Trichinellosis or trichinosis is one of the infectious diseases caused by parasites. The notifiable disease is one of the most widespread worm diseases of humans worldwide.
What is trichinellosis?
Trichinellosis is a worm disease caused by the larvae of trichinae. Trichinae can enter the human body by eating raw or undercooked meat. Pork is particularly dangerous, but also meat from other domestic or wild animals. Pigs or wild animals are the carriers of the parasite, and humans are intermediate or final hosts.
Causes
Trichinae are tiny nematodes. They can be found in raw meat, especially pork, or even meat from wild animals. If a person eats this meat raw or insufficiently roasted or cooked, the larvae of these nematodes enter the person’s stomach. The enzymes in the stomach are ideally suited for the larvae to free themselves from their cocoon. Through the movements of the intestine, the larvae enter the small intestine. There they nest in the intestinal wall and grow into adult worms within 24 to 30 hours. Mating then takes place, after which the males quickly die. However, a fertilized female can produce up to 1500 larvae into the intestinal wall. From here they enter the human bloodstream. The females themselves survive up to 8 weeks. The worms finally reach their full development in the transversely striated muscles, where the parasites encapsulate and damage the muscles. Particularly affected are muscles with a good blood supply (shoulder girdle and upper arms, neck and chewing muscles). The eyes, tongue, and diaphragm can also be affected.
Symptoms, complaints, and signs
The course of trichinellosis depends on both the number of larvae ingested and the immune response. In addition to very severe clinical pictures, some of which are fatal, there are also mild forms of trichinellosis that are often not recognized. After an incubation period of five to fourteen days, intestinal symptoms initially occur because the larvae are initially located in the intestinal mucosa. There is a severe feeling of illness with abdominal pain, diarrhea, faintness, and insomnia. In a second stage, the larvae migrate via the bloodstream into the muscles. This stage is initially characterized by very high fever up to 41 degrees Celsius, chills, eye inflammation and hoarseness. Later, muscle pain is added to a variety of muscles. After about three to four weeks, muscle pain and fever subside. However, without treatment, several symptoms such as muscle pain, muscle and joint stiffness, sensory dysfunction, conjunctivitis of the eyes, or increased sweating may persist for a long time. However, these symptoms usually disappear completely after a year. Since the larvae can sometimes also encapsulate themselves in the central nervous system, neurological symptoms are sometimes also observed. However, there are also very severe courses of the disease, which not infrequently lead to death. Thus, heart muscle inflammation, brain inflammation, pneumonia or even sepsis can occur as dangerous complications.
Diagnosis and course
Initially, a patient with trichinellosis will show symptoms of gastrointestinal distress. Once the trichinae have entered the human gastrointestinal tract, nausea, vomiting, and diarrhea occur. Fever is also possible. However, the symptoms do not have to occur in all affected patients. In the second phase, the actual symptoms of the infectious disease occur. The worms have reached the bloodstream and eventually the muscles, causing high fever and muscle pain. At first, the patient often mistakes the muscle pain for joint pain. Swallowing and breathing problems occur as well. Edema forms around the eyes. Conjunctivitis and skin rash are also possible. The symptoms can persist for a year and usually heal without complications. The physician confirms the diagnosis by examining the patient’s blood and stool. Antibodies in the patient’s blood indicate trichinellosis. At a later stage, a sample of muscle tissue is also indicative.
Complications
Infection with nematodes of the genus Trichinella can vary widely.In mild cases, when only a small number of larvae have been ingested, the infection is often mistaken for an upset stomach and heals in a short time without complications. In severe forms of the disease, on the other hand, a whole range of serious complications, including death, can occur. In severe infections, the typical symptoms initially intensify. The often observed muscle hardening as well as muscle and joint pain no longer occur only during movement attempts, but also at rest. The typical hoarseness may intensify to the point that the patient temporarily loses his voice; in addition, severe discomfort during swallowing may require intravenous feeding. Breathing problems can lead to an acute risk of suffocation. If the eye muscles are affected, migraine-like headaches and visual disturbances may also occur, and sufferers often perceive double vision. In addition to encephalitis, the most dangerous complications include secondary infections such as bronchopneumonia or sepsis. Myocarditis (inflammation of the heart muscle), which is associated with permanent damage to the organ, cannot be ruled out either. In the worst case, which is rare in industrialized countries, however, the disease assumes life-threatening proportions and ends with the death of the patient.
When should you go to the doctor?
If there is a decrease in well-being, a persistent feeling of illness, and faintness, there is cause for concern. If the irregularities persist over a longer period of time or increase in intensity, a doctor is needed. Abdominal pain, chills, an elevated body temperature, and hoarseness should be investigated and treated. Pain of the musculoskeletal system, disturbances of sensitivity as well as abnormalities of the musculoskeletal system should be presented to a physician. Sleep disturbances, states of exhaustion as well as a decrease of the usual resilience are further indications of a disease. If irregularities or dysfunctions of the digestive tract occur, medical help is needed. Since trichinellosis is a notifiable disease, special care should always be taken if there are abnormalities in the bowel movements. If worm movements or other activity is noted in the bowel movements, this should be discussed with a physician. Sweating, stiffness of the joints or an irregularity in the eye area are other complaints that require action. Without a doctor’s consultation and medical care, the death of the affected person may occur if the disease is severe. For this reason, a doctor is needed as soon as there are inconsistencies in memory, heart rhythm or breathing. In the event of neurological deficits, an ambulance service should be alerted. Disturbances of consciousness, severe pain, coordination difficulties, and a body temperature above 40° should be presented to a physician immediately.
Treatment and therapy
If trichinellosis is detected in time, drug treatment is possible. The severity of the infection depends on how many larvae the patient has ingested. For therapy, the physician prescribes drugs that kill the worms and larvae in the patient’s body. An early start of therapy holds the possibility that the worms will not settle into the patient’s muscles. If the amount of ingested pathogen is very high, complications can occur and trichinellosis can also be fatal. Complications include heart disease (myocarditis), pneumonia, or blood poisoning. Meningitis and meningitis are also possible complications. The doctor reports the trichinellosis disease to the health department, which then has the task of finding out where the meat came from and who the meat producer is. In this way, possible others affected can be found.
Prevention
The most important prevention is not to eat meat raw or undercooked. A cooking temperature of at least 65 degrees Celsius will most definitely kill larvae in meat. The pathogens also do not survive prolonged freezing (at least 20 days below -15 degrees Celsius). Curing, smoking, salting or drying, on the other hand, does not kill the pathogens. In Germany, meat is also tested for trichinae by law. Caution is advised when importing meat from non-EU countries or consuming raw or undercooked meat abroad, as there are no laws in place to test meat for trichinae.
Aftercare
Basically, the further course of trichinellosis continues to be monitored by physicians after the diagnosis and treatment. The aftercare measures usually focus on the care of the damaged musculature and the prevention of irreversible damage to the musculature. However, the extent of follow-up examinations and treatments in trichinellosis depends on the effectiveness of the treatment measures. This is because the disease is regularly treated first with medication (anthelmintic based on benzimidazoles). However, the drug intervention is only effective as long as the Trichinella larvae are migrating or in the intestine of the affected person. Once the larvae have arrived in the striated muscle, therapeutic success is no longer guaranteed. The parasite then encapsulates itself permanently and damages the musculature. The parasite capsule does not calcify until a year has passed. Calcification also sets in much later in the parasite itself. The focus of the follow-up measures is now on the symptoms that may occur as a late consequence. Neurological focal symptoms (for example muscle twitching) are frequently observed. This is caused by Trichinella larvae encapsulated in the central nervous system. Neurological symptoms are regularly examined during follow-up and alleviated with medication. In individual cases, symptoms can even be life-threatening, so that chemotherapy becomes necessary as follow-up treatment. Rheumatic pain and chronic conditions (for example, anemia) are treated with medication for life during follow-up.
What you can do yourself
In case of infection with the trichinellosis pathogens, all possible sources of infection must first be removed. The health authority and, if necessary, various veterinary and food control authorities must be informed. These will take over securing the diagnosis and, if necessary, identify other affected persons. In addition, it must be determined where the infected meat came from. For this purpose, the affected person must be questioned in detail on occasion. After the actual treatment, which is usually carried out with medication using mebendazole, the patient requires a lot of bed rest. Particularly after chemotherapy, as is the case with very advanced diseases, the immune system is severely weakened and rest is essential. The most important measure is to take the prescribed medication as prescribed. The earlier the therapy is initiated, the less aggressively trichinellosis must be treated. Nevertheless, the patient must usually be quarantined to minimize the risk of infection. If complaints of the lungs, cardiovascular system or brain occur after the initial treatment, the responsible physician must be informed immediately. The Federal Institute for Risk Assessment provides further information on the prevention and treatment of trichinellosis for those affected.
