Trichinellosis is caused by larvae of roundworms - mainly the species Trichinella (T.) spiralis. To date, four species of trichinella are known in Europe. These pathogens are called trichinella or trichinae. The last known autochthonous outbreak of disease in humans caused by a domestic pig occurred in 1970 after the consumption of poorly smoked meat from a domestic pig infested with trichinae.

Trichinellosis is a worldwide food-borne zoonosis that occurs regardless of climatic conditions. In Central Europe, trichinellosis is now rare. In some eastern and Baltic EU states, the incidence is higher, with most cases being caused by meat products from wild boar.

Domestic pigs, wild boar and horses are hosts for trichinae. Rodents (e.g. rats) and wild animals (e.g. foxes) are considered reservoirs. Humans are a false host for this parasite.

Infection occurs through the consumption of raw or insufficiently cooked meat containing Trichinella larvae. The larvae are released from the meat by digestive enzymes in the stomach and mature into small worms in the cells of the upper small intestinal mucosa within a few days. The females begin to lay up to 1,500 larvae just four to seven days after ingestion by the host. The young larvae pass through the intestinal mucosa and enter the muscles via the bloodstream, where they can survive encapsulated in muscle cells for years. Oxygen-rich muscles, i.e. muscles with a good blood supply, such as the diaphragm, neck muscles, chewing muscles, muscles of the shoulder girdle or upper arms are favoured.

The incubation period is between 1 and 4 weeks and depends on the number of Trichinella larvae ingested. 100 to 300 ingested Trichinella larvae are currently thought to be a pathogenic dose for humans. Under certain circumstances, the consumption of a few grams of infectious meat is sufficient. Infection from person to person is not possible.

Trichinellosis is a mild to fatal foodborne disease in humans, who are considered highly susceptible hosts. The severity of the disease depends on the number of larvae ingested and the immune response of the individual. The symptoms of the disease in humans are characterized in the initial phase by fever, abdominal pain and diarrhea. In the later course of the disease, muscle and joint pain as well as typical edema in the facial area are in the foreground.

Slightly infected patients usually recover without complications by bed rest and with the help of a painkiller. Severe infections are treated with drug therapy against worm larvae infestation. Drug treatment is more successful the earlier it is carried out.

All animals susceptible to Trichinella intended for human consumption must be tested for the presence of Trichinella larvae in the muscles or subjected to freezing treatment. Killing the parasites by deep freezing is only a suitable method for domestic pigs, whereby 15 cm thick pieces of meat must be frozen at a temperature of at least -15 °C for at least three weeks. Parasites are reliably killed by heating when temperatures in the centre of the meat of at least 71 °C have been reached for one minute. Smoking, curing and drying are not suitable for killing the larvae.

In Austria, cases of the disease in humans are very rare: In the past 50 years, only so-called "imported" cases of trichinellosis have been registered by the health authorities in Austria. These were people who became infected with Trichinella larvae during a stay abroad or took infected meat products with them to Austria and fell ill in Austria after eating them.

In 2024, 5 cases were registered in the EMS (EMS, as at 03/02/2025).

In Austria, 4,645,174 domestic pigs, 469 horses and 43,682 wild boars from the wild and 764 farmed wild boars were tested for Trichinella as part of the official meat inspection in 2023. Trichinella infestation was not detected in any of the animals tested. No positive Trichinella cases have been detected in Austrian breeding pigs, fattening pigs or horses for decades.

The parasite has been significantly reduced in domestic pigs in Central Europe thanks to legal measures and improved biosecurity in animal husbandry. In Austria, however, particular attention must be paid to the fox-wild boar infection chain, as there has been a sharp increase in the wild boar population in recent years. Scientific studies have shown that the parasite is also present in the fox population in Austria, although there is a west-east divide in its distribution.

The suspected diagnosis can be confirmed by the detection of specific antibodies in the blood of the patient; in the case of massive infestation, the larvae can be detected in the tissue by histological examination of muscle biopsy specimens.

Animals that may be carriers of Trichinella and are intended for human consumption must be examined for Trichinella larvae after slaughter or killing and before the meat is placed on the market (Implementing Regulation (EU) 2015/1375; EN ISO 18743/2015). The examination is carried out using the so-called digestion method: A precisely defined amount of muscle by weight of the carcass subject to examination (usually from the area of the diaphragm pillar) is dissolved by means of artificial digestion and the sediment of the digestion liquid is checked under microscopic observation for the presence of Trichinella larvae.

In the event of positive Trichinella detection, the entire carcass is confiscated by the competent veterinary authority and sent for verifiable disposal.