Internal parasites of pigs

Pigs can be infected with a number of different roundworms. These can result in poor weight gain in adults. In young pigs infection with roundworms can cause diarrhoea, weight loss, lung problems and death. Worms from pigs can cause disease in human.

Roundworm infections of the pig

Pigs can be infected with a number of different roundworms. People who keep pigs can notice large roundworms, 25 – 40 cm long in the animals’ dung. In pigs 2 to 5 months old the worms cause diarrhoea, weight loss and lung problems. The young worm lives in the liver and lungs before passing into the intestine. The damage to the lungs can allow germs to attack and cause coughing and lung infections. The young pig can die. The worm in the liver of young and adult pigs causes white spots (milk spot) to develop. Such a liver should not be eaten by humans.

Treatment and control of roundworms

Infected pigs are easily treated by dosing with a suitable treatment, e.g. piperazine. The pregnant sow should be treated before giving birth or she will pass on infection to her litter. One female worm will produce a million eggs a day which pass out in the dung. These eggs infect new hosts and can stay in the ground or the pigsty for up to 5 years.

The pigsty, shelter or pen should be cleaned out and the walls and floor treated with caustic soda which is left for 2 – 3 days before washing it off. If infected pigs have been kept out in a field the land should be ploughed and used for a crop, or as grazing for other animals, before pigs are put back on it.

Problems caused by pig parasites in humans

Pigs can be infected with a parasitic worm called Trichinella. The adult worm lives in the intestine while young worms are found in the muscles (meat). It does not appear to be a problem to the pig. Any animal which eats the pig meat can be infected with the worm.

Pigs can be infected with Trichinella from eating rats which have the infection. Pigs will also be infected from contaminated meat so all meat fed to the animals (e.g. in swill) should be thoroughly cooked. Thorough cooking of pork will also kill the worm. If humans eat undercooked pig meat from an animal infected with this parasite they will become infected too. If a pig is left to wander around it may eat plants contaminated with human faeces. In this way the pig meat can become infected with a tapeworm from humans. If the meat of that pig is not properly cooked people who eat it can become infected with the pork tapeworm.