Hepatitis A is a form of viral hepatitis caused by the hepatitis A virus (Human Hepatitis A Virus, HAV). The infection always manifests in acute form, sometimes in severe fulminant form, and is potentially fatal.
The virus is spread through the faecal-oral route, generally through the ingestion of water or contaminated foods (for example salads, unpeeled fruit, seafood, ice cubes). Hepatitis A is still frequent especially in countries with a poor level of health and hygiene (Asia - including Turkey, the entire continent of Africa, Central and South America, Eastern Europe). Poor personal hygiene and overcrowding facilitate the spread of the virus.
The virus is eliminated in the faeces both before and after the onset of symptoms. Children can spread the virus for longer, up to 10 weeks after the onset of symptoms (infants can reach over 6 months). This pronounced capacity for spreading the disease, combined with the fact that in children the infection is usually asymptomatic, means that they are a significant source of infection.
Symptoms and complications
Symptoms include jaundice, moderate fever, loss of appetite, nausea, vomiting, fatigue, malaise, joint or muscle pain, headache, photophobia (sensitivity to light), cough, and pharyngitis. In children the disease is usually asymptomatic whereas 8 in 10 adults develop jaundice.
The disease generally has a self-limiting and benign course but it is sometimes severe with a protracted course and or a rapidly fatal fulminant form.
Overall, the disease is fatal in 0.3-0.6% of cases but can reach percentages 3-4 times higher in adults over 50 years.
Impact on the population
Hepatitis A is sporadically and epidemically spread throughout the world, with an estimated 1.4 million cases per year. The most endemic areas are Central and South America, Africa, the Middle East, Asia and the western Pacific. The prevalence of infection is greater in places with poor sanitation (e.g. inadequate sewage system) and overcrowding. In developing countries there are epidemic outbreaks, while in industrialised countries most cases of hepatitis A occur sporadically, even though epidemics can occur in particular conditions.
Italy is an area with medium-low endemicity and, after peaks in 1992, 1994 and 1997 linked to the consumption of seafood in some regions of southern Italy, incidence is stable with values of around 1 in 100,000 inhabitants.
Sources / Bibliography
- Modern Infectious Disease Epidemiology - (A. Krämer, M. Kretzschmar, K. Krickeberg; pg.142)
- Manuale per il Controllo delle Malattie Trasmissibili - (Rapporto ufficiale dell'APHA - D. L. Heymann; pg.214-221)
- Encyclopedia of Virology - 3rd Ed. - (B.W.J. Mahy, M.H.V. Van Regenmortel et al.; Vol. 2 pg.343-350)
- Virology: Principles and Practice - (J. Carter, V. Saunders et al.; pg.182-197)
- Foundations in Microbiology - 8th Ed. - (K. P. Talaro, B. Chess et al.; pg. 775-776)
- Vaccini e vaccinazioni - 3rd Ed. - (G. Bartolozzi et al.; pg. 367-403)
- Harrison's Principles of Internal Medicine - 16th Ed. - (Kasper, Braunwald, Fauci. Longo et al.; pg. 1822-1838)
- Essential of Anatomic Pathology - 3d Ed. - (L. Cheng, D. G. Bostwick et al.; pg.1776)