Pork Tapeworm Larvae Disease: What are the Symptoms of Infection? How to Effectively Treat the Disease?
What are the symptoms of pork tapeworm larval infection?
According to Sections 2 and 3 of the Guidance issued alongside Decision 1383/QD-BYT dated May 30, 2022 by the Ministry of Health, the symptoms of pork tapeworm larval infection are as follows:
“2. CLINICAL SYMPTOMS
Depending on the location, number, and size of cysts, the following clinical forms can be observed:
2.1. Pork tapeworm larvae in the muscles
- Most common among the cases of pork tapeworm larvae infection, however, symptoms are often unclear and hence, go undetected or are found incidentally.
- Cysts of pork tapeworm larvae under the muscle sheath: round or oval, usually 1-2cm in size, up to 3cm, easily moveable, painless, and non-itchy. Commonly found in the arms and chest. The cysts may regress and calcify on their own.
- Muscle tissue cysts of pork tapeworm larvae: usually asymptomatic, if infected with multiple cysts, muscle twitching or spasms can occur. Calcified cysts can be detected via X-ray.
- Pork tapeworm larval cysts in the heart muscles: Depending on the location, there may be no symptoms or it can cause arrhythmia or conduction disturbances.
2.2. Pork tapeworm larvae in the central nervous system
- May be found in the brain and spinal cord: often causing serious complications for the patient, potentially leading to death.
- Clinical symptoms vary and are non-specific depending on the location, number, and size of the cysts in the brain and spinal cord.
2.2.1. Pork tapeworm larvae in the brain
Common clinical symptoms include:
+ Seizures: the most common symptom, occurring in 50-80% of cases with brain parenchymal cysts.
+ Headache, nausea, vomiting due to increased intracranial pressure: occurring in 20-30% of cases.
+ Hydrocephalus due to cysts obstructing the cerebrospinal fluid circulation in the ventricles.
+ Memory loss, mental disorders.
+ Patients may experience paralysis, motor dysfunction, sensory disturbances, blurred or double vision...
+ Multiple cyst cases can lead to strokes or coma, resulting in death.
2.2.2. Pork tapeworm larvae in the spinal cord.
Rare cases, clinical symptoms may include: back pain, numbness in limbs, muscle weakness, urinary and fecal disorders, paralysis.
2.3. Pork tapeworm larvae in the eyes
- Rare, accounting for 1-3% of total cases of pork tapeworm larval infection.
- Cysts invade the eyes via retinal blood vessels and can parasitize anywhere within the orbit such as the anterior chamber, retina, fundus, conjunctiva... or freely float in the vitreous, subretinal space.
- Common clinical symptoms: eye pain, decreased vision, exophthalmos (protruding eyes), blurred or double vision...
3. LABORATORY SYMPTOMS
3.1. Cyst biopsy
Considered the “gold standard” for diagnosing pork tapeworm larval disease.
- Macroscopic image: Cyst is oval-shaped, shiny white, 1-2cm in diameter, filled with fluid inside, thin-walled. Under light microscopy, the head of the tapeworm with a rostellum (snout), 4 suckers, and 2 rows of hooks can be seen.
- Microscopic: Hematoxylin-Eosin (HE) stained cysts feature an outer enveloping layer, and hooks inside. The shell has a characteristic tri-layer structure: the outer membranous layer, middle cellulose layer, and inner fibrous layer.
3.2. Imaging diagnosis
3.2.1. CT/MRI
- Can detect lesion images of pork tapeworm larval cysts, particularly in the brain.
- This method can identify the location and developmental stages of the lesions, wherein the MRI can identify lesions in the active stage.
- Cysts usually progress through 4 stages: vesicular, colloidal, granular, and calcified. Active pork tapeworm larval cysts typically have a thick outer shell (2-4mm), clearly delineated from the surrounding parenchyma and tissues, with a 2-3mm head located on one side, and surrounding tissues may or may not show edema.
3.2.2. Ultrasound
- Can detect muscle cases, subcutaneous cysts: round or oval, 2x3 cm in size, echo-free, with strong echogenic nodules with no shadow, located peripherally; surrounded by a thick echogenic ring measuring 2-3mm, continuous, with possible inflammatory reactions in the surrounding tissues.
3.2.3. X-ray
- Can detect calcified cysts in muscles, heart, brain... but is rarely used in diagnosis. X-ray images can help guide the need for CT or MRI scans.
3.3. Immunological tests
- Depending on the facility's conditions, the following tests can be used:
+ Enzyme-linked immunoelectrotransfer blot assay (EITB) to detect antibodies against pork tapeworm larvae.
+ ELISA for detecting antibodies against pork tapeworm larvae.
+ ELISA for detecting antigens of pork tapeworm larvae.
3.4. Ophthalmoscopy
- For all suspected cases of cerebral pork tapeworm infection.
- Specific image: A clear, round or oval cyst with a tapeworm head within.
3.5. Fecal examination
- To find tapeworm eggs, proglottids, and other parasites.
3.6. Other tests
- Generally non-specific
- Blood count: May show increased eosinophils.
- Liver and kidney function tests.
- Cerebrospinal fluid: May show increased pressure and eosinophils.”*
According to clinical symptoms, depending on the organ infected by pork tapeworm larvae, different symptoms may appear in the eyes, central nervous system, or muscles.
Symptoms of pork tapeworm larval infection? How to effectively treat pork tapeworm larval disease?
Guidelines for treating pork tapeworm larval disease?
Based on Section 5 of the Guidance issued alongside Decision 1383/QD-BYT dated May 30, 2022 by the Ministry of Health, the guidelines for treating pork tapeworm larval disease are as follows:
“5. TREATMENT
5.1. Treatment principles
- Specific treatment combined with symptomatic treatment. Only use specific drugs for cases where the cysts are still active.
- Surgical treatment: Applied in certain cases:
+ Pork tapeworm larvae in the brain causing hydrocephalus.
+ Pork tapeworm larvae parasitizing in the ventricles blocking the cerebral aqueduct.
+ Pork tapeworm larvae in the eyes.
+ Pork tapeworm larvae in the spinal cord causing compression.
5.2. Specific treatment
One of the following regimens can be used:
5.2.1. Regimen 1: Albendazole
Before treating pork tapeworm larvae, treat adult tapeworms with praziquantel 10-15mg/kg as a single dose on the first day, taken away from meals.
a) Dosage of Albendazole: 15mg/kg/day, divided into 2 doses x 8-30 days taken after meals in the following days.
Repeat treatment can be administered one or more times based on the progression of the disease. Each treatment course is at least 1 month apart.
b) Contraindications
- Allergy to the components of the drug.
- Pregnant women, especially in the first trimester.
- Not for children under 1 year old.
c) Precautions when taking the drug
- For eye pork tapeworm larvae (treat inflammation or surgically before specific drug treatment).
- People suffering from acute illnesses or chronic heart, liver, kidney diseases...
- Breastfeeding women: avoid breastfeeding for 72 hours after taking the drug.
- Avoid alcohol, beer, and stimulants.
- Do not drive or operate machinery within 24 hours of taking the drug.
d) Adverse effects and management
Long-term use of albendazole can cause liver toxicity and leukopenia, thus for prolonged use, liver and kidney functions, blood counts, white blood cell and neutrophil counts should be checked every 10-15 days.
5.2.2. Regimen 2: Praziquantel
a) Dosage
Praziquantel 50mg/kg/day divided into 3 doses, taken after meals for 15 days.
Repeat treatment can be administered one or more times based on the progression of the disease. Each treatment course is at least 1 month apart.
b) Contraindications
- Allergy to the components of the drug.
- Pregnant women, especially in the first trimester.
- Not for children under 1 year old.
c) Precautions when taking the drug
- For eye pork tapeworm larvae (treat inflammation or surgically before specific drug treatment).
- People suffering from acute illnesses or chronic heart, liver, kidney diseases...
- Breastfeeding women: avoid breastfeeding for 72 hours after taking the drug.
- Avoid alcohol, beer, and stimulants.
- Do not drive or operate machinery within 24 hours of taking the drug.
d) Adverse effects and management
- Dizziness, headache, drowsiness, nausea, discomfort in the epigastrium, rash, allergy.
- Management: Allow the patient to rest in bed, use appropriate symptomatic treatments and follow careful monitoring.
5.3. Symptomatic treatment
5.3.1. Anti-inflammatory drugs (Corticosteroids)
- Use the lowest dose for the shortest duration possible.
- Corticosteroids are recommended to be used concomitantly with specific anti-parasitic drugs or prior to specific drug treatment for cases with brain pork tapeworm larvae with multiple cysts, eye cysts, cysts in the ventricles, cysts in the subarachnoid space, brainstem cysts.
5.3.2. Anti-epileptic drugs (if symptomatic)
5.3.3. Supportive drugs
- Cerebral circulation enhancers.
- Liver function support drugs.
- B vitamins.
- Drugs for preventing and treating gastric ulcers.
- Pain relief drugs.
5.4. Monitoring during and post-treatment
- During and after each treatment cycle, assess the progression of clinical symptoms and conduct blood tests, liver and kidney function tests.
- MRI/CT scans to reassess every 6 months.
- Monthly ELISA antigen testing.
- If clinical symptoms do not improve, repeat the treatment cycle. The interval between treatment cycles should be at least 1 month. If ineffective, combine imaging evaluations to decide on changing the regimen.
- If clinical symptoms disappear post-treatment, reassess with imaging diagnostics after 6 months:
+ If active cysts disappear: discontinue specific treatment.
+ If active cysts persist, continue treatment with a new regimen.
- In cases where tests are negative but clinical symptoms persist, treat the symptoms.”*
The principle of treating pork tapeworm larval infection includes both specific and symptomatic treatments. Surgical treatment is only applied in certain cases.
What are the criteria for considering a patient cured?
Based on Section 6 of the Guidance issued alongside Decision 1383/QD-BYT dated May 30, 2022 by the Ministry of Health, the criteria for considering a patient cured of pork tapeworm larval disease are as follows:
“6. CRITERIA FOR CURE
- Clinically: symptoms gradually return to normal (except for some cases of sequelae); and
- MRI/CT: No images of active pork tapeworm larval cysts; or
- ELISA antigen test: negative.”*
Thus, to be considered cured, the patient’s clinical symptoms need to return to normal, and MRI results must show no active pork tapeworm larval cysts or a negative ELISA antigen test.
LawNet