Science 1999 285: 27. (in News Focus)
Roughly 24% of the people in Egypt are estimated to carry hepatitis C virus (HCV), making it the hardest hit country in the world. Researchers have long suspected that the culprit might be a decades-old strategy to combat a parasitic disease known as schistosomiasis. Now a study headed by Thomas Strickland, an epidemiologist at the University of Maryland, Baltimore, takes this idea from the realm of the possible to the probable. Maryland's Christina Frank, who presented the data at the Sixth International Symposium on Hepatitis C and Related Viruses for Strickland's lab and their collaborators at Ain Shams University in Cairo, Egypt, says the schisto-HCV link "may very well be the world's largest iatrogenic transmission scenario known to date."
Schistosomiasis in Egypt dates back at least to the time of the Pharaohs. Caused by a flatworm that propagates in water snails, the disease attacks the intestines, bladder, liver, and other organs. In 1918, Frank explained, physicians began popularizing various injectable treatments, called parenteral antischistosomal therapy, or PAT, which typically required 10 to 12 injections and was usually given with reusable syringes. The campaigns began tapering off in the 1970s when oral schisto drugs became available.
By studying schistosomiasis archives at the World Health Organization, PAT records at the Egyptian Ministry of Health, census records, and HCV infection surveys of 10,000 Egyptians, the researchers pieced together the link between the two diseases. Age and demographic data indicate that people who were most exposed to PAT had the highest HCV prevalence. "That's the first time the data convincingly show this," says Robert Purcell, a virologist at the U.S. National Institute of Allergy and Infectious Diseases, whose laboratory has played central roles in the study of every hepatitis-causing virus.