Blood-Borne Disease

by Food and Drug Administration (FDA)

Concern about transmission of AIDS and other blood-borne diseases during medical and dental treatment was heightened recently when a study found that the human immunodeficiency virus (HIV) can survive in dental tools that are not heat-sterilized.

Scientists from the University of Georgia reported in the British medical journal The Lancet last November that they found traces of HIV, the virus that causes AIDS, in dental instruments cleaned with disinfectant. The tools had previously been used to treat a dental patient who had AIDS. The scientists recommended that dental instruments be heat-treated between patient uses to eliminate the risk of transmitting HIV and other blood-borne viruses from one patient to another.

FDA reached the same conclusion last September, two months before the University of Georgia study was published. In a letter to all dentists in the United States, the agency advised that "reusable dental handpieces and related instruments (such as air/water syringes and ultrasonic scalers) be heat sterilized between each patient use. ... Chemical disinfection is not recommended."

Since 1990, when news reports first suggested that HIV could be transmitted from a health-care provider to a patient, federal agencies and medical and dental professional societies have endeavored to do two things: assure patients that the risk of becoming infected with HIV, or another blood-borne disease, while getting medical or dental treatment is extremely small, and introduce additional precautions into health-care practice to further reduce this very small risk.

Health-care providers are at greater risk of blood-borne infections from their patients than the other way around. The national Centers for Disease Control and Prevention, the federal agency responsible for monitoring and controlling infectious disease in the United States, has reported 28 proven cases of HIV transmission from patients to health-care workers since surveillance of occupationally acquired HIV began in 1981. In another 18 cases, such transmission was deemed possible but not proven.

Hepatitis B

Although HIV is the infection people fear most, the hepatitis B virus (HBV) is both more common and more easily transmitted. CDC estimates that about 250,000 Americans become infected with HBV every year. Among them are about 10,000 health-care workers, most of whom are infected because of an injury from a hypodermic needle, or other sharp object, in the workplace.

A safe and effective vaccine, approved by FDA in 1982, prevents HBV infection, but many health-care workers are not vaccinated, and about 250 of them die every year from complications of HBV acquired on the job.

However, since HBV blood testing was introduced in the early 1970s, CDC has reported only about 300 cases of transmission of the virus from a health- care worker to a patient.

"The message to patients is, 'You pose a much greater risk to the clinician than the clinician poses to you.' That is scientifically supportable," says Tom Arrowsmith-Lowe, D.D.S., who is AIDS coordinator and deputy director of the Office of Health Affairs in FDA's Center for Devices and Radiological Health (CDRH).

Measures that protect the clinician also protect the patient, adds Arrowsmith-Lowe. "If we reduce the risk of the clinician becoming infected, we also reduce the risk of the clinician transmitting an infection to anybody else."

HBV and HIV are spread primarily through blood and through sexual activity. An infected woman can also transmit the virus to her fetus or newborn baby before or during delivery, or through breast milk.

Mucous membranes — the moist linings of the mouth, sinuses, and body cavities such as the abdominal tract — are also a portal of entry for infection. A blood-borne infection may be transmitted by cross-contamination- -using an improperly sterilized or disinfected device to treat an uninfected patient after treating an infected one.

Needlesticks

The most frequent cause of blood-borne infections in health-care settings is a "needlestick" — an injury with a needle or other sharp device. No one knows for sure how many such injuries occur because they often go unreported.

"Estimates range in the neighborhood of 800,000 needlesticks a year happening to health-care workers," says Arrowsmith-Lowe.

Since 1987, CDC has recommended the use of "universal precautions" to prevent the spread of blood-borne infections in health-care settings (see accompanying article, "Universal Precautions"). However, studies have shown that, even when universal precautions are fully observed, they prevent only one out of three needlestick injuries because gloves and other barriers are not impervious to sharp objects.

That is a matter of great concern to FDA, says Arrowsmith-Lowe. The devices involved in needlestick injuries — such as syringes and intravenous (IV) equipment — are regulated by the agency.

"This is a public health problem related to the use of a regulated product. It's clear that more needs to be done than just say, 'Be careful.' The obvious next step is to start looking at some ways to eliminate the problem.

"For example, when is the use of a 'sharp' [a needle or other sharp instrument] essential? To penetrate the skin. Well, if that's not the intended use of the 'sharp', perhaps you shouldn't be using one."

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.