The number of hepatitis A infections may be several times higher than the number of cases actually reported, especially in youngsters aged 0 to 4 years, researchers announced at the 10th International Symposium on Viral Hepatitis and Liver Disease here.
Hepatitis A is a liver-infecting virus that can be spread in fecally contaminated food and water. Symptoms include nausea, vomiting and sometimes jaundice, a yellowing of the skin due to reduced liver function
The number of cases of hepatitis A may be as high as 60,000 to 140,000 cases per year, two to five times higher than the number of cases reported, estimate Dr. Gregory L Armstrong and colleagues from the National Center for Infectious Diseases, Centers for Disease Control and Prevention (CDC) in Atlanta.
Armstrong and his colleagues came to this conclusion after looking at data from two large nationwide studies and the National Notifiable Diseases Surveillance System (NNDSS), which include data on the number of people with hepatitis A antibody in their blood (a sign of past infection). They then developed a mathematical model to compute an estimated incidence of hepatitis A.
The researchers estimate that the overall incidence of hepatitis A infection has declined by 4.4% per year during this century. Approximately 35% to 65% of cases occur in children between the ages of 0 to 4 years. Data from the National Notifiable Disease Surveillance System indicates that only 1.4% to 1.8% of cases occurring in this age group are reported to the CDC.
Armstrong told Reuters Health that he thinks the disparity in the actual numbers and numbers of cases reported are due to the fact that most children do not show signs of jaundice when infected with hepatitis A. Furthermore, he said, physicians may not always report cases of hepatitis A infection to the CDC.