Author: Prof Joop Boomker

Infections of the skin and adnexa

Approximately 16% of the buffaloes in the KNP have lesions of one or more of the three species of Onchocerca which occur in buffaloes. The infection manifests as small nodules in the subcutis of the mainly the thoracic, sternal and abdominal regions, but are also present in eyelids, the prepuce and testis (Basson et al., 1970). Unidentified Onchocerca spp. occurs in thirteen species of antelope throughout southern Africa as well as in leopards in Tanzania (Round, 1968).

Fig. 26: Microfilaria of an Onchocerca sp. In the blood of a buffalo

During the late 1980’s and early 1990’s a skin condition was noticed in buffaloes in the KNP, from which Parafilaria bassoni, a filarid nematode that has previously only been recorded from springbuck in Namibia, was recovered. Haemorrhagic perforations or bleeding points were seen dorsally and laterally on the body. Complications due to bacterial infection that cause subcutaneous abscesses, and a type 1 hypersensitivity, that caused large ulcers were seen in a small number of animals. Red-billed oxpeckers often enlarged the bleeding points by feeding on the blood and skin, in the process causing large ulcers. The oxpeckers also played an important part in limiting the spread of the helminths by ingesting blood that contains eggs and first stage larvae (Figs. 27-29, after Keet, Boomker, Kriek, Zakrisson & Meltzer, 1997).

Fig. 27: The lesion caused by Parafilaria bassoni starts out as a small bleeding point

Fig. 28: Oxpeckers enlarge the bleeding point to skin ulcers up to 15 cm in diameter.

Fig. 29:  The skin lesions heal during winter, leaving a distinct scar

Occasionally the coenuri of Taenia multiceps may be found under the skin or in the intermuscular connective tissue of blue wildebeest, oryx and roan antelope, all three being intermediate hosts. The coenuri are recognized by the flabby “sac” in which numerous protoscoleces are seen. Contrary to what is observed in antelope, only those oncospheres of T. multiceps that end up in the central nervous system and spinal cord of sheep will develop into coenuri. The adult tapeworm occurs in dogs and jackals.

A whole host of microfilariae of which the adult worms are not known, have been reported in the literature, from dik-dik in Ethiopia, giant African otter in the Democratic Republic of the Congo, zebra, waterbuck, bushbuck and warthog in South Africa and steenbuck in Mozambique  (Neitz, 1931; Van den Berghe, Chardome &  Peel, 1957; Round, 1968; Palmieri, Pletcher, De Vos & Boomker, 1985). These microfilariae may be those of Setaria species, which are quite common in many antelope and warthog in South Africa, or they may represent new species of filarid nematodes. The microfilariae have not been associated with any pathology. However, microfilariae, presumably those of Elaeophora, were associated with mononuclear myocarditis (Basson et al., 1971; Boomker et al., 1989b).