Amebiasis ◊

 

Literature Recommendations

Exclusion-Case in SOS*
(Symptomatic)

Yes [1, 2,3,5, 8,17]
(foodhander only ◊)
Grade III-A

Exclusion-Case in SOS*
(Asymptomatic or previously symptomatic but now recovered)

Yes [5, 7,11a,12] 
(foodhander only ◊)
Grade III-A

Clearance-Case in SOS*

Yes
(foodhander only ◊)
Disagreement exists among sources regarding clearance of other SOS, so no grade. b

 

Exclusion of Contact
(Symptomatic)

Yes [1, 2, 3, 5, 8, 17]
(foodhander only ◊)
Grade III-A

Exclusion of Contact
(Asymptomatic)

No (screening recommended)[8,9]
Grade III-A

Exclusion-Case in Children
(Group setting with children ≤ 5 years of age)
(Symptomatic)

Yes [1, 3, 4]
Grade III-A

Exclusion-Case in Children
(Group setting with children ≤ 5 years of age)
(Asymptomatic or previously symptomatic but now recovered)

Insufficient evidence for recommendation

◊ Applicable Code

CCR 2550
* SOS (Sensitive Occupations or Situations) is not defined precisely in either the Code of Regulations or Health & Safety Code. See Attachment 2 for the definition of food workers.
◊ See California Code of Regulations, Attachment 1, for details.
+ Local health departments may elect to follow more restrictive exclusion and clearance criteria

a Hal et al (2007) do not specifically recommend exclusion of asymptomatic cases; however, they do recommend treatment of asymptomatic cases to prevent transmission [11].
b See Preventive measures under symptomatic heading #1, and #5.

Disease Trends in the U.S.:
April 2002, an outbreak of gastroenteritis in 59 people occurred in Palau. Entamoeba histolytica was isolated in 9 of the 30 stool specimens. All of the cases reported consuming untreated drinking water from the same water tank that collected water from a stream. The water tested positive for fecal matter [21].
From July through September of 1998, 177 suspected cases of Entamoeba histolytica were identified in Tbilisi, Republic of Georgia. The outbreak was a result of contaminated water; fruits and vegetables purchased at an unofficial market and dairy products from an official market were also implicated in the outbreak [22].
In February of 1996, two institutions for the mentally retarded reported an Entamoeba histolytica outbreak. Thirteen residents from the first institution and twenty-nine residents from the second institution tested positive for the Entamoeba histolytica cyst. No cysts were found in the parents of the residents; none of the employees from the first institution tested positive, one employee from the second institution tested positive. The risk of infection for the parents and the employees was very low [23].
Amebiasis (intestinal) is caused by a single-celled parasite, Entamoeba histolytica. Most infections are asymptomatic. E. dispar infection and E. moshkovkii infections and 90 percent of Entamoeba histolytica infections are asymptomatic [8, 10, 16]. Symptoms of Amebiasis include bloody stool, abdominal cramps, chills, fever, prostration, nausea, headache and tenesmus [8, 15]. Entamoeba histolytica exist in two forms, the cyst stage, which is the infective form, and the trophozoite stage, which is the invasive form of the disease [16].
Reservoir of Infection: Humans are the reservoir and they are usually identified as a chronically ill or asymptomatic cyst passer [1, 6, 8].
Mode of Transmission: Primarily through ingestion of focally contaminated food or water containing amebic cysts (chlorine resistant). Transmission can occur sexually through oral-anal contact [6, 8, 14, 17]. Amebiasis is usually spread by a chronically ill or asymptomatic cyst shedder [1]. Amebiasis can also be transmitted through the unwashed hands of food handlers and fresh vegetables contaminated by human excrement [8]. A study which reviewed symptomatic amoebic patients between 2000 and 2001 in the big cities of Japan, found that 95% were male and over half of these male patients were homosexual [19].
Attack Rates: specific information was unavailable in the literature reviewed.
Infectious Dose: the ingestion of one viable cyst can cause an infection [24].
Incubation Period: Can range from days to years; commonly lasts 2-4 weeks [6, 8, 18].
Infectious Period: Cysts may be passed for years [6, 8]. Untreated individuals may be intermittently infectious for years [8].
Asymptomatic Carrier State: Intestinal Amebiasis can have a clinical presentation of chronic, nondysenteric diarrhea, weight loss, and abdominal pain, which can persist for years [16]. A study on adult carriers found that the vast majority of carriers remained asymptomatic during a 15 months observation period [13].
Diagnosis: An enzyme immunoassay kit to specifically detect E. histolytica in fresh stool specimens is commercially available. Polymerase chain reaction (PCR)-based diagnosis is not readily available [18]. Antigen detection assays are the best method for diagnosing intestinal Amebiasis [16].

Preventive Measures:
Exclusions:
Symptomatic

  1. According to an article published in Communicable Disease and Public Health (2004) Symptomatic individuals can return to work 48 hours after first normal stool; “people whose work involves preparing or serving unwrapped foods not subjected to further heating and clinical and social care staff who have direct contact with highly susceptible patients or persons whom gastrointestinal infection would have particularly serious consequences require microbiological clearance...one stool obtained at least one week after the end of treatment should be examined for E. histolytica cysts” [1]. Guidelines and Consensus Document {Grade III-A}
  2. Bolyard et al (1998) states, “Restriction from patient care and the patient environment or from food handling is indicated for personnel with diarrhea or acute gastrointestinal symptoms, regardless of causative agent” [2]. Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
  3. The American Academy of Pediatrics American Public Health Association and the National Resource Center for Health and Safety in Child Care (2004) state, “Children and caregivers who excrete intestinal pathogens but no longer have diarrhea may be allowed to return to child care once diarrhea resolves” [3]. Guidelines and Consensus Document {Grade III-A}
  4. According to the American Academy of Pediatrics American Public Health Association and the National Resource Center for Health and Safety in Child Care (2004) “Children with diarrheal illness of infectious origin generally may be allowed to return to child care once the diarrhea resolves” [4]. Guidelines and Consensus Document {Grade III-A}
  5. According to Guerrant et al (2001)“because food-handlers and health care workers can transmit bacterial and parasitic diseases even if they are asymptomatic, it is recommended that before returning to their jobs, these persons have 2 consecutive negative stools samples taken 24 hours apart and at least 48 h after resolution of symptoms” [5]. Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
  6. According to Allason-Jones et al (1988) “To determine the natural course of infections with E. histolytica we did not treat the patients but reassessed them at three month intervals. At each visit we recorded details of any gastrointestinal symptoms and coincidental treatment and carried out a general examination; at least one fresh stool sample was examined for presence of parasites. The patients were considered to be clear of E. histolytica if three consecutive stool specimens gave negative results” [17]. Review of Outbreaks and Epidemiology {Grade III-A}
  7. According to the Communicable Disease Management Protocol (2001) “Exclusion of persons infected with E. histolytica from food handling and from direct contact of hospitalized and institutionalized patients for the duration of antimicrobial therapy” [8]. “Microscopic examination of feces of household members and other suspected contacts” is recommended [8]. The Communicable Disease Management Protocol also recommends that “symptomatic carriers should be treated the same as cases” [8]. Guidelines and Consensus Document {Grade III-A}
  8. Petri and Singh (1999) state, “Since Amebiasis often spreads through a household; it is prudent to screen family members of an index case for intestinal (Entamoeba) histolytica infection” [9]. Evidence Based Literature {Grade III-A}

Asymptomatic

  1. According to Van Hal et al., (2007) “Generally, asymptomatic patients never become symptomatic. They may excrete cysts for a short period of time, but the majority of these patients will clear the infection within 12 months. Patients with confirmed (Entamoeba) histolytica should be treated to eliminate the organism and prevent further transmission” [11]. Evidence Based Literature {Grade III-A}
  2. According to Guerrant et al., (2001)“because food-handlers and health care workers can transmit bacterial and parasitic diseases even if they are asymptomatic, it is recommended that before returning to their jobs, these persons have 2 consecutive negative stools samples taken 24 hours apart and at least 48 hours after resolution of symptoms” [5]. Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
  3. Gatti et al (1995) state, “Our report confirms the importance of asymptomatic carriers of pathogenic amoebic strains in the dissemination of disease and the epidemiological risk presented by such carriers. In the outbreak we described, it is almost certain that the Philippino maid represented the primary source of infection, probably transmitted via food or beverages” [7]. Review of Outbreaks and Epidemiology {Grade III-A}
  4. According to Gatti et al. (1999), “Case 1 was infected during repeated food-exchanges with his North African workmates, although it was not possible to test his colleagues for overt disease or asymptomatic infection.  The asymptomatic male partner of the second couple most likely acquired his amoebic infection, along with his giardiasis, during a visit to India. Thus, it was the male partner in each couple who probably brought the parasite into their households. Their female partners are then assumed to have ingested amoebic cysts excreted by the men, by an indirect fecal-oral route, probably through handling contaminated house furnishings or by ingesting food handled and contaminated by the men”  [12]. Review of Outbreaks and Epidemiology {Grade III-A}

References

    1. Public Health Laboratory Services, Advisory Committee on Gastrointestinal Infections. (2004). Preventing Person-to-Person Spread Following Gastrointestinal Infections: Guidelines for Public Health Physicians and Environmental Health Officers. Communicable Disease and Public Health , 7 (4), 362-384.Guidelines and Consensus Document
    2. Bolyard EA, Ofelia CT, Water W.W. et al (1998). Guidelines for Infection Control in Health Care Personnel. America Journal of Infectious Disease, 26(3), 307-8. Evidence based reviews with guidelines formed out of reviewed literary sources
    3. APHA, AAP and NRCHS. (2004). Child Care Provider's Health and Well Being. National Health and Safety Performance Standards: Guidelines for Out-of-Home Child Care. Second Edition. American Academy of Pediatrics, the American Public Health Association and the National REsoiurnce Center for Health and Safety in Child Care , 1-95. Guidelines and Consensus Document
    4. APHA, AAP and NRCHS. (2002). Exclusion and Inclusion of Ill children in Child Care Facilities and Care of Ill Children in Child Care. National Health and Safety Performance Standards: Guidelines for Out-of-Home Child Care. Second Edition . A Joint Collaborative Project of the American Academy of Pediatrics, The American Public Health Association, and the National Resource Center for Health and Safety in Child Care . Guidelines and Consensus Document 
    5. Guerrant R L, Van Gilder T, Steiner T S, et al (2001). Practical Guideline for Management of Infectious Diarrhea. Clinical Infectious Diseases, 32,331-50. Evidence based reviews with guidelines formed out of reviewed literary sources
    6. Heymann, David (2004). Control of Communicable Disease Manual 18th ed. Washington D.C.: American Public Health Association; 160-4. Guidelines and Consensus Document
    7. Gatti S, Cevini C, Novati S and Scaglia M. (1995). Transmission of Entamoeba histolytica within a family complex. Transactions of the Royal Society of Tropical Medicine and Hygiene,  93(8), 829-834. Review of Outbreaks and Epidemiology
    8. Manitoba Public Health Communicable Disease Control Unit. Amebiasis. (2001). Communicable Disease Management Protocol , 1-3. accessed on 7/20/07 at www.gov.mb.ca/health/publichealth/cdc/protocol/amebiasis.pdf Guidelines and Consensus Document
    9. Petri W and Singh U. (1999). Diagnosis and Management of Amebiasis. Clinical Infectious Diseases, 29, 1117-1125. Evidence Based Literature
    10. Wells C and Arguedas M. (2004). Amebic Liver Abscess. Southern Medical Journal, 97 (7): 673-682. Evidence Based Literature
    11. Van Hal SJ, Stark DJ, Fotebar R et al. (2007). Amoebiasis: current status in Australia. Medical Journal Australia, 186(8), 412-416. Evidence Based Literature
    12. Gatti S, Cevini C, and Bernuzzi AM (1999).Symptomatic and asymptomatic Amoebiasis in Two Heterosexual Couples. Annals of Tropical Medicine & Parasitology, 93(8):829-834. Review of Outbreaks and Epidemiology
    13. Blessman J, Ali IKM, Nu PA, Ton D, and Binh T. (2003). Longitudinal Study of Intestinal Entamoeba histolytica Infections in Asymptomatic Adult Carriers. Journal of Clinical Microbiology, 4745-50. Review of Outbreaks and Epidemiology
    14. Stanley, S. (2003). Amoebiasis. Lancet, 361, 1025-1034.  Evidence Based Literature
    15. Kitchen, L. (1999). Case Studies in International Travelers. American Family Physician 1999, 1-6. Review of Outbreaks and Epidemiology
    16. Leder K and Weller P. Intestinal Amebiasis. UpToDate.com, 1-7. Evidence Based Literature
    17. Allason-Jones E, Mindel A, Sargeaunt P, and Katz D. (1988). Outcomes of Untreated Infection with Entamoeba Histolytica in Homosexual Men With and Without HIV Antibody. British Medical Journal, 297,654-7. Review of Outbreaks and Epidemiology
    18. Center for Disease Control and Prevention. (2007).Amebiasis. Yellow Book CDC Traveler’s Health; chapter 4.  Retrieved August 2007, www.cdc.gov. Evidence Based Literature
    19. Ohnishi K, Kato Y, Imamura A. et al. (2003). Present Characteristics of Symptomatic Entamoeba Histolytica Infection in the Big Cities of Japan. Epidemiology and Infection, 132, 57-60. Review of Outbreaks and Epidemiology
    20. Center for Disease Control and Prevention. Foodborne Pathogenic Microorganisms and Natural Toxins Handbook: Entamoeba Histolytica. US FDA/CFSAN Bad Bug Book. Retrieved September 200. www.cfsan.fda.gov/~mow/chap23.html. Guidelines and Consensus Document
    21. Center for Disease Control and Prevention. (2006). Surveillance for Waterborne Disease and Outbreaks Associated with Recreation Water—United States, 2003-2004 and Surveillance for Waterborne Disease and Outbreak Associated with Drinking Water and Water Intended for Drinking—United States, 2003-2004. Morbidity and Mortality Weekly Report, 55(2), 1-68. Review of  Outbreaks and Epidemiology
    22. Barwick R, Uzucanin A, Lareau S et al. (2002). Outbreak of Amebiasis in Tbilisi, Republic of Georgia, 1998. American Journal of Tropical Medicine and Hygiene, 67(6), 623-631. Review of Outbreaks and Epidemiology
    23. Abe N, Nishikawa Y, Yasukawa A and Haruki K. (1999). Entamoeba Histolytica Outbreaks in Institutions for the Mentally Retarded.  Japanese Journal of Infectious Diseases, 52(3): 135-136. Review of Outbreaks and Epidemiology
    24. Center for Disease Control and Prevention. (2004). Diagnosis and Management of Good Illnesses. A Primer for Physicians and Other Health Care Professionals. Morbidity and Mortality Weekly Report, 53 (RR-4), 1-29