President's Message

Viral Epidemics -- Are There Cures?

N.H. Tucker, III, M.D., President

Viral epidemics have caused a tremendous amount of morbidity and mortality throughout recorded human history. I would like to examine three of them and their status as of 1999.

Smallpox was described as early as 1122 B.C. in China, and the mummified head of Ramses V of Egypt, who died in 1156 B.C., had evidence of smallpox. It appears to have been introduced into Mediterranean Europe in 165 A.D. by Roman Legionnaires returning from conquests in Asia and Africa. The European population had no natural smallpox immunity and the physician Galen estimated that between a quarter and a third of the Italian population died in this 15 year epidemic. However, after the initial outbreak, the general population developed immunity and no longer was smallpox as prevalent. It primarily became a disease of previously unexposed children and of previously unexposed and therefore non-immunized adults. It was noted that once a patient had smallpox, he could never again become infected. This led to inoculation with smallpox, but such inoculations could be fatal.

In 1796, Edward Jenner developed a vaccination using the cowpox virus that proved to be safe and effective. As a result, vaccination became more aggressive and, by 1977, smallpox as a naturally occurring disease was wiped out. So ended the saga of a viral disease that had killed over a hundred million humans.

Influenza was known in the Middle Ages, but seems to have become more virulent with the colder and wetter weather that began in Europe in the 13th Century. Generally the disease produces a mild reaction, but at times a highly lethal strain develops. This occurred in 1426-1427 when the flu swept through Spain, France, the Netherlands, and the British Isles. Eastern England mortality was as high as 5% of the total population. There were successive flu epidemics from then on as different strains of the virus appeared.

The Spanish Flu Epidemic of 1918 was one of the most severe natural disasters ever and has been called the Great Plague of 1918. It was first reported in the summer of 1918 in the German Army WWI trenches and rapidly spread to both German civilians and the opposing Allied Armies, which included the American troops. As the wounded and disabled American soldiers were furloughed home from the front, they carried the deadly virus with them. On August 1, New York City's Lower East Side became the location of the first flu death in America. From that point on, America's deadliest epidemic began. In October alone, 195,000 Americans succumbed. Then, as suddenly as it began, the flu epidemic was gone. By mid November, the crisis had passed but in its wake were 550,000 American and 20 million worldwide dead. To place this in perspective, consider that WWI ended November 11, 1918 and during 4 years of war, the death count was 10 million which was only half the 20 million flu mortalities of the latter 5 months of 1918.

Flu is a highly contagious disease spread by the respiratory route and is therefore almost virtually impossible to quarantine. However, today we have inactive influenza vaccines that are effective if given annually, and if closely related to the currently circulating flu strain. Amantadine and Rimantidine are also effective treatment and prophylaxis for influenza. Therefore, the likelihood of a major severe flu pandemic is much less than in the past.

Then there is the present epidemic -- AIDS. In 1981, AIDS reared its ugly head in the United States when an unusual number of previously healthy homosexual men in New York and California developed Kaposi's Sarcoma and/or Pneumocystis Carinii Pneumonia -- two diseases associated with immune deficiency. A massive search was launched to find the etiology of this new disease, and by 1984 the HIV1 virus had been identified as the culprit. With the virus known, stored blood samples from Central Africa from the past 4 decades were studied and indeed revealed HIV1. The first known case was a Bantu man who died in 1959 in what is now Congo. Thus, it would appear that AIDS arose from Central Africa, either from a previously unknown isolated virus, or by mutation of a more common virus -- possibly the Simian HIV virus. The newest evidence suggests that the chimpanzees of West Equatorial Africa carried the virus, which was subsequently passed by chimpanzee blood contamination to the open wounds of human hunters in the late 1940's or early 1950's. The HIV1 virus has been known to have a latent period of up to 10 years before clinical disease is present. Therefore, it would be logical to assume the 1981 AIDS patients in America had contracted the virus sometime in the 1970's.

We now know the virus is spread by sexual (both homosexual and heterosexual), parenteral, and perinatal routes. Treatment is with HIV reverse transcriptase inhibitors in combination with protease inhibitors; but of course prevention is the way to break this epidemic. Safe sex significantly reduces the transmission rate as does treating sexually transmitted diseases(STDs). The vaginal mucosa is probably interrupted by STDs and this probably leads to greater ease of HIV infection during sexual intercourse. Also treatment of HIV infected women with Zidovudine during the third trimester of pregnancy and subsequently treating the infant with Zidovudine for 6 weeks post delivery has been shown to reduce maternal-fetal transmission by 67%. Other important preventive measures include universal precautions and post needle-stick prophylaxis with Zidovudine.

Ultimately though, the "cure" for this epidemic will likely be what has been the cure for other viral epidemics — an effective vaccine. Research is ongoing to develop this vaccine but has proven to be extremely difficult given the unique nature of the AIDS virus. HIV1 is constantly mutating and therefore a vaccine can quickly become non-protective for the new mutated virus. However there is no reason to believe we will not ultimately be successful. Of note is that the Duval County Health Department has been selected to vaccinate 150 volunteers at high risk for contacting HIV. This is part of an FDA approved experimental vaccine trial (AIDSVAX B/B) to vaccinate 5,000 high risk individuals in North America. When compared to other viral epidemics, we have moved with amazing speed in the past 18 years to identify the organism, develop treatments, and institute vaccine research. The war continues to be waged.

1. REFERENCES
2. Wills C. Yellow Fever, Black Goddess. 1996.
3. Gottfried RS. The Black Death — Natural and Human Disaster in Medieval Europe. 1983.
4. Fauci. Harrison's Principles Of Medicine. 14th edition.
5. Andreoli C. Essentials Of Medicine. 4th edition.
6. Encyclopedia Britannica
7. World Book Encyclopedia
8. Waldholz M. Wall Street Journal article; Feb 1, 1999.
9. Florida Times-Union. Feb 1, 1999.

Jacksonville Medicine / May, 1999