Plasmodium Health Dictionary

A protozoan disease of humans caused by blood parasites of the species, Plasmodium falciparum, P. vivax, P. ovale or P. malariae and transmitted by anopheline mosquitoes. P. falciparum is most likely to cause death, if untreated,. and can also be a great mimicker in its presentation. Malaria should be suspected in anyone with a fever or who is otherwise unwell and has returned from a malarious area.... malaria

The generic name of a widely distributed group of mosquitoes, certain species of which transmit to humans the parasitic protozoa Plasmodium, the agent that causes MALARIA. Anopheles maculipennis and A. bifurcatus are both found in England and can both transmit the malaria parasite.... anopheles

The name of a group of parasitic PROTOZOA which includes the parasitic Plasmodium that causes MALARIA. The life-cycles of sporozoa are complex, often with sexual and asexual stages.... sporozoa

A stage in the life of the parasite Plasmodium, that is the cause of MALARIA. It has a ring-shaped body and single nucleus and grows in the blood cell, after which it divides to form a schizont.... trophozoite

Desf.

Synonym: A. altissima (Mill.) Swingle

Family: Simaroubaceae.

Habitat: Native of China and Japan. Found in the hills of northern India up to an altitude of 2,400 m.

English: Tree of Heaven, Ailanto.

Ayurvedic: Aralu (related sp.).

Action: Bark—astringent, anti- spasmodic, parasiticidal, narcotic, cardiac depressant (exercises powerful depressing influence on nervous system similar to that of tobacco).

Leaves produce dermatitis; their accumulation in well-water produces chronic gastritis.

Many quassinoids and ailanthone derivatives are vermifuge and amoe- bicidal. Constituents of the bark and stem, particularly ailanthone, have an- timalarial activity in vitro against Plasmodium falciparum and in mice against P. berghei. (Alkaloids do not appear to have these properties.) Some quassinoids are antineoplastic, and are reported to have antileukaemic properties.

The rootbark is used in traditional Chinese medicine for dysentery and leucorrhoea. In Africa, rootbark is used in epilepsy.... ailanthus glandulosa

R. Br.

Family: Apocynaceae.

Habitat: Throughout moist regions of India, especially in West Bengal and west-coast forests of southern India.

English: Devil's tree, Dita Bark tree.

Ayurvedic: Saptaparna, Sapta- chhada, Saptaparni, Saptaahvaa, Vishaaltvak, Shaarada, Visham- chhada.

Unani: Chhaatim, Kaasim (Kaasim Roomi, Anjudaan Roomi is equated with Myrrhis odorata Scope.)

Siddha/Tamil: Ezhilamippalai, Mukkampalai.

Folk: Chhitavan, Sataunaa.

Action: Bark—febrifuge, antiperi- odic, spasmolytic, antidysenteric, uterine stimulant, hypotensive; used for internal fevers.

Along with other therapeutic applications, The Ayurvedic Pharmacopoeia of India indicates the use of stembark in phosphaturia and recommends it as a blood purifier.

Alstonia sp. is known as Fever Bark. A. constricta is native to Australia; A. scholaris to Australia and Southeast Asia. The bark of both the species contains indole alkaloids. A. constric- ta contains reserpine (a hyptotensive agent). A. scholaris contains echita- mine, which has also demonstrated hypotensive effects. Though A. schol- aris produces fall in the temperature of human patients with fever, there are conflicting reports about the activity of echitamine against Plasmodium berghei.

Dosage: Stembark—20-30 g for decoction. (API Vol. I.)... alstonia scholaris

Sporozoan protozoa which have no organs of locomotion. Includes the malaria parasites (Plasmodium) and Toxoplasma.... apicomplexa

Also called Arteether and more soluble forms called Artesunate. An antimalarial drug derived from artemisinin. Artemisinin is produced from the Chinese herbal drug Qinghaosu. It is used for rapid clearance of susceptible peripheral parasites, especially in the treatment of severe malaria, due to Plasmodium falciparum.... artemether

A. Juss.

Synonym: Melia azadirachta Linn.

Family: Meliaceae.

Habitat: Native to Burma; found all over India.

English: Neem tree, Margosa tree.

Ayurvedic: Nimba, Nimbaka, Arishta, Arishtaphala, Pichumarda, Pichumanda, Pichumandaka, Tiktaka, Sutiktak, Paaribhadra.

Unani: Aazaad-Darakht-e-Hindi.

Siddha/Tamil: Vemmu, Veppu, Veppan, Arulundi.

Action: Leaf, bark—antimicrobial, antifungal, anthelmintic, insecti- cidal, antiviral, antipyretic, anti- malarial, antiperiodic, mosquito larvicidal, anti-inflammatory, antifertility, spermicidal, hypogly- caemic; used in inflammation of gums, gingivitis, periodonitis, sores, boils, enlargement of spleen, malarial fever, fever during childbirth, measles, smallpox, head scald and cutaneous affections. Oil—used as a contraceptive for intravaginal use, for the treatment of vaginal infections, and as a mosquito repellent.

Plant tetranortriterpenoids have been examined extensively for their antibiotic, antitumour, insecticidal, antibacterial and antifungal activities.

The methanolic extract of the bark shows antimalarial activity against Plasmodium falciparum.

The aqueous extract of leaves exhibited antiulcer and anti-inflammatory activity.

The water-soluble portion of alcoholic extract of leaves reduces blood sugar in glucose-fed and adrenaline- induced hyperglycaemic rats (but not in normal and streptozotocin-induced diabetic rats).

A volatile fraction of the Neem oil is reported to be responsible for sper- micidal activity at a dose of 25 mg/ml for human sperm. The oil has been found to retard the growth of human immunodeficiency virus.

Neem oil has caused mitochondri- al injury in mice; poisonous in high doses. (Sharon M. Herr.)

Dosage: Dried leaf—1-3 g powder; 10-20 g for decoction; stembark— 2-4 g powder decoction for external use. (API Vol. II.) Leaf juice— 10-20 ml; oil—5-10 drops; bark decoction—50-100 ml. (CCRAS.)... azadirachta indica

A 4-aminoquinoline drug commonly used for treating malaria. Resistence is widespread in Plasmodium falciparum.... chloroquine

This is caused by rapid breakdown of red blood cells (acute intravascular haemolysis), with resulting kidney failure as the breakdown products block the vessels serving the kidney ?ltration units (see KIDNEYS). It is associated with severe Plasmodium falciparum infection.

The complication is frequently fatal, being associated with HAEMOGLOBINURIA, JAUNDICE, fever, vomiting and severe ANAEMIA. In an extreme case the patient’s urine appears black. Tender enlarged liver and spleen are usually present. The disease is triggered by quinine usage at subtherapeutic dosage in the presence of P. falciparum infection, especially in the non-immune individual. Now that quinine is rarely used for prevention of this infection (it is reserved for treatment), blackwater fever has become very unusual. Treatment is as for severe complicated P. falciparum infection with renal impairment; dialysis and blood transfusion are usually indicated. When inadequately treated, the mortality rate may be over 40 per cent but, with satisfactory intensive therapy, this should be reduced substantially.... blackwater fever

Lour.

Family: Saxifragaceae.

Habitat: The temperate Himalayas from Nepal to Bhutan and Khasi Hills.

Folk: Basak

Action: Febrifuge, antipyretic, antiparasitic (used for malarial fever). Dried roots, known as Chang Shan, dried leafy tops, known as Shu Chi, in Chinese medicine, are used for malarial fever. Dried roots (Chang Shan) contain the alkaloid dichroine A and B, dichrin A and B.

The active principle febrifugine compared to quinine was estimated to be 16 to 64 times more efficacious against Plasmodium gallinaceum in chicks, about 100 times against Plasmodium lophurae in ducks also against Plasmodium relictum in canaries. The aqueous extract of the plant inhibited the infecting rate of the parasite Plasmodium berghei up to 10 days and increased the mean survival time to twice that of untreated control at 2.5 g/kg dose.

Clinical trials with febrifugine indicated that the drug given in four oral doses totalling 2-5 mg/day reduces the parasite count.... dichroa febrifuga

An antibiotic of the tetracycline class also used to suppress malarial parasites and has variable effects against the liver stages of Plasmodium falciparum.... doxycycline

See also Tefanoquine. An anti-relapse drug used to prevent relapses in malaria due to Plasmodium vivax or P. ovale. When used with a chemotherapeutic drug such as chloroquine for these malaria species, it thus can achieve a radical cure.... etaquine

US Army discovered antimalarial related to mefloquine, used to kill blood parasites, especially in the treatment of severe malaria due to Plasmodium falciparum.... halofantrine

Ham. ex Smith.

Synonym: H. album Buch-Ham. Ex Wall.

Family: Zingiberaceae.

Habitat: Central Himalaya at 1,1002,500 m, East India and hills of South India.

English: Spiked Ginger Lily.

Ayurvedic: Shathi, Shati, Gand- hashathi, Gandhapalaashi, Kapu- urkachari, Suvrataa, Gandhaarikaa, Gandhavadhuu, Gandhamuulikaa.

Unani: Kapuurkachari.

Siddha/Tamil: Poolankizangu, Kichilikizangu.

Folk: Ban-haldi (Kumaon).

Action: Rhizome—carminative, spasmolytic, hepatoprotective, anti-inflammatory, antiemetic, antidiarrhoeal, analgesic, expectorant, antiasthmatic, emmenagogue, hypoglycaemic, hypotensive, antimicrobial, anthelmintic, insect- repellent.

The rhizome shows hypotensive effect in dogs at low doses, lowers blood pressure in high doses.

EtOH (50%) extract—anti-inflammatory and hypoglycaemic; gave encouraging results in tropical pulmonary eosinophilia in clinical studies. Alcoholic extract of the plant—vasodilator, mild hypotensive and antiseptic in animals. Essential oil from rhizome—mild tranquilizer in male albino rats; antimicrobial.

Rhizome gave sitosterol and its glu- coside, a furanoid diterpene—hedy- chenone and 7-hydroxyhedychenone. The essential oil contains cineole, gamma-terpinene, limonene, beta- phellandrene, p-cymene, linalool and beta-terpineol as major constituents.

The oil inhibits the growth of several fungi. The ethanol (95%) extract showed antibacterial activity. The 50% extract showed antimalarial activity in vitro against Plasmodium berghei strain.

Dosage: Rhizome—1-3 g powder. (API Vol. I.)... hedychium spicatum

The latent liver forms in Plasmodium vivax and P.ovale which give rise to clinical relapses of malaria byinvasion of the circulating erythrocytes.The hypnozoites are not eliminated by the usual chemotherapeutic drugs used in the treatment of malaria (chloroquine, quinine etc) and to achieve a radical cure in these relapsing malarias an antirelapse drug must be added to the treatment regime (e.g. primaquine or etaquine/Tefanoquine).... hypnozoite

An antimalarial related to quinine, tetracycline and halofantrine used to suppress blood parasites, especially chloroquine resistant strains of Plasmodium falciparum. There has been increasing resistance to mefloquine reported in malaria due to Plasmodium falciparum.... mefloquine

Linn.

Family: Euphorbiaceae.

Habitat: Native to Brazil; cultivated as an ornamental.

English: Tua-Tua.

Ayurvedic: Rakta-Vyaaghrairanda.

Siddha/Tamil: Stalai.

Folk: Laal Bagharenda.

Action: Leaf and seed—purgative. Leaf—antidermatosis. Bark— emmenagogue. Seed—emetic. Seed fatty oil—used in paralytic affections, also in skin diseases.

The leaves contain triterpenes, a tri- hydroxy ketone and corresponding diosphenol. The root contains the diterpenes, jatropholone A and jat- rophatrione. A tumour-inhibitor ma- crocyclic diterpene, jatrophone, has been isolated from roots.

The seeds contain phorbol derivatives, jatropholones A and B, hydroxy- jatrophone and hydroxyisojatrophone.

Hot water extract of the plant exhibits antimalarial activity against Plasmodium falciparum.... jatropha gossypifolia

Benth.

Synonym: J. dolomiacea Boiss.

Family: Compositae; Asteraceae.

Habitat: The Himalayas from Kashmir to Kumaon.

Ayurvedic: Jaatukanda, Gugguluka.

Folk: Guugal, Dhuup.

Action: Roots—used as incense. Stimulant, given in colic, also in fever after child birth. Bruised roots are applied to eruptions.

The alcoholic extract of the root inhibits about 50% growth of NK65 strain of Plasmodium berghei at a dose of 2 g/kg per day in 4 days.... jurinea macrocephala

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

An antimalarial drug used with either sulfadoxine or DAPSONE to treat Plasmodium falciparum malariae (see MALARIA). It should not be used for PROPHYLAXIS because of potentially severe side-effects when used in the long term.... pyrimethamine

The final stage of development of Plasmodium in the mosquito; this is the infective form of the malarial parasite; occurring either in a mature oocyst before its rupture or in the salivary gland of a mosquito.... sporozoites

Linn.

Habitat: Cultivated and naturalized throuhout India. Wild in the Sub-Himalayan tract up to 1,800 m.

English: Persian Lilac, Pride of India.

Ayurvedic: Mahaanimba, Ramyaka, Dreka. (Neem is equated with Azadirachta indica.)

Unani: Bakaayan.

Siddha/Tamil: Malaivembu.

Action: Leaf—diuretic, anthelmintic, antilithic. Leaf and flower—febrifuge, sedative, em- menagogue. Leaf, fruit and stem bark—antileprotic. Leaf, flower, fruit, root bark—deobstruent, resolvent. Seed oil—antirheumatic, insecticidal. Leaves, bark and fruit—insect repellent. Gum— used in spleen enlargement. Heart- wood—an aqueous extract, used in asthma.

The Ayurvedic Pharmacopoeia ofIn- dia indicated the use of the dried stem bark in increased frequency and turbidity of urine, skin diseases, nausea, emesis, asthma, gastroenteritis, giddiness and vertigo.

The bitter constituents are present exclusively in the pericarp, not in the kernel as in the case of Neem fruit. Bakayanin has been isolated from the pericarp (bitter in dilutions of 1 in 10,000).

The heartwood also yielded bakaya- nin and a lactone, bakalactone. Leaves gave quercitrin and rutin and tetranor- triterpenoids, salanin and vilasinin.

An infusion of the bark is effective against ascariasis. The activity resides in the inner bark which is bitter but not astringent (outer bark contains tannins and is astringent).

The ethanolic extract of the leaves is fungicidal and antibacterial. The activity is attributed to azadrine and me- liotannic acid.

The fruits are considered poisonous to man and animals; contain melianon- inol, melianol, melianone, meliandi- ol, vanillin and vanillic acid. Vanillic acid analogues show micro- and macro-filaricidal activity.

Gedunin, present in the plant, inhibits Plasmodium falciparum, while the seed extract does not show anti- malarial activity against P. berghei.

The plant exhibited sedative and psychostimulant properties. Antitu- mour and antiviral activities have also been reported. Intraperitoneal administration of partially purified extracts of fresh green leaves reduced the spread of Tacaribe virus (that causes typical encephalitis) to kidneys, liver and brain in inoculated neonatal mice.

Dosage: Stem bark—5-10 g (API, Vol. IV.); leaf, seed, root—50- 100 ml decoction; 3-5 g powder. (CCRAS.)... melia azedarach

Linn.

Family: Compositae; Asteraceae.

Habitat: Tropical and subtropical countries of the world.

English: Congress Grass.

Folk: Pichhi, Machhipatri.

Action: Anti-amoebic, antidysen- teric, febrifuge, analgesic, emmena- gogue.

The grass was introduced into India during 1950 s (it first appeared in Pune).

The grass exhibits in vitro anti- amoebic activity against axenic and polygenic cultures of Entamoeba his- tolytica, comparable to the standard drug for amoebiasis, Metronidazole.

Parthenin and some of its derivatives exhibited significant antimalarial activity against a multi drug-resistant strain of Plasmodium falciparum.

The main toxic constituent of the grass responsible for causing dermatitis and other forms of allergy are parthenin and coronopilin. Parthenin in present up to 8% in the capitulum and 5% in the leaves.... parthenium hysterophorus

An animal that is the carrier of a particular infectious disease (see INFECTION). A vector picks up the infectious agent (bacterium – see BACTERIA; also RICKETTSIA; VIRUS) from an infected person’s blood or faeces and carries it in or on its body before depositing the agent on or into a new host. Fleas, lice, mosquitoes and ticks are among common vectors of disease to humans. When a vector is used by the infectious agent to complete part of its life-cycle – for example, the malarial agent PLASMODIUM conducts part of its life-cycle in the mosquito – the vector is described as biological. If the vector simply carries the agent but is not a host for part of its life-cycle, the vector is described as mechanical. Flies, for example, may carry an infection such as bacterial dysentery from infected faeces to the ?ngers of another ‘host’.... vector

The most severe form of malaria, caused by the parasitic protozoan PLASMODIUM FALCIPARUM.... falciparum malaria

n. the active ingredient of qinghaosu, a Chinese herbal medicine prepared from a species of wormwood (Artemisia annua) and long used for treating malaria. Derivatives of artemisinin (including artesunate and artemether) have been developed for the treatment of malignant (falciparum) malaria; they act by killing the asexual stages of the parasite (see Plasmodium) and are used in combination with other antimalarial drugs. In the UK, for example, artemether is available in combination with lumefantrine.... artemisinin

adj. describing those stages in the life cycle of the malarial parasite (see Plasmodium) that develop inside the red blood cells (see trophozoite). Compare exoerythrocytic.... erythrocytic

n. the formation and release of mature flagellated male sex cells (see microgamete) by the *microgametocytes of the malarial parasite (see Plasmodium). The process, which is completed in 10–15 minutes, occurs after the microgametocytes have been transferred from a human to the stomach of a mosquito.... exflagellation

adj. describing those stages in the life cycle of the malarial parasite (see Plasmodium) that develop in the cells of the liver. Each parasite (*sporozoite) divides repeatedly to produce a schizont containing many merozoites.... exoerythrocytic

n. a method of asexual reproduction in which the body of a protozoan or bacterium splits into two equal parts (binary fission), as in the *amoebae, or more than two equal parts (multiple fission), for example sporozoite formation in the malarial parasite (see Plasmodium). The resulting products of fission eventually grow into complete organisms.... fission

An acute arbovirus (see ARBOVIRUSES) infection caused by a ?avivirus of the togavirus family, transmitted from animals to humans by various species of forest mosquito (jungle/sylvan yellow fever), and from human to human by Aëdes aegypti (urban yellow fever). Mosquito transmission was shown by Walter Reed and his colleagues in 1900. It is ENDEMIC in much of tropical Africa and Central and South America but does not occur in Asia. In the urban cycle, humans constitute the reservoir of infection, and in the jungle/sylvan variety, mammals – especially subhuman primates – are involved in transmission. Historically, yellow fever was enormously important, causing devastating epidemics (see EPIDEMIC); it also carried a high mortality rate in travellers and explorers. Differentiation from other infections associated with JAUNDICE was often impossible.

Clinically, yellow fever is characterised by jaundice, fever, chills, headache, gastrointestinal haemorrhage(s), and ALBUMINURIA. The incubation period is 3–6 (up to 10) days. Differentiation from viral hepatitides, other viral haemorrhagic fevers, severe Plasmodium falciparum malaria, and several other infections is often impossible without sophisticated investigative techniques. Infection carries a high mortality rate. Liver histology (biopsy is contraindicated due to the haemorrhagic diathesis) shows characteristic changes; a fulminating hepatic infection is often present. Acute in?ammation of the kidneys and an in?amed, congested gastric mucosa, often accompanied by haemorrhage, are also demonstrable; myocardial involvement often occurs. Diagnosis is primarily based on virological techniques; serological tests are also of value. Yellow fever should be suspected in any travellers from an endemic area.

Management consists of instituting techniques for acute hepatocellular (liver-cell) failure. The affected individual should be kept in an isolation unit, away from mosquitoes which could transmit the disease to a healthy individual. Formerly, laboratory infections were occasionally acquired from infected blood samples. Prophylactically, a satisfactory attenuated VACCINE (17D) has been available for around 60 years; this is given subcutaneously and provides an individual with excellent protection for ten years; international certi?cates are valid for this length of time. Every traveller to an endemic area should be immunised; this is mandatory for entry to countries where the infection is endemic.... yellow fever

n. a drug that kills *gametocytes. Drugs such as *primaquine destroy gametocytes of the malaria parasite (see Plasmodium), so interrupting the life cycle and preventing infection of the mosquito.... gametocide

n. an iron-containing pigment present in the organisms that cause malaria (*Plasmodium species).... haemozoin

n. the nonmotile female sex cell of the malarial parasite (Plasmodium) and other protozoans. The macrogamete is similar to the ovum of animals and larger than the male sex cell (see microgamete).... macrogamete

n. a cell that undergoes meiosis to form mature female sex cells (macrogametes) of the malarial parasite (see Plasmodium). Macrogametocytes are found in human blood but must be ingested by a mosquito before developing into macrogametes.... macrogametocyte

n. a stage in the life cycle of the malaria parasite (*Plasmodium). Many merozoites are formed during the asexual division of the schizont (see schizogony). The released merozoites may invade new red blood cells or new liver cells, and continue the asexual phase with the production of yet more merozoites, effectively spreading the infection. Alternatively, merozoites invade red blood cells and begin the sexual cycle with the formation of male and female sex cells (see microgametocyte; macrogametocyte).... merozoite

n. the motile flagellate male sex cell of the malarial parasite (Plasmodium) and other protozoans. The microgamete is similar to the sperm cell of animals and smaller than the female sex cell (see macrogamete).... microgamete

n. a cell that undergoes meiosis to form 6–8 mature male sex cells (microgametes) of the malarial parasite (see Plasmodium). Microgametocytes are found in human blood but must be ingested by a mosquito before developing into microgametes.... microgametocyte

n. a spherical structure, 50–60 ?m in diameter, that develops from the zygote (see ookinete) of the malarial parasite (Plasmodium) on the outer wall of the mosquito’s stomach. The oocyst steadily grows in size and its contents divide repeatedly to form *sporozoites, which are released into the body cavity of the mosquito when the oocyst bursts.... oocyst

n. the motile elongated *zygote of the malarial parasite (*Plasmodium), formed after fertilization of the *macrogamete. The ookinete bores through the lining of the mosquito’s stomach and attaches itself to the outer wall, where it later forms an *oocyst.... ookinete

n. 1. the condition in which an individual assumes a number of different forms during its life cycle. The malarial parasite (Plasmodium) displays pleomorphism. 2. a feature of malignant neoplastic cells, which show a marked variation in the shapes of individual cells and cell nuclei.... pleomorphism

pl. n. a group of microscopic single-celled organisms. Most protozoa are free-living but some are important disease-causing parasites of humans; for example, *Plasmodium, *Leishmania, and *Trypanosoma cause *malaria, *kala-azar, and *sleeping sickness respectively. See also amoeba.... protozoa

n. a drug used in the treatment of *malaria due to Plasmodium falciparum. Large doses can cause severe poisoning, symptoms of which include headache, fever, vomiting, confusion and damage to sight and hearing (see cinchonism). Small doses of quinine are used to treat nocturnal leg cramps.... quinine

n. a phase of asexual reproduction in the life cycle of a sporozoan (protozoan parasite) that occurs in the liver or red blood cells. The parasite grows and divides many times to form a schizont, which contains many *merozoites. The eventual release of merozoites of *Plasmodium, the malaria parasite, from the blood cells produces fever in the patient.... schizogony

n. one of the many cells formed as a result of *sporogony during the life cycle of a sporozoan. In *Plasmodium sporozoites are formed by repeated divisions of the contents of the *oocyst inside the body of the mosquito. The released sporozoites ultimately pass into the insect’s salivary glands and await transmission to a human host at the next blood meal.... sporozoite

a form of *malaria resulting from repeated infection by Plasmodium falciparum and characterized by continuous fever.... subtertian fever