| Hepatitis A virus (HAV) is spread by fecal-oral contact or ingestion of contaminated food or water. Life-long immunity is conferred by infection or vaccination, so anti-HAV seroprevalence studies can be used to indicate which populations are susceptible to infection. We undertook an exhaustive metaanalysis of publications on HAV epidemiology and interpreted these findings in the context of diverse aspects of global development. Seroprevalence rates are highly correlated with socioeconomic status and access to clean water and sanitation. Increasing household income, education, water quality and quantity, sanitation, and hygiene leads to decreases in HAV prevalence.; Although many water-related risk factors have been identified, the specific contributions of water in transmission have not been explored. We used an SIR (susceptible-infectious-removed) compartmental model with age compartments, separate pathways for direct and waterborne transmission, and risk group compartments for exposure to contaminated water to assess the effects of changing rates of exposure to contaminated water and levels of contamination, direct and waterborne transmission rates, and endogenous and exogenous contamination of water sources on the shapes of age-seroprevalence curves over time.; We then used an SIR (susceptible-infectious-removed) compartmental model with age structure to fit a time-dependent logistic function for HAV force of infection for 157 published age-seroprevalence data sets. Average force of infection rates were highest in Africa, followed by the Americas, the Middle East, Asia, and Europe. The proportion of the population with access to clean drinking water, the value of the human development index (HDI), and per capita gross domestic product (GDP) are all inverse predictors of HAV force of infection. Declining infection rates were observed in 65.6% of the surveys, and were found mostly in surveys with already low force of infection rates. The proportion of susceptible adults, who are vulnerable to severe hepatitis A disease, increases with decreasing force of infection. This work demonstrates the utility of HAV seroprevalence studies to reveal patterns of change in force of infection and to assess the association between socioeconomic risk factors and transmission rates. |
