Taeniasis - Risk Factors, Symptoms, Pathophysiology, Diagnosis and Treatment

Introduction:

Taeniasis is caused by the tapeworm species Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), and Taenia Asiatica (Asian tapeworm). Humans are infected by these species when they consume raw or undercooked beef or pork. Individuals with taeniasis may not be aware of a tapeworm infection because the symptoms are nonexistent or mild. Taenia solium infection can cause cysticercosis, which causes seizures in humans.

What Causes Taeniasis?

Taeniasis is caused by the infection of parasitic tapeworms belonging to the genus Taenia. The two most common types of tapeworms causing taeniasis in humans are Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm). These tapeworms typically infect humans when they ingest undercooked or raw contaminated meat containing cysts or larvae of the tapeworm. For instance, consuming raw or improperly cooked pork that contains cysts harboring the tapeworm larvae can lead to an infection. Once ingested, the larvae develop into adult tapeworms within the human intestines, attaching themselves to the intestinal wall and growing into mature tapeworms. The infection may not always cause immediate symptoms, but over time, it can lead to digestive discomfort, abdominal pain, weight loss, and other complications if left untreated. Practicing good hygiene, proper cooking of meat, and maintaining sanitary conditions while handling food can significantly reduce the risk of taeniasis.

What Are the Risk Factors of Taeniasis?

Taeniasis cases are reported all around the globe. The main risk factor for acquiring taeniasis is consuming raw or uncooked beef. Infections with Taenia saginata are common in Eastern Europe, Russia, eastern Africa, Latin America, and Eastern Africa. Taeniasis caused due to T. saginata is seen in places where cattle and people are exposed to overpopulated regions and poor sanitation. It is also seen in areas where cattle may be exposed to human feces. Tapeworm infection caused by T. solium is common in underdeveloped countries with poor sanitation, where people consume raw or undercooked meat. Incidence rates are higher in countries like India, Latin America, Eastern Europe, sub-Saharan Africa, and Asia.

What Are the Clinical Symptoms of Taeniasis?

Most individuals with taeniasis are often asymptomatic or present with mild symptoms. However, the most common symptom is the passage of proglottids (a tapeworm segment containing a sexually mature reproductive system) in the feces, which can cause discomfort.

The signs and symptoms involve:

• Colicky abdominal pain (often seen in hollow organs of the abdomen such as the large and small intestine, gallbladder, and rectum).

• Nausea.

• Weakness.

• Loss of appetite.

• Increased appetite.

• Headache.

• Constipation.

• Dizziness.

• Diarrhea.

• Pruritus.

• Hyperexcitability.

Nausea and abdominal pain may be common in the morning and are relieved by eating a small quantity of food. Children seem to be more symptomatic than adults and show symptoms of decreased or increased appetite. Infants may show severe symptoms such as nausea, vomiting, diarrhea, fever, irritability, and weight loss. A major complication of tapeworm infection is appendicitis.

• Obstruction of bile ducts.

• Obstruction of pancreatic ducts.

• Tapeworm growth in ectopic locations such as adenoid tissue, middle ear, and uterine cavity.

• Mild eosinophilia is seen in 5 to 45 percent of individuals.

• Taeniasis is also found to mimic Crohn's disease.

Physical Examination Findings:

Children with intestinal taeniasis are often asymptomatic. Other findings may include the following:

• Weight loss is more common in infants due to loss of appetite.

• Subcutaneous nodules are common in adults.

• Neurologic abnormalities such as sensory disturbances, hemiparesis, and papilledema.

• Intraocular larvae may be present.

• Muscular pseudohypertrophy.

Taeniasis is also seen in individuals with weak immune systems, such as:

• HIV (human immunodeficiency virus).

• AIDS (acquired immune deficiency syndrome).

• An organ transplant.

• Diabetes.

• Chemotherapy.

What Is the Pathophysiology of Taeniasis?

Human taeniasis is caused by three tapeworm species T. solium, T. saginata, and T. asiatica. Humans are the only hosts for these species. Humans excrete the proglottids of tapeworm segments into the soil leading to contamination in areas where contamination is poor. Taenia eggs can grow and survive in a moist environment for days to months. The cattle, usually pigs and cows, get infected while feeding in the contaminated areas. Once these eggs enter the intestine of the animals, they hatch and migrate to the striated muscles and develop into cysticerci, causing cysticercosis. Cysticerci remains in the animal muscle for years. When humans consume this uncooked or raw meat, they get taeniasis. In humans, the taenia cysticerci travel to the small intestine and mature into adult tapeworms that produce proglottids in feces that continue the tapeworm's life cycle.

What Is the Differential Diagnosis of Taeniasis?

The differential diagnosis involves:

• Amebic meningoencephalitis.

• Appendicitis imaging.

• Gnathostomiasis.

• Inflammatory bowel disease.

• Pediatric aseptic meningitis.

• Pediatric tuberculosis.

• Pediatric small bowel obstruction.

• Pediatric neurocysticercosis.

• Pediatric cholecystitis.

How Is Taeniasis Diagnosed?

The diagnostic tools involve:

Laboratory Studies:

• Blood tests for complete blood count may show mild eosinophilia (an increase in the number of eosinophils in the blood). The stool test collects the individual's three stool samples in three days. The stools are checked for the following:

• Determination of species by ova examination. However, it is challenging to differentiate T. solium and T. saginata eggs as they are identical.

• Examination of the tapeworm segments or gravid proglottids helps in species identification. The main branches of the species are counted. T. solium has 7 to 16 branches, T. saginata has 14 to 32 branches, and 11 to 32 branches in T. asiata.

• The stools are examined for scolex, which helps differentiate species, as T. solium has four suckers and an armed rostellum and hooks, which is absent in T. saginata. T. asiatica has no hook.

Serology:

Copro-Ag ELISA detects T. solium tapeworm with a sensitivity and specificity of 84.5 % and 92 %, respectively.

Molecular Analysis:

• Copro-PCR detects T. solium. Multiplex loop-mediated isothermal amplification helps identify taenia species.

• Endoscopy or capsule endoscopy.

What Are the Factors that Influence the Transmission and Burden of Taeniasis?

Cultural dietary habits and preferences, such as consuming raw or undercooked meat, can increase the risk of tapeworm transmission. In areas where certain raw meat dishes are popular or where meat inspection standards are inadequate, the risk of taeniasis transmission may be higher. The level of sanitation and hygiene practices within a region can impact the transmission of tapeworm infections. Poor sanitation, inadequate access to clean water, and improper waste disposal may contribute to the spread of tapeworm eggs through contaminated food, water, or soil. The prevalence of taeniasis can also be influenced by livestock management practices. In regions where animals are raised in close proximity to humans or where there's a lack of proper animal husbandry, the risk of tapeworm transmission from infected animals to humans may be higher. The burden of taeniasis can be affected by the availability of healthcare services and awareness programs.

What Is the Treatment for Taeniasis?

Taeniasis is treated by a medical approach where the healthcare professional may prescribe anthelmintic drugs. The drugs prescribed may be Abandezol or Praziquantel. These drugs kill adult worms as well as eggs.

How Is Taeniasis Prevented?

The most successful method of prevention is consuming thoroughly cooked food. Meat should be cooked at a temperature above 140 degrees. Getting educated about meat safety. Other preventive methods involve:

• Mass drug administration for taeniasis.

• Identifying and treating taeniasis cases.

• Health education, including food safety and hygiene.

• Improved sanitation.

• Improved cultivation and production of pigs.

• Anthelmintic treatment for pigs (oxfendazole).

• Vaccination of pigs (TSOL18 vaccine).

• Better meat inspection and processing of meat products.

Post-treatment, the individuals are advised to examine stools for proglottids for weeks for T. solium infection and three months for T.saginata infection. A follow-up examination is necessary after one week of treatment. Individuals are advised for coAg-ELISA at one and three-month intervals. The treatment is repeated if positive.

Who Is Screened for Taeniasis?

The guidelines involve:

• Individuals with cysticercosis and live parenchymal cysts or growing lesions.

• Households and daily contacts of individuals with cysticercosis or individuals with a recent history of travel to endemic countries.

• Individuals with a recent history of proglottids.

Conclusion:

Taeniasis is caused by the tapeworm species Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), and Taenia Asiatica (Asian tapeworm). Most taeniasis cases are symptomatic or have mild symptoms. Therefore, treatment is primarily medical or preventive care.