Doctors in the US must be more alert
than ever for both new and re-emerging infectious diseases, military researchers
said at an annual Preventive Medicine Conference here on Saturday, which was
sponsored by the Centers for Disease Control and Prevention (CDC).
"There are no more geographic limits to infectious diseases," said Dr.
Russell Eggert, of the military's Office for Prevention and Health Services
Assessment. Troops are stationed all over the world and may encounter these
infectious diseases and bring them home, according to Eggert.
"Diseases can now be transported from Africa and Asia to the US by way of
commercial airlines," he said. "And it's not just people who can carry them.
It's rodents and insects inadvertently imported into this country."
Dr. Gregory Gray, a medical epidemiologist for the US Department of Defense,
said that tracking disease in military personnel can predict epidemics in the US
population at large.
New strains of HIV imported into the US have been traced to military
personnel. A particularly deadly strain of influenza that caused millions of
deaths around the world in 1918 was spread to the US population by troops
returning from World War I.
Surveillance of military troops has taken on new importance with the
emergence of drug-resistant microbes, the researchers report.
The Defense Department, the CDC, and the World Health Organization are
working to improve surveillance of emerging infections at military bases around
the world. Adenovirus (a respiratory virus), mycoplasma pneumonia (a contagious
disease of children and young adults), influenza, and drug-resistant
staphylococcus and streptococcus (common disease-causing bacteria) are
especially important to watch, said Gray. The effectiveness of vaccines and
prophylactic (disease-preventing) antibiotics are also under study.
Despite preventive efforts, epidemics still plague the military. Respiratory
illness is the number one threat, the investigators noted.
In 1996, 77% of the freshman class at the US Merchant Marine Academy was
diagnosed with acute mycoplasma pneumonia. Four years ago, the USS Arkansas
sailed into San Diego harbor with the commanding officer and most of the crew
incapacitated by influenza. Ninety-nine percent of the crew had received the flu
vaccine, but they encountered a new strain in the South Pacific -- and they
brought it back to the US.
"Military populations, by their nature, aggregate people from around the
country," Gray said. "There's tremendous opportunity for pathogens to be mixed
in this setting, with close contact and person-to-person transmission."
Surveillance should be used to guide preventive action, he commented. In the
1970s, adenovirus was found to cause about 10% of all trainees to be
hospitalized, so a vaccine was developed. It was used for many years, until the
manufacturer recently decided to stop producing it.
"We've lost a vaccine which was very effective, and we're now having a
number of epidemics," Gray warned. "Surveillance systems at crowded recruit
training sites told us what happened as a result.... Adenovirus causes severe
infections, high fevers, and incapacitated trainees. We're now moving to find a
new manufacturer for an adenovirus vaccine, but it will be 4 or 5 years before
we have one."
