Hepatitis A virus (HAV) is responsible for common acute viral hepatitis worldwide. Improvement in sanitation and use of efficient vaccines have reduced HAV incidence in developed countries. However, naive adult population are most susceptible to severe outcomes, and high endemic areas persist in developing regions. The transmission of HAV through the fecal-oral route is established. However, considering evolving consumption habits and global market exchange of food, investigations on risk factors associated with HAV infection are needed. Thus, a systematic review and a meta-analysis of case-control, cohort and transversal studies was performed to determine the main risk factors associated with sporadic HAV infection. Relevant scientific articles were identified through systematic literature search and subjected to a methodological quality assessment. Mixed-effects meta-analyses models were adjusted by population type to appropriate data partitions. HAV infections are defined by serological testing. The quality assessment stage selected 78 studies investigating risk factors for sporadic infections with hepatitis A conducted between 1985 and 2013. This meta-analysis confirmed that HAV infections are mostly related to inter-human transmissions, either due to contact with an ill person, through oral-anal sex practice, or lack of personal hygiene. Travel to endemic countries, occupational exposure such as working in child daycare, and exposure to wastewater were associated with HAV infection. As HAV can persist in the environment, it was not surprising that consumption of untreated drinking water, shellfish consumed raw, and crop products were risk factors. Food contamination could be due to the use of contaminated water (fruits, vegetables) or originate from infected food handlers at every point of the food chain (from picking to serving). Eating or drinking outside were associated with HAV infection. A lack of recent case-control studies was identified, with only three studies eligible between 2011 and 2017. Case-control studies required a more precise definition of risk factors such as type of crop product, and storing/preparation information (e.g. washed, frozen). The frequency of consumption or duration of environmental exposure could also better inform relationship between exposure and risk of infection. In a context of epidemiological change of HAV, international travel and trade of foods, future case-control studies are needed and should focus on populations at risk of severe infections and acute cases.
