The chimpanzees of the Kasoje area in the Mahale Mountains National Park have been studied for more than 40 years¹. We noticed a skin disease developing among some members of M group in 2001 and 2002.

RK observed M group chimpanzees for the whole years of 2001 and 2002, SF from June to October 2001, TM from September 2000 to June 2001, TN from September to October 2001 and from September to November 2002, and MS from September 2001 to October 2002. We recorded any observable injuries, disease symptoms such as coughing, and abnormalities of the skin, faces and eyes.

On May 10, 2001, we first noticed that an infant male, Caesar, had a whitish nose and left cheek; it looked as if white chalk had been applied to the part. On July 2, a female infant, Rubicon, had a whitish face. On September 9, an adult male, Alofu, had a whitish upper lip. In September, as many as 7 individuals at once showed this skin disease.

Table 1. List of chimpanzees that suffered from dermatophytosis.

Table 1 shows the first and last observed dates of the disease in 13 individuals. Its occurrence biased to seasons with high humidity might suggest a fungal infection, so that the disease may be some form of dermatophytosis. Victims were from all age-sex classes and no conspicuous age or sex differences were found (1 of 8 adult males, 3 of 20 adult females, 2 of 5 adolescent males, 0 of 2 adolescent females, 2 of 2 juvenile males, 2 of 3 juvenile females, 1 of 3 infant males, 2 of 10 infant females). These 12 chimpanzees had dermatophytosis on their faces, in particular, upper lip, nose, cheek, and supraorbital ridge (Fig.1). The exception was Michio, who had a white mark on the back of his hand, as well as a white face. Although we could not always check all individuals during the study periods, it was likely that the skin disease lasted several weeks (minimum, median = 14 days) for each victim and the longest span was 35 days. The infectious nature of the disease was inferred from the victims being concentrated to the short period of September to October, 2001 and from the close relationships among at least some victims: for example, Miya is the mother of Michio, and Ruby is the mother of Rubicon. Roy² described a fungal disease from the chimpanzees of Gombe, but not this type of skin disease. Bill Wallauer's³ recent blog shows a photograph of a Gombe chimpanzee, Faustino, who appeared to show the same skin disease as described here.

Fig. 1. Dermatophytosis on the faces of the Mahale M-group chimpanzees. See the text for details.

Neither victims nor the others showed any attention to the infected parts of the body; the victims did not scratch the whitish parts of their faces. Later, all individuals recovered their normal dark faces without experiencing any apparent health problems (Cf. Hubbard⁴).

ACKNOWLEDGMENTS

The research was funded by MEXT Scientific Research Fund A1 (#12375003 & 16255007 to TN) and Global Environment Research Fund of the Ministry of Environment (F-061 to TN). We thank Bill McGrew for useful comments.

REFERENCES

1. Nishida T (ed) 1990. The Chimpanzees of the Mahale Mountains. Tokyo: The University of Tokyo Press.
2. Roy AD 1974. Rhinophycomycosis entomophthorae occurring in a chimpanzee in the wild in East Africa: further report. American Journal of Tropical Medicine and Hygiene, 23: 935.
3. Wallauer W 2007. The Jane Goodall Institute's Gombe Chimpanzee Blog (http://www.janegoodall.org/Gombe-Chimp-Blog/detail.asp?Entry_ID=44)
4. Hubbard GB 2001. Nonhuman primate dermatology. Veterinary Clinics of North America: Exotic Animal Practice, 4: 573–583.