What is Trichinella spiralis Infection (Trichinosis)?
Trichinellosis, also known as trichinosis, is an infection caused by a type of roundworm that belongs to the Trichinella species. This infection happens when you eat undercooked or raw meat, especially pork. The species most often responsible for this disease in humans is called Trichinella spiralis.
This infection can also originate from wild meat-eating animals and horses, which can carry the worms. The symptoms of this disease can range from relatively mild, like a high fever, stomach pain, diarrhea, nausea, vomiting, and muscle aches, to severe conditions like inflammation of the heart (myocarditis) and brain inflammation (encephalitis).
What Causes Trichinella spiralis Infection (Trichinosis)?
Trichinella spiralis is a type of parasitic worm, also known as a nematode. It can infect various animals like pigs, horses, reptiles, and birds, but it only causes disease in humans. People can get infected by eating undercooked or raw meat from these animals or from wild game like bear meat. In rare cases, eating reptile meat, such as lizards and turtles, has also been associated with the infection. There is no known case of transmission from one person to another.
Risk Factors and Frequency for Trichinella spiralis Infection (Trichinosis)
Trichinellosis, a disease that occurs globally, affects around 10,000 people each year. Cases typically happen in group clusters who share meat from the same infected animal. Can be caused by nine different species and twelve genotypes of Trichinella, with Trichinella spiralis being the most commonly associated with human disease. Other species that can cause disease in humans include: T. nativa, T. nelson, T. britovi, T. pseudospiralis, T. murelli, and T. papuae.
- In the 1940s, the Centers for Disease Control and Prevention recorded around 400 cases of Trichinellosis each year.
- However, the number of reported cases has significantly decreased, with approximately 20 cases annually documented from 2008 to 2010.
- People at high risk include hunters and those who consume wildlife meat.
- China, a region where pig consumption is highest, has the most number of reported cases.
- In the Arctic, Trichinella has been found in polar bears, seals, and walruses.
- There has been a recent uptick of Trichinella in Europe due to the growing preference for antibiotic-free meat.
Signs and Symptoms of Trichinella spiralis Infection (Trichinosis)
Trichinellosis is a disease that you can get if you eat raw or undercooked meat, particularly pork. The time between eating the contaminated meat and the first symptoms appearing can range between 1 to 6 weeks. People who ate a lot of contaminated meat generally have more severe symptoms.
The first symptoms appear 2 to 7 days after eating the contaminated meat and include stomach issues – like stomach pain, diarrhea, nausea, and vomiting. People with trichinellosis also often complain of muscle pain, mainly in the middle of their abdomen, face, and chest. The pain can sometimes be so bad that it limits their daily activities.
Later on, usually around 2 weeks after eating the contaminated meat, the person might experience other symptoms like fever, chills, muscle pain, swelling around the eyes or face, weakness, and tiredness. These symptoms can last for up to 8 weeks. Some people also have ongoing diarrhea. Other symptoms include eye redness and bleeding under the skin, around the eyes, or in the nails. People might also get a rash, often similar to hives, but sometimes accompanied by petechiae, small red or purple spots caused by bleeding under the skin. Many times, this illness can also cause swelling of the eyelids, which can lead to other eye symptoms like proptosis and chemosis – the protrusion and swelling of the eyes, respectively. Other, less common symptoms, include headache, cough, difficulty breathing, and swallowing. Some people might also experience an enlarged liver.
In severe cases, trichinellosis can lead to complications like inflammation of the heart muscle (myocarditis), dangerous heart rhythms (life-threatening arrhythmias), inflammation of the brain and its protective membranes (meningitis and encephalitis), muscle inflammation that makes it hard to breathe (respiratory myositis), bacterial pneumonia, blood in urine (hematuria), and kidney failure.
- Stomach pain
- Diarrhea
- Nausea
- Vomiting
- Severe muscle pain
- Fever
- Chills
- Swelling around the eyes or face
- Weakness
- Tiredness
- Eye redness
- Bleeding under the skin
- Rash
- Headache
- Cough
- Difficulty breathing
- Difficulty swallowing
- Enlarged liver
- Possible severe complications include myocarditis, life-threatening arrhythmias, meningitis, encephalitis, respiratory myositis, secondary bacterial pneumonia, hematuria, and renal failure
Testing for Trichinella spiralis Infection (Trichinosis)
The initial diagnosis of a disease is usually based on the patient’s symptoms and the doctor’s physical examination of the patient. However, to confirm the diagnosis, more detailed tests like blood tests or even a muscle biopsy might be required.
A complete blood count is a common test that can reveal things like leukocytosis, or an increase in white blood cells, and eosinophilia, an increase in a specific type of white blood cell. These increases often happen when the body is responding to an infection. The severity of these increases can also help your doctor estimate the number of worms causing the infection.
Other tests, like those checking Creatine kinase, lactate dehydrogenase, aldolase, and aminotransferases levels, may be used to assess the extent of muscle damage caused by the parasitic invasion. Additionally, patients may exhibit low potassium, low albumin, and increased serum IgE levels. However, these are non-specific changes and can be seen in other parasitic infections as well as in autoimmune diseases.
Serological tests, which identify antibodies or antigens in the blood, are another diagnostic tool. Available ones include ELISA (enzyme-linked immunosorbent assay), indirect IF (immunofluorescence), and a latex agglutination test. A western blot test can be used to confirm these results. However, these tests aren’t always reliable, particularly in the early stages of an infection (the first three weeks or more). Also, infections with other organisms or certain autoimmune diseases can cause a false positive result on these tests.
To rule out other causes of neurological dysfunction, a computed tomography (CT) scan may be performed. Additionally, an electrocardiogram (ECG), a test that measures the electrical activity of the heart, may show symptoms of conditions such as pericarditis (inflammation of the membrane surrounding the heart), ischemia (insufficient blood flow), or myocarditis (inflammation of the heart muscle). It may also reveal irregular heart rhythms or conductivity issues.
The most definitive method for diagnosing this disease is a muscle biopsy, where a small piece of muscle is removed and examined under a microscope. This test has a high success rate if performed four weeks after the start of an infection. However, if performed too early in the course of the disease, it might return a negative result even if the patient is infected.
Treatment Options for Trichinella spiralis Infection (Trichinosis)
Trichinellosis, an infection caused by a type of roundworm, tends to run its course naturally and without complications in most people. When the infection is mild, it can be managed by treating symptoms like fever and inflammation. This often involves medicines to reduce fever (antipyretics) and to bring down swelling (anti-inflammatory agents).
However, in cases where the Trichinella infection results in severe or system-wide issues, different types of medication might be required. These include medicines to kill parasites (antiparasitic agents) and medicines to reduce inflammation and immune system activity (corticosteroids). Albendazole and mebendazole are examples of antiparasitic agents often used.
It’s important to note though that albendazole and mebendazole are not safe for use in pregnant women and children aged two or younger. Because these medicines can be risky, it’s vital to get advice from a specialist who can assess the potential benefits against the possible risks. According to the World Health Organization, pregnant women can use certain anti-worm drugs (like mebendazole, albendazole, pyrantel, or levamisole) after their first trimester.
If the Trichinella infection affects the heart, doctors may need to monitor the heart activity of the patient to ensure their safety.
Furthermore, if someone has been exposed to the Trichinella parasite, taking mebendazole within six days of the exposure might possibly help in preventing an infection.
What else can Trichinella spiralis Infection (Trichinosis) be?
Your doctor may consider a variety of conditions when examining a patient with eosinophilia. These could include:
- Gastroenteritis – either viral or bacterial
- Autoimmune diseases like polymyositis and dermatomyositis
- Periorbital cellulitis (an eye infection)
- Eosinophilia-myalgia syndrome (a rare condition that affects muscles and nerves)
Your doctor may also look into other infections related to helminths, or parasitic worms. These might include:
- Fasciola
- Schistosomiasis
- Toxocariasis
- Cysticercosis
- Visceral larva migrans
- Sarcocystosis
What to expect with Trichinella spiralis Infection (Trichinosis)
Trichinellosis is a disease that often has a mild course and can heal by itself. Patients are usually expected to fully recover within 2 to 6 months of getting the infection. However, some cases can be severe, and in rare instances, this can lead to death. Death is usually rare as long as the heart and central nervous system (CNS) — which includes the brain and spinal cord — are not affected. However, if the central nervous system is involved, some people might have long-term health issues. How severe this disease can be is mainly connected to how many parasites are in the body.
Possible Complications When Diagnosed with Trichinella spiralis Infection (Trichinosis)
Possible Complications:
- Heart inflammation (Myocarditis)
- Lung inflammation (Pneumonitis)
- Secondary lung infection (Secondary bacterial pneumonia)
- Kidney inflammation (Nephritis)
- Long-lasting diarrhea (Chronic diarrhea)
- Brain and nerve disorders related to Trichinella infection (Neurotrichinellosis)
Preventing Trichinella spiralis Infection (Trichinosis)
Trichinellosis is a disease that you can get if you eat raw or undercooked meat from an animal that is infected. It’s crucial to be aware of the risk of getting this disease if you consume meat that’s not properly cooked. It’s important to note that there’s no evidence that this disease can be passed from one person to another. However, there can be outbreaks within a community or family if people eat from the same infected animal.
The best way to prevent trichinellosis is by heating meat to at least 77 degrees Celsius. At this temperature, the harmful larvae in the meat, known as Trichinella, get killed. It’s also important to follow proper food safety practices. Your doctor can provide guidance on how to handle and cook meat safely to avoid diseases like trichinellosis.
