Tags: Pentam

Leishmania

Leishmania & Trypanosoma The genera Leishmania and Trypanosoma are members of the family Trypanosomatidae. These protozoans cause diseases with widely varied clinical presentations as well as geographic distributions, including leishmaniasis, American trypanosomiasis (Chagas’ disease), and African trypanosomiasis (sleeping sickness). For example, the endemic zones for African and American trypanosomiasis do not overlap, the diseases are transmitted by different vectors, they involve distinct mechanisms of pathogenesis, and they follow different clinical courses. Nonetheless, the causative agents share important biological features. Each is a hemoflagellate with a kinetoplast containing its own chromosomal DNA with highly conserved and repeated elements, each forms a single flagellum at some point during its life cycle, and each …

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African Trypanosomiasis

In Africa, a wide variety of trypanosomes infect wild animals but only two cause significant disease in humans: T brucei gambiense and T brucei rhodesiense. Essentials of Diagnosis • Epidemiologic factors: living or traveling in an endemic zone; exposure to tsetse fly. • History and physical exam: 1. General: periodic fevers, wasting, nutritional deficiencies. 2. Skin: chancre at the site of inoculation, fleeting truncal rash, posterior cervical lymphadenopathy. 3. Neurologic: disturbed sleep patterns (diurnal somnolence, nocturnal insomnia), mental status changes, cerebellar signs. • Laboratory: 1. Blood smear with Giemsa stain shows hemoflagellates. 2. Aspiration and stain of chancre (may be positive for visible organisms before parasitemia occurs). 3. Serology: indirect immunofluorescence, …

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Pathogenic Amebas

ENTAMOEBA HISTOLYTICA & ENTAMOEBA DISPAR Essentials of Diagnosis Patient living in or having traveled to endemic area increases risk. Frequent loose stools with blood and mucus. Demonstration of cyst or trophozoite on stool wet mount or in biopsy specimen. Serology positive within 7-10 days of infection, may remain positive for years after infection resolved. Monoclonal antibodies and polymerase chain reaction emerging; may help differentiate E histolytica and E dispar. General Considerations A. Epidemiology. There are numerous distinct species of ameba within the genus Entamoeba, and the majority of these do not cause disease in humans. E histolytica is a pathogenic species that is capable of causing disease, such as colitis or …

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Pneumocystis Carinii

Essentials of Diagnosis Pneumocystis carinii, when examined using molecular techniques, most closely resembles a fungus. Stains of either bronchoalveolar-lavage (BAL) or transbronchial-biopsy samples yield a diagnosis in > 90% of patients and should be considered the gold standard in diagnosis. BAL with transbronchial biopsy increases diagnostic yield to ~ 100%. P carinii has not yet been cultured in vitro. Polymerase chain reaction (PCR) (especially on sputum) increases sensitivity but reduces specificity. The prophylactic use of aerosolized pentamidine reduces the sensitivity of sputum and bronchoscopic samples. General Considerations A. Epidemiology. In 1983, P carinii pneumonia (PCP) was described as the AIDS-defining illness in = 60% of the first 1000 patients diagnosed with …

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Extrapulmonary P Carinii Infections

Extrapulmonary P carinii infections occur in < 3% of patients and must be diagnosed with histopathologic samples. Primary prophylaxis for PCP with pentamidine may confer a higher risk for extrapulmonary infection. Symptoms of extrapulmonary involvement are nonspecific, usually consisting of fevers, chills, and sweats. Although any area of the body may be involved, splenomegaly with cysts and thyroiditis are most common. Diagnosis The practice of diagnosing PCP morphologically by traditional staining methods (silver methenamine and toluidine blue) of induced sputum samples in HIV-infected individuals has fallen out of favor. Although relatively simple and inexpensive, staining of sputum samples induced by hypertonic saline inhalation is clearly dependent on operator and laboratory experience, …

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Vibrio Cholerae Infections: Clinical Syndromes

Cholera is a fulminant diarrheal disease caused by V cholerae (Box 1). Patients with cholera develop frequent, watery stools, which may reach volumes =1 L/h. If these patients are untreated, they will develop rapid dehydration and electrolyte abnormalities, which may result in death within hours from the onset of disease. Therefore cholera is a medical emergency. V cholerae is noninvasive and produces diarrhea by the elaboration of a potent enterotoxin. This enterotoxin consists of two subunits that have been well characterized. The circular, pentameric B-subunit binds monosialosyl ganglioside residues on the surface of the intestinal epithelial cell and introduces the enzymatic A-subunit into the cytoplasm. The A-subunit functions as an adenosine …

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Babesiosis

Description of Medical Condition • Babesiosis is a worldwide tick-borne hemolytic disease that is caused by intraerythrocytic protozoan parasites of the genus Babesia • Babesiosis has rarely been reported outside the US. Sporadic cases have been reported from a number of countries including France, Italy, the former Yugoslavia. United Kingdom, Ireland, the former Soviet Union and Mexico. In the US, infections have been reported from many states but the most endemic areas are the islands off the coast of Massachusetts (including Nan-tucket and Martha’s Vineyard) and New York (including eastern and south central Long Island, Shelter Island and Fire Island) and in Connecticut. In these areas, asymptomatic human infection seems to …

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Parasitic Infections

What does the infectious disease specialist mean by parasitic infection? Most infectious agents fulfill the definition of a parasite: an organism that grows, feeds, and shelters on or in a different organism and contributes nothing to the host. However, medical science has created the classification “parasite” to include a complex group of nonfungal eukaryotic human pathogens. Unlike fungi, parasites have no cell wall and are often motile. In addition, many parasites require two or more host species to complete their life cycle, and they reproduce both sexually and asexually. The host in which sexual reproduction takes place is called the “definitive host,” and the one in which asexual reproduction occurs is …

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Tissue Protozoa

Leishmaniasis Prevalence, Epidemiology, and Life Cycle Leishmania has caused major epidemics in eastern India, Bangladesh, and East Africa. Urban outbreaks have been reported in the cities of northeastern Brazil. A small number of American military personnel contracted leishmaniasis during the Persian Gulf War in 1991 and in Afghanistan more recently. Indigenous cases have been reported occasionally in the United States, but most U.S. cases result from travel to a tropical country. Leishmaniasis has emerged as an opportunistic infection in patients with HIV or an organ transplant. The Leishmania parasite is transmitted by the female phlebotomine sandfly. Sandflies breed in cracks in the walls of dwellings, in rubbish, and in rodent burrows. …

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HIV / AIDS

Definition Table Centers for Disease Control and Prevention 1993 Revised Classification System for HIV Infection in Adults and AIDS Surveillance Case Definition and Table Centers for Disease Control and Prevention 1994 Revised Classification System for HIV Infection in Children Younger than 13 Years present the revised classification systems for adult and child HIV infection. Pathogenesis Transmission of HIV Infection with HIV occurs through three primary modes: sexual, parenteral, and perinatal. Sexual intercourse, primarily receptive anal and vaginal intercourse, is the most common vehicle for transmission. The probability of HIV transmission from receptive anorectal intercourse is 0.1% to 3% per sexual contact and 0.1% to 0.2% per sexual contact for receptive vaginal …

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