Selected helminthoses in domestic ruminants: Infections of the musculature
Selected helminthoses in domestic ruminants:
Infections of the musculature
Author: Prof Joop Boomker
Licensed under a Creative Commons Attribution license.
Onchocerca spp.
These parasites occur in the connective tissue of cattle. Their presence often results in the formation of
hard nodules in which the nematodes are coiled up. The different species occur in different localities
within the host, e.g. Onchocerca gutterosa is found in ligaments and Onchocerca dukei in the
subcutaneous tissue. The parasites produce microfilariae which circulate in the blood. These are taken in
by biting flies of the genera Simulium and Culicoides in which the infective stage develops and which
transmit the worms to the next host.
An unidentified parasite, which could be a Stephanofilaria species has been found in cattle in the
previous Venda, now in extreme north of the Limpopo province of South Africa. The lesions were
associated with an intense Haematobia meridialis infestation and characterized by ulcerations behind the
scapulae. The causative agent could, however, not be identified.
Large Onchocerca sp. nodules clearly visible and indicated by arrows (left) and nodules in the muscle, also
indicated by arrows (right)
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Selected helminthoses in domestic ruminants: Infections of the musculature
Taenia ovis
The adult worms occur in dogs, jackal and hunting dogs and the larvae, Cysticercus ovis, in the muscles
of sheep and goats. The larvae do not cause significant pathology but render the meat aesthetically
objectionable and thus cause economical losses.
The metacestodes of Taenia ovis are indicated by the black arrows
Taenia saginata
The beef tapeworm uses cattle as intermediate host and humans as the final hosts. The metacestodes
are known as cysticerci, and are not very numerous in cattle. One may find them in the active muscles,
such as the diaphragm, and the iliopsoas and masseter muscles. They are particularly common in the
cardiac muscles. The cycticerci are non-pathogenic and are incidental findings at necropsy or slaughter.
It is, however, a condition of much economic importance, as many organs and carcasses are condemned
because of the infection.
Numerous cysticerci in the heart (left) and a few in the muscles of a bovine (right)
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