate? How did amphibians in
this area come to live robustly with this fungus? Can we use
this knowledge to efficiently protect other species
worldwide?
How can we control further disease spread?
How do some species survive with infection while others do
not?
How does this particular microbe interact as a skin disease?
Does it compete for food and space with other skin
microbes? Does this have to do with why some species are
more susceptible than others?
How does Bd’s assn. with it’s abiotic environment influence
it’s dispersal, susceptibilty and other factors?
Emerging disease in Asia
Worldwide
distribution
?
Fisher et al 2009
Bd has been well documented all over
the world except Asia
Emerging disease in Asia
Bd in Asia
 Most
unique and diverse areas in the
world for amphibian fauna
 Recent papers in China, Japan and South
Korea show low infection rates and no
signs of mass amphibian declines
Emerging disease in Asia
Disease Dymanics
K Upton
 Two


hypothesis for Bd emergence
Novel pathogen hypothesis (NPH)
Emerging endemic hypothesis (EEH)
EEH pattern would show constant infection prevalence
levels demonstrating coevolution in area of origin
Berger et al 1998; Rashowicz et al 2005; Pounds et al 2006
Emerging disease in Asia
Bd in Japan
M olecular Ecology (2009)
doi: 10.1111/ j.1365-294X.2009.04384.x
A mphi bi an chytri di omycosi s i n Japan: di stri buti on,
hapl otypes and possi bl e route of entry i nto Japan
K O I C H I GO K A ,* JU N Y O K O Y A M A ,† Y U M I U N E,‡ T O SH I RO K U RO K I ,§ K A Z U T A K A SU Z U K I ,*
M I RI N A K A H A RA ,* A REI K O BA Y A SH I ,* SH I GEK I I N A BA , – T O M O O M I Z U T A N I * * and
A L EX D . H Y A T T ††
*National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan, †Department of Biology,
Faculty of Sciences, Yamagata University, 1-4-12 Kojirakawa, Yamagata-shi, Yamagata 990-8560, Japan, ‡Laboratory of
Veterinary Pathology, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa 229-8501, Japan, §Kanagawa Prefectural
Institute of Public Health, 1-23-1 Shimomachiya, Chigasaki, Kanagawa 253-0087, Japan, –Biotechnology Development Center,
Department of Biotechnology, National Institute of Technology and Evaluation, 2-5-8 Kazusakamatari, Kisarazu, Chiba 2920818, Japan, **Nature Conservation Bureau, M inistry of the Environment, 1-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8975,
Japan, ††Australian Animal Health Laboratory, CSIRO Livestock Industries, Private Bag 24, Geelong, Vic. 3220, Australia
 1st
distribution of Bd in Japan
 Low infection rates
A bstract
 Many
A seri ous haplotypes
di sease of amphi bi ans caused by the chytri d f ungus Bat rachochyt ri um
dendrobat i di s w as f i rst f ound i n Japan i n D ecember 2006 i n i mported pet f rogs. Thi s w as
the f i rst report of chytri di omycosi s i n A si a. To assess the ri sk of pandemi c chytri di  Vector
mediated spread
omycosi s to Japanese f rogs, w e surveyed the di stri buti on of the f ungus among capti ve
and w i l d f rog popul ati ons. We establ i shed a nested PCR assay that uses tw o pai rs of PCR
pri mers to ampl i f y the i nternal transcri bed spacer (I TS) regi on of a ri bosomal RN A
cassette to detect mi l d f ungal i nf ecti ons f rom as l i ttl e as 0.001 pg (1 f g) of B. dendrobat i di s
D N A . We col l ected sw ab sampl es f rom 265 amphi bi ans sol d at pet shops, 294 bred at
i nsti tutes and 2103 col l ected at f i el d si tes f rom northern to southw estern Japan. We
detected i nf ecti ons i n nati ve and exoti c speci es, both i n capti vi ty and i n the f i el d.
Emerging disease in Asia
 AS
well as the oldest museum specimen record
documented with Bd
 1902 Andrias japonicus
K Sweet 2008
Emerging disease in Asia
Using museum specimens and
PCR to test for Bd
 New
method developed
From Dr. Alex Hyatt’s PCR
detection method adapted
by Tina Cheng allows Bd
detection in preserved
museum specimens
Emerging disease in Asia
Bd disease Map of Japan