Pneumonic and nonpneumonic forms of legionellosis. The result of a common-source exposure to Legionella pneumophila.

Two male maintenance workers contracted legionellosis while cleaning the interior of a cooling tower contaminated with Legionella pneumophila. In one man severe, life-threatening Legionnaires' disease developed, whereas the other experienced a comparatively mild, self-limiting illness that was consistent with previous descriptions of cases of Pontiac fever. This report represents the first documentation of the development of both of these syndromes following exposure to a common source of the organism. The implications of this observation for the pathogenetic mechanisms that underly the different clinical manifestations of legionellosis are discussed.

Human immunodeficiency virus infection in health care workers. A method for estimating individual occupational risk.

Physicians and other health care workers are concerned about their occupational risk of acquiring human immunodeficiency virus infection. We have developed an approach that can help health care workers estimate their cumulative risk of infection with human immunodeficiency virus. Illustrations are used to develop a score that reflects an individual's occupational exposures and social behavior. This score is then translated into the probability that the worker is infected.

Vinyl versus latex gloves as barriers to transmission of viruses in the health care setting.

One type of vinyl and seven types of latex gloves without visual defects were tested with respect to their barrier function against high concentrations of three viruses of varying size: herpes simplex virus type 1 (HSV-1, 180 nm), human immunodeficiency virus type 1 (HIV-1, 100 nm), and echovirus type 9 (Echo 9, 25 nm). Viral suspensions of HSV-1 (10(8) TCD50/ml), HIV-1 (10(5) TCD50/ml), and echovirus type 9 (10(7.5)TCD 50/ml) were placed in an inverted glove finger immersed in media and maintained for 3 h at room temperature with sampling performed from outside the glove at 10 min, 30 min, 1 h, 2 h, and 3 h. No cytopathic effect (CPE) was identified after inoculation onto Vero cells or RhMK cells for HSV-1 and Echo 9, respectively, and reverse transcriptase activity was not detected in Hut 78 cells after inoculation of HIV-1 during any of the time intervals. Stretching of a glove finger for 18 h with repetition of the procedure with Echo 9 revealed no CPE. We conclude that under these experimental conditions, intact gloves act as effective barriers to the transmission of viral particles, including HIV in the health care setting.

Airborne rabies encephalitis: demonstration of rabies virus in the human central nervous system.

A veterinarian contracted rabies in the course of laboratory work with homogenates of rabid goat brain. Epidemiologic study determined a respiratory mode of transmission. After a fulminant encephalitic illness, formed rabies virions were identified in the synaptic zones of the olfactory glomeruli. Identification, isolation, experimental disease production, and tissue cytopathic effects of virus recovered from the brain fulfilled Koch's postulates in this unusual instance of virus disease of the nervous system.

Nosocomial transmission of tuberculosis from unsuspected disease.

Tuberculosis remains an occupational hazard for hospital employees. A case of acute generalized tuberculosis occurring in a patient with a malignancy who had received corticosteroids was undetected during life and during a gross autopsy examination. Histologic examination of tissue performed one month later was necessary to establish the diagnosis. Of susceptible hospital staff members who were exposed to the index case, infection developed in nine of 56 (16 percent) compared with three of 333 (0.9 percent) unexposed personnel with similar risk but no known exposure (p less than 0.001). This was a 17.8-fold increase in the infection rate for the exposed group. Three employees infected had evidence of active disease: two had pleural effusions and one had cavitary pulmonary infiltrates; six were asymptomatic. The high rate of infection was associated with inadequate air ventilation and exposure to uncontained infectious aerosol. Preventive therapy with isoniazid, high-change-ventilating systems, ultraviolet radiation, and primary barrier systems are recommended methods to reduce the infection risk.

Bat-associated histoplasmosis in Maryland bridge workers.

An epidemic of acute prolonged febrile respiratory disease affecting nine of 19 workers on a Maryland State bridge maintenance crew was diagnosed as histoplasmosis by serologic testing in all and by isolation of the organism in one. In our investigation, it was revealed that work on a particular bridge was associated with disease. Culture of bat guano from the site two months later revealed H. capsulatum. Four previously uninfected epidemiologic investigators also became ill with histoplasmosis following collection of soil and bat guano. This outbreak reveals that bats and bat guano are a source of histoplasmosis, suggests that only brief exposure is necessary for acute infection and reemphasizes that histoplasmosis is not confined to the midwestern states.

Nosocomial hepatitis A transmission by an adult patient with diarrhea.

Hepatitis A occurred in five registered nurses, a licensed practical nurse, and a recently discharged patient at a community hospital; one of these seven was asymptomatic. All had been exposed to a woman with confirmed hepatitis A who had undergone elective cholecystectomy and who had had vomiting, diarrhea, and fecal incontinence during the eight days before onset of jaundice. Of the 107 hospital workers identified as having at least some exposure to the source patient, 58 (54.2 percent) had no pre-existing antibody to hepatitis A virus (anti-HAV) and were considered susceptible. Six persons, including the five clinically ill registered nurses, had IgM-specific anti-HAV. The infection attack rate was 5.6 percent for all exposed hospital workers but 10.3 percent for the 58 who were serosusceptible. Risk of infection was highest for persons with documented or probable contact with the source patient and for registered nurses. Among hospital personnel, the prevalence of anti-HAV increased with age but varied inversely with socioeconomic status. Hospital personnel and patients may be at risk for hepatitis A infection when exposed to patients who are in the prodromal stage of hepatitis A. Vomiting, diarrhea, and fecal incontinence may increase the risk of transmission.

Risk of cytomegalovirus infection among educators and health care personnel serving disabled children.

To determine the risk of cytomegalovirus (CMV) infection for personnel who provide services to young disabled children, we studied the prevalence of CMV infection among such children and determined the seroconversion rate among exposed personnel. The prevalence of CMV excretion was 9.8% among children aged 0 to 5 years in a University-based outpatient program vs. 3.3% in 3- to 5-year-old children attending community-based preschools. Initial serologic studies of personnel demonstrated no differences in CMV seropositivity rates among staff with occupational child contact vs. staff without such contact (40% (40 of 99) vs. 34% (26 of 77] (P = 0.37). However, 21 of the 31 personnel 40 years and older who had occupational child contact were seropositive vs. 10 of 26 personnel of comparable age who had no occupational child contact (P = 0.026). During a 1-year follow-up, 2 of 86 (2.3%) susceptible personnel seroconverted. Rates were 4.4% (2 of 45) among staff with occupational child contact vs. no seroconversions (0 of 41) for those without (P = 0.27). These results indicate that the risk of CMV infection for personnel who work with disabled children is low. However, we cannot exclude the possibility that there may be a small cumulative risk of CMV infection that may exceed that of adults who do not have occupational contact with children.

Measles (rubeola) infection in a hospital setting.

Although acquisition of measles infection in medical facilities is well documented, hospital outbreaks have been rare. During a recent community measles epidemic, one patient and four employees of the Mary Hitchcock Memorial Hospital developed the disease. Two of the employees were born before 1956, the year recommended by the Centers for Disease Control as an appropriate cutoff year for routine measles vaccination. Screening of 456 hospital employees for measles immunity demonstrated a 5% incidence of susceptibility in 135 individuals born between 1950 and 1956. This experience demonstrates the significant potential for the spread of a community measles outbreak into the hospital setting. Because of the high transmissibility of this disease and its potentially serious consequences in hospitalized patients, we suggest that all hospital employees born after 1950 who have significant patient contact should have documented immunity against measles.

Factors associated with cytomegalovirus excretion in hospitalized children.

Hospital employees, especially pregnant women, have expressed concern over exposure to patients excreting cytomegalovirus (CMV). However, the vast majority of CMV excreters are asymptomatic and are not identified while hospitalized. As part of a 2-year, longitudinal study of nosocomial transmission of CMV in a children's hospital, the prevalence rates of CMV excretion by patients in different areas of the hospital were determined. The average prevalence rates were neonatal intensive care unit, 5.7%; intermediate care nurseries, 4%; premature nursery, 6.3%; normal newborn nursery, 3%; hematology-oncology, 3.7%; pediatric intensive care unit, 3.6%; general pediatric ward, 6%; and a chronic care unit, 16%. During this 2-year study, 315 patients admitted to the chronic care unit were investigated to determine which clinical factors might help predict children likely to excrete CMV. With the use of multiple logistic regression analysis of variables, prior excretion of CMV, multiple hospital admissions, female sex, and Hispanic ethnic background were correlated with excretion. Although not identified as significant factors, a history of premature, bronchopulmonary dysplasia and positive results of CMV serologic studies were more commonly associated with excretion. CMV excretion occurred in all areas within a children's hospital, and certain factors were associated with excretion, but it is unlikely that this information could adequately identify "safe" patients or safe areas within a hospital. This study reinforces the need to follow proper precautions with all patients.

Cytomegalovirus infections: occupational risk for health professionals.

Health care personnel are becoming increasingly aware of potential hazards associated with caring for patients with contagious diseases. The cytomegalovirus is of special concern, because infection with this virus in a pregnant female employee could be associated with significant neurologic injury in her fetus. Nosocomial transmission from patient to health care worker has not been documented. A review of cytomegalovirus excretion in hospitalized patients and prospective evaluations of primary infection in hospital personnel do not support frequent occurrence of cytomegalovirus infection despite ample opportunity for exposure. Adherence to proper isolation techniques should be adequate to prevent nosocomial transmission of the cytomegalovirus.

Prevention of human immunodeficiency virus infection: our responsibilities as health care professionals.

The prevention of human immunodeficiency virus (HIV) infection is a major responsibility of health care professionals. This paper deals with the virus itself--its history and prevalent modes of transmission. The low risk of HIV transmission in health care settings and through casual contact is emphasized. A discussion of prevalence rates in the United States is followed by an explanation of methods to prevent HIV infection through testing, counseling, limiting sexual transmission, screening of blood and blood products, reducing risk among intravenous drug users, avoiding perinatal transmission, practicing safety measures in health care settings, and implementing educational goals.

Risk of hepatitis B infection among medical and paramedical workers in a general hospital in Zimbabwe.

To evaluate the addition of hepatitis vaccine to health schemes for hospital workers in Zimbabwe we undertook a cross sectional study of viral markers in 226 hospital workers and compared the results with 97 volunteer blood donor controls. One hundred and thirty one (58%) hospital workers had hepatitis markers compared with 45 (46%) of the donor group. Racial group was the strongest risk factor. Blacks were 70% more likely to have markers than whites. This racial difference was not explained by job status or patient contact. Our data suggest that work in a district general hospital does not constitute a clinically important hazard for hepatitis B infection. Because of the high cost of the vaccine, additional studies to assess the risk of hospital work in other settings in Zimbabwe are required before health policy regarding routine hepatitis B vaccination is determined.

Airborne spread of brucellosis.

review of epidemic and endemic brucellosis at six abattoirs demonstrates a correlation between case distribution and flow of air from the kill department (stage II) to other areas within an abattoir. Air from the kill department disseminated to nearby departments led to abnormally high brucellosis attack rates for persons who worked in these areas at two abattoirs. Complete physical separation or maintaining negative air pressure in the kill department was associated with reduced risk for workers in other areas at four abattoirs. Cases in persons who had exposure to kill department air but no contact with animal tissues provide strong evidence for airborne transmission of infection. Brucellosis is also contracted through skin contact with infectious animal tissues, but this route of transmission appears less important than formerly believed.

Rubella exposure in an obstetric clinic.

Despite a massive national rubella immunization program, rubella infection remains a public health problem. When a nurse employed in a hospital-based obstetric clinic became ill with rubella, a crisis was precipitated. The hospital staff implemented a plan to inform the exposed 151 patients and 44 employees of the potential danger to themselves and their fetuses. To identify persons at risk, a program of rubella antibody testing of contacts was instituted. In 3 distinct attempts to obtain blood specimens, patient compliance rates fell progressively from 79 to 14%. One additional infected employee was detected. A list of recommendations designed to prevent or lessen the impact of future rubella exposures in hospitals is presented.

Occupational health issues for providers of care to patients with HIV infection.

The perception that HIV is a highly contagious nosocomial pathogen persists despite a great deal of evidence to the contrary. However, health care workers are at a low but finite risk of occupational infection with the virus, particularly through accidental needle-stick inoculations with infected blood. Universal blood and body fluid precautions minimize the risk of nosocomial transmission of a variety of pathogens, including HIV, and should be routinely employed by all health care workers for all patients.

Leptospirosis in zoo workers associated with bears.

Leptospirosis due to Leptospira interrogans serovar icterohaemorrhagiae was diagnosed in two zoo animal keepers. The implicated source of infection was bear cubs that had microscopic agglutination antibody titers to leptospires of the Icterohaemorrhagiae serogroup.

A case of human strongyloidosis apparently contracted from asymptomatic colony dogs.

A 63-year-old, white, animal caretaker suffered intermittent abdominal pain and diarrhea of 3 weeks duration. Hematological findings included leukocytosis (18,600) with eosinophilia (73%). Fecal examination revealed Stongyloides rhabditiform larvae which on culture yielded a preponderance of filariform larvae and a few free-living adults. Thiabendazole therapy resulted in rapid recovery. Epidemiological investigation yielded no history of previous Strongyloides infection or exposure; his wife and pet dog were not infected, but about one-third of the dogs in the colony under his care were found to be discharging Stongyloides rhaditiform larvae in their feces. Strongyloides infection was successfully trasmitted to specific pathogen-free pups using filariform larvae derived both from the human case and from the dog colony. Specimens recovered from one pup infected with filariform larvae of human origin were identified as Strongyloides stercoralis.

Primary inoculation tuberculosis of the skin. Prosector's paronychia,.

Subsequent to an autopsy of a tuberculotic cadaver, a pathology resident presented with a painless paronychia and axillary adenopathy after surgical incision and broad-spectrum antibiotics had failed to improve his condition. Demonstration by culture of Mycobacterium tuberculosis var hominis, positive smears, and findings of acid-fast organisms in a skin biopsy specimen proved the diagnosis of tuberculosis. Conversion of a previously negative skin test permitted the diagnosis of primary inoculation tuberculosis of the skin. The disease responded well to treatment with isoniazid, rifampin, and pyridoxine hydrochloride.

Ocular findings associated with encephalomyelitis caused by Herpesvirus simiae.

A 29-year-old monkey handler developed acute encephalomyelitis with serological evidence of Herpesvirus simiae infection. He had sudden unilateral loss of vision on the 32nd day of illness caused by vitreous hemorrhage. This cleared gradually, revealing chorioretinal scarring and a gliovascular vitreous band which eventually caused local tractional retinal detachment.