Hepatitis at 20x Magnification
The means of hepatitis transmission varies depending upon the virus responsible for the inflammation. The hepatitis viruses A, E, and F are predominantly spread via the fecal-oral route through food or water that has been contaminated. These viruses are primarily responsible for epidemics of hepatitis in many less-developed regions of the world where crowded conditions and inadequate sanitation are often problems. The other main hepatitis viruses, B, C, D, and G, are chiefly spread through bodily fluids or blood, making their transmission through sexual activity and accidental contact with infected blood a common occurrence. Blood transfusions were also widely responsible for the transmission of the blood-borne varieties of hepatitis until adequate screening measures were introduced in the 1970s. Needle-exchange programs in some areas have also helped decrease incidence of the disease in recent years among intravenous drug users.