The CDC's tracking of infectious diseases

Although most of these diseases are not directly related to the practice of dental hygiene, the bloodborne and respiratory diseases are related, and many others are of general concern to all.

Although most of these diseases are not directly related to the practice of dental hygiene, the bloodborne and respiratory diseases are related, and many others are of general concern to all.

The notification process for infectious diseases is one for which regular, frequent, and timely information regarding individual cases is considered necessary for the prevention and control of the disease. Currently, state health departments report the occurrences of 58 diseases for national compilation. Although most of these diseases are not directly related to the practice of dental hygiene, the bloodborne and respiratory diseases are related, and many others are of general concern to all.

Below is a summary of the most current national data (1999) on some infectious diseases (CDC, "Summary of notifiable diseases," United States, 1999. Morbidity and Mortality Weekly Reports 2001; 48 [No. 53]). The thoroughness of the data is influenced by many factors. In some cases, the number reported is most likely accurate since the diseases involve severe clinical illness. In contrast, people with diseases that are clinically mild might not even seek medical care, and the disease would be unreported.

Bloodborne diseases
AIDS: There were 45,104 cases of AIDS reported in 1999. This is compared to 46,521 cases in 1998, 58,492 in 1997, and 66,885 in 1996.
Hepatitis B: The reported cases of acute (symptomatic) hepatitis B have decreased from 21,102 in 1990 to 7,694 in 1999. Remember, most cases of hepatitis B (about 66 percent) are asymptomatic.

Respiratory diseases
Tuberculosis: There were 17,531 cases of TB reported in 1999. This is a 5 percent decrease from 1998 and a 34 percent decrease from 1992.
Hantavirus pulmonary syndrome: A rodent virus that is inhaled by humans causes this disease. It has been emerging since 1993 with a total of 42 probable cases in 1999.

Legionellosis: This disease was first recognized in 1976 and is spread by inhalation/oral contact with contaminated water. It has occurred in fairly steady numbers since 1987, ranging from 1,038 to 1,615 cases each year. The number of reported cases in 1999 was 1,108.

Measles: Only 100 confirmed cases of measles were reported. Of the 100 cases, 33 were imported from outside the United States, and exposure to these cases caused 33 more cases. The source of the remaining 34 cases is unknown.

Pertussis: In 1999, 7,288 cases of pertussis (whooping cough) were reported. Of these, 27 percent occurred in children who were too young to have received all three doses of the vaccine.

Diphtheria: There were no confirmed cases of diphtheria in the United States in 1999. This is great evidence of the effectiveness of vaccination programs.

Intestinal diseases
Hemolytic uremic syndrome: This disease emerged in the early 1990s and is caused by ingesting E. coli O157:H7 from animals. In 1999, 181 cases were reported from 26 states. In the previous year, 17 states reported 119 cases. Eight states still do not list this disease as "notifiable," substantially affecting the data.

Salmonellosis: This usually underreported disease has been occurring at about 41,000 to 46,000 cases per year since 1992, with 40,596 in 1999. In addition, there were 346 cases of the typhoid fever type of salmonella disease reported in 1999.

Cholera: From 1995 through 1999, there have been 53 cases of cholera reported in the United States (six cases in 1999). Of these, 68 percent were acquired outside the country and four more were acquired from contaminated seafood harvested from Gulf Coast waters.

Hepatitis A: In 1999, there were 17,074 cases of hepatitis A reported. This is the lowest number of cases ever reported. There is a vaccine for hepatitis A.

Sexually transmitted diseases
AIDS and hepatitis B are sexually transmitted diseases but were listed above under bloodborne diseases.

Chlamydia trachomatis: In 1999, 656,721 cases of chlamydial genital infection were reported. This rate is the highest reported to the CDC since this disease became part of the notification system in 1995 (when 477,638 cases were reported). Some of this increase is undoubtedly due to the increased ability to diagnose the disease.

Gonorrhea: A total of 360,076 cases of gonorrhea were reported in 1999. This is higher that the three previous years, but some of this is likely due to new diagnostic tests with increased sensitivity.

Syphilis: In 1999, there were 6,657 cases of primary and secondary syphilis reported to the CDC. This is the lowest level since reporting began in 1941.

Other diseases
Tetanus: In 1999, a total of 40 cases of tetanus were reported. Seven cases involved intravenous drug users, and two cases involved children who had never been vaccinated.

Lyme disease: This disease emerged in the early 1990s and is caused by a bacterium transmitted by ticks. In 1999, 16,273 cases were reported. The highest number of cases reported since 1991 was 16,801 in 1998.

Chris Miller, PhD, is professor of oral microbiology and executive associate dean at the Indiana University School of Dentistry.

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