Parasitic infections protozoal

While nitrofurans are often prepared as antibacterial agents, nitroimidazole forms the basis for an extensive class of agents used in the treatment of infections by the protozoans. Unlike bacterial infections, protozoal infections are seldom life-threatening. The physical discomfort occasioned by such infections is, however, of sufficient importance to provide a useful therapeutic place for antiprotozoal agents. A particularly common set of such conditions are parasitic infections of the genitalia caused by Trichomonas vaginalis. These disorders are called trichomoniasis. 

The pharmacologic treatment of parasitic infections is a complex and extensive topic. In this limited space, it is difficult to describe the many species of each parasite, all the diseases caused by parasites, and the chemical methods currently available to selectively destroy various fungi, protozoa, and helminths in humans. Consequently, the general aspects of each type of parasitic infection are reviewed briefly, followed by the primary drugs used to treat specific fungal, protozoal, and helminthic infections. This discussion will acquaint physical therapists and occupational ther-... 

Bacterial Infections Fungal Infections Viral Infections Protozoal Ineections Parasitic Ineestations Infective Endocarditis Prophylaxis for GI Procedures... 

Acute viral diarrheal illness often occurs in day care centers and nursing homes. As person-to-person contact is the mechanism by which viral disease spreads, isolation techniques must be initiated. For bacterial, parasite, and protozoal infections, strict food handling, sanitation, water, and other environmental hygiene practices can prevent transmission. If diarrhea is secondary to another illness, controlling the primary condition is necessary. Antibiotics and bismuth subsalicylate are advocated to prevent traveler s diarrhea, in conjunction with treatment of drinking water and caution with consumption of fresh vegetables. 

Other protozoal infections (e.g., giardiasis, leishmaniasis, and malaria) and helminths are less common eye pathogens in the United States. Systemic pharmacological management as well as vitrectomy may be indicated for selected parasitic infections. 

The immune system of the mouse may also be susceptible to the effects of acute oral exposures to di-/ -octylphthalate (Dogra et al. 1989). Three-month-old Swiss albino mice were exposed to di-n-octylphthalate by gavage for 5 days at 0, 650, or 2,600 mg/kg/day (acute LD50 was 13,000 mg/kg). Mice were subsequently exposed by intraperitoneal injection to either encephalomyocarditis virus or the malarial protozoan, Plasmodium berghei. Maximum mortality levels were reached 8-10 days after viral infection and were 20% (0 mg/kg/day), 40% (650 mg/kg/day), and 70% (2,600 mg/kg/day). Malarial lethality reached plateau levels 4-11 days postinfection of approximately 20% (0 mg/kg/day), 25% (650 mg/kg/day), and 70% (2,600 mg/kg/day), then increased to 55%, 70%, and 85%, respectively, by postinfection day 19. Respective mean survival times were calculated to be 13.50, 12.15, and 6.25 days. During the first 14 days after protozoal infection, the percentage of mouse erythrocytes infected with the parasite in the high-dose... 

The development of the "sulfa drugs,"a c derivatives of sulfanilamide, originated with studies of the staining of protozoal parasites by Paul Erhlich. In 1932 it was shown that the red dye 2,4-diamino-azobenzene-4 -sulfonamide (Prontosil) dramatically cured systemic infections by gram-positive bacteria. Subsequent studies revealed that bacteria converted... 

One relatively common disease caused by protozoal infection is malaria. Malaria is caused by several species of a protozoan parasite known as plasmodia. Although this disease has been virtually eliminated in North America and Europe, malaria continues to be a primary health problem throughout many other parts of the world.44 Individuals who live in these areas, as well as those traveling to parts of the world where malaria is prevalent, must often undergo antimalarial chemotherapy. Hence, drugs that prevent and treat malaria are extremely important. 

In addition to malaria, several other serious infections may occur in humans due to parasitic invasion by protozoa.2,44 Severe intestinal infections (dysentery) produced by various protozoa occur quite frequently, especially in areas where contaminated food and drinking water are prevalent. Infections in tissues such as the liver, heart, lungs, brain, and other organs may also occur because of protozoal infestation. As mentioned in this chapter s introduction, individuals with a compromised immune system may be especially susceptible to these intestinal and extraintestinal infections.2,70... 

Pyrimethamine may also be combined with other antimalarials such as artemisinin derivatives, but these regimens should only be used if the malarial parasites are not resistant to the specific drugs in the regimen.13 Pyrimethamine can also be combined with a sulfonamide drug such as dapsone, sulfadiazine, or sulfamethoxazole to treat protozoal infections that cause toxoplasmosis, or fungal infections that cause Pneumocystis pneumonia.These agents are administered orally. 

Clinical Use. lodoquinol (Diquinol, Yodoxin, other names) is used primarily to treat protozoal infections within the intestinal tract,51 and it is often combined with a second tissue amebicide, which kills protozoa at extraintestinal sites. For instance, iodoqui-nol may be combined with metronidazole to ensure the destruction of parasites throughout the body, lodoquinol is usually administered orally. Because iodoquinol is relatively toxic, the routine use of this drug has been replaced somewhat by other agents such as paromomycin, which may be somewhat safer. 

Protozoal infections. Malaria is the major transmissible parasitic disease in the world. The life cycle of the plasmodium that is relevant to prophylaxis and therapy is described. Drug resistance is an increasing problem and differs with geographical location, and species of plasmodium. 

The broad-spectrum anthelmintic nitazoxanide has been undergoing efficacy trials in the USA for the treatment of EPM (Vatistas et al 1999). This drug is currently used to combat intestinal parasites of humans in developing countries and in patients with the acquired immimodeficiency syndrome complicated by secondary protozoal infections. Nitazoxanide is administered daily for 28 days as an oral paste. The side-effects of this drug are more serious than with other medications because it kills other parasites in addition to S. neurona. This has led to recommendations for deworming with another anthelmintic prior to starting this treatment (McClure Palma 1999). Nitazoxanide may also cause colic in treated horses. 

The presence of pathogenic protozoans in domestic animals also produces debilitating effects and, therefore, eradication of these parasites is essential for better health of livestock and improved socio-economic status of the farmers. The economic importance of protozoal infections may be judged by the fact that more than US 280 million are spent worldwide in poultry industry alone for prophylactic treatment of chicken against coccidiosis [42]. Another fatal protozoal infection of animals is Theil-eria parva parva responsible for East Coast fever in cattle. The pathogenicity of theil-eriasis is so pronounced that the mortality among the infected dairy herds may reach upto 100% [43]... 

A large number of parasitic protozoans infect cattle, horses, pigs, sheep, goats and birds causing a serious threat to the livestock health. The important protozoal diseases of domestic animals are described below. 

Unlike helminth infections where a variety of drugs derived from arsenic, antimony, phosphorus, tin and lead have been used to eradicate intestinal and extrain-testinal parasites, only organo-arsenicals and -antimonials find use in the treatment of protozoal diseases [1-10]. 

Protozoa usually can be identified in tissue sections stained with hematoxylin and eosin or Giemsa stain however, because of the small size of the organisms and the subtle distinguishing features, an unequivocal diagnosis cannot always be made. The role of IHC in the detection of protozoal infections has been particularly valuable in cases in which the morphology of the parasite is distorted by tissue necrosis or autolysis. In addition, in immunocompromised patients, toxoplasmosis can have an unusual disseminated presentation with numerous tachyzoites without bradyzoites (Fig. 

Pathology in the host can be produced by the adult worms, the larvae, or the eggs, and the intensity is usually directly related to the worm load. Unlike protozoal disease, clinical symptoms with worm infections are not well defined. Diagnosis usually depends on recovery and identification of the parasite or its eggs. Immunoserological tests are sometimes available. 

Fairlamb, A. H. and Henderson, G. (1987) Metabolism of trypanothione and glutathionyl-spermidine in trypanosomes. In Host Parasite Molecular Recognition and Interaction in Protozoal Infections (eds Chang, K. P. and Snary, D.), NATO ASl series, pp. 29-45. 

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