Trophozoites Health Dictionary

A clinical state arising from invasive colo-rectal disease; it is accompanied by abdominal colic, diarrhoea, and passage of blood/mucus in the stool. Although the two major forms are caused by Shigella spp. (bacillary dysentery) and Entamoeba histolytica (amoebic dysentery), other organisms including entero-haemorrhagic Escherichia coli (serotypes 0157:H7 and 026:H11) and Campylobacter spp. are also relevant. Other causes of dysentery include Balantidium coli and that caused by schistosomiasis (bilharzia) – Schistosoma mansoni and S. japonicum infection.

Shigellosis This form is usually caused by Shigella dysenteriae-1 (Shiga’s bacillus), Shigella ?exneri, Shigella boydii, and Shigella sonnei; the latter is the most benign and occurs in temperate climates also. It is transmitted by food and water contamination, by direct contact, and by ?ies; the organisms thrive in the presence of overcrowding and insanitary conditions. The incubation is between one and seven days, and the severity of the illness depends on the strain responsible. Duration of illness varies from a few days to two weeks and can be particularly severe in young, old, and malnourished individuals. Complications include perforation and haemorrhage from the colo-rectum, the haemolytic uraemic syndrome (which includes renal failure), and REITER’S SYNDROME. Diagnosis is dependent on demonstration of Shigella in (a) faecal sample(s) – before or usually after culture.

If dehydration is present, this should be treated accordingly, usually with an oral rehydration technique. Shigella is eradicated by antibiotics such as trimethoprimsulphamethoxazole, trimethoprim, ampicillin, and amoxycillin. Recently, a widespread resistance to many antibiotics has developed, especially in Asia and southern America, where the agent of choice is now a quinolone compound, for example, cipro?oxacin; nalidixic acid is also e?ective. Prevention depends on improved hygiene and sanitation, careful protection of food from ?ies, ?y destruction, and garbage disposal. A Shigella carrier must not be allowed to handle food.

Entamoeba histolytica infection Most cases occur in the tropics and subtropics. Dysentery may be accompanied by weight loss, anaemia, and occasionally DYSPNOEA. E. histolytica contaminates food (e.g. uncooked vegetables) or drinking water. After ingestion of the cyst-stage, and following the action of digestive enzymes, the motile trophozoite emerges in the colon causing local invasive disease (amoebic colitis). On entering the portal system, these organisms may gain access to the liver, causing invasive hepatic disease (amoebic liver ‘abscess’). Other sites of ‘abscess’ formation include the lungs (usually right) and brain. In the colo-rectum an amoeboma may be di?cult to di?erentiate from a carcinoma. Clinical symptoms usually occur within a week, but can be delayed for months, or even years; onset may be acute – as for Shigella spp. infection. Perforation, colo-rectal haemorrhage, and appendicitis are unusual complications. Diagnosis is by demonstration of E. histolytica trophozoites in a fresh faecal sample; other amoebae affecting humans do not invade tissues. Research techniques can be used to di?erentiate between pathogenic (E. dysenteriae) and non-pathogenic strains (E. dispar). Alternatively, several serological tests are of value in diagnosis, but only in the presence of invasive disease.

Treatment consists of one of the 5nitroimidazole compounds – metronidazole, tinidazole, and ornidazole; alcohol avoidance is important during their administration. A ?ve- to ten-day course should be followed by diloxanide furoate for ten days. Other compounds – emetine, chloroquine, iodoquinol, and paromomycin – are now rarely used. Invasive disease involving the liver or other organ(s) usually responds favourably to a similar regimen; aspiration of a liver ‘abscess’ is now rarely indicated, as controlled trials have indicated a similar resolution rate whether this technique is used or not, provided a 5-nitroimidazole compound is administered.... dysentery

Linn.

Family: Oleaceae; Nyctanthaceae.

Habitat: Outer Himalaya, Assam, West Bengal; cultivated in many parts of India.

English: Tree of Sorrow, Night Jasmine, Coral Jasmine.

Ayurvedic: Paarijaata, Shephaali, Shephaalikaa, Mandaara.

Unani: Harasingaar.

Siddha: Pavazha mattigai.

Action: Leaves—bitter tonic, chola- gogue, febrifuge, anti-inflammatory, antispasmodic, hypotensive, respiratory stimulant. Used for fevers, rheumatism, obstinate sciatica.

The leaves and seeds contain iri- doid glycosides; other constituents reported from the leaves are mannitol, beta-amyrin, beta-sitosterol, hentria- contane, benzoic acid, astragalin, nico- tiflorin, oleanolic acid, nyctanthic acid, friedelin and lupeol. The seeds contain a polysaccharide glucomannan.

All parts of the plant are used for allergic disorders. Alcoholic extract of the plant was found to inhibit passive cutaneous anaphylaxis (PCA) in experimental animals. The inhibition was comparable to standard drugs used for allergy and bronchial asthma.

Ethanolic extract of the leaves, flowers and seeds demonstrated strong stimulation of antigen specific and non-specific immunity in mice.

The 50% ethanolic extracts of the leaves, flowers, seeds and roots were found effective in treating caecal amoe- biasis caused by Entamoeba histolytica in rats. But the extracts did not exhibit direct amoebicidal activity in vitro against trophozoites of the parasite.

The iridoid glucosides showed an- tileishmanial activity both in vivo and in vitro.

Dosage: Leaf—10-20 ml juice. (CCRAS.)

Seeds—used in diabetes, also in cutaneous diseases. Filaments— astringent and cooling; prescribed for bleeding piles and menorrhagia. Plant—toxic on the nervous system.

The flowers contain flavonoids including quercetin, kaempferol, api- genin. Cardiac glucoside, nymphalin, showed sedative action in small doses.

The petroleum ether extract of the plant of Nymphaea species, given at a dose of 300 mg/kg i.p. prevented necrosis of the liver tissue and promoted, to some extent, liver regeneration in CCl4-induced toxicity.

Dosage: Dried flowers—3-6 g (API, Vol. III); seed—3-6 g. powder (CCRAS.).... nyctanthes arbor-tristis

A parasitic disease caused by four species of PLASMODIUM: P. falciparum, P. vivax, P. ovale, and P. malariae. Clinically, malaria is characterised by recurrent episodes of high fever, sometimes associated with RIGOR; enlargement of the SPLEEN is common. P. falciparum infection can also be associated with several serious – often fatal – complications (see below): although other species cause chronic disease, death is unusual.

During a bite by the female mosquito, one or more sporozoites – a stage in the life-cycle of the parasite – are injected into the human circulation; these are taken up by the hepatocytes (liver cells). Following division, merozoites (minute particles resulting from the division) are liberated into the bloodstream where they invade red blood cells. These in turn divide, releasing further merozoites. As merozoites are periodically liberated into the bloodstream, they cause the characteristic fevers, rigors, etc.

Malaria occurs in many tropical and subtropical countries; P. falciparum is, however, con?ned very largely to Africa, Asia and South America. Malaria is present in increasingly large areas; in addition, the parasites are developing resistance to various preventative and treatment drugs. The disease constitutes a signi?cant problem for travellers, who must obtain sound advice on chemoprophylaxis before embarking on tropical trips – especially to a rural area where intense transmission can occur. Transmission has also been recorded at airports, and following blood transfusion.

The World Health Organisation (WHO) has listed malaria as one of Europe’s top ten infectious diseases. In 1992, 20,000 cases were reported: this had risen to more than 200,000 by the late 1990s. The resurgence of malaria has been worldwide, in part the result of the development of resistant strains of the disease, and in part because many countries have failed (or been unable) to implement environmental measures to eliminate mosquitoes. Nearly 40 years ago the WHO forecast that by 1980 only four million people would be affected worldwide; now, at the beginning of the 21st century, around 500 million people a year are contracting malaria with about 3,000 people a day dying from the infection – as many as 70 per cent of them children under the age of ?ve, according to WHO ?gures. The apparently steady advance of global warming means that countries with temperate climates may well warm up su?ciently to enable malaria to become established as an ENDEMIC disease. In any case, the great increase in international air travel has exposed many more people to the risk of malaria, and infected individuals may not exhibit symptoms until they are back home. Doctors seeing a recent traveller with unexplained pyrexia and illness should consider the possibility of malarial infection.

Diagnosis is by demonstration of trophozoites – a stage in the parasite’s life-cycle that takes place in red blood cells – in thick/thin blood-?lms of peripheral blood. Serological tests are of value in deciding whether an individual has had a past infection, but are of no value in acute disease.

P. vivax and P. ovale infections cause less severe disease than P. falciparum (see below), although overall there are many clinical similarities; acute complications are unusual, but chronic ANAEMIA is often present. Primaquine is necessary to eliminate the exoerythrocytic cycle in the hepatocyte (liver cell).

P. falciparum Complications of P. falciparum infection include cerebral involvement (see BRAIN – Cerebrum), due to adhesion of immature trophozoites on to the cerebral vascular endothelium; these lead to a high death rate when inadequately treated. Renal involvement (frequently resulting from HAEMOGLOBINURIA), PULMONARY OEDEMA, HYPOTENSION, HYPOGLYCAEMIA, and complications in pregnancy are also important. In complicated disease, HAEMODIALYSIS and exchange TRANSFUSION have been used. No adequate controlled trial using the latter regimen has been carried out, however, and possible bene?ts must be weighed against numerous potential side-effects – for instance, the introduction of a wide range of infections, overload of the circulatory system with infused ?uids, and other complications.

P. malariae usually produces a chronic infection, and chronic renal disease (nephrotic syndrome) is an occasional sequel, especially in tropical Africa.

Gross SPLENOMEGALY (hyper-reactive malarious splenomegaly, or tropical splenomegaly syndrome) can complicate all four human Plasmodium spp. infections. The syndrome responds to long-term malarial chemoprophylaxis. BURKITT’S LYMPHOMA is found in geographical areas where malaria infection is endemic; the EPSTEIN BARR VIRUS is aetiologically involved.

Prophylaxis Malaria specialists in the United Kingdom have produced guidance for residents travelling to endemic areas for short stays. Drug choice takes account of:

risk of exposure to malaria;

extent of drug resistance;

e?cacy of recommended drugs and their side-effects;

criteria relevant to the individual (e.g. age, pregnancy, kidney or liver impairment). Personal protection against being bitten by

mosquitoes is essential. Permethrinimpregnated nets are an e?ective barrier, while skin barrier protection and vaporised insecticides are helpful. Lotions, sprays or roll-on applicators all containing diethyltoluamide (DEET) are safe and work when put on the skin. Their e?ect, however, lasts only for a few hours. Long sleeves and trousers should be worn after dark.

Drug prophylaxis should be started at least a week before travelling into countries where malaria is endemic (two or three weeks in the case of me?oquine). Drug treatment should be continued for at least four weeks after leaving endemic areas. Even if all recommended antimalarial programmes are followed, it is possible that malaria may occur any time up to three months afterwards. Medical advice should be sought if any illness develops. Chloroquine can be used as a prophylactic drug where the risk of resistant falciparum malaria is low; otherwise, me?oquine or proguanil hydrochloride should be used. Travellers to malaria-infested areas should seek expert advice on appropriate prophylactic treatment well before departing.

Treatment Various chemoprophylactic regimes are widely used. Those commmonly prescribed include: chloroquine + paludrine, me?oquine, and Maloprim (trimethoprim + dapsone); Fansidar (trimethoprim + sulphamethoxazole) has been shown to have signi?cant side-effects, especially when used in conjunction with chloroquine, and is now rarely used. No chemotherapeutic regimen is totally e?ective, so other preventive measures are again being used. These include people avoiding mosquito bites, covering exposed areas of the body between dusk and dawn, and using mosquito repellents.

Chemotherapy was for many years dominated by the synthetic agent chloroquine. However, with the widespread emergence of chloroquine-resistance, quinine is again being widely used. It is given intravenously in severe infections; the oral route is used subsequently and in minor cases. Other agents currently in use include me?oquine, halofantrine, doxycycline, and the artemesinin alkaloids (‘qinghaosu’).

Researchers are working on vaccines against malaria.... malaria