Praziquantel Health Dictionary

Also known as BILHARZIASIS. This infection results from one of the human Schistosoma species. It is common in Africa, South America, the Far East, Middle East, and, to a limited extent, the Caribbean. The life-cycle is dependent on fresh-water snails which act as the intermediate host for the ?uke; the cercarial stage of the ?uke enters via intact human skin and matures in the portal circulation. Clinically, ‘swimmers’ itch’ may occur at the site of cercarial skin penetration. Acute schistosomiasis (Katayama fever) can result in fever, an urticarial rash (see URTICARIA), and enlargement of LIVER and SPLEEN. The adult male is about 12 mm and the female 24 mm in length.

S. haematobium causes CYSTITIS and haematuria – passage of blood in the urine; bladder cancer and ureteric obstruction, giving rise to hydronephrosis and kidney failure, are long-term sequelae in a severe case. S. mansoni can cause colonic symptoms and in a severe case, POLYPOSIS of the COLON; diarrhoea, which may be bloody, can be a presenting feature. In a heavy infection, eggs surrounded by granulomas are deposited in the liver, giving rise to extensive damage (pipe-stem ?brosis) associated with PORTAL HYPERTENSION, oesophageal varices, etc. However, unlike in CIRRHOSIS, hepatocellular function is preserved until late in the disease. S. japonicum (which is con?ned to the Far East, especially Indonesia) behaves similarly to S. mansoni infection; liver involvement is often more severe.

Diagnosis can be made by microscopic examination of URINE or FAECES. The characteristic eggs are usually detectable. Alternatively, rectal or liver BIOPSY are of value. Serological tests, including an ELISA (see ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)), have now largely replaced invasive procedures used in making a parasitological diagnosis.

Treatment CHEMOTHERAPY has been revolutionised by the introduction of praziquantel (administered orally); this compound has no serious side-effects, although its cost may limit its use in developing countries. Oxamniquine is cheaper and e?ective in S. mansoni infection, although evidence of resistance has been recorded in several countries. Metriphonate is also relatively cheap and is of value in S. haematobium infection. Prevention is by complete avoidance of exposure to contaminated water; all travellers to infected areas should know about this disease. It is increasing in frequency as new expanses of fresh water appear as a result of irrigation schemes and dam projects. Molluscicides can be employed for snail-control.... schistosomiasis

ACUTE LIVER DISEASE The hepatitis viruses (A– F) are of paramount importance. Hepatitis E (HEV) often produces acute hepatic failure in pregnant women; extensive epidemics – transmitted by contaminated drinking-water supplies – have been documented. HBV, especially in association with HDV, also causes acute liver failure in infected patients in several tropical countries: however, the major importance of HBV is that the infection leads to chronic liver disease (see below). Other hepatotoxic viruses include the EPSTEIN BARR VIRUS, CYTOMEGALOVIRUS (CMV), the ?avivirus causing YELLOW FEVER, Marburg/Ebola viruses, etc. Acute liver disease also occurs in the presence of several acute bacterial infections, including Salmonella typhi, brucellosis, leptospirosis, syphilis, etc. The complex type of jaundice associated with acute systemic bacterial infection – especially pneumococcal PNEUMONIA and pyomiositis – assumes a major importance in many tropical countries, especially those in Africa and in Papua New Guinea. Of protozoan infections, plasmodium falciparum malaria, LEISHMANIASIS, and TOXOPLASMOSIS should be considered. Ascaris lumbricoides (the roundworm) can produce obstruction to the biliary system. CHRONIC LIVER DISEASE Long-term disease is dominated by sequelae of HBV and HCV infections (often acquired during the neonatal period), both of which can cause chronic active hepatitis, cirrhosis, and hepatocellular carcinoma (‘hepatoma’) – one of the world’s most common malignancies. Chronic liver disease is also caused by SCHISTOSOMIASIS (usually Schistosoma mansoni and S. japonicum), and acute and chronic alcohol ingestion. Furthermore, many local herbal remedies and also orthodox chemotherapeutic compounds (e.g. those used in tuberculosis and leprosy) can result in chronic liver disease. HAEMOSIDEROSIS is a major problem in southern Africa. Hepatocytes contain excessive iron – derived primarily from an excessive intake, often present in locally brewed beer; however, a genetic predisposition seems likely. Indian childhood cirrhosis – associated with an excess of copper – is a major problem in India and surrounding countries. Epidemiological evidence shows that much of the copper is derived from copper vessels used to store milk after weaning. Veno-occlusive disease was ?rst described in Jamaica and is caused by pyrrolyzidine alkaloids (present in bush-tea). Several HIV-associated ‘opportunistic’ infections can give rise to hepatic disease (see AIDS/HIV).

A localised (focal) form of liver disease in all tropical/subtropical countries results from invasive Entamoeba histolytica infection (amoebic liver ‘abscess’); serology and imaging techniques assist in diagnosis. Hydatidosis also causes localised liver disease; one or more cysts usually involve the right lobe of the liver. Serological tests and imaging techniques are of value in diagnosis. Whilst surgery formerly constituted the sole method of management, prolonged courses of albendazole and/or praziquantel have now been shown to be e?ective; however, surgical intervention is still required in some cases.

Hepato-biliary disease is also a problem in many tropical/subtropical countries. In southeast Asia, Clonorchis sinensis and Opisthorchis viverini infections cause chronic biliary-tract infection, complicated by adenocarcinoma of the biliary system. Praziquantel is e?ective chemotherapy before advanced disease ensues. Fasciola hepatica (the liver ?uke) is a further hepato-biliary helminthic infection; treatment is with bithionol or triclabendazole, praziquantel being relatively ine?ective.... liver disease in the tropics

A drug used to treat SCHISTOSOMIASIS. Praziquantel is the drug of choice, with a combination of e?ectiveness, broad-activity spectrum and few side-effects.... schistomicide

1. n. any drug or chemical agent used to destroy parasitic worms (helminths), e.g. tapeworms, roundworms, and flukes, and/or remove them from the body. Anthelmintics include *albendazole, *mebendazole, *niclosamide, and *praziquantel. 2. adj. having the power to destroy or eliminate helminths.... anthelmintic

n. a condition caused by the presence of the fluke Clonorchis sinensis in the bile ducts. The infection, common in the Far East, is acquired through eating undercooked, salted, or pickled freshwater fish harbouring the larval stage of the parasite. Symptoms include fever, abdominal pain, diarrhoea, liver enlargement, loss of appetite, emaciation and – in advanced cases – cirrhosis and jaundice. Treatment is unsatisfactory although *praziquantel has proved beneficial in some cases.... clonorchiasis

n. a disease, common in the Far East, caused by the fluke *Fasciolopsis buski in the small intestine. At the site of attachment of the adult flukes in the intestine there may be inflammation with some ulceration and bleeding. Symptoms include diarrhoea, and in heavy infections the patient may experience loss of appetite, vomiting, and (later) swelling of the face, abdomen, and legs. Death may follow in cases of severe ill health and malnutrition. The flukes can be removed with an anthelmintic (such as praziquantel).... fasciolopsiasis

n. a condition caused by the presence of the parasitic fluke *Opisthorchis in the bile ducts. The infection is acquired through eating raw or undercooked fish that contains the larval stage of the parasite. Heavy infections can lead to considerable damage of the tissues of the bile duct and liver, progressing in advanced cases to *cirrhosis. Symptoms may include loss of weight, abdominal pain, indigestion, and sometimes diarrhoea. The disease is treated with praziquantel.... opisthorchiasis

(endemic haemoptysis) n. a tropical disease that occurs principally in Asia, caused by the presence of the fluke *Paragonimus westermani in the lungs or other organs. The infection is acquired by eating inadequately cooked shellfish. Early symptoms include fever, cough, chest pain, fatigue, and sweating. Later symptoms vary depending on which organs are affected: in the case of the lungs, symptoms resemble those of tuberculosis. Paragonimiasis is treated with praziquantel.... paragonimiasis