Taenia solium

Scientific classification Taenia solium Scientific classification Kingdom: Animalia Phylum: Platyhelminthes Class: Cestoda Order: Cyclophyllidea Family: Taeniidae Genus: Taenia Species: T. solium

Taenia solium is the pork tapeworm belonging to cyclophyllid cestodes in the family Taeniidae. It is an intestinal zoonotic parasite found throughout the world, and is most prevalent in countries where pork is eaten. The adult worm is found in humans and has a flat, ribbon-like body, which is white in color and measures 2 to 3 m in length.but can become much larger, sometimes over 8 m long

Morphology: Adult T. solium  having no body cavity. It is white in colour and flattened into a ribbon-like body. The anterior end is a knob-like head called a scolex, which is 1 mm in diameter. The scolex bears four radially arranged suckers that surround the rostellum. These are the organs of attachment to the intestinal wall of the host. The rostellum is armed with two rows of spiny hooks. The elongated body is called the strobila, which is connected to the scolex through a short neck. The entire body is covered by a special covering called tegument

which is an absorptive layer consisting of a mat of minute hair-like microtriches. The strobila is divided into segments called proglottids. Body growth starts from the neck region, so the oldest proglottids are at the posterior end. Thus, the three distinct proglottids are immature proglottids towards the neck, mature proglottids in the middle, and gravid proglottids at the posterior end, each mature proglottid contains a set of male and female reproductive systems. The numerous testes and a bilobed ovary open into a common genital pore. The oldest gravid proglottids are full of fertilised eggs,

The infective larave, cysticerci, in humans, called "cellulose" cysticercus, which has a fluid-filled bladder 0.5 to 1.5 cm in length

life cycle Humans develop intestinal infection with adult worms after ingestion of contaminated pork or may develop cysticercosis after ingestion of T. solium eggs (making humans intermediate hosts). 1. Humans ingest raw or undercooked pork containing cysticerci (larvae). 2. After ingestion, cysts evaginate, attach to the small intestine by their scolex, and mature into adult worms in about 2 mo. 3. Adult tapeworms produce proglottids, which become gravid; they detach from the tapeworm and migrate to the anus

4. Detached proglottids, eggs, or both are passed from the definitive host (human) in feces. 5. Pigs or humans become infected by ingesting embryonated eggs or gravid proglottids (eg, in fecally contaminated food). Autoinfection may occur in humans if proglottids pass from the intestine to the stomach via reverse peristalsis. 6. After eggs are ingested, they hatch in the intestine and release oncospheres, which penetrate the intestinal wall. 7. Oncospheres travel through the bloodstream to striated muscles and to the brain, liver, and other organs, where they develop into cysticerci. Cysticercosis can result.

Pathogenesis and signs: Intestinal infection of T.solium is called taeniasis which is quite asymptomatic. Only in severe cases, conditions of intestinal irritation, anaemia, and indigestion occur, which can lead to loss of appetite and emaciation. Cysticercus is clinically pathogenic. Ingestion of T. solium eggs or proglottids which rupture within the host intestines can cause larvae to migrate into host tissue to cause cysticercosis. This is the most frequent and severe disease caused by T. solium.

In symptomatic cases, a wide spectrum of symptoms may be expressed, including headaches, dizziness, and occasional seizures. In more severe cases, dementia or hypertension can occur due to perturbation of the normal circulation of cerebrospinal fluid. The severity of cysticercosis depends on location, size and number of parasite larvae in tissues, as well as the host immune response. Other symptoms include sensory deficits, involuntary movements, and brain system dysfunction. In children, ocular location of cysts is more common than cystation in other locations of the body.

In many cases, cysticercosis in the brain can lead to epilepsy, seizures, lesions in the brain, blindness, tumor-like growths, and low eosinophil levels. It is the cause of major neurological problems, such as hydrocephalus, paraplegy, meningitis, convulsions, and even death

Diagnosis Inspection of carcasses   Microscopic examination of stool for ova and proglottids CT and serologic testing for patients with CNS symptoms Intestinal infection with adult T. solium worms can usually be diagnosed by microscopic examination of stool samples and identification of ova and/or proglottids

Treatment For intestinal infection: Praziquantel or niclosamide . For neurocysticercosis: Corticosteroids, anticonvulsants, and sometimes albendazole or praziquantel and/or surgery

Prevention and control The best way to avoid getting tapeworms is to not eat undercooked pork. Moreover, a high level of sanitation and prevention of faecal contamination of pig feeds also plays a major role in prevention. Infection can be prevented with proper disposal of human faeces around pigs, cooking meat thoroughly and/or freezing the meat at −10 °C for 5 days. For human cysticercosis, dirty hands are attributed to be the primary cause, and especially common among food handlers.[7] Therefore, personal hygiene such as washing one's hands before eating is an effective measure.

Immune response  is the immunological response originating from immune system activation by antigens, including immunity to pathogenic microorganisms and its products, as well as autoimmunity to self-antigens allergies, and graft ejections. In this process main cells involved are the T cells, B cells of lymphocytes, and macrophagea. These cells produce lymphokines that influence the other host cells activities. B cells mature to produce immunoglobulins or antibodies, that react with antigens. At same time, macrophages are processing the antigens into immunogenic units which stimulate B lymphocites to differentiation into antibody secreting plasma cells, stimulating the T cells to realise lymphokines