Amebiasis

1. AMEBIASIS

2. Definition Amebiasis is infection with intestinal pathogen Entameba histolytica (tissue lysing ameba) Most Infection are asymptomatic disease ranging from Dysentry to extaintestinal infectons like liver absess Most of asymptomatic infection is due to E.dispar Endemic area Mexico,India & tropical regions of Africa,South and Central America

3. Life cycle and transmission E. histolytica exists in two stages multinucleate cyst Motile Trophozoite

4. transmission E. histolytica are most common in areas where poor sanitation and crowding compromise the barrier to contamination of food and drinking water with human feces Infection is acquired by ingestion of cysts in faecally contaminated water or food Cysts are resistant to the acid in the stomach

5. Life cycle

6. Pathogenesis and pathology E. histolytica trophozoites invade through the submucosal layer, creating the classic flask shaped ulcers that appear on pathologic examination as narrow-necked lesions broadening in the submucosal region Ulcers tend to stop at the muscularis layer, and full-thickness lesions and colonic perforation are unusual

7. Flask shaped ulcer

8. Pathogenesis and pathology In some individuals, trophozoites invade the portal venous system and reach the liver, where they cause amebic liver abscesses characteristic appearance on pathologic examination: the roughly circular abscesses contain a large necrotic center resembling anchovy paste

9. Clinical manifestations Two types- Intestinal and Extra Intestinal Amebic colitis generally appear 2-6 weeks after ingestion of the cyst of parasite diarrhea and lower abdominal pain are the most common complaints Fever is present in 40% cases Severe dysentry with 10-12 small volume, blood and mucus containing stools may develop

10. Clinical manifestations Fulminant amebic colitis – profuse diarrhea, severe abdominal pain , fever,and pronounced leukocytosis It affects young children , pregnant women, individuals treated with steroids and in diabetes and alcoholism Intestinal perforation occus in >75% of pts.with fulminant disease Complications includes Toxic Megacolon in .5% with severe bowel dilatation and intraluminal air Ameboma -presents as abd . mass

11. Amebic liver abscess Most common extraintestinal complication Most individuals do not have concurrent signs or symptoms of colitis The classical presentation of ALA are right upper quadrant pain , fever and liver tenderness Its acute in nature lasting < 10 days Jaundice is uncommon most common laboratory findings are leukocytosis (without eosinophilia), an elevated alkaline phosphatase level, mild anemia, and an elevated ESR

12. Other manifestations and complications Rt -sided pleural effusion - common in cases of ALA In 10% rupture of abscess through diaphragm may cause pleuro -pulmonary amebiasis Sudden onset cough , pleuritic chest pain and shortness of breath Hepatobronchial fistula is dramatic complication in which pt has complaint of cough with content of liver abscess Liver abscess may rupture into pericardial cavity and can cause pericarditis with 30% mortality due to cardiac temponade

13. Diagnostic tests Demonstration of E. histolytica trophozoite or cyst in the stool or colonic mucosa of pts with diarrhea presence of amebic trophozoites containing red blood cells in a diarrheal stool is highly suggestive of E. histolytica infection Antigen detection based ELISAs that can specifically identify E.histolytica in the stool colonoscopy with examination of brushings or mucosal biopsies for E. histolytica trophozoites Amebic serology

14. Diagnostic tests Diagnosis of amebic liver abscess is based on the detection of one or more space occupying lesions in the liver by Ultrasound and CT scan and a positive serology classically described as single, large and located in right lobe of liver When a pt. with space ahs a occupying lesion in the liver, a positive serology is highly sensitive(>94% ) and highly specific(>95%) for the diagnosis of the liver abscess

15. Ct scan liver with ALA in Rt lobe

16. Treatment The nitroimidazole compounds tinidazole and metronidazole are the drug of choice Tinidazole appears to be better tolerated and more effective Whenever possible fulminant amebic colitis should be managed conservatively

17. treatment Aspiration of liver abscess reserved for pyogenic abscess or a bacterial superinfection is suspected, for pts failing to respond to tinidazole or metronidazole ( those who have persistent fever or abdominal pain after 4 days of treatment), for individuals with large liver abscesses in the left lobe large abscess with risk of imminent rupture Pleuropulmonary amebiasis Amebic pericarditis

18. treatment luminal agents ( Paramomycin or iodoquinol ) to ensure eradication of infection Paramomycin is preferred agent Asymptomatic individuals with documented E. histolytica infection should be treated because of the risks of developing amebic colitis or amebic liver abscess in the future and of transmitting the infection to others

19. treatment Drug Dosage Duration Amebic Colitis Or ALA Tinidazole 2g/day with food 3 Metronidazole 750mg tid PO or IV 5-10 Luminal Infection Paramomycin 30mg/kg qd PO in 3 divided dose 5-10 Iodoquinol 650 mg PO tid 20