Taeniasis is an intestinal infection caused by adult tapeworms. Humans can get infected with two species of tapeworms-Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm). T.saginata has no major impact on human health while T. solium leads to neurocysticercosis-most severe form of the disease.
Neurocysticercosis is a common cause of seizures; and the most frequent preventable cause of epilepsy worldwide. According to World Health Organization (WHO) 30% of all epilepsy cases in endemic countries and 3% epileptic cases globally may be due to neurocysticercosis.
Taeniasis/cysticercosis mainly affects the people in developing countries of Africa, Asia and Latin America. Taeniasis and (neuro)cysticercosis are common in areas where animal husbandry practices are such that pigs and cattle come into contact with human faeces. But imported taeniasis can also lead to cases in the population of countries where T.solium is not considered a public health problem.
The disease is prevalent in all states of India, although the prevalence varies between the states. The National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore reported neurocysticercosis (NCC) in 2% of unselected series of epilepsy patients. In a study from New Delhi, NCC accounted for 2.5% of all intracranial space occupying lesions. An unusual feature of the disease was seen that more than 95% of Indian patients with NCC are vegetarians.
Cysticercosis is highly prevalent in the northern States of Bihar, Orissa, Uttar Pradesh and Punjab. In a rural pig farming community of Mohanlalganj block, Lucknow district, Uttar Pradesh, the prevalence of taeniasis was found to be 18.6%.In the same community, active epilepsy was confirmed in 5.8% of the populations and 48.3% of people with epilepsy fulfilled either definitive or probable diagnostic criteria for NCC.
Humans become infected after consuming raw or undercooked, infected meat, or food and water contaminated with tapeworm eggs, or through poor hygiene practices. When T.solium larvae invade body tissues, a more serious condition known as cysticercosis develops. When larvae invade the central nervous system, muscles, skin and eyes, it leads to neurocysticercosis.
Neurocysticercosis is an important and preventable cause of epilepsy which creates burden through stigmatization, incapacitation and loss of work productivity. In Southeast Asia T. solium taeniasis/cystcercosis is considered one of the major neglected tropical diseases by WHO as these have not been given enough importance at national or international levels.
A tapeworm infection does not always cause symptoms. Sometimes symptoms are mild and non-specific such as abdominal pain, nausea, diarrhoea or constipation. Symptoms may arise 6–8 weeks after ingestion of meat containing cysticerci; when the tapeworms become fully developed in the intestine. These symptoms may continue until the tapeworm dies following treatment, otherwise it may live for years.
In the case of cysticercosis due to T.solium, the incubation period is variable, and infected people may remain asymptomatic for years. In some endemic regions (particularly in Asia), infected people may develop visible or palpable nodules (a small solid bump or node that can be detected by touch) beneath the skin (subcutaneous).
Neurocysticercosis is associated with different signs and symptoms depending on the number, size, stage, and location of the pathological changes as well as the host’s immune response and the parasite’s genotype. Symptoms may include chronic headaches, blindness, seizures, and dementia. Signs and symptoms of hydrocephalus, meningitis, and space occupying lesions in the central nervous system may be present. In severe cases, neurocysticercosis may be fatal.
Clinically asymptomatic cases can also be found.
Taeniasis is intestinal infection caused by two species of tapeworms Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm).
Taeniasis is acquired by humans through the ingestion of undercooked pork or beef, infected with cysticerci or contaminated food (mainly vegetables) and water. In the human body, cysticerci develop into adult tapeworms that live in the intestine and release egg-bearing gravid proglottids (segments) which are passed with faeces.
When proglottids or eggs are ingested by pigs and cattle with egg-contaminated vegetation, the eggs hatch and burrow through their intestinal wall. The larvae burrow into muscles and form fluid-filled cysts, called cysticercosis.
In the case of T. solium, when the central nervous system is affected, the infection is called neurocysticercosis.
Taeniasis and (neuro) cysticercosis are common in areas where animal husbandry practices are such that pigs and cattle come into contact with human faeces.
(a) Examination of stool samples-Diagnosis of Taenia tapeworm infections can be made by examination of stool samples; Stool specimens should be collected on three different days and examined in the lab for taenia eggs using a microscope. Tapeworm eggs can be detected in the stool 2 to 3 months after the tapeworm infection is established.
(b) Serological diagnosis- complement fixation tests (CFT) and indirect haemagglutination tests (IHA)] may be used for the diagnosis of cysticercosis. Enzyme-linked immunoelectrotransfer blot (EITB) and Coproantigen enzyme linked immunosorbant assay (ELISA) test are also used for diagnosis.
(c) Neuroimaging diagnosis- Imaging methods play very important roles in the diagnosis of human cysticercosis.
Treatment of taeniasis may include administration of praziquantel (single-administration) or niclosamide (single-administration) and if the patient has cysticercosis in addition to taeniasis, praziquantel should be used with caution. Praziquantel is cysticidal and can cause inflammation around dying cysts in those with cysticercosis, which may lead to seizures or other symptoms.
After treatment, stools should be collected for 3 days to search for tapeworm proglottids for species identification. Stools should be re-examined for Taenia eggs one and three months after treatment to be sure the infection is cleared.
The treatment of human cysticercosis may include long courses with praziquantel and/or albendazole, as well as supporting therapy with corticosteroids and/or anti-epileptic drugs.
Ocular, ventricular, and spinal lesions may require surgical treatment because treatment with anthelmintic drugs can provoke irreversible drug-induced inflammation.
To prevent and control T.solium infection proper public health interventions with an approach involving veterinary and human health, food safety, sanitation and environment sectors are required.
(a)Access to preventive chemotherapy- Preventive chemotherapy involves the distribution of drugs at regular intervals to human populations at risk in endemic areas in order to destroy parasitic worms. It can be implemented in three ways:
(b)Health education-Health education may be given to general population, health workers, pig farmers and meat workers. The focus of health education should be on the biology of the disease, improvements in meat preparation and personal hygiene and the need for adequate sanitation/ improved pig husbandry.
(c) Improved sanitation-Ensure that sanitation facilities are available and should be used. It has public health advantages in T. solium control and also in the prevention of diarrhoeal diseases.
(d) Improved pig husbandry- Encouraging farmers to adopt better farming practices, specifically by confining pigs to prevent their access to human faecal material, is consistently included in recommendations for the control of T. solium.
(e) Anthelmintic treatment of pigs- Chemoprophylaxis in pigs has been widely used as a control strategy with demonstrated high efficacy in protecting pigs from porcine cysticercosis cases.
(f) Vaccination of pigs- Use of the vaccine together with anthelmintic treatment of pigs can greatly reduce the transmission of T. solium from pigs to humans.
(g) Improved meat inspection- The aim of meat inspection is to break the life-cycle of T. solium, considered to be the most important food borne parasitic infection.