Seroconversion to simian immunodeficiency virus in two laboratory workers.

Simian immunodeficiency viruses (SIVs) are lentiviruses that cause acquired immunodeficiency syndrome (AIDS)-like illnesses in susceptible macaque monkeys and are used in the study of AIDS (1). In November 1988, CDC published guidelines to minimize the risk of SIV transmission to research laboratory workers (2). This report summarizes the investigation of two laboratory workers who seroconverted following occupational exposures to SIV.

Arbovirus infections among laboratory personnel in Ibadan, Nigeria.

Laboratory-acquired infections encountered between 1963 and 1977 among personnel of the Virus Research Laboratory, Ibadan, Nigeria, are reported. Two cases of chikungunya infection occurred and one each with Dugbe, Wesselsbron, and dengue viruses. In each case, virus was isolated or development of antibody demonstrated. Among virus and two each to chikungunya and Rift Valley fever viruses, without experiencing any clinically recognized disease.

Rabies pre-exposure prophylaxis using intradermal human diploid cell vaccine: immunologic efficacy and cost-effectiveness in a university medical center and a review of selected literature.

The authors studied the antigenicity of intradermal human diploid cell rabies vaccine administered to 40 laboratory workers considered to be at-risk at the University of Virginia Medical Center. A 1-year postvaccination serology was determined for 20 of those 40, all of whom demonstrated an antirabies titer greater than or equal to 1:50 by the raped fluorescent focus inhibition test. By 2 years' postvaccination, 5 of 40 subjects had "unprotective levels" (less than 1:5), whereas 35 had titers greater than or equal to 1:5, and none had a titer greater than or equal to 1:50. Booster doses given to four subjects whose titers had declined produced a 1-month postvaccination antirabies titer greater than or equal to 1:50 in all cases. Vaccine administration by the intradermal rather than the intramuscular route resulted in a cost savings of $120 (U.S.) per employee. This data indicate that the intradermal administration of human diploid cell vaccine for rabies pre-exposure prophylaxis achieves an immunologic response thought to be protective while providing a substantial cost savings when compared with the intramuscular route of administration. Those who receive primary pre-exposure rabies vaccination should have serologic confirmation of immunologic protection every 2 years with a booster dose given to subjects demonstrating a titer less than 1:5.

Outbreak of laboratory-acquired Brucella abortus in Brazil: a case report.

Human brucellosis is an occupational disease affecting workers in slaughterhouses, butcher shops and the milk and dairy product industry as well as individuals who work in clinical or research laboratories. We report the first outbreak of a Brucella abortus infection in a Brazilian laboratory and compare the data obtained with reports available in the literature. Exposure was a result of damage to a biological safety cabinet and failure of the unidirectional airflow ventilation system. An epidemiological investigation identified 3 seroconverted individuals, 1 of whom had clinical manifestations and laboratory results compatible with infection at the time of exposure (n=11; attack rate=9.1%).

Outbreak of laboratory-acquired Brucella abortus in Brazil: a case report

Human brucellosis is an occupational disease affecting workers in slaughterhouses, butcher shops and the milk and dairy product industry as well as individuals who work in clinical or research laboratories. We report the first outbreak of a Brucella abortus infection in a Brazilian laboratory and compare the data obtained with reports available in the literature. Exposure was a result of damage to a biological safety cabinet and failure of the unidirectional airflow ventilation system. An epidemiological investigation identified 3 seroconverted individuals, 1 of whom had clinical manifestations and laboratory results compatible with infection at the time of exposure (n=11; attack rate=9.1%).

Serological studies on a case of laboratory dengue infection.

One of the authors (Y.O.), who had previously been immunized with Japanese encephalitis (JE) vaccine, showed symptoms of typical dengue fever 6 days after accidental infection with a newly isolated dengue type 4 virus strain from a patient with dengue hemorrhagic fever (DHF) in Thailand. His sera were examined by hemagglutination inhibition (HI), complement fixation (CF) and neutralization (N) tests. The JE N antibody titers of his sera were high even on the first day of the illness and remained almost constant during the next year. Antibodies that reacted with dengue viruses were detected from a very early stage of the illness by all three serological tests. In addition, his convalescent phase sera showed high titers against all 4 types of dengue virus. These data suggest that the dengue infection caused secondary stimulation of antigens of flavivirus. Sedimentation analysis of antibodies in Y.O.'s serum (day 9) was carried out and IgM antibody that reacted only with dengue type 4 virus and homologous infecting virus was separated. These findings clearly demonstrated that the laboratory infection of Y.O. was primary dengue infection with dengue type 4 virus.

Immunization against tularemia: analysis of the effectiveness of live Francisella tularensis vaccine in prevention of laboratory-acquired tularemia.

A retrospective analysis was made of cases of laboratory-acquired infections with Francisella tularensis among civilian employees at Fort Detrick, Maryland. The incidence and clinical presentation of tularemia during the decade 1950-1959, when the phenol-killed Foshay vaccine was used routinely for immunization of employees, were compared with similar data from the first decade (1960-1969) after the live tularemia vaccine had come into use. The incidence of typhoidal tularemia fell (from 5.70 to 0.27 cases per 1,000 at-risk employee-years; P less than 0.001), whereas the incidence of ulceroglandular tularemia remained unchanged (from 0.76 to 0.54 cases per 1,000 at-risk employee-years). Ulceroglandular tularemia in employees immunized with live vaccine was characterized by clinical signs and symptoms that were milder than those in employees vaccinated with the Foshay vaccine.

Comparison of different serotests for specific Toxoplasma IgM-antibodies (ISAGA, SPIHA, IFAT) and detection of circulating antigen in two cases of laboratory acquired Toxoplasma infection.

Two symptomatic Toxoplasma infections of laboratory personnel have been serologically followed up for 5.5 and 10 months, respectively. Results obtained by commonly used test systems (indirect fluorescent antibody tests for IgG and IgM antibodies, complement fixation test) were compared with those of two recently developed and improved tests for IgM detection (immunosorbent agglutination assay [ISAGA] and solid-phase indirect haemadsorption assay [SPIHA] as well as with those of a test designed for the detection of circulating antigen (cag-ELISA).

Risk of occupational exposure to Herpesvirus simiae (B virus) in Quebec.

Herpesvirus simiae (B virus) causes a mild infection in macaques. Transmission to humans may result in life-threatening encephalomyelitis. To evaluate the risk of occupational exposure to B virus we surveyed the directors of 11 biomedical laboratories in Quebec that use monkeys. Information was obtained on the monkey population and on the use of infection control measures recommended by the US Centers for Disease Control (CDC), Atlanta. Of the 519 monkeys belonging to susceptible species the serologic status was positive in 264 (51%), all captured in the wilds, and it was unknown in 24 (5%). All of the monkeys were caged individually, and newly acquired ones were quarantined for 2 to 8 weeks. Of the 84 workers 52 (62%) handled monkeys whose serologic status was either positive or unknown. Only five laboratories (representing 61% of the workers) complied fully with the CDC guidelines. Nine of the laboratories had a wound management protocol, but only six had a designated specialist for consultation and prophylaxis. Although no cases of B virus infection have been reported from Quebec the severity of human illness necessitates strict adherence to infection control measures and expert management of occupational exposure to susceptible monkeys.

California encephalitis group viruses isolated from mosquitoes collected in Southern and Arctic Norway.

Three virus strains serologically related to the California encephalitis group (Bunyaviridae) of arboviruses were isolated from 7331 mosquitoes collected in Norway in June-August 1975. Two of the isolates (S 548 and S 618) seemed to be closely related and the third, S 568, more distantly related by serological techniques to Tahyna virus. Viruses were found in the mosquito species Aedes sticticus, A. diantaeus and A. hexodontus colllected (in order) from Oyern (59 degrees N, 11 degrees 12' E), Trandum (60 degrees 08' N, 11 degrees 10' E) and Masi (69 degrees 26' N, 23 degrees 39' E). The Masi isolate seems to be the northernmost arbovirus isolate in the world so far. Strain S 568 was from 16 male A. diantaeus, indicating transovarial transmission of the virus. An accidental infection demonstrated the potential human pathogenicity of one of the newly-isolated strains (S 568), and the ability of CE viruses to persistently infect suckling mouse brains was indicated by in vivo findings. The biological characteristics of the new strains so far investigated are consistent with those of the California encephalitis group. During this work the Aerosil absorption method for production of haemagglutinating antigens proved useful for Tahyna virus and the newly-isolated strains. Trypsinization of erythrocytes improved the haemagglutinating capacities of these viruses.