AmoebiasisAmebiasis is a disease which is caused by the intestinalprotozoan Entamoeba histolytica.- About 90 % of diseases are asymptomatic, andthe remaining 10 % produce a spectrum of clinical syndromesranging from dysentery to abscesses of the liver or otherorgans.
LIFE CYCLE AND TRANSMISSION• E. histolytica is acquired by ingestion of viable cysts from fecally contaminated water, food or hands.• Less common means of transmission include contaminated water, oral and anal sexual practices, and in rare instances direct rectal inoculation through colonic irrigation devices
• Motile trophozoites are released from cysts in the small intestine and, in most patients, remain as harmless commensals in the large bowel.• After encystation, infectious cysts are shed in the stool and can survive for several weeks in a moist environment.• In some patients, the trophozoites invade either the bowel mucosa, causing symptomatic colitis, or the bloodstream, causing distant abscesses of the liver, lungs, or brain
EPIDEMIOLOGY• About 10 % of the worlds population is infected with E. histolytica;• Amebiasis is the third most common cause of death from parasitic disease (after schistosomiasis and malaria).• Areas of highest incidence (due to inadequate sanitation and crowding) include most developing countries in the tropics, particularly Mexico, India, and nations of Central and South America, tropical Asia, and Africa.• The main groups at risk in developed countries are travelers, recent immigrants, homosexual men, and inmates of institutions.
PATHOGENESIS AND PATHOLOGY• Both trophozoites and cysts are found in the intestinal lumen, but only trophozoites invade tissue.• The trophozoite is 20 to 60 um in diameter and contains vacuoles and a nucleus with a characteristic central karyosome.• In animals, depletion of intestinal mucus, diffuse inflammation, and disruption of the epithelial barrier occur before trophozoites actually come into contact with the colonic mucosa.• Trophozoites attach to colonic mucus and epithelial cells by a galactose-inhibitable lectin.
PATHOGENESIS AND PATHOLOGY• The earliest intestinal lesions are microulcerations of the mucosa of the cecum, sigmoid colon, or rectum that release erythrocytes, inflammatory cells, and epithelial cells.• Proctoscopy reveals small ulcers with heaped up margins and normal intervening mucosa.• Submucosal extension of ulcerations under viable- appearing surface mucosa causes the classic "flask-shaped" ulcer containing trophozoites at the margins of dead and viable tissues.
ETIOLOGYEntamoeba histolytica –forma magna, f. minuta, f. cystica CLINICAL SYNDROMEIntestinal Amebiasis• The most common type of amebic infection is asymptomatic cyst passage. Even in highly endemic areas, most patients harbor nonpathogenic strains.
Incubation period – some days to 3-4 months Acute amoebiasis• Symptomatic amebic colitis develops 2 to 6 weeks after the ingestion of infectious cysts.• Lower abdominal pain and mild diarrhea develop gradually and are followed by malaise, weight loss, and diffuse lower abdominal or back pain.• Cecal involvement may mimic acute appendicitis.• Patients with full-blown dysentery may pass 10 to 12 stools per day.• The stools contain little fecal material and consist mainly of blood and mucus.• In contrast to those with bacterial diarrhea, fewer than 40 % of patients with amebic dysentery are febrile.• Virtually all patients have heme-positive stools.
• In contrast to those with bacterial diarrhea, fewer than 40 % of patients with amebic dysentery are febrile.• Virtually all patients have heme-positive stools.• More fulminant intestinal infection, with severe abdominal pain, high fever, and profuse diarrhea, is rare and occurs predominantly in children.• Patients may develop toxic megacolon, in which there is severe bowel dilation with intramural air.
• Amebomas are inflammatory mass lesions that develop owing to chronic intestinal forms of amebiasis.• An occasional patient presents only with an asymptomatic or tender abdominal mass caused by an ameboma, which is easily confused with cancer on barium studies. A positive serologic test or biopsy can prevent unnecessary surgery in this setting.• The syndrome of postamebic colitis persistent diarrhea following documented cure of amebic colitis is controversial; no evidence of recurrent amebic infection can be found, and re- treatment usually has no effect.
Amebic Liver Abscess• Extraintestinal infection by E. histolytica most often involves the liver. Pleuropulmonary involvement, which is reported in 20 to 30 % of patients, is the most frequent complication of amebic liver abscess.• Liver scans, ultrasonography, computed tomography and magnetic resonance imaging are all useful for detection of the round or oval hypoechoic cyst.
• the typical patient with amebic colitis has less prominent fever than in these conditions and heme-positive stools with few neutrophils,• correct diagnosis requires bacterial cultures, microscopic examination of stools, and amebic serologic testing.
TREATMENT Tissue amebicides• Metronidazole ( Trichomonacid, Flagyl, Klion, Efloran) tb. 0,25 gr, 30 mg/kg, 3/day, 8-10 days;• Tinidazole (Fasigyn) tb. 0,150, 0,5 gr, 2,o gr , 2/day, 3-5 days;• Dehydroemetin tb. 0,01 gr, amp. 2 ml.(0,06 gr), dose 1-1,5 mg/kg/day, per os - 2 tb. 3 /day, i.m. - 1-1,5 mg/kg max. 90 mg/day, 3/day, 5-10 days.• Amoebic abscesses Dehydroemetin – Arthrochin или Chloroquin 1 gr/day, 4 х 1, 2 days and 2х1 tb 25 days, In children - 10 mg/kg/day, 2-3 weeks, till 300 mg/day, Tetracyclin tb. 0,25 gr, 2,о gr , 4 times per day, 10 days.• Patients with cysts - Metronidazole, Diloxinide tb.0,5 gr 3 x1, 10 days, Dijodoquin
PREVENTION• Amebic infection is spread by ingestion of food or water contaminated with cysts.• Since an asymptomatic carrier may excrete up to 15 million cysts per day, prevention of infection requires adequate sanitation and eradication of cyst carriage.• In high-risk areas, infection can be minimized by the avoidance of unpeeled fruits and vegetables and the use of bottled water.• Because cysts are resistant to readily attainable levels of chlorine, disinfection by iodination (tetraglycine hydroperiodide) is recommended.• There is no effective prophylaxis.• Dispanserisation – 5 years with control examinatins
Lambliosis GIARDIASISGiardia lamblia is a cosmopolitan protozoalparasite that inhabits the small intestines ofhumans and other mammals.Giardiasis is one of the most common parasiticdiseases worldwide and causes both endemicand epidemic intestinal disease and diarrhea.
Life Cycle• Infection follows the ingestion of the environmenta lly hardy cysts, which excyst in the small intestine, releasing trophozoites that multiply by binary fission