Large ascarid roundworm
Toxocara vitulorum is an uncommon parasite of cattle but have been recorded in calves 1 to 3 months of age in eastern Australia. Older animals are resistant to re-infection. T. vitulorum is of little pathogenic importance in the southern regions of Australia although infection is considered pathogenic in buffalo calves in humid tropical and subtropical regions in other parts of the world.
Figure 1. Egg of Toxocara vitulorum, the large ascarid roundworm of cattle. Image courtesy of the National Centre for Veterinary Parasitology, ncvetp.org
Worms are large, creamy-white in colour and up to 30 cm long. Infection is only found in calves 1-6 months of age. The adult female worm is a most prolific egg layer and an infected calf can pass 8 million eggs into the dung each day. Typically, the eggs remain viable in the soil for many years.
Further ecological information on worms and their control:
Adult worms are found in the small intestine of calves or in the tissues such as the mammary glands and the placenta.
Adults in the small intestine can cause diarrhoea and weight loss. Coughing due to pneumonia may occur when larvae migrate through or become lodged within the lungs.
The characteristic eggs are found on a worm egg count (WEC) when analysing dung samples for eggs of other roundworms.
Anthelmintic treatment is rarely indicated in cattle in Australia. If necessary, treatment during pregnancy will control infection to prevent prenatal infection of calves. Eggs are very resistant to adverse climatic conditions.
Gongylonema pulchrum and G. verrucosum are sometimes found in cattle as well as other ruminants including sheep and goats. Gongylonema pulchrum has a wider host range and can also be found in horses, swine, poultry, dogs, cats and numerous other wild and domestic mammals and birds.
Gongylonema pulchrum adults reach about 30-145 mm in length while G. verrucosum are 35-90 mm. These worms have a long slender shape and are yellowish-brown to reddish-brown in colour and are covered with a cuticle (skin) which is flexible but strong. They usually form a zig-zag pattern in the walls of the oesophagus and pharynx.
Figure 1. The gullet worm, Gongylonema pulchrum, leaves a zig zag pattern in the walls of the oesophagus. Image courtesy of the National Centre for Veterinary Parasitology, ncvetp.org
Gullets and rumens are sometimes used for sausage casings but infected organs are rejected during meat inspection procedures.
Further ecological information on worms and their control:
Figure 2. Adult gullet worms, Gongylonema verrucosum. Image courtesy of the National Centre for Veterinary Parasitology, ncvetp.org
Worms are prevalent in the wall of the oesophagus (G. pulchrum) and rumen (G. verrucosum).
These worms are usually harmless. Infections of livestock, horses or pets may cause a slight inflammation of the oesophagus or rumen wall but are mostly benign and no clinical signs are observed, or treatment warranted.
Diagnosis in livestock or pets is usually incidental after slaughter or necropsy.