Infectious Disease Express Report
Infectious Disease Society of America
New Orleans, LA

Treatment & Control of Influenza

This report was reviewed for medical and scientific accuracy by William C. Waters, III, MD , Internist-Nephrologist, Piedmont Medical Center, Atlanta, Georgia.

We take the common "flu", or influenza, for granted, but three times in the history of the planet, catching the flu meant far more than battling a case of body aches and chills. During the pandemics of 1918, 1957, and 1968 (severe outbreaks occurring throughout the world), the flu turned deadly.

"When we think of an influenza pandemic, the spectre of the Spanish influenza of 1918 is often conjured up. There is reason to fear a recurrence of such an event, as it was truly catastrophic," said Nancy Cox, PhD, Influenza Branch, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia. Dr. Cox, along with other infectious disease specialists, spoke at a symposium on influenza during the 38th Annual Meeting of the Infectious Diseases Society of America (IDSA).

The Spanish flu of 1918 infected 25 million Americans and killed half a million. It orphaned many children and vastly disrupted community life. The deadly nature of this flu strain was largely due to its ability to develop into bacterial pneumonia. Death was also not limited to the elderly or otherwise-ill-half occurred in people ages 20-45. Healthy citizens tried to avoid contagion, whether by vaccination, wearing bags of camphor around their necks, or using breathing machines. No method was effective.

"In just a few months, about 30 million people died worldwide. The historian Alfred Crosby stated that the Spanish flu killed more humans than any other disease of similar duration in the history of the world," she said.

Larry J. Strausbaugh, MD, Portland VA Medical Center, Oregon, offered a more detailed description: "Hospitals were so crowded that they stationed undertakers at the doors to remove bodies and to make room for patients. The living came in one door, and the dead went out the other. There were half a million casualties in our country alone." Dr. Cox continued, "It's easy to believe that a pandemic of this magnitude could not occur now, with the antibiotics, antivirals, and improved supportive medical care of today, but I think we need to challenge this. We should consider a pandemic on the order of 1918 to be more like an earthquake of seven to eight on the Richter scale-it could occur. And we have to be aware that advances in genetics make it possible to create designer viruses that could be released, not by change of nature, but by human hands. We need to examine past pandemics to get lessons for the future."

The influenza pandemics of the 20th century-the Spanish flu of 1918, the Asian flu of 1957, and the Hong Kong flu of 1968-altogether claimed more than 600,000 American lives. If effective preventive strategies are not implemented, experts predict the next pandemic could result in 314,000-734,000 hospitalizations, 89,000-207,000 deaths, 18-40 million outpatient clinic visits, and 20-47 million people "sick at home" in this country alone. The projected economic impact is staggering: $70-166 billion.

"The highly infectious nature of influenza viruses, the large numbers of infections in all age groups, the ability of these viruses to precipitate serious medical complications, and their propensity to undergo continuous change pose challenges for controlling epidemic disease," Dr. Cox remarked.

But such disasters can be attenuated, she maintained, if certain conditions are met today. One of these conditions is the surveillance of viral strains to detect and monitor their spread. This is accomplished through the World Health Organization (WHO) global surveillance network.

For example, in 1997 and 1998, a potent new viral strain jumped the host-species barrier in Hong Kong and was transmitted from chickens to humans, causing over 18 infections and six deaths. But the WHO surveillance network detected this virus early and was able to contain and destroy the source, thus preventing widespread illness among humans.

Other means of preventing a flu pandemic include the rapid development and distribution of vaccines, the use of antiviral medications, the development of reliable, rapid diagnostic tests, the availability of adequate emergency medical and communication services, and better education of healthcare professionals and the public. The CDC has developed FluAid, special software that helps healthcare planners calculate the potential burden of a flu pandemic on their healthcare system and to plan accordingly. On the local level, many communities are getting ready, Dr. Cox said.

"In the meantime, we should be working hard to enhance flu vaccine coverage, especially in high-risk minority groups, where coverage levels are low, and in persons younger than 65 who have high-risk conditions," she said.

"We can be almost certain that another pandemic will occur; we just cannot predict when," she concluded. "It is hard to garner the kind of financial support needed for pandemic planning, since it may not even occur in our lifetime, and public officials are somewhat unwilling to provide the necessary resources. But there is a tremendous amount of effort now, and we hope that we will be ready, whenever it does occur."

Current Treatment of Influenza

The flu is virtually a yearly occurrence, having appeared in 20 out of the last 25 years. The best way to avoid becoming a flu victim is by joining 75 million other Americans in getting a flu vaccine this fall.

The flu vaccine is especially important for persons over age 65, individuals who have chronic health conditions, patients undergoing treatment for cancer and other immunocompromising conditions, pregnant women, people who work in the healthcare industry, residents of long-term care facilities, and anyone coming in close contact with people at risk for the flu.

For those who fail to get vaccinated or those who get the flu in spite of it, there are now medications that can help relieve symptoms and shorten the duration of illness. According to Arnold S. Monto, MD, University of Michigan School of Public Health, Ann Arbor, "antivirals" have become a hot topic of research in the past few years.

The newest antivirals-the oral drug oseltamivir (Tamiflu®) and the inhaled drug zanamivir (Relenza®)-seem to be more effective than rimantadine hydrochloride (Flumadine®) and amantadine hydrochloride (Symmetrel®, Amantadine HCl®), which were the first flu medications. Rimantadine hydrochloride and amantadine hydrochloride were effective only against "Type A viruses," whereas many strains of the flu are "Type B," and they could produce side effects.

Oseltamivir and zanamivir, however, cover both types of viruses, shorten the duration and severity of symptoms, and have few side effects. Both drugs are indicated for the treatment of uncomplicated influenza in adults and adolescents age 12 and older, but they are not yet approved for use in children. When used within two days of symptom onset, the drugs reduce the degree and duration of fever, headache, body ache, nasal congestion, cough, sore throat, and other similar symptoms. The duration of symptoms is usually shortened by one to three days, Dr. Monto confirmed.

While these drugs are currently approved for the treatment of the flu, they are also being studied for the prevention of the flu after exposure to the virus. In studies, such treatments have been 67-84 percent effective in preventing flu in college students and 92 percent effective in nursing home residents. As "seasonal prophylaxis," these drugs could conceivably be given for seven to ten days for people living with those who come down with the flu. "Typically you would vaccinate people before flu season and give these antivirals as prophylaxis [as needed] during flu season," he said. "This is the evolving story. There is much work going on, so stay tuned."