Diagnostics and Epidemiology of Infectious Agents in Mountain Gorillas.
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Date
2010-04-27
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Abstract
ABSTRACT
WHITTIER, CHRISTOPHER ALAN. Diagnostics and Epidemiology of Infectious
Agents in Mountain Gorillas. (Under the direction of Michael K. Stoskopf and
Barrett D. Slenning)
Infectious diseases are one of the major threats to remaining populations
of free-ranging great apes. Infections from humans are a particular concern
because of increasing contact between apes and human researchers, tourists, and
local communities. This study advances our understanding of infectious disease
risks to free-ranging mountain gorillas (Gorilla beringei beringei) by developing
and utilizing improved noninvasive diagnostics to survey wild gorillas;
performing serosurveys of gorillas and locally confiscated primates to identify
exposure patterns; and designing a disease transmission model to better evaluate
and predict pathogen spread and epidemic outcomes in the mountain gorilla
population.
The risk from human and any other infections to wild apes is difficult to
quantify partly because of limited diagnostic sampling. Sample collection is often
restricted by the challenges of sampling free-ranging apes, while sample analysis
can be constrained by storage and shipping protocols that often require fresh or
frozen samples. This study expands diagnostic capabilities by showing that noninvasively
collected gorilla fecal samples can be stored in guanidine
isothiocyanate solution at room temperature for 6 months and allow diagnostic
detection of rotavirus RNA by polymerase chain reaction (PCR). Additionally it
demonstrates that advanced molecular diagnostics using real-time PCR
technology can be performed directly in the field thereby bypassing the need for
sample preservation and shipping. This study used a portable real-time PCR
instrument to detect an 87% prevalence of a Campylobacter spp. in 157 fecal
samples, and to further reveal that this gorilla Campylobacter spp. appears to be
a novel isolate.
Using opportunistically collected blood samples, free-ranging mountain
gorillas (N=57) are shown to be exposed to 19 of 37 pathogens assayed including
many that are prevalent in local human populations. Evidence of exposure from
local human populations is further confirmed by a companion survey of 32
confiscated gorillas and other nonhuman primates that documented cases of
seroconversion associated with captivity and in some cases with only human
contact, in 2 subspecies of gorillas and three species of other primates.
The infectious disease outbreak model developed in this study
demonstrated the importance of modeling the mountain gorilla population as a
realistic network of interconnected groups. The model shows that, in the absence
of humans, the known low gorilla intergroup contact rates severely restrict the
spread of infection between gorilla groups. More significantly, the model
suggests that even a small group of regular human visitors with limited gorilla
contact can facilitate the spread of infections between gorilla groups and thereby
increase gorilla population outbreak levels.
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Keywords
modeling, zoonoses, Gorilla, epidemiology, diagnostics, infectious disease
Citation
Degree
PhD
Discipline
Comparative Biomedical Sciences
