Pathologic lesions in chimpanzees (Pan trogylodytes schweinfurthii) from Gombe National Park, Tanzania, 2004-2010

Abstract

During a population decline or disease outbreak, the true risk of specific diseases to a wild population is often difficult to determine because of a lack of baseline disease information. To better understand the risk of disease in an endangered and scientifically important population of chimpanzees (Pan trogylodytes schweinfurthii), a health monitoring program was initiated in Gombe National Park, Tanzania. As part of this health monitoring program, comprehensive necropsies with histopathology were conducted on chimpanzees (n = 11; 5 male, 6 female), ranging in age from fetal to 44 yr, that were found dead between August 2004 and January 2010. In contrast to previous reports, respiratory disease was not noted as a cause of morbidity or mortality. Trauma was the most common cause of death in these 11 chimpanzees. All of the chimpanzees greater than 1 yr of age had intestinal and mesenteric parasitic granulomas associated with true strongyles consistent with Oesophagostomum spp. The relative numbers of granulomas increased with age and, in some cases, may have been a cause of weight loss and diarrhea. Simian immunodeficiency virus (SIV)cpz infection was documented in four deceased apes, all of whom exhibited varying amounts of lymphoid depletion including two females with marked CD4+ T cell loss consistent with endstage SIVmac or human immunodeficiency virus infections. Myocardial megalokaryosis was common in chimpanzees greater than 1 mo of age; yet myocardial interstitial fibrosis, a common lesion in captive chimpanzees, was uncommon and only noted in two aged chimpanzees. These findings provide important information on causes of morbidity and mortality in wild chimpanzees, information that can be used to interpret findings during population declines and lead to better management of this population in the context of disease risk.

Figure 1

Prepared skeletal remains of a chronic nonunion fracture of the ischium (chimpanzee Ch-045).

Figure 2

Gross photograph of a formalin-fixed longitudinal section of vertebra and spinal cord with a nonunion fracture of T5 (arrowhead), regional swelling of the spinal cord (arrow), and distal myelomalacia (asterisk) (chimpanzee Ch-099).

Figure 3

Cross-section of a true strongyle (Oesophagostomum sp.) within a mesenteric granuloma from a chimpanzee (Ch-016). Characteristic features evident in this section include low lateral chords (asterisks), triradiate esophagus (arrowhead), and large intestine with prominent brush border (arrow). Bar = 100 μm.

Figure 4

Megalokaryosis in cardiac myocytes (chimpanzee Ch-099). Note the variation in myocyte nuclear size. Bar = 50 μm.