Hepatitis A: transmission routes and prevention strategies

Hepatitis A

Causative agent

Virus

Affects the liver

Symptomatic 2-6 weeks after exposure

Speaker notes: Hepatitis A is caused by a virus. Symptoms of hepatitis A include dark-colored urine, pale stools, chronic fatigue (with no other explanation), itching, anorexia (loss of appetite) and nausea, fever, vomiting, and jaundice. The symptoms usually present manifest 2-6 weeks after the initial exposure (Zieve 2011). To test for the disease, the doctor may test for raised IgM and IgG antibodies to hepatitis A and elevated liver enzymes through liver function tests (Zieve 2011). Persons in high-risk occupations may wish to be periodically tested.

Reservoir

Food and water

Stool and blood

Sexual contact

Speaker notes: Disease reservoirs for hepatitis A include food that has been contaminated by the feces of carriers of the disease; contaminated water or ice; direct contact with stool or blood of persons with the disease; and sexual contact. To protect against food-borne transmission requires careful hand-washing, and the use of clean, sanitary water when growing or washing food or storing food in ice. Careful hand-washing is also required to ensure contact does not occur through touching other contaminated objects. To prevent sexual transmission, condoms are required. Because the disease can be transmitted through blood, IV drug users are also at great risk.

Slide 3: Portal of exit

Through fluids: feces or semen

Refraining from contact is essential

Many carriers are asymptomatic

Speaker notes: Food, sexual practices, and IV drug use are the major modes of transmission. Given this, it is wise for all persons to wash their hands after coming into contact with someone else's bodily fluids (Zieve 2011). Even if asymptomatic, the person may still be a carrier. Avoiding potentially contaminated food and water is also essential. This includes the water that may have been used to wash fruit and vegetables, as well as seemingly innocent ice cubes in drinks. When traveling abroad, relying upon bottled water is suggested (Zieve 2011). To avoid the transmission of fluids by air, good ventilation and proper air filtration in healthcare settings and in kitchens and dining halls is also suggested.

Slide 5: Portals of entry

Oral (ingestion)

Intercourse and needle-sharing (semen and blood)

Being in an environment where bodily fluids are often exchanged

Speaker notes: Common portals of entry include eating contaminated food or water (ingestion); exchanging bodily fluids through needle-sharing or sexual practices; living in a nursing home, rehabilitation center, or having an extended hospital stay, or being in a profession which requires close contact with other persons, such as healthcare, food, sewage, or daycare. Because of the difficulty of controlling one's food and water purity, frequent international travel also places one at high risk, where sanitary practices may be less carefully observed (Zieve 2011). Patients with frequent wounds (such as hemophiliacs) or patients with conditions which require them to use catheters (like dialysis) are also at much greater risk, as are the persons who care for them. Using disposable medical devices; proper hand-washing with hot water and soap; using gloves; guarding against potential 'puncture' wounds are necessary in a healthcare environment. In a food service environment, frequent hand-washing is also required; responsible sourcing of foods and disposal of potentially contaminated food; and educating all workers in proper food sanitation is demanded.

Travelers should avoid street food and diners should eat food that is properly prepared: food should be properly chilled or cooked. Undercooked or raw meat and fish should be avoided. Boiling water for one minute or more kills the virus and can be used as an alternative source of decontamination if no bottled water is available (Zieve 2011).

Slide 6: Susceptible host

Persons in high-risk occupations should be vaccinated

Vaccines also suggested for persons likely to suffer complications

Speaker notes: For persons in high-risk occupations; persons who are in relationships with known carriers; and persons with compromised immune symptoms vaccinations are available. Healthcare workers, IV drug users, and food service personnel are at the highest level of occupationally-related risk. The elderly or persons with compromised immune systems or liver are at greatest risk for suffering complications from hepatitis A, which is considered to be the 'mildest' form of hepatitis. Vaccines are protective after four months, and are then followed by six-month or yearly booster shots to provide longer protection (Zieve 2011).

There is no specific treatment for hepatitis A, once it is contracted, although infected persons should be medically supervised. However, it can cause acute liver failure, which can be fatal, so patients should be under the treatment of a physician when identified as infected and monitored until they no longer test positive (Hepatitis A, 2012, WHO).

Reference

Hepatitis A (2013). World Health Organization (WHO). Retrieved:

http://www.who.int/mediacentre/factsheets/fs328/en/

Zieve, David. (2011). Hepatitis A PubMed Health. A.D.A.M. Medical Encyclopedia.

Retrieved http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001323/