GEOGRAPHICAL DISTRIBUTION
This is a common parasite rats and mice in many parts of the world. It is an occasional accidental parasite of humans, particularly children.
LOCATION IN HOST
The worm is found in upper part of the ileum. It may move up or down as it is known in rats.
MORPHOLOGY
The worm measures about 300-600 mm* 4 mm. It has about 800-1000 segments. The scolex is small (0.2-0.4 mm). It has a retractable rostellum but no hooks. Four small suckers are also present on the scolex. The mature segments is broader than length and measures 0.75*0.25 mm.
The eggs are ovoid (60-80 µm) and have thick yellowish outer shells and thin colourless inner membranes. The intermediate layer appears granular. The embryo has three pairs of hooklets.
LIFE CYCLE
The adult worm is in the small intestine of rat which is the definitive host. Larval rat fleas ingest the eggs passed in the rat faeces. The embryo grows into a cysticercoid larva (cysticercus like) in the flea. When humans accidentally ingest the rat flea the released cysticercoid larva matures into an adult worm. Four beetles may also act as intermediate hosts.
PATHOGENESIS
Multiple infections are not uncommon. The scolices may damage the mucosa leading to inflammation. Frequent movements of worm may also cause pathology. Metabolic products of the worm mar also cause different clinical manifestations.
CLINICAL FEATURES
Most of the time patients are asymptomatic. Some patients may experience abdominal pain. High degree of clinical suspicious is needed for the diagnosis.
DIAGNOSIS
Demonstration of the characteristics eggs in the stool is the most reliable method.
PREVENTION AND CONTROL
Improvement of personal and environmental sanitation is important. Elimination of household rats helps to reduce the disease.
TREATMENT
Identification of the infected persons is very important. There are few treatments methods available. Praziquantel and Niclosamide can be used as treatment.
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