A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group

BACKGROUND

The average risk of human immunodeficiency virus (HIV) infection after percutaneous exposure to HIV-infected blood is 0.3 percent, but the factors that influence this risk are not well understood.

METHODS

We conducted a case-control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were those who became seropositive after exposure to HIV, as reported by national surveillance systems in France, Italy, the United Kingdom, and the United States. The controls were health care workers in a prospective surveillance project who were exposed to HIV but did not seroconvert.

RESULTS

Logistic-regression analysis based on 33 case patients and 665 controls showed that significant risk factors for seroconversion were deep injury (odds ratio= 15; 95 percent confidence interval, 6.0 to 41), injury with a device that was visibly contaminated with the source patient's blood (odds ratio= 6.2; 95 percent confidence interval, 2.2 to 21), a procedure involving a needle placed in the source patient's artery or vein (odds ratio=4.3; 95 percent confidence interval, 1.7 to 12), and exposure to a source patient who died of the acquired immunodeficiency syndrome within two months afterward (odds ratio=5.6; 95 percent confidence interval, 2.0 to 16). The case patients were significantly less likely than the controls to have taken zidovudine after the exposure (odds ratio=0.19; 95 percent confidence interval, 0.06 to 0.52).

CONCLUSIONS

The risk of HIV infection after percutaneous exposure increases with a larger volume of blood and, probably, a higher titer of HIV in the source patient's blood. Postexposure prophylaxis with zidovudine appears to be protective.

Duration of time between exposure and seroconversion in healthcare workers with occupationally acquired infection with human immunodeficiency virus

Through December 1994, 41 healthcare workers with a documented seroconversion to human immunodeficiency virus (HIV) in temporal association to an occupational exposure were reported to the Centers for Disease Control and Prevention (CDC). Each tested positive for HIV antibodies within 12 months of the occupational exposure. Two (5%) of the 41 tested negative for HIV antibodies >6 months following the occupational exposure but were seropositive within 12 months of the injury. Both denied any subsequent exposures to HIV after the initial exposure, and in one case genetic sequencing confirmed the source of the infection. Four of the healthcare workers took postexposure zidovudine prophylaxis; each reported an acute retroviral syndrome within 6 weeks of their exposure, and each of the four seroconverted to HIV within 6 months of the exposure. Our data suggest that zidovudine prophylaxis does not delay the development of HIV antibodies beyond 6 months. Because many of the healthcare workers had follow-up testing at irregular intervals, with long periods between tests, it was not possible to define precisely when seroconversion occurred. However, our findings are compatible with previously published estimates that 95% of infected persons will develop HIV antibodies within 6 months of infection.

Surveillance for thrombocytopenia in persons infected with HIV: results from the multistate Adult and Adolescent Spectrum of Disease Project

Thrombocytopenia in persons infected with HIV is prevalent and has numerous causes. To study the occurrence, associations, and effect on survival of thrombocytopenia in HIV-infected persons, we used surveillance data from a longitudinal survey of the medical records of 30,214 HIV-infected patients who received medical care from January 1990 through August 1996 in more than 100 medical clinics in 10 U.S. cities. Thrombocytopenia was defined as a physician diagnosis of thrombocytopenia or a platelet count of < 50,000 platelets/ microliter. Analysis of associations of thrombocytopenia was conducted using logistic regression. In HIV+ patients, the 1-year incidence [corrected] of thrombocytopenia was 8.7% in persons with one or more AIDS-defining opportunistic illnesses (clinical AIDS), 3.1% in patients with a CD4 count < 200 cells/mm3 but not clinical AIDS (immunologic AIDS), and 1.7% in persons without clinical or immunologic AIDS. The incidence of thrombocytopenia was associated with clinical AIDS (adjusted odds ratio [AOR] 2.2; 99% confidence interval [CI] 1.7-3.0), immunologic AIDS (AOR 1.5, CI 1.0-2.1), history of injecting drug use (AOR 1.4, CI 1.0-1.9), anemia (AOR 5.0, CI 3.8-6.7), lymphoma (AOR 3.7, CI 1.3-10.6), and black race (AOR 0.7, CI 0.5-0.9). After controlling for anemia, clinical AIDS, CD4 count, neutropenia, antiretroviral therapy, and Pneumocystis carinii pneumonia prophylaxis, thrombocytopenia was significantly associated with decreased survival (risk ratio 1.7; 95% CI, 1.6-1.8). Thrombocytopenia in HIV-infected persons is an important clinical condition associated with shorter survival.

Impact of the 1993 expanded AIDS surveillance case definition on reporting of persons without HIV risk information

To evaluate the impact of the 1993 expansion of the acquired immunodeficiency syndrome (AIDS) surveillance definition on reporting of persons with no HIV risk exposure information, we compared persons reported with and without risk in 1992 and 1993. The expanded case definition resulted in a large increase in both the number of persons reported with risk (121% increase) and without risk (167% increase). The changes in demographic characteristics for each group were similar from 1992 to 1993. Persons reported based on immunologic criteria were more likely and persons with pulmonary tuberculosis (PTB) less likely than those meeting the pre-1993 definition criteria to be reported with risk. Many persons with PTB were retrospectively identified from tuberculosis registries that do not systematically include HIV risk information. Ascertainment of risk information continues to be an essential part of AIDS surveillance with >90% of reports including risk exposure.

Toxoplasmic encephalitis in HIV-infected persons: risk factors and trends. The Adult/Adolescent Spectrum of Disease Group

OBJECTIVE

To evaluate the incidence of and risk factors for toxoplasmic encephalitis among HIV-infected persons.

DESIGN

Medical facility-based prospective medical record reviews of consecutive patients.

METHODS

We analysed data collected from January 1990 through August 1995 in more than 90 inpatient and outpatient medical facilities in nine US cities. Incidence was calculated as cases per 100 person-years and risk ratios (RR) for annual incidence were calculated using proportional hazards regression while controlling for city, sex, race, age, county of birth, HIV exposure mode, and prior prescription of trimethoprim-sulfamethoxazole (TMP-SMX).

RESULTS

The incidence of TE was 4.0 cases per 100 person-years among persons with a CD4+ T-lymphocyte count of < 100 x 10(6)/l. In multivariate analysis, among the nine cities the annual incidence of toxoplasmosis was significantly lower only in Denver [RR, 0.3; 95% confidence interval (CI), 0.1-0.7; referent city, Seattle]. Persons prescribed TMP-SMX were half as likely to develop toxoplasmic encephalitis as those who were not (RR, 0.5; 95% CI, 0.4-0.7). Of the 4173 persons with AIDS (1987 Centers for Disease Control and Prevention definition) who died during the study period, 267 (6.4%) had toxoplasmic encephalitis in the course of HIV disease.

CONCLUSIONS

Toxoplasmic encephalitis in HIV-infected persons varies by geographic area in the United States. TMP-SMX reduces the risk for toxoplasmic encephalitis.

Preventing bloodborne pathogen transmission from health-care workers to patients. The CDC perspective

The development of recommendations to manage the risk of bloodborne pathogen transmission from health-care workers to patients during invasive procedures has been difficult, primarily because of the limitations of available scientific data. Ultimately, both health-care workers and patients will be protected best by compliance with infection control precautions and by development of new instruments, protective equipment, and techniques that reduce the likelihood of intraoperative blood exposure without adversely affecting patient care.

Occupational risk of infection with human immunodeficiency virus

The risk of HIV infection in surgical settings is a composite of overlapping risks related to the local prevalence of HIV, the route of exposure to HIV-infected blood, and the susceptibility of the worker. Studies continue to suggest that the risk of blood contact, including percutaneous injuries, remains appreciable. Prevention of such exposures in the operating and delivery room by adoption of safer instruments, work practices, and techniques and by the consistent use of appropriate personnel protective equipment must be viewed as a priority.

National trends in the concurrence of tuberculosis and acquired immunodeficiency syndrome

BACKGROUND

Elucidation of the relationship between tuberculosis (TB) and the acquired immunodeficiency syndrome (AIDS) is needed to help predict the future course of these two epidemics. We examined nationwide trends in TB and AIDS occurring in the same individual.

METHODS

Health departments in the 50 states, District of Columbia, Puerto Rico, and Guam matched their TB and AIDS case registries to determine the number of persons diagnosed with both TB and AIDS. The number of AIDS cases, TB cases, AIDS cases that matched with a TB case on the TB registry, and TB cases that matched with an AIDS case on the AIDS registry were reported to the Centers for Disease Control and Prevention, Atlanta, Ga. Data were analyzed for the period from 1981 through 1991. The number of matched TB-AIDS cases was compared with a modeled estimate of excess TB cases during the period from 1985 through 1990.

RESULTS

From 1981 through 1991 there were 11,299 AIDS cases that matched with a TB case on the TB registry, representing 5.1% (geographic variation, 0% to 9.3%) of AIDS cases. The TB cases that matched with an AIDS case on the AIDS registry represent 4.3% (geographic variation, 0% to 15.1%) of TB cases from 1981 through 1991. Since 1981, matched TB and AIDS cases increased yearly through 1990. When examined by year of AIDS report, the percentage of AIDS cases that matched with a TB case increased from 1981 to 1982 (1.9% to 5.1%), remained fairly constant from 1983 through 1987 (range, 4.0% to 4.7%), increased in 1988 (5.4%) after extrapulmonary TB was added to the AIDS case definition, and increased slightly through 1990 (5.8%). When examined by year of TB report, the percentage of TB cases that matched with an AIDS case increased steadily from 1981 through 1990 (0.1% to 9.5%). The calculated fraction of excess TB cases during the period from 1985 through 1990 that could be accounted for by identified TB-AIDS cases was 30%.

CONCLUSION

The risk of TB or AIDS among persons already diagnosed with one disease is much higher than among the general population. The percentage of persons with TB who are also diagnosed with AIDS has been increasing rapidly. Human immunodeficiency virus-induced immunosuppression is an important contributor to the TB epidemic and probably accounts for a minimum of 30% of excess TB cases during the period from 1985 through 1990.

Coccidioidomycosis among persons with AIDS in the United States

Adults and adolescents diagnosed with AIDS from 1987 through 1992 residing in counties endemic (selected counties in California, Arizona, Texas, New Mexico, Nevada, Utah) and not endemic for Coccidioides immitis were assessed to determine the frequency of and risk factors for disseminated coccidioidomycosis. Of 602 AIDS patients reported with disseminated coccidioidomycosis, 323 (1.1% of AIDS patients) resided in C. immitis-endemic counties and 279 (0.1% of AIDS patients) resided in C. immitis-nonendemic counties in 35 states. In multivariate analysis, patients with disseminated coccidioidomycosis in C. immitis-endemic counties were more likely to be injecting drug users (odds ratio, 2.6; 95% confidence interval, 1.8-3.7) and blood product recipients (odds ratio, 3.6; 95% confidence interval, 1.5-8.3) than to be homosexual or bisexual men. Of patients with disseminated coccidioidomycosis, 63% had died by 1 year after AIDS diagnosis. Disseminated coccidioidomycosis should be considered in AIDS patients in all areas of the United States.

The 1990 Florida dental investigation. The press and the science

Since human immunodeficiency virus (HIV) transmission from a dentist to six of his patients was first reported in 1990 by the Florida Department of Health and Rehabilitative Services and the Centers for Disease Control and Prevention, controversy and speculation have surrounded the investigation of that case. This controversy has been fueled by the inability to determine exactly how the transmissions occurred. Many theories have appeared in the media and have led to confusion and uncertainty about the facts of this investigation. Recently, a magazine article and a newspaper article, as well as a segment on the television newsmagazine "60 Minutes," presented information that was largely based on findings by investigators hired as part of private litigation and that cast doubt on the conclusion that the patients had been infected by the dentist. However, these reports omitted pertinent epidemiologic and laboratory evidence that shows that no other sources of HIV infection could be documented for the six dental patients. The scientific evidence indicates that the Florida dentist transmitted HIV to six of his patients.

Gender differences in reported AIDS-indicative diagnoses

To compare AIDS-defining conditions in women and men, US adult AIDS cases diagnosed between January 1988 and June 1991 and reported to the Centers for Disease Control and Prevention through June 1992 were examined. For most AIDS-defining conditions, the prevalence was similar for women and men when differences in race/ethnicity and mode of transmission were accounted for. Pneumocystis carinii pneumonia was the most prevalent condition (> 50%) regardless of gender, race/ethnicity, or mode of transmission. By logistic regression analysis, among injection drug users, conditions reported significantly more frequently in women than in men include esophageal candidiasis (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.40-1.62), herpes simplex virus (HSV) disease (OR, 1.68; CI, 1.46-1.94), and cytomegalovirus (CMV) disease (OR, 1.43; CI, 1.18-1.73). More knowledge of the interrelationships in women between HIV infection and secondary opportunistic infections, including candidiasis and sexually transmitted disease (e.g., HSV and CMV) is needed.

Increasing frequency of heterosexually transmitted AIDS in southern Florida: artifact or reality?

Acquired immunodeficiency syndrome (AIDS) cases reported as the result of heterosexual contact have been increasing in the United States, with Florida reporting a disproportionate number. We investigated 168 such AIDS cases from southern Florida. After follow-up, 50 (30%) patients were reclassified into other transmission categories. The data suggest that the increased rate of heterosexually acquired AIDS cases reported from southern Florida was partially related to misclassification of risk.

Mammography use and outcomes in a community. The Greater Lansing Area Mammography Study

BACKGROUND

Mammography is widely known to reduce morbidity and mortality from breast cancer, but a population-based assessment of mammography use and follow-up of mammography findings has not been reported previously.

METHODS

An observational, population-based, follow-up study was conducted of all women having mammograms in the Greater Lansing, Michigan, metropolitan area, between June 1987 and June 1988. A total of 17,811 Greater Lansing women participated. The adherence of women to mammography screening guidelines was estimated, and mammography's utility to detect breast cancer was assessed through follow-up review of breast biopsy results.

RESULTS

Thirty-seven percent of the expected number of women 35 years of age and older had mammograms. Adherence to screening guidelines declined with age, and less than 5% (302 of 6700) of women 55 years of age and older reporting having annual mammograms. Seventy-six percent of women reported that their physicians prompted the examination. The predictive value of a positive mammogram was 21.9% for women without symptoms and 32.4% for women with symptoms. Mammography's sensitivity and specificity for breast cancer detection were 71% and 98%, respectively.

CONCLUSIONS

The study highlights the need to target mammography to women 50 years of age and older, underscores the importance of physicians in promoting mammography, and demonstrates the analytic value and limitation of mammography in clinical decision-making.

Molecular epidemiology of HIV transmission in a dental practice

Human immunodeficiency virus type 1 (HIV-1) transmission from infected patients to health-care workers has been well documented, but transmission from an infected health-care worker to a patient has not been reported. After identification of an acquired immunodeficiency syndrome (AIDS) patient who had no known risk factors for HIV infection but who had undergone an invasive procedure performed by a dentist with AIDS, six other patients of this dentist were found to be HIV-infected. Molecular biologic studies were conducted to complement the epidemiologic investigation. Portions of the HIV proviral envelope gene from each of the seven patients, the dentist, and 35 HIV-infected persons from the local geographic area were amplified by polymerase chain reaction and sequenced. Three separate comparative genetic analyses--genetic distance measurements, phylogenetic tree analysis, and amino acid signature pattern analysis--showed that the viruses from the dentist and five dental patients were closely related. These data, together with the epidemiologic investigation, indicated that these patients became infected with HIV while receiving care from a dentist with AIDS.

Health care workers with AIDS. National surveillance update

OBJECTIVES

To characterize health care workers with the acquired immunodeficiency syndrome (AIDS) in the United States and to evaluate the role of occupational transmission of the human immunodeficiency virus (HIV).

DATA SOURCE

National AIDS surveillance data.

METHODS

Health care workers with AIDS are reported to the Centers for Disease Control by state and local health departments. Health care workers who do not report a nonoccupational risk for HIV infection are termed undetermined risk cases and are investigated by health departments using a standard protocol.

RESULTS

Through June 30, 1990, there were 5425 cases of AIDS in health care workers reported in the United States. Three of these workers developed AIDS following well-documented occupational exposure to HIV-infected blood. Of the 539 health care workers initially reported without a nonoccupational risk, follow-up investigations were completed for 303. Nonoccupational risk factors were established for 237 (78.2%) of the 303 investigated health care workers; 66 workers (21.8%) remained in the undetermined category. Follow-up information was incomplete for 236 health care workers who also remained in the undetermined category, resulting in 5120 health care workers (94.4%) with AIDS with nonoccupational risks for HIV infection. Overall, health care workers were more likely than non-health care workers with AIDS to have an undetermined risk for HIV infection (5.6% vs 2.8%; P less than .001). While many of the 66 investigated health care workers had jobs involving contact with patients and/or potential contact with blood, none reported percutaneous, mucous membrane, or cutaneous exposures to blood or body fluids known to be infected with HIV.

CONCLUSION

Surveillance data suggest that most health care workers with AIDS acquired their HIV infection through a nonoccupational route.

Transmission of HIV from infected health-care workers to patients

The five patients of the Florida dentist remain the only cases in which HIV transmission from an infected health-care worker to patients during invasive procedures had been reported by 1991. In this instance, neither the precise mode of HIV transmission to these patients nor the reasons for transmission to multiple patients are known. However, even in the HBV outbreaks that have been investigated, the causes of increased transmissibility by the health-care worker are not always clear, and may include variations in the procedures performed, surgical or dental techniques used, infection control precautions taken, titer of the infecting agent, and the susceptibility of the patients to infection. The investigation of the Florida dentist's practice is ongoing. Additional studies of the patients of other infected health-care workers are being conducted in an attempt to answer some of the remaining questions about the risk and circumstances which allow the transmission of HIV from infected health-care workers to patients.

Acquired immunodeficiency syndrome and extrapulmonary tuberculosis in the United States

Of 48,712 acquired immunodeficiency syndrome (AIDS) cases reported to the Centers for Disease Control from October 1987 through March 1989, 1239 (2.5%) were diagnosed with extrapulmonary tuberculosis. Extrapulmonary tuberculosis was diagnosed in 1013 (2.3%) of the US-born persons with AIDS, compared with 26 (8%) of the Mexican-born, 82 (13%) of the Haitian-born, and 4 (1%) of the Cuban-born. Patients with AIDS with and without extrapulmonary tuberculosis were similar in age, except that extrapulmonary tuberculosis was relatively rare in patients with AIDS under the age 10. Compared with white homosexual/bisexual men, black race (odds ratio, 2.7), intravenous drug use (odds ratio, 2.0), heterosexual AIDS transmission category (odds ratio, 1.9), and Hispanic ethnicity (odds ratio, 1.6) were independently associated with extrapulmonary tuberculosis. In 1988, extrapulmonary tuberculosis in persons known to be human immunodeficiency virus seropositive represented 21% of national extrapulmonary tuberculosis morbidity.

Lyme disease surveillance in the United States, 1983-1986

During 1983-1986, 5,016 cases of Lyme disease were reported to the Centers for Disease Control. Cases were acquired in 31 states; however, 86% of the cases were acquired in seven states: Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Wisconsin, and Minnesota. For 63% of patients the disease began in summer; 52% recalled a tick bite. Erythema chronicum migrans (ECM) occurred in 91% of the patients; arthritis, in 57%; neurologic complications, in 18%; and cardiac manifestations, in 10%. When serum samples were obtained greater than or equal to 21 days after onset of symptoms, 14% (6 of 42) with ECM alone and 19% (17 of 89) with complicated Lyme disease (ECM plus organ-system involvement) had positive serologic tests. Antimicrobial therapy did not appear to affect serologic response. Lyme disease is now the most commonly reported tick-borne illness in the United States and has been reported from 32 states since 1980. Physicians nationwide need to be familiar with the protean signs and symptoms associated with Lyme disease and with the limitations of current serologic techniques in diagnosing early illness.

Association of sporadic listeriosis with consumption of uncooked hot dogs and undercooked chicken

In 1986-87 the Centers for Disease Control conducted an active population-based survey of Listeria monocytogenes infections in six regions of the United States. Listeriosis was reported in 154 patients: one-third of cases were perinatal and the remaining two-thirds occurred in the elderly and immunosuppressed. 28% of cases were fatal. 82 cases and 239 controls matched for age and underlying disease were enrolled in a study of risk factors for listeriosis. Cases were significantly more likely than controls to have eaten uncooked hot dogs or undercooked chicken, with 20% of the overall risk of listeriosis attributable to consumption of these foods. No other risk factors were identified.

The geographic distribution of Lyme disease in the United States

In 1982, national surveillance for Lyme disease was established by the Centers for Disease Control to monitor trends and determine endemic geographic areas. Initially, the endemic areas corresponded to the known distribution of Ixodes dammini, a five-state area of the northeastern seaboard (New York, New Jersey, Connecticut, Rhode Island, and Massachusetts) and Wisconsin and Minnesota. Increasing numbers of cases have been reported outside these areas, however, 86% of the provisional 5731 cases reported to CDC were acquired in these seven states. The number of reported cases increased from 491 in 1982 to approximately 1500 per year in 1984-1986, making Lyme disease the most commonly reported tick-borne illness in the United States. The apparently widening distribution of Lyme disease indicates that physicians in all regions of the country should be familiar with its signs and symptoms. Investigations of the vector in areas endemic for Lyme disease where Ixodes ticks are not found are warranted.

Listeriosis in the United States: 1980-1982

The magnitude of the public health problem associated with Listeria monocytogenes in the United States has been unknown, and the route of transmission is largely undetermined. Investigations of recent outbreaks, however, have shown that the infection can be foodborne. We estimated the expected frequency of sporadic listeriosis based on hospital discharge data from the Professional Activity Study of the Commission on Professional and Hospital Activities for the years 1980 through 1982. The incidence of listeriosis was 3.6 per million population per year, with an estimated 800 cases occurring in the United States each year. Attack rates were highest in neonates and in those aged 70 years and older (568 and 11 per million population per year, respectively). Overall mortality was 19.1%, with mortality rates increasing with advancing age. We estimated that listeriosis accounts for at least 150 deaths in the United States per year (fetal mortality not included). Throughout the nation, no marked regional differences in the incidence of the disease were apparent. We were able to identify three time-space clusters, which suggests the possibility that a portion of sporadic cases may, in fact, be previously unrecognized common-source clusters.

Combined plasmid and peptide analysis of clinical and environmental Legionella pneumophila strains associated with a small cluster of Legionnaires' disease cases

Plasmid and peptide analysis was used to characterize Legionella pneumophila strains isolated in the study of a small cluster of cases in hospitalized patients. The isolates from the Denver Veterans' Administration Medical Center could be clearly separated into three groups. Two of the three clinical isolates were found to be plasmidless, as were five of 19 environmental isolates. The patient isolates had plasmid and peptide profiles which were identical to the showerhead isolates to which each patient was exposed. Thus, the data suggest that the patients acquired their disease strains from environmental sites in their particular hospital wing, and that each wing of the building had its own unique flora of Legionella strains. The results also confirm the usefulness of using both these techniques when tracing transmission patterns of nosocomial disease.

Role of stagnation and obstruction of water flow in isolation of Legionella pneumophila from hospital plumbing

The stagnation of water in two of four hospital hot-water storage tanks found to contain Legionella pneumophila was reduced by keeping the two tanks continually on-line for 1 year. L. pneumophila colony counts in these two tanks fell quickly to low levels, whereas the organisms persisted in the two tanks that were not in use. L. pneumophila continued to be isolated from 50 to 100% of the hospital showerheads which were sampled during this period. We also examined aerators and other hospital faucet fixtures which obstruct water flow. L. pneumophila was isolated from 22 of 30 faucet aerators and 2 of 16 vacuum breakers but not from 26 nonobstructed faucets or 6 backflow preventers. Over a 7-month period, after nine faucet aerators were sterilized, 10 of 60 surveillance cultures revealed L. pneumophila, despite the inability to isolate the organism from the potable-water tanks in use. These data suggest that prevention of stagnation in hot-water tanks may be effective in reducing L. pneumophila concentrations in potable-water systems serving high-risk populations. We have also shown that faucet aerators, by providing a surface for L. pneumophila to colonize, can become secondary reservoirs for the organism in hospital plumbing.