For years, officials who monitor the spread of diseases noticed an odd fact: Egypt had by far the world's highest rate of infection with the deadly hepatitis C virus. But Egypt's hepatitis epidemic, unlike the biblical plagues, has its origins in the work of man. In fact it may well turn out to be the largest medically caused infectious epidemic in history.
According to a study published in the Lancet on Saturday, the virus, which was only identified a decade ago, was spread unintentionally through the Nile valley over two decades by rural health officials giving injections to fight another scourge -- the parasitic disease schistosomiasis. "It's really heartbreaking," says Christina Frank, a graduate student at the University of Maryland School of Medicine who is the lead author in the study.
Hepatitis C infection can lead to serious liver diseases, and the population infected decades ago has since spread the virus throughout the country. Frank said that the injections stopped long ago but the pool of carriers keeps spreading, which has led to rising rates of cirrhosis and liver cancer.
Schistosomiasis, also known as bilharzia, is a serious infection of the urinary and intestinal tracts caused by blood flukes -- tiny flatworms -- whose larvae are carried by snails living in stagnant water in the tropics.
From the late 1950s through the early 1980s, Egyptian teams went from village to village taking stool and urine samples. People infected with the worms were administered shots of tartar emetic -- up to 16 injections over three months were required to kill the parasites.
No one knew that hepatitis C was lurking in the blood of some of these patients. And accounts of the campaigns indicate that needles were rarely sterilized sufficiently to kill a virus like hepatitis C. "The high number of injections is why this campaign could be responsible for the huge outbreak," says Frank.
By correlating regional rates of hepatitis C infection with historical accounts of the anti-schistosomiasis campaigns, Frank and the other researchers, including Egyptian Health Ministry and World Health Organization scientists, found the highest rates of hepatitis infection in Egyptian regions where the injections were given for the longest time.
In Egypt, a country of 67 million people, an estimated 15 to 20 percent of the population has been exposed to hepatitis C -- compared to less than 5 percent in neighboring Sudan and 2 percent in the United States. In some areas of Egypt the rates are even higher.
The first pills against schistosomiasis were introduced in the mid-1970s, but they weren't effective against the strain of flatworm prevalent in northern Egypt, around the Nile delta. The pills were introduced first in southern Egypt, near the Sudanese border, but it wasn't until about 1982 that the arrival of an effective new drug, praziquantel, enabled health officials to stop giving shots against schistosomiasis in the Nile delta.
Hepatitis C infection rates track smoothly down the Nile with the introduction of oral therapies, the study found. The infection rate among Egyptians 10 to 50 years old was 19.4 percent in southern Egypt, 26.5 percent in central Egypt and 28.4 percent in northern Egypt. In the megalopolis of Cairo, where one would expect high rates of a disease spread commonly by IV drug use and prostitution in much of the world, only 8.2 percent of the population show signs of infection.
The hepatitis epidemic is particularly poignant in that it was the unintended consequence of a government effort to help farmers and peasants. Under the ambitious leadership of Gamal Abdal Nasser and subsequent governments, Egypt battled schistosomiasis with more energy than any other third world country, where neglect of the countryside is the rule.
"Egypt was foresighted and ahead of the region in attempts to give first class medical care," says Robert Purcell, a hepatitis C expert at National Institutes of Health. "Some other countries had just as much schistosomiasis but weren't as effective at fighting it. And as a consequence, they didn't get as much hepatitis C spread around."
Schistosomiasis has been known in Egypt from the pharaohs' time but it was paradoxically an earlier technological intervention -- the series of dams and flood-control projects, culminating in the Aswan High Dam, which opened in 1970 -- that vastly enhanced the parasite's ecosystem and gave rise to the need for the campaign against it. Whereas the snails frequently died off during Egypt's dry season, when the Nile was low and the irrigation canals empty, flood control projects kept standing water in the canals year-round, creating an ideal environment for the snails and the worm. The irony was that flood control was also the Nile-centric nation's single most important technical achievement.
"If Egypt had stuck with basin irrigation they would never have fed their population," says Frank, a geographer by training. "You can say what you want about ecological problems with the Aswan dam, but it feeds a huge population."
Hepatitis C has lurked in the world's blood supplies since at least the 1940s. In the United States, it propagated rapidly through IV drug users in the 1960s and also, apparently, spreads through sex. Unlike hepatitis A and B, there is no vaccine available to combat the quickly mutating virus, and current drug therapies have major side effects. Of the estimated 4 million Americans with hepatitis C antibodies, perhaps a fifth may contract serious liver disease unless better treatments become available, CDC officials estimate.