Emory Report

March 23, 1998

 Volume 50, No. 25

Conference yields abundant
new data on infectious diseases

The International Conference of Emerging Infectious Diseases was held in Atlanta the week of March 9. Emory professors presented papers on several research projects conducted in conjunction with the Centers for Disease Control and Prevention-sponsored Emerging Infection Program.

Bacterial meningitis patients, subtypes evolving
Although the incidence of sporadic outbreaks of bacterial meningitis in the United States has remained steady over the last three decades, a recent survey of cases in metropolitan Atlanta and Georgia has revealed a marked shift in the last eight years in both the age-specific incidence and in the specific subgroups of the disease.

Emory School of Medicine infectious diseases specialists David Stephens and Monica Farley led an eight-county metro-Atlanta survey of cases of meningitis caused by the bacterium Neisseria meningitidis between 1989 and 1996.

In Atlanta 225 cases of invasive bacterial meningitis occurred during the eight-year period. Although the number of cases per year remained fairly constant, the incidence of disease in adults over the age of 17 increased from 29 percent of cases in 1989 to 54 percent in 1996. In contrast, the incidence in children less than 4 years old decreased from 61 percent of cases in 1989 to 46 percent in 1996. Meningitidis serogroup Y was not detected in 1989-90 but in 1995-96 accounted for over 30 percent of cases.

The researchers concluded that this shift in the age-specific and serogroup incidence of bacterial meningitis cases may indicate that a limited number of new, virulent clones of meningitidis are introduced and spread slowly in certain segments of the population. Detecting these changes may improve understanding of bacterial meningitis outbreaks and the ability to prevent them.

Pneumonia increasingly resistant to antibiotics
A seven-state survey of pneumonia cases from July 1996 to June 1997 has identified substantial numbers of samples resistant to one or more of the most commonly used antibiotics. Significant increases were noted in resistance to erythromycin and in multi-drug resistance, the survey found. The laboratory surveillance was conducted at a number of universities and state health departments.

Farley led the Georgia component of the survey. Of 3,701 identified cases of invasive pneumonia, the researchers have tested 2,578 people so far for susceptibility to antibiotics. Overall, 23.9 percent of them were resistant to penicillin, 11.9 percent were resistant to cefotaxime and 14.6 percent were resistant to erythromycin.

These significant increases in drug resistance, the study sponsors concluded, should sound a warning for concerted efforts to promote vaccination and more judicious use of antibiotics to limit the impact and reduce the prevalence of drug-resistant pneumonia.

Camphylobacter most common food-borne illness
A yearlong surveillance of clinical laboratories identified Campylobacter as the most common foodborne pathogen, followed by Salmonella.

The survey was conducted in 1996 in Georgia, California, Oregon, Minnesota and Connecticut, in areas with a combined population of 13.2 million. The Georgia component of the study was led by Molly Bardsley, an investigator with the School of Medicine.

Researchers found 3,359 cases of Campylobacter, with an incidence that varied from 14 cases per 100,000 population in Georgia to 58 per 100,000 in California. Three-hundred twenty-seven patients were hospitalized, and four patients died. Patients stayed in the hospital an average of four days, and most cases occurred in June, July and August.

Generalized to the entire U.S. population, the data indicates that between 37,000 and 154,000 cases of Campylobacter infections occurred in 1996, with more than 30,000 persons of hospitalized.

Geographic, racial variation in yersinia infection
A yearlong surveillance of clinical laboratories in five states, including Georgia, revealed considerable geographic and racial variation in the incidence of Yersinia Enterocolitica infection, an acute infection of the intestinal tract primarily affecting children. Y. enterocolitica (YE) is spread through contaminated food or water, particularly raw pork or pork products, or from infected people or animals.

Conducted in 1996, the study was described at the conference by Emory infectious diseases specialists Susan Ray and Monica Farley. Within the surveillance area, which included Georgia, Minnesota, Oregon, California and Connecticut, researchers identified 149 cases of YE. The infection was much more common among black, Hispanic and Asian populations and in children under 12 months. Although the overall incidence of YE infection was only 0.98 per 100,000, the rates were higher in younger age groups (28.6 per 100,000 in children under 12 months and three per 100,000 in children ages 1 to 6) and in non-whites (3.98 per 100,000 in blacks; 1.68 in Asians, 0.96 in Hispanics and 0.42 in whites). The incidence was highest in black children under 12 months of age (166.5 per 100,000).

Atlanta and metropolitan Hartford, Conn., had the highest incidence of YE infection within the surveyed areas.

-Holly Korschun

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