Herpetological Review 47(2), 2016
AMPHIBIAN AND REPTILE DISEASES 227
Herpetological Review, 2016, 47(2), 227–230.
© 2016 by Society for the Study of Amphibians and Reptiles
Widespread Presence and High Prevalence of
Batrachochytrium dendrobatidis in Gabon
Despite its small size, Gabon is a biodiversity hotspot with
198 mammal species, 680 bird species, 138 reptile species, 184
fish species, and 97 amphibian species (Lee et al. 2006; Pauwels
and Vande weghe 2008). Emerging infectious diseases and habi-
tat degradation pose the most immediate threats to amphibian
diversity in Gabon. Batrachochytrium dendrobatidis (Bd) and
B. salamandrivorans (Bsal) are the causative agents of the am-
phibian disease chytridiomycosis which has been implicated in
worldwide population decline and extinction (Berger et al. 1998;
Lips et al. 2006; Wake and Vredenburg 2008; Martel et al. 2013).
Across sub-Saharan Africa, Bd has been widely reported (Con-
radie et al. 2016). Despite extensive sampling, Bd has not been
reported from West Africa (west of Nigeria; Penner et al. 2013).
In Gabon, there have been four independent surveys for Bd with
varied results. Bell et al. (2011) reported high prevalence of Bd
from three sites in northern Gabon. Three subsequent studies
at other sites across Gabon did not find Bd (Daversa et al. 2011;
Gratwicke et al. 2011; Zimkus and Larson 2013). Here we present
results from the most extensive survey for Bd in Gabon to date,
based on the number of individuals, diversity of species, and
geographic area sampled.
Gabon is a small equatorial country (267,667 km2) that is
dominated by continuous tropical moist forest (80% total land
GREGORY F. M. JONGSMA*
New Brunswick Museum, 277 Douglas Avenue,Saint John, NB,
Canada E2K 1E5
ABRAHAM BAMBA KAYA
JEAN-HERVÉ MVE BEH
Institut de Recherches Agronomiques et Forestières, Libreville, Gabon
Center for Conservation and Sustainability Smithsonian
Conservation Biology Institute, Gamba, Gabon
ANDREA M. EMRICH
141 Wentworth Ave., Saint John, NB, Canada E2L 2S7
GRAHAM P. DIXON-MacCALLUM
Department of Biology, University of Victoria, P.O. Box 3020,
STN CSC, Victoria, BC, Canada V8W 3N5
DREW R. DAVIS
JACOB L. KERBY
Department of Biology, University of South Dakota, 414 E. Clark St.,
Vermillion, South Dakota 57069, USA
DAVID C. BLACKBURN
Florida Museum of Natural History, University of Florida, Gainesville,
Florida 32611, USA
*Corresponding author; e-mail: Gregor.Jongsma@gmail.com
Fig. 1. Map of Gabon showing Batrachochytrium dendrobatidis (Bd) sampling locations for this study. Pie-charts are scaled by the total num-
ber of individuals swabbed at each site. Numbers refer to sites described in Table 1.
Herpetological Review 47(2), 2016
228 AMPHIBIAN AND REPTILE DISEASES
cover; Lee et al. 2006). The dominant hydrological feature is the
Ogooué River basin. There are four seasons: a long rainy season
from January to May, a long cold dry season from June to Sep-
tember, a short rainy season from October to December, and a
short dry season from December to January. The average annual
temperature is 26°C (Lee et al. 2006).
We visited seven sites in three provinces: Moyen-Ogooué;
Ogooué-Lolo; and Haut-Ogooué. We hand-caught individu-
als and stored them in separate plastic bags. The next morning,
we swabbed live amphibians following protocols described by
Hyatt et al. (2007) using sterile medical swabs (MW113; Medi-
cal Wire and Equipment Co., Wiltshire, UK). Our swab samples
were stored in 1.5-mL snap-cap tubes with 95% EtOH and kept
as cool as possible in the field. A subset of individuals was eutha-
nized, tissued, stored in formalin and deposited at the California
Academy of Sciences (CAS, San Francisco, California, USA) or in
Gabon’s national collection (curated by the Smithsonian Institu-
tion’s Gabon Biodiversity Program in Gamba, Gabon).
Samples were extracted following the PrepMan Ultra extrac-
tion protocol (Hyatt et al. 2007) and diluted 1:10 with TE buffer
to reduce potential inhibition during quantitative polymerase
chain reaction (qPCR) analysis. Following fast qPCR methods de-
scribed by Kerby et al. (2013), we used 10μL reactions (3μL DNA
extract plus 7μL cocktail) to determine if samples were Bd-pos-
itive or Bd-negative. Additionally, each plate contained a nega-
tive control (nanopure water) and four synthetic DNA (sDNA)
standards. Samples were run on a StepOnePlus qPCR machine
and the number of Bd gene copies was quantified with StepOne
software v2.3 (Applied Biosystems). All samples were run in trip-
licate and considered Bd-positive if: 1) amplification occurred in
at least two of the three wells; and 2) the quantity was above 1.0.
Samples were rerun if there were two wells with quantities near
1.0, or if independent values for a sample differed by an order
of magnitude. All qPCR analyses were conducted at the Disease
Testing Center at the University of South Dakota.
We swabbed a total of 463 frogs, representing 46 species from
18 genera in 10 families, across 7 sites (Table 1; Fig. 1). The overall
prevalence across all sites was 18.6% with 60% of the sampled
species testing Bd-positive, and Bd-positive results from all seven
sites (across three provinces) (Table 2). Our results support Bell
et al.’s (2011) findings that Bd is present in Gabon with high prev-
alence. In addition, we demonstrate that Bd is widespread across
much of the country. Our raw data, including field and catalogue
numbers are available at amphibiandisease.org: <https://n2t.
There does not appear to be a strong association between
the presence of Bd and specific taxa tested. The genus Amni-
rana (Ranidae) had both the highest prevalence and highest Bd
gene copy number of any genus or family. One individual Am-
nirana albolabris (field# ORB-010) had a gene copy count of
43,422 (Fig. 2). Phrynobatrachidae was the only family that did
not test positive for Bd during this study. However, because Sker-
ratt et al. (2008) reported that >59 animals should be sampled
to detect Bd when prevalence is low and our sampling includes
only 23 individuals of Phrynobatrachus, this family may still be
susceptible to Bd in Gabon. Bell et al. (2011) did report positive
cases for three Phrynobatrachus auritus from northern Gabon.
The Hyperoliidae, the most species-rich group sampled, had a
prevalence of 18.7%. There were 6 species that made up 51% of
the total sampling and each of these species had over 25 total
individuals sampled (Table 2). Scotobleps gabonicus (19.2% prev-
alence), Conraua crassipes (19.2%), Hyperolius cinnamomeoven-
tris (19.2%), H. ocellatus (16.7%) all had Bd prevalence close to
the total prevalence. Sclerophrys regularis (10.7%) had the lowest
prevalence of any highly sampled species, and Amnirana albola-
bris (38.7%) had the highest prevalence.
There was a lower prevalence of Bd at forest-savanna sites (N
= 2 sites; mean = 9.4%, ± 1.1% SD) versus strictly forested sites
(N = 5 sites; mean = 23.6%, ± 6.70% SD; t = 2.84, P = 0.036, d.f.
= 5). Because there is no significant difference in the species
composition of these sites based on a Sørensen similarity test,
this suggests that either environmental variables are driving
this difference in Bd prevalence, or there are transmission fac-
tors at play. For example, savanna-forest mosaic sites in Gabon
are known to exhibit greater seasonal temperature fluctuations
than surrounding forest sites (Bonnefille 2011). This temperature
taBLe 1. Summary information on sampling locations for Batrachochytrium dendrobatidis in Gabon. Site numbers correspond with numbers
in Fig. 1.
# Site Province Lat/Long Elevation (m) Dates Habitat
1 Mitone Moyen-Ogooué 00.6410°S, 10.2176°E 43 3–7 April 2015 Forest
2 Carivenville Moyen-Ogooué 00.1770°S, 10.7795°E 44 8–13 April 2015 Forest
3 Junkville Moyen-Ogooué 00.0621°S, 11.1587°E 86 15–18 April 2015 Forest-Savanna mosaic
4 Ogooué Cinq Ogooué-Lolo 00.8105°S, 12.7995°E 419 4–5 May 2015 Forest
5 Madoukou Ogooué-Lolo 00.8683°S, 12.6724°E 246 6–7 May 2015 Forest
6 Mboua Haut-Ogooué 02.1532°S, 13.6398°E 504 26 April–1 May 2015 Forest
7 Doumaye Haut-Ogooué 02.2402°S, 13.5812°E 526 21–25 April 2015 Forest-Savanna mosaic
Fig. 2. An apparently healthy adult male Amnirana albolabris (field#
ORB-010) infected with Batrachochytrium dendrobatidis (43,422
PHOTO BY A. EMRICH
Herpetological Review 47(2), 2016
AMPHIBIAN AND REPTILE DISEASES 229
taBLe 2. Amphibians sampled for Batrachochytrium dendrobatidis (Bd) in Gabon. Numbers indicate no. Bd-positive individuals/total no.
sampled by species and site. Sites are numbered (1–7) in correspondence to Table 1.
1 2 3 4 5 6 7 Total
Arthroleptis poecilonotus - - - - 2/3 - 0/2 2/5
Arthroleptis sylvaticus 0/1 1/1 - - - - - 1/2
Arthroleptis variabilis 0/2 1/3 1/2 - - - 0/1 2/8
Astylosternus batesi - - - - - 0/1 0/6 0/7
Cardioglossa gracilis 0/1 - - - - - 0/3 0/4
Cardioglossa leucomystax 0/1 - - - - - - 0/1
Leptodactylodon sp. 0/2 - - - - - - 0/2
Leptopelis aubryi 0/2 0/5 1/2 - - - - 1/9
Leptopelis calcaratus - - - - - - 0/3 0/3
Leptopelis millsoni 0/2 1/4 0/2 - - - - 1/8
Leptopelis notatus 0/2 - - - - - - 0/1
Leptopelis ocellatus - - 0/1 - 2/2 - 0/2 2/4
Leptopelis rufus - - 1/1 - - - - 1/1
Leptopelis sp. 0/1 - - - - - - 0/1
Scotobleps gabonicus 4/21 - 1/5 2/11 2/5 0/5 1/5 10/52
Sclerophrys gracilipes 1/2 0/1 - - - - 0/1 1/4
Sclerophrys regularis 1/15 1/4 0/5 - 1/5 - - 3/28
Sclerophrys superciliaris - - - - - - 0/1 0/1
Conraua crassipes 2/3 - 3/20 - 0/3 - - 5/26
Hoplobatrachus occipitalis - - - - - - 0/2 0/2
Afrixalus dorsalis 0/2 - 1/10 - - - - 1/12
Afrixalus paradorsalis 0/1 0/5 - - - - - 0/6
Cryptothylax greshoffii - - - - - 1/3 - 1/3
Hyperolius adspersus - - - - - - 1/10 1/10
Hyperolius cinnamomeoventris 4/12 3/5 1/22 - - 1/8 - 9/47
Hyperolius concolor - - - - - - 2/12 2/12
Hyperolius guttulatus 5/6 - - - - - - 5/6
Hyperolius ocellatus 2/6 2/3 0/9 - 1/5 3/12 1/19 9/54
Hyperolius pardalis - - - - 1/5 - 1/8 2/13
Hyperolius phantasticus - - - - - - 0/3 0/3
Hyperolius platyceps 0/1 - - - - - - 0/1
Hyperolius sp. 1 - - - - - - 0/1 0/1
Hyperolius sp. 2 - 0/1 - - - - - 0/1
Hyperolius tuberculatus 0/3 5/15 0/5 - - - - 5/23
Phlyctimantis leonardi - 0/6 1/4 - - - 0/1 1/11
Phrynobatrachus africanus 0/6 - - - 0/1 - 0/5 0/12
Phrynobatrachus auritus 0/1 0/1 - - 0/1 - - 0/3
Phrynobatrachus sp. - - - - - - 0/5 0/5
Xenopus cf. mellotropicalis 1/3 0/2 - - - - - 1/5
Xenopus amieti sp. group - 2/4 0/2 - - - - 2/6
Ptychadena perreti - 0/2 0/1 - 1/4 - - 1/7
Amnirana albolabris 9/12 1/1 0/7 - - 0/4 2/7 12/31
Amnirana amnicola 0/1 - - - - - 0/5 0/6
Amnirana lepus - - - - - - 1/3 1/3
Chiromantis rufescens 0/1 2/8 0/1 - 1/1 - - 3/11
Total: 29/109 19/71 10/99 2/11 11/35 5/33 9/105 85/463
%: 26.6 26.8 10.1 18.2 31.4 15.2 8.6 18.6
Herpetological Review 47(2), 2016
230 AMPHIBIAN AND REPTILE DISEASES
fluctuation might be expected to influence the prevalence of Bd
(Berger et al. 2004; Gaertner et al. 2012; Kinney et al. 2011; Kriger
and Hero 2006; Whitfield et al. 2012). However, given our small
sample sizes, many more forest and forest-savanna sites should
be sampled to test this possible correlation.
All frogs that we encountered in the field appeared healthy.
However, the high prevalence and widespread nature of Bd in
Gabon demands future work to determine its impact on amphib-
ians. A better understanding is needed of: 1) the historical pres-
ence of Bd in Gabon; 2) the contemporary genomic make-up of
Bd in the country; and 3) which species, if any, exhibit symptoms
of chytridiomycosis. Each of these will help to establish the ex-
tent to which Bd poses a threat to amphibians in tropical forests
in Gabon and Central Africa.
Acknowledgments.—We thank the Centre National de la Recher-
che Scientifique et Technologique (CENAREST; permit #AR008/15/
CSAR) for scientific permits and the Direction de la Faune et de la
Chasse for export permits. For logistical support, we thank The Na-
ture Conservancy (Marie-Claire Paiz) and Smithsonian Institution
(Lisa Korte). We thank our lovely hosts in Libreville, Glen Ratel and
Marie Coupé. For assistance in the field, we thank Freye Pavel for get-
ting us safely to our destination and keeping us fed once there. We are
indebted to the chiefs of each village (Mitoné, Carivenville, Junkville,
Ogooué Cinq, Madoukou, Doumaye, and Mboa) for their hospital-
ity, warmth, and knowledge. And finally, we thank our local guides
from each village that never led us astray during our nocturnal quests
for frogs. This project was supported by the NSF grant (#1202609) to
DCB and funding by Shell Gabon and the Smithsonian Conservation
Biology Institute for ET.
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