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27 Cards in this Set
- Front
- Back
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• There are four intestinal protozoa that cause diarrhea:
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1. Entamoeba histolytica- causes bloody diarrhea
2. Giardia lamblia- causes a non-bloody diarrhea 3. Cryptosporidium parvum 4. Isospora belli- both of these cause severe diarrhea in individuals with defective immune systems (AIDS). |
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Entamoeba histolytica
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motile amoeba and non-motile cyst
no animal reservoir flask-shaped ulcer tropical male homosexuals amoebic dysentery and liver abscess anchovy-paste |
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Isospora
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• severe non-bloody diarrhea in immunocompromised individuals, including AIDS patients.
• transmitted via the fecal-oral route • same signs and symptoms as Crytposporidium. • Tx: Trimethoprim-sulfamethoxazole (Sulfa drugs). |
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toxoplasmosis
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• (CT scan, MRI: intracranial calfications around ventricles
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Pneumocystis carinii Infection
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• (goes hand in hand w/ AIDs pts!!)
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Pneumocystis carinii Infection
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fungus and protozoan
interstitial pneumonia in AIDs cup or boat-shaped cysts in alveoli |
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pinworms
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• Enterobius vermicularis
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1. Entamoeba histolytica- causes bloody diarrhea
2. Giardia lamblia- causes a non-bloody diarrhea 3. Cryptosporidium parvum 4. Isospora belli- both of these cause severe diarrhea in individuals with defective immune systems (AIDS). |
There are four intestinal protozoa that cause diarrhea:
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Causes amoebic dysentery and liver abscesses.
There are two stages: 1) the motile amoeba (trophozoite: found in intestine and extraintestinal lesions (liver) 2) non-motile cyst; predominate in nondiarrheal stools and readily killed by boiling. It has four nuclei which is an important diagnostic criterion. |
Entamoeba histolytica
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acquired by ingestion of cysts transmitted by fecal-oral route in contaminated food and water.
Anal-oral transmission no animal reservoir. ingested cysts differentiate into trophozoites in the ileum but tend to colonize the cecum and colon. trophozoites invade the colonic epithelium and secrete enzymes that cause localized necrosis. As lesion reaches muscularis mucosae layer, “Flask-Shaped” Ulcer forms that can destroy large areas of the intestinal epithelium. Progression into the submucosa leads to the invasion of the portal circulation by the trophs, to the liver, where abscesses form. |
Entamoeba histolytica
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found worldwide, most frequently in tropical countries, in areas with poor sanitation.
About 1-2% of U.S. affected. widely prevalent among male homosexuals. Acute intestinal amebiasis presents as a Dysentery (bloody, mucus-containing diarrhea) accompanied by lower abdominal discomfort, flatulence, and tenesmus. Amebic abscesses of the liver is characteristic by RUQ pain, weight loss, fever, and a tender, enlarged liver. The abscesses can penetrate the diaphragm and cause lung disease. The liver abscesses, when chronic, are cysts filled with “Anchovy-paste”, thick substance. TX: Metronidiazole (Flagyl). |
Entamoeba histolytica
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Causes ______ which causes a non-bloody diarrhea. (no mucosal cells)(common in day care)
(does not invade; no dysentary) Also contains two stages, (like Entramoeba histolytica) 1 )the trophozoites (pear-shaped with two nuclei, four pairs of flagella, and a sucking disk with which it attaches to the intestinal wall) and 2) a cyst (oval and thick-walled with four nuclei). |
Giardia lamblia
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Transmission occurs by ingestion of the cyst in fecally contaminated food or water.
Excystation in duodenum, where trophozoites attach to the gut wall but does not invade. trophozoites cause inflammation of the duodenal mucosa, leading to malabsorption of protein and fat. |
Giardia lamblia
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found worldwide, 5% in U.S.
1/2 of those infected are asymptomatic carriers, who continue to excrete the cysts for years. Occurs in outbreaks related to contaminated water supplies, and chlorination does not kill it. common in male homosexuals as a result of oral-anal contact. incidence high among children in day-care centers and patients in mental hospitals. Non-bloody foul-smelling diarrhea is accompanied by nausea, anorexia, and abdominal cramps persisting for weeks or months. No fever. (no invasion) Treatment is with Flagyl. |
Giardia lamblia
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diarrhea, most severe in immunocompromised patients (AIDS).
acquired by fecal-oral transmission of oocysts from either human or animal species. The oocysts excyst in the small intestines, where the trophozoites attach to the gut wall. Invasion does not occur. The pathogenesis is unknown and there is no toxin. |
Cryptospordium
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Causes diarrhea worldwide, and large outbreaks of diarrhea in the U.S. are attributed to inadequate purification of drinking water.
The disease in AIDS patients presents as a watery non-bloody diarrhea causing a large fluid loss that persists for long periods of time, leading to dehydration and malnutrition. Diagnosis is by finding oocysts in fecal smears, and there is no effective drug therapy. |
Cryptospordium
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severe non-bloody diarrhea in immunocompromised individuals, including AIDS patients.
transmitted via fecal-oral route Causes the same signs and symptoms as Crytposporidium. Treatment is with Trimethoprim-sulfamethoxazole (Sulfa drugs). |
Isospora
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Transmitted sexually and found in female vagina and male urethra.
pear-shaped organism with a central nucleus and four anterior flagella. It exists only as a trophozoite with no cyst form. One of the most common infections worldwide. Roughly 25-50% of women in the U.S. can harbor the organ |
Trichomonas vaginalis
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frequency of symptomatic disease highest among sexually active women in their 30’s and lowest in postmenopausal women.
Causes a watery, foul-smelling greenish discharge accompanied by itching and burning. Infection in men is usually asymptomatic, but about 10% have a urethritis. Tx. is with Flagyl Diagnosis is by wet mount prep of vaginal or prostatic secretions for moving trophozoites. |
Trichomonas vaginalis
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T in TORCH
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Toxoplasmosis
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Caused by the protozoan tissue ________ gondii that normally cause subclinical infection withmild lymphadenopathy, but can be devastating in infants in-utero and immunosuppressed.
The definitive host is the cat. infection begins with ingestion of cysts in undercooked meat or contact with cat feces. (also lamb meat) also transmitted transplacentally from mother to fetus. |
Toxoplasmosis
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cysts differentiate in gut and invade gut wall where they infect macrophages where numerous tachyzoites are produced. cysts > tachyzoits > kill macrophages
The tachyzoites kill the macrophages, are liberated and enter into brain, lungs, liver, eyes and muscle tissue and develop into cysts again which can be liberated if the patient becomes immunosuppressed. Progression of infection halted if immunocompetent, and most initial infections are asymptomatic. |
Toxoplasmosis
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Congenital infection only occurs when the mother is infected during pregnancy.
-About one-third of mothers infected during pregnancy give birth to infected infants, but only 10% of these infants are symptomatic. -Infected infants present with encephalitis, chorioretinitis, and hepatospenomegaly. -Fever, jaundice and intracranial calcifications. -(CT scan, MRI: intracranial calfications around ventricles****) |
Toxoplasmosis
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can also cause abortion or stillbirth.
In immunosuppressed patients, life-threatening disseminated disease can result in pneumonia or encephalitis. Dx by immunoflourescence assay for IgM antibody for both acute and congenital infections. Giemsa-stained tissue preps showing tachyzoites during acute infections can also be done. Tx for both congenital and immunosuppressive cases is combined sulfadiazine and Pyrimethamine |
Toxoplasmosis
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(goes hand in hand w/ AIDs pts!!)
-important cause of diffuse interstitial pneumonia in immunocompromised patients. -characteristics of both a fungus and a protozoan parasite. -Transmission by inhalation that produces no disease in healthy patients, but pneumonia in AIDS (frequently the first diagnosed opportunistic infection and the leading cause of death). |
Pneumocystis carinii Infection
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-cup or boat-shaped cysts in alveoli induces inflammatory response, resulting in a frothy, eosinophilic, edema fluid that blocks oxygen exchange. (crinkled ping-pong balls)
-Sudden onset of fever, cough, dyspnea and tachypnea. -bilateral rales and rhonchi and CXR reveals diffuse interstitial pneumonia. -dx: microscopic examination of lung tissue obtained by bronchoscopy, BAL, or open lung biopsy. -cysts visualized with Silver Stains. There is no serologic test. (fungal stain is best) Tx: combo Trimethoprim and Sulfamethoxazole. Untreated, mortality 100%, with treatment about half survive the first episode |
Pneumocystis carinii Infection
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Caused by the intracellular protozaon parasite Plasmodium
four species: vivax, malariae, ovale and falciparum >> falciparum is bastard: dark red urine The vector and definitive host is the female Anopheles mosquito (only the female takes a blood meal). |
Malaria
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