Chimpanzee respiratory disease and visitation rules at Mahale and Gombe National Parks in Tanzania.код для вставкиСкачать
American Journal of Primatology 70:734–737 (2008) COMMENTARY Chimpanzee Respiratory Disease and Visitation Rules at Mahale and Gombe National Parks in Tanzania MAGDALENA LUKASIK-BRAUM AND LUCY SPELMAN Mountain Gorilla Veterinary, Musanze, Rwanda INTRODUCTION Multiple outbreaks of often fatal respiratory disease have occurred in Tanzania’s habituated Eastern chimpanzees, Pan troglodytes schweinfurthii, since long-term research studies began there in the 1960s. Disease events similar to those recently reported among the Taı̈ Forest chimps have been described at the Gombe Stream Research Center and Mahale Mountain National Park [Goodall, 1986; Hanamura et al., 2007; Kamenya, 2002; Lonsdorf et al., 2006; Nishida, 1990]. The mortality rate during some of these outbreaks has ranged as high as 30% at Gombe and 20% at Mahale. The Taı̈ Forest findings provide the first evidence that chimp respiratory disease can be caused by introduced viral pathogens. These findings help us better understand the disease outbreaks at Gombe and Mahale. They also emphasize the importance of veterinary involvement during all stages of an outbreak, from daily clinical observations to post mortem exams and sample collection. HISTORY OF RESPIRATORY DISEASE OUTBREAKS AT MAHALE AND GOMBE Since many years veterinarians suspected a possibility of human disease transmission to free ranging Great Apes in Africa (Leendertz et al., 2006; The Mountain Gorilla Veterinary Project, 2002). Though viral pathogens introduced by people have not yet been proven to cause respiratory disease at Mahale (see article by Kaur et al., 2008) or Gombe, the clinical signs and post mortem findings among the chimps there closely resemble those described by Köndgen et al.  for the chimps of the Taı̈ Forest. Numerous outbreaks of respiratory disease have been recorded at Gombe over the years [Kamenya, 2002; Lonsdorf et al., 2006]. Gombe chimp population has declined for various reasons, including habitat loss and mortality from disease. The impact of disease on the Mahale chimps, which live in the well-protected piece of forest, is even more evident. In 1965, the total population of chimps under habituation was estimated to be at least 140 r 2008 Wiley-Liss, Inc. individuals living in two communities. In 1984, there were 101 chimps in just one community. By 2006, that number had declined to a low of 52 animals, with 12 deaths from one outbreak during that same year. Because of the high mortality rates at Mahale, researchers responsible for naming the new born animals waited until infants reached the age of 2 years. Some of these individuals were the victims of natural causes, but many have died during the recorded outbreaks of disease. Officials with the Tanzanian National Parks (TANAPA) recommended that all visitors, including tourists and researchers, follow standard visitation rules at Gombe in 2000 and Mahale in 2006. It took some time for the rules to be implemented and even now they are not always entirely followed. However, there have been no serious outbreaks—and no deaths from respiratory disease—at Gombe since the end 2002 (S. Kamenya, E. Lonsdorf, personal communication) and at Mahale since August 2006 (Lukasik-Braum, unpublished data). Veterinary Management of Respiratory Disease Outbreaks: Mahale Historically, veterinary clinicians have not been involved in the management of respiratory disease outbreaks at Mahale. Interventions were not allowed, clinical data were not collected, and no veterinary equipment was available before 2006. During the June 2006 outbreak when chimps started dying, TANAPA officials, Frankfurt Zoological Society scientists, and Kyoto University researchers invited me to participate in the daily veterinary assessment of sick animals and to conduct post mortem examinations when possible. Sample collection and analysis from sick chimps at Mahale were limited because researchers felt that the disease outbreaks were natural and Correspondence to: Magdalena Lukasik-Braum, Regional Field Veterinarian, Mountain Gorilla Veterinary Project BP 115 Musanze, Rwanda. E-mail: email@example.com DOI 10.1002/ajp.20568 Published online 20 May 2008 in Wiley InterScience (www. interscience.wiley.com). COMMENTARY / 735 therefore should run their natural course. No clinical exams were performed and no invasive samples were obtained from individuals with clinical signs of respiratory disease apart from few fecal, urine, and wadge samples. Results of analysis are pending at Kyoto University (see Kaur et al. in this issue). Clinically, chimps affected during the June 2006 outbreak at Mahale showed signs of moderate to severe upper and lower respiratory tract disease. Sneezing, rhinitis, wet and dry coughs, lethargy, and tachypnea were observed. Some animals seemed to develop signs of illness acutely, from one day to the next. Severely affected animals showed signs consistent with pneumonia including increased respiratory effort, malaise, and anorexia. Review of the clinical notes recorded for the 65 animals in the community revealed high morbidity as well as mortality. Six chimps were observed to be severely ill and another 44 were affected with mild to moderate signs. Three infants died but were not recovered from their mothers. Two other chimps died and post mortem exams were conducted. One carcass was decomposed; the other had severely decongested lungs consistent with acute pneumonia. These findings are similar to those found during post mortem exams of the Taı̈ Forest chimps [Köndgen et al., 2008, Leendertz personal communication], but histopathology results are not available. The overall morbidity was 50 of 65 chimps with a mortality of 12 of 65, or 20%, of which half were infants or juveniles. However, 9 of the12 chimps noted as dead during this outbreak were never observed sick. They were presumed dead. During the June 2006 outbreak at Mahale, the first case was an adult male chimp, DW. As reported in Hanamura et al.  two males MA (Masudi) and DW (Darwin) were suspected to be the likely source of infection to the other chimps. Both of these males were known to be the most habituated and therefore regularly found in closer contact with people compared to other chimpanzees. At the beginning of June 2006 there also was an outbreak of respiratory disease at one of the five Mahale camps. Visitation rules were not yet in place and people with respiratory symptoms did visit the chimps. Because the outbreak of illness began among the chimps at the same time, the disease transmission could have gone either way: from chimps to humans or from humans to chimps. There were two other, milder outbreaks of respiratory disease after June 2006, both of which occurred during the end of the rainy season, one in November 2006 and another in late October 2007. There was no mortality, only a few animals were affected, their clinical signs were limited sneezing, coughing, and nasal discharge and most were older animals. There had also been a reportedly severe outbreak of respiratory disease previous year in 2005, around June/July and another in October 2003, both with recorded mortalities among the infants. There is a common pattern to these outbreaks. All six occurred during June/July, the end or the beginning of rainy season at Mahale, which starts in late October and ends at the end of May. The weather is colder at the beginning and the end compared to middle of the rains, and during these periods preferred chimp foods are scarce. June/July is also the beginning of the busy tourist season while researchers study the chimps year round. Ecotourism and chimp trekking are extremely popular at Mahale Mountains National Park. Film crews also visit regularly. There were days when the habituated group was visited by up to five tourist groups, two teams of researchers, and a film crew (two film crews visited at the same time in mid2007). Gombe has never drawn anywhere near as many tourists compared with Mahale, and the Taı¨ Forest chimps are mostly visited only by researchers. It is possible that some outbreaks are ‘‘natural’’ or endemic among chimps, rather than foreign or introduced by people and, for whatever reason, the time around the season change favors the transmission of diseases. Veterinary Management of Respiratory Disease Outbreaks: Gombe Although veterinarians have worked closely with researchers at Gombe for years, interventions were rarely performed and diagnostic testing has never been as complete as reported recently at the Taı̈ Forest. Noninvasive samples, including fecal, urine, wadge, and post mortem samples have been regularly collected and stored frozen or fixed in formalin/alcohol/RNA later. During my employment as a resident veterinarian at Gombe between 2000 and 2003, these samples were analyzed to every extent possible during a disease outbreak. We regularly performed basic bacteriology examinations in the local laboratory. We also developed a healthmonitoring sheet for the research assistants to report daily on all the disease symptoms observed during their chimp observation. As at Mahale, we did not intervene to obtain diagnostic samples for several reasons. Generally, anesthesia of free-ranging chimps carries high risk. In the case of respiratory tract infection, it may even be contraindicated. Virus isolation and identification require considerable expertise. Finally, antibiotic therapy does appear to be life-saving in various infections and in Gombe it can be administered without anesthesia by the oral route with bananas. On rare occasions, very sick chimps have been treated for a presumptive illness at Gombe, including respiratory disease. Am. J. Primatol. 736 / Lukasik-Braum and Spelman The decision to treat the animal was based on the age, clinical signs, and severity of illness, and, if there had been a recent death, the results of post mortem. It is important to note that food provisioning, which made the treatment possible, might also had contributed to disease transmission before the year 2000 when it was finally stopped. VISITATION RULES AT GOMBE AND MAHALE Visitation rules for mountain gorillas were first developed in 1985 and subsequently revised in January 1999 in Gisakura (Rwanda). The initial set of recommendations was based only on behavioral concerns, including the risks of over-habituated gorillas. Disease transmission between humans and great apes was not a consideration at that time (Bill Weber, personal communication). The 1999 rules were produced by a team of veterinarians, human doctors, and researchers concerned with the possibility of human pathogen transmission to chimpanzees as well as gorillas. At that time, visitation rules were proposed for all African great apes alike, including chimps. These rules were gradually established in most East African countries. Officials with TANAPA recommended that all visitors, including tourists and researchers, follow standard visitation rules at Gombe in 2000 and Mahale in 2006. The rules include the following: tourists are to remain 10 m away from the chimpanzees and researchers 7.5 m. People with disease symptoms are not allowed to visit chimps and tourist visit cannot last longer than 1 hr. Many Mahale chimps are over-habituated and will break the safe distance rule, sometimes coming in contact with people. The Gombe researchers and Mahale guides and trackers have been instructed to discourage such contact by moving away as soon as the chimpanzees approach. Given that it will take time to change the chimp’s behavior, the researchers from Kyoto University studying at Mahale decided to wear surgical masks beginning in 2006. All visitors and researchers now wear disposable surgical masks while visiting chimps. Although there were concerns about the reaction of tourists and chimps to the mask rule, none have been observed. By explaining the reason for the masks, tourists have become more aware of the risks to chimps. The animals showed no change in their behavior toward visitors wearing this new piece of equipment. It should also be noted that these are not the N95-type masks. The effectiveness of such masks, especially when wet and used for any length of time, is widely questioned, but together with other rules they appear to have made a significant difference. Am. J. Primatol. At Gombe there is rarely more than one group of six tourists visiting chimps in a day, and often there are no visitors apart from researchers. At Mahale, the Frankfurt Zoological Society has recently recommended rules that would limit the number of tourists visiting chimps to three groups of six people a day and the number of researchers to two groups of two people a day maximum. The rules for film crews have not yet been revised. It has taken some time for the visitation rules to be implemented at Gombe and Mahale, the visitation rate during the tourist season remains higher than recommended at Mahale, and not all of the rules are followed at either location all of the time. However, there have been no serious outbreaks—and no deaths from respiratory disease—at Gombe since end 2002 (S. Kamenya, E. Lonsdorf, personal communication) and at Mahale since August 2006 (Lukasik-Braum unpublished data). CONCLUSION The trend of improved chimp health is encouraging. But whether or not the visitation rules will continue to be enforced at Mahale and Gombe remains a concern. The Taı̈ Forest example underscores the fact that no one rule will protect the chimps from respiratory disease. Distance, number of visitors, preventing sick people from visiting, and masks all contribute. Similar guidelines would undoubtedly improve chimp health in all settings where tourists or researchers visit the animals. Taı̈ Forest and now Mahale researchers have shown us that we can identify the disease agent responsible for respiratory disease among chimps, and very likely for all great apes. It is our collective responsibility to work together to improve our data collection methods and pursue the diagnosis. It is equally important that we work together on the epidemiology of these outbreaks and prove or disprove a correlation between visitation rates, rules, or lack thereof, seasonality, and natural vs. introduced diseases. It may take years before clear patterns emerge that definitively show the value of the visitation rules, but waiting to implement rules puts the animals at risk. Disease management may be the most important thing we can do to ensure the future health of habituated great apes in Africa. Visitation rules will be accepted and successful only if we work together to sensitize tourists, researchers, and park staff about the risks. Given the endangered status of the world’s great apes, it seems prudent to be conservative as possible. We need not assume that visitors to the great apes will view the rules as a negative. On the contrary, they can be positive for all those who are involved. COMMENTARY / 737 REFERENCES Goodall J. 1986. The chimpanzees of Gombe: patterns of behaviour. Cambridge, MA: Harvard University Press. Hanamura S, Kiyono M, Lukasik-Braum M, Mlengeya T, Fujimoto M, Nakamura M, Nishida T. 2007. Chimpanzee deaths at Mahale caused by a u-like disease. Primates 49:77–80. Kamenya S. 2002. Diseases as one of the key factors causing population decline among the chimpanzee communities of Gombe National Park. Proceedings of the Second Tanzania Wildlife Research Institute Annual Conference. 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