Trichinellosis – colloquially known as trichinosis – (ICD-10 B75.-) is an infectious disease caused by parasites of the species Trichinella (nematodes/filamentous worms).
The following species of Trichinella can be distinguished:
- Trichinella spiralis – the most common species.
- Trichinella nelsoni
- Trichinella nativa
- Trichinella bitovi
- Trichinella pseudospiralis
The disease belongs to the parasitic zoonoses (animal diseases).
Pathogen reservoir: trichinella can infect all mammalian species, but in Europe are predominantly affected pigs (especially wild boar). However, they can also occur in horses, bears and seals.
Occurrence: Trichinellosis in humans occurs primarily in North and Central America, as well as Argentina, East Africa, and Southeast Asia. In Germany, cases of disease occur rarely. These then have their origin mostly abroad. Trichinellosis is independent of climatic conditions, as there are no free parasite stages in trichinella.
The Trichinella larvae are killed when heated to temperatures of at least 70° C in the nucleus over a period of one minute.
Transmission of the pathogen (route of infection) occurs through consumption of raw or insufficiently heated contaminated meat.
Human-to-human transmission: No.
The incubation period (time from infection to onset of the disease) is usually between 5 and 14 days, occasionally up to 45 days.
The following stages of trichinellosis can be distinguished:
- Enteral phase – in this phase, the larvae are in the intestinal mucosa (about day 2-7); symptoms: severe feeling of illness, faintness, insomnia, diarrhea (diarrhea), abdominal discomfort (abdominal pain) and others.
- Migration phase (1-3 weeks) – in this phase, the larvae migrate via the bloodstream into the muscles Days 7-11: Symptoms: subfebrile to high fever (40-41 °C, mainly in the evening or at night), chills, hoarseness, swelling of the eyelids and face, conjunctivitis (conjunctivitis), et al. a. Days 12-20: Myalgias (muscle pain): first eye muscles, then chewing muscles, neck muscles, tongue, then flexor muscles of extremities, respiratory and back muscles 3. -4th week: without therapy, fever and muscle pain subside; in the convalescence phase: muscle weakness, stiffness and ;joint contractures (stiffening of joints), muscle weakness, increased sweating, conjunctivitis, paresthesias (insensitivity) or sensitivity disorders can persist for years.
- Parenteral phase – in this phase there are symptoms due to larvae encapsulated in the central nervous system.
Course and prognosis: the severity of infection depends on the host’s defenses, but also on the number of larvae ingested. It is assumed that an ingestion of more than 70 larvae leads to disease. Mild and unspecific courses are usually not recognized. For further information on the course of the disease, see above under “Stages of trichinellosis”.
In Germany, direct or indirect detection of the pathogen is reportable by name according to the Infection Protection Act (IfSG), provided that the evidence indicates an acute infection.
