Edited by: Nur A. Hasan, University of Maryland, United States
Reviewed by: Ben Davies Tall, United States Food and Drug Administration, United States; Timothy Joe Wade, Environmental Protection Agency (EPA), United States
This article was submitted to Environmental Health, a section of the journal Frontiers in Public Health
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Mountain gorillas (
The IUCN status of Mountain gorillas has changed from critically endangered to endangered with a recent population estimate of 1,004 (
These biodiversity hotspots provide critical habitat for gorillas and other endangered species including chimpanzees and elephants, and are surrounded by human population densities ranging from 300 to 600 people per square kilometer. Bwindi Impenetrable National Park was gazetted in 1991 and gorilla tourism began in 1993, bringing an end to commercial logging, but leaving a hard edge with most of the park having no buffer zone with the surrounding local communities. Gorillas frequently leave the park to forage on banana plants and eucalyptus trees found on community land and sometimes on other plants in community household gardens (
There have been studies of intestinal helminth parasites in Bwindi gorillas (
Conservation Through Public Health (CTPH), a non-governmental organization and non-profit, was founded in 2003, to address scabies and other zoonotic diseases at the human/gorilla/livestock interface. CTPH promotes biodiversity conservation by enabling people, wildlife and livestock to coexist through improving their health and livelihoods in and around protected areas in Africa and has three integrated programs: wildlife health and conservation, community health and alternative livelihoods. As part of setting up a long term gorilla health monitoring program to provide information to Uganda Wildlife Authority for timely wildlife management, CTPH built a Gorilla Research Clinic at Buhoma, Bwindi's main tourist site, which analyzes abnormal and monthly fecal samples from habituated gorilla groups to test for intestinal helminths parasites, as well as, comparative pathogen analysis with people and livestock through specific studies (
Both
Though several species of Cryptosporidium and Giardia have caused clinical signs in humans and livestock (
Various methods have been used to test for these pathogens including conventional staining, fluorescein isothiocyanate–conjugated monoclonal antibodies (
Though
This study also assessed a practical test used routinely in human medicine to detect and further prevent zoonotic disease transmission. We tested the feasibility of using simpler ImmunoSTAT tests as a routine screening tool in human medicine to detect zoonotic disease transmission of
Results from the study were used to recommend and implement management actions in the wildlife, human and livestock health sectors to minimize disease transmission at the human/gorilla/livestock interface.
All human specimens were collected and used in this study under guidelines established in Institutional Review Board approved protocols of the Bwindi Community Hospital. The animal research was approved by the University of California Davis STAR program committee, and Morris Animal Foundation who awarded a grant and complied with the legal requirements of Uganda and adhered to the research protocol submitted to conservation authorities. Permission to collect the fecal samples from gorillas was obtained from Uganda Wildlife Authority. Since the collection of fecal samples from gorillas was non-invasive and did not cause any observable distress to the animals, no animal ethic committee was consulted regarding our study. The gorilla fecal sampling was performed during routine health checks by Conservation Through Public Health employees through an MOU with UWA. Sampling from livestock was with full consent from farmers as part of livestock health checks through MOUs between CTPH and Kanungu District Local Government in Uganda.
Multistage cluster sampling by sector and family group was conducted to obtain a similar number of samples from each sector while collecting a proportionate number of samples per family group for (i) gorillas, both habituated gorillas during routine fecal sample collection for gorilla health monitoring and unhabituated gorillas during the 2011 gorilla census; (ii) livestock in Bujengwe and Mukono parishes, which have high human and gorilla conflict; (iii) and humans, where targeted sampling comprised of people presenting for clinical diarrhea from Bwindi Community Hospital (BCH), and staff working with gorillas from the Institute of Tropical Forest Conservation (ITFC) and Bwindi Impenetrable National Park (BINP) as part of a pilot Employee Health Program conducted by CTPH. Figure
Linking the gorilla (green) and livestock (blue) data points where samples were collected using GPS.
Samples were collected from night nests of 97 individual habituated gorillas and 50 individual unhabituated gorillas; from the rectum of 127 individual livestock from Mukono and Bujengwe parishes at Bwindi, and fresh fecal samples from 106 individual humans including five clinical cases, who were all infants from BCH, 27 asymptomatic research staff from ITFC and 74 asymptomatic tourism and law enforcement staff from BINP.
Samples were collected in fecal collection pots from fresh nests of the previous evening (<24 h from defecation). Each gorilla sample was identified if possible with the group name, feces diameter, age, and sex group if known or deduced from fecal diameter, date, GPS location, appearance, and time. Livestock samples were gathered by routine visits into communities surrounding Bwindi Impenetrable National Park and taking fresh fecal samples from representative animals, while also assessing their age, health, sex, living conditions, history, date, time, appearance, and GPS location. Health assessments and management advice was also given at each village sampled, which was written up in SOAP format in the “Health Assessment” documents.
Fresh unpreserved gorilla and livestock samples were divided into formalin and frozen samples and formalin samples tested using the ImmunoSTAT method at the CTPH Gorilla Research Clinic in Buhoma.
Field screening was implemented using the ImmunoSTAT Commercial Kit, which is a fecal antigen enzyme-linked immunosorbent assay test and Lateral flow immunochromatographic test with an embedded membrane to which antibodies raised against
In the field, samples were tested using the ImmunoSTAT Cards following the manufacturer's instructions. To prepare the samples, 1 g of feces was suspended in 3 ml of deionized water. The feces was macerated using a wooden applicator stick, the sample was thoroughly mixed, then 60 μl of the suspension was added to 2 drops of Sample Buffer, 2 drops of Reagent A, and 2 drops of Reagent B per the manufacturer's instructions. The mixture was then added to the ImmunoCard STAT sample well and then allowed to move via capillary motion into the testing area. The results were read 10 min later and compared to positive and negative controls. A black or gray line had to appear in the CONT position in order for the test to be valid and to ensure enough capillary motion had taken place. A “positive” was recorded when a black or gray line appeared at the CRYP or GIAR indicator and a “negative” was recorded if no line appeared at all. Although according to the manufacturer, a yellow or brown line at either the GIAR or CRYP position is considered invalid, it was decided to define these samples as “Negative Yellow” and re-test these samples using different techniques because of the large debris content in the animal samples.
Doubtful samples were tested with Direct Fluorescence Antibody Test of Fecal Samples for
Frozen samples were carried to the Microbiology Laboratory, Faculty of Veterinary Medicine, Makerere University for DFA testing. Specimens kept at −20°C were sent to the Faculty to confirm the presence of
The Direct Fluorescent Antibody (DFA) test was performed after the specimens were stained using Modified Ziehl Neelsen (MZN) stain to test for
Two habituated gorilla fecal samples tested using the ImmunoSTAT were positive for
Five livestock samples tested positive using the ImmunoSTAT for
Eight humans tested positive using the ImmunoSTAT for
Results of ImmunoSTAT and direct immunoflorescent antibody tests for
The prevalence of
The prevalence of both pathogens from sympatric goats and cattle was relatively low ranging from 4.7 to 5.5%. Both goats and cows are grazed at the edge of the park and could be a source of infection for gorillas when they forage in community land. This has been implied in previous studies at Bwindi (
Similar to previous studies in humans, the DFA test in gorillas and livestock was more sensitive than the ImmunoSTAT test (
This study showed that a combination of both tests in gorillas and livestock had the same effects as human medicine making the protocol feasible for detection of
The presence of
The poor health status of these communities prompted Conservation Through Public Health (CTPH) to select a second community conservation health volunteer (CCHV) or VHCT in Mukongoro and Kyogo villages in December 2009 to intensify hygiene and sanitation behavior change communication. CTPH also shared the results with BCH and recommended education and public outreach with patients regarding water collection from protected water sources. A baseline survey conducted in 2009 showed that only 53% of households collected water from protected water sources (CTPH, unpublished information). CTPH also taught farmers to build water troughs for their cattle to prevent them defecating in water sources shared by gorillas, people and livestock.
Molecular typing of both parasites in humans, domestic animals, and wildlife to date indicates a complex picture of both anthroponotic, zoonotic and spill-back transmission cycles that requires further investigation and a One Health approach to reduce cross species disease transmission (
“One Health” is a terminology used to describe an approach that addresses human, animal and ecosystem health together. This paper has described elements of a One Health field program established by CTPH at Bwindi Impenetrable National Park to promote gorilla conservation through comparative pathogen analysis at the human/gorilla/livestock interface and implementing targeted management interventions in the human health and livestock health sectors. Conducting comparative pathogen analysis between people, wildlife and livestock presents the opportunity to provide timely information for more rapid management of disease by wildlife, veterinary, and public health managers.
GK-Z initiated the research topic, provided some funding, and supervised the research as a principal investigator. This involved contributing to design of the study, sample collection and analysis, interpretation of results, and implementation of management actions based on research findings, as well as drafting the manuscript. SR contributed to the design of the research, participated in sample collection and laboratory analysis, as well as results interpretation and implementation of management actions based on research findings. BM contributed to the design of the study and participated in sample analysis of people, interpretation of the results and writing of the manuscript. RS got the donation of fecal antigen test kits from the manufacturer, provided some funding, contributed to the design of the research, and conducted the research by participating in sample collection and analysis, and results interpretation.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We thank Ryan Sadler, veterinary student from the University of California, Davis, CA USA, who negotiated a donation of kits and positive (control) samples from the manufacturer. We thank the management and staff of Bwindi Impenetrable National Park, Institute of Tropical Forest Conservation, Bwindi Community Hospital and Conservation Through Public Health for their collaboration during the study.