The pathological and parasitological findings from 100 free-ranging chacma baboons are described. One of the most striking discoveries was a heretofore unknown coccidian parasite, Isospora papionis, and even more important than its presence in the small intestine was its occurrence in skeletal muscles. Serological and histopathological evidence of toxoplasmosis was found in several animals. Other previously unknown parasites encountered included two mites- Rhinophaga elongata, an unusually long mite that produced small granulomas in the nasal mucosae, and Pneumonyssus vocalis, a mite found in the laryngeal ventricles. A new species of filarid, Tetrapetalonema papionis was found in the subcutis and intermuscular fascia.
New records for the chacma baboon of known parasites were R. papionis, a mite found only in the maxillary recess, where it stimulated a polyplike growth, and, in the skeletal muscles, cysticerci of Taenia crocutae, a tapeworm of hyenas (Crocuta crocuta and Hyaena brunnea). Apart from the pathological changes associated with the above parasites, another important finding was numerous cases of "capture myopathy", a syndrome that resembles Meyer-Betz disease of man. One of the most severe diseases encountered was pulmonary acariasis (P. mossambicensis), which at times caused large foci of supportive pneumonia and diffuse pleuritis. The mite pigment was also found in draining lymph nodes. The most serious diseases of the liver were cytomegaly, which was similar to that produced by mycotoxins in other animal species, multiple granulomatous foci caused by Hepatocystis simiae and microgranulomas caused by ova of Schistosoma mattheei. Adult schistosomes were also found in the mesenteric vessels.
The most important lesion in the central nervous system was an axonal hamartoma, which was found in two cases and involved a large portion of the brain stem. Also of note were a meningioma in the falx cerebelli, a few examples of non-suppurativc encephalitis and several cases in which neurons in the medulla oblongata had been replaced by a globular eosinophilic mass.
Other tumours found were a fibroma in the subcutis of the face and a basal cell carcinoma in the skin on the back. Both were of local importance only. Developmental anomalies included an accessory spleen, ectopic pancreatic tissue in the duodenum, thymic tissue embedded in the thyroid and parathyroid and microcysts in the thymus, parathyroid and adenohypophysis.
Arteriosclerosis of limited severity was found in the aorta and coronary and renal arteries of many of the older baboons (males and females). Another vascular change related to previous pregnancy was sclerosis of the ovarian and uterine vessels. Degenerative changes were found in the central arteries of germinal follicles in various lymph nodes and the spleen.
Other noteworthy findings included the presence of spargana in the skeletal muscles; ranula formation of the ducts of the glands of Ebner; para-ovarian crystals; large intranuclear inclusions in the submandibular salivary gland compatible with those produced by cytomegalovirus and intranuclear inclusions in the epididymis. Various gastro-intestinal parasites were found and their corresponding lesions are described. Selected bacterial studies for shigellae and salmonellae were negative, as were intradermal tests for tuberculosis and serological tests for leptospirosis and brucellosis. The brain, heart, spleen, liver, lungs and kidneys were mass measured and were compared to the body mass. In all age groups the heart varied the least when expressed as percent body mass. The brain was the most variable in this regard but changed the least in total mass.