After you eat roundworm (trichinella) larvae, they grow into adult worms in your small intestine. The adults then produce larvae that move through the bloodstream to muscle tissues, shown here.
Signs and symptoms of trichinosis infection and how severe the infection is can vary. This depends on the number of larvae eaten in the infected meat.
Possibly no signs or symptoms
Mild cases of trichinosis — those with only a small number of parasites in your body — may cause no signs or symptoms. Symptoms can develop with moderate or heavy infestation ⸺ a large number of parasites in your body. These symptoms sometimes get worse as the roundworm (trichinella) larvae travel through your body.
Initial signs and symptoms
You swallow roundworm (trichinella) larvae in tiny sacks (cysts) containing the parasite. Your digestive juices dissolve the cysts, releasing the larvae into your body. The larvae then enter the wall of your small intestine, where they grow into adult worms and mate. Digestive symptoms can begin 1 to 2 days after infection. At this stage, you may experience:
Later signs and symptoms
About a week after infection, the adult female worms produce larvae. The larvae go through the wall of your intestine and enter your bloodstream, They travel around the body and bury themselves in muscle tissue. Here, each larva coils up and forms a cyst around itself. The larvae can live for months to years inside the muscle tissue.
Symptoms caused by muscle tissue invasion usually start 2 to 8 weeks after infection and include:
- High Fever and Chills
- Muscle pain and tenderness
- Aching joints
- Swelling of the eyelids or face
- Sensitivity to light
- Pink eye (conjunctivitis)
- Itchy, irritated skin
With a large number of parasites, muscle pain and Weakness can be severe. This can limit moving, breathing and speaking.
Symptoms last for several months. But symptoms generally lessen when the larvae form cysts. Even after the infection is gone, Fatigue, mild pain, Weakness and Diarrhea may last for months or years.