Abstract
Conservation activities that involve relocation of animals present unique situations in which disease transmission may occur. As part of a proposed restocking project for black and white ruffed lemurs, a medical evaluation program was designed. Three populations were assessed: the wild population at the release site, the Malagasy captive population, and the North American population. Testing protocols were designed to identify diseases likely to have significant impact—contagious diseases with carrier states, which could become established in wild populations and significantly impact health and population dynamics. Medical evaluation consisted of a complete physical examination, complete blood count, serum biochemical profile, intradermal tuberculin test, serum viral profile (hepatitis A and B, herpes simplex, cytomegalovirus, Ebstein Barr virus, measles, and simian immunodeficiency virus), fecal culture, and fecal parasite examination. No evidence of infectious disease was found in any population; however, the Malagasy captive population had evidence of a possibly compromised nutritional status.
Introduction
The significance of infectious disease to reintroduction projects has become an increasingly important question. As captive propagation and management practices improve, and remaining areas of natural habitat are secured, opportunities develop for animals in captivity to be released into native habitat. The movement of animals is accompanied by the inherent risk of exposure to disease in a variety of scenarios. This report describes the rationale and application of a medical evaluation program for a potential restocking program of black and white ruffed lemurs (Varecia variegata variegata) in Madagascar.
The opportunity for restocking of ruffed lemurs occurred due to ongoing projects supported by the Madagascar Fauna Group (MFG). Due in part to support by MFG, a forestry research station near Tamatave (on the east coast of Madagascar) has been converted into a small zoo (Parc Ivoloina). As a result of donations and government confiscations, the number of ruffed lemurs in the collection has grown beyond the carrying capacity. This large population is pushing the limits of both the physical facility and the budget for animal care. At the same time, Reserve Naturelle Integrale No. 1, Betampona, is reasonably accessible and underutilized for research purposes. It is small enough to be well censused and monitored (5500 acres), and it has the potential for holding more Varecia than are currently there. The reserve is 30 km from Ivoloina and is surrounded by degraded forest and agricultural lands. The project proposed by the MFG advisors involves alleviating the overcrowding by releasing selected Varecia from the Ivoloina collection into the Betampona Reserve.
Methods
For the Betampona restocking project, three populations were considered. Health assessments were to be done on each population, using comparisons between the populations to identify significant health issues. The populations were: 1) the potential release population at Ivoloina, 2) the resident population at Betampona, and 3) the North American captive population (provided reference values). To assess the wild population, samples were to be collected at two locations during radiocollaring projects conducted by field researchers: at Betampona and on the Masoala Peninsula. Although the samples from Masoala were not part of the resident population at the release site (and in fact were a different subspecies, V. v. rubra), it was felt that the samples would be useful for comparative purposes.
Diagnostic evaluations were selected based on diseases felt to have potential for significant impact on the restocking project. Exposure to humans played a major part in determination of disease testing. The assumption was made that the captive population had been exposed to many human diseases to which the wild population had not.
Health profiles were completed on all lemurs in the study. This consisted of 18 Varecia variegata variegata held in captivity at Parc Ivoloina and four Varecia variegata rubra from the Masoala Peninsula. No animals were captured in the reserve at Betampona. Health profiles were designed to assess the physical health of the animals, as well as to detect exposure to disease.
Each animal was physically or chemically (Telazol) restrained. A complete physical examination was performed. Each captive animal received an intradermal tuberculin test (0.1 ml Cooper’s old tuberculin, upper palpebra). Whole blood was collected for a complete blood cell count and hemoparasite examination and was preserved for genetic evaluation. Blood was collected and separated, and serum was saved frozen for serum biochemical profile and viral serology. Fecal samples were collected and preserved in 10% formalin for microscopic examination for endoparasites. Rectal swabs were collected in transport media for enteric pathogen culture. Hair samples and pelage color pattern descriptions were collected for genetic research.
Results
Physical Examinations
Ivoloina—All examined animals were found to be in adequate condition. Bodyweights and composition seemed appropriate. Hair coats appeared dry and slightly dull. Although some reproduction was occurring, many adults of appropriate reproductive age were not bearing young. No evidence of external parasites, injuries, or other medical problems were detected on physical examination.
Betampona—Although no animals were captured, several were visually examined at close distances. All animals observed appeared in good health, and all had dense, lustrous hair coats. All animals were active, and no evidence of compromised health (gait abnormalities, wounds, ocular or nasal discharges, etc.) were detected. Infants were seen on one occasion and heard in a nest on another, indicating that reproduction is occurring.
Masoala—All examined animals were found to be in good health. No evidence of compromised health was detected. External parasites, thought to be mites, were present in the ear canals of all four lemurs. Identification of the parasite has not yet been completed. It was felt that these parasites did not present a clinically significant health concern.
Tuberculin Testing
All the captive Varecia had negative intradermal tuberculin tests at 72 hours.
Hematology
Complete blood cell counts were within normal limits for all animals. With the exception of blood urea nitrogen (BUN), serum chemistry values of captive and wild animals fall within normal ranges as established for the captive North American population. BUN levels in wild (3.8 mg/dL) and Malagasy captive lemurs (7.83 mg/dL) are below the normal range for North American captive ruffed lemurs (mean±2SD=8.3–39.9 mg/dL).
No abnormalities were detected for captive animals at Ivoloina that would suggest specific health problems. No hemoparasites were detected in any blood smear.
Viral Serology
Serological assays were done for the following viral diseases: hepatitis A (HEP A), hepatitis B (HBsab), herpes simplex 1 (HSV-1), cytomegalovirus (CMV), Epstein-Barr virus (EBV), measles, and simian immunodeficiency virus (SIV). These diseases were selected based on several criteria. These diseases are present in the human population of Madagascar. They all have a carrier state, such that they could be maintained latent in a host and shed at a later date. They all have potential to produce significant disease, either by direct mortality or reduced reproduction. The exception is simian immunodeficiency virus. Immunodeficiency viruses are being discovered in a variety of species, including nonhuman primates. Although no immunodeficiency diseases have been documented in lemurs, samples were surveyed for evidence of infection.
None of the 22 Malagasy animals tested positive for any of the viral diseases.
Fecal Flotations
Saline flotations of formalin-fixed feces were done for detection of parasite ova. None of the captive lemurs had evidence of internal parasites. These animals are routinely treated with ivermectin (every 4 months). One of the wild Varecia had a single nematode ovum detected in the flotation.
Fecal Cultures
An enteric pathogen screen was performed on the fecal culture swabs. Each sample was cultured for Salmonella, Shigella, Campylobacter, and Yersinia. These organisms all cause disease syndromes in humans and a variety of animal species, and they have the potential of persisting in a carrier state. All 22 Varecia sampled were negative for enteric pathogens.
Discussion
Ivoloina—Excess animals present a variety of problems for this collection. Budgetary constraints limit the ability to provide further cage space and may affect provision of a proper diet. Current diets are functional but may be lacking in vitamins or trace minerals, or they may lack adequate levels of basic nutrients. The possibility of a marginal diet is evidenced by the dry, dull hair coats of the animals examined, as well as the decreased reproductive rate. Complete blood work does not indicate any specific nutritional deficiencies. No evidence of infectious disease exists in this captive population that would restrict their inclusion in release projects. Although these animals were held as pets by private individuals, no transmissible diseases that occur in the human population in Madagascar were detected in the animals.
Betampona—No specific medical conclusions may be made for the ruffed lemurs in Betampona. In general, the animals appeared in good health.
Masoala—Although the subspecies and location differ from the ruffed lemurs of Betampona, basic health parameters may be used for comparison. Examination of the animals and evaluation of the blood and fecal samples suggest that this group of wild lemurs does not harbor any of the potentially serious infectious diseases surveyed.
The blood urea nitrogen levels of both the Malagasy captive and the wild ruffed lemurs are significantly lower than the (International Species Information System) ISIS values, the wild animals having values roughly half those of the Ivoloina animals. One possible cause of this difference may be diet related, but this would suggest that the wild animals eat a diet even lower in protein than that fed at Ivoloina. Levels of dietary protein required by lemurs have been discussed, and this result may suggest that dietary levels in captivity are higher than in the wild. The small sample size might also be introducing artifact into the comparison.
Conclusions
No evidence of infectious disease as a limiting factor for release into the wild was identified. Although the captive lemurs live in close contact with humans, there was no evidence of transmission to lemurs of diseases present in the human population (measles, TB, enteric pathogens, hepatitis). However, the animals held at Ivoloina were determined not to be prime candidates for release due to suspected nutritional deficiencies. Subsequently, four pairs of these animals were imported into the United States to bolster the U.S. captive population with new founders. These animals quickly improved in condition, and reproduction occurred in the second year.
Healthy, compatible pairs of ruffed lemurs were identified in the captive population to be potential reintroduction candidates. These animals will undergo an extensive medical evaluation and pre-release conditioning, with the goal of releasing them into Betampona in the fall of 1997.
Acknowledgments
Funding for travel expenses for Dr. Junge was provided by the Philadelphia Zoological Society Conservation Committee. In-country expenses were provided by the Madagascar Fauna Group. Medical supplies and laboratory costs were paid by the St. Louis Zoological Park, which also granted leave for travel. Funding for travel for Dr. Garell was provided in part by the Seneca Park Zoo Society and Monroe County Parks Department.