A SHORT HISTORY OF OCCUPATIONAL DISEASE: 1. LABORATORY-ACQUIRED INFECTIONS.

Laboratory-acquired infections are as old as laboratories themselves. As soon as the culture of microorganisms was introduced, so too was their transfer to laboratory workers. It is only in relatively recent history that such infections have been fully understood, and methods of spread and their prevention or avoidance developed. This paper endeavours to provide an overview of the history of laboratory-acquired infection and the steps taken, particularly in the UK, for its prevention.

Semliki forest virus: cause of a fatal case of human encephalitis.

A fatal case of human encephalitis has been observed for which our results indicate that Semliki Forest virus (SFV) was the etiologic agent. This is surprising in view of the fact that this virus, which has been widely studied, was believed to be one of the arboviruses nonpathogenic for man. Described are the clinical course, the virological examinations performed, and the histopathological findings in the central nervous system.

Evaluation of Moloney murine sarcoma and leukemia virus complex as a model for airborne oncogenic virus biohazards: survival of airborne virus and exposure of mice.

Aerosols of the Moloney murine sarcoma virus (MuSV-M) and leukemia virus (MuLV-M) complex (MuSV-M/MuLV-M) were generated from refluxing atomizers and then aged in rotating drums at 21 degrees C holding temperature with relative humidities ranging from 25 to 76%. The MuSV-M and MuLV-M aerosolized from the same tumor extract preparation survived almost equally at the four humidity levels. Both viruses remained viable in the airborne state for at least 2 hours after aerosolization. When mice were exposed to airborne MuSV-M/MuLV-M, no macroscopic lesions were observed in lungs or other tissues examined during the 2-month postexposure period. On the basis of this study, MuSV-M was determined unsuitable as a "model system" in which a simple aerosol dose response could be used for biohazard evaluation of oncogenic virus aerosols.

The epidemiology of HIV transmission among paid plasma donors, Mexico City, Mexico.

Screening of blood product donations for antibody to HIV began in Mexico in May 1986. From June to October 1986, the HIV cumulative seroprevalence increased from 6.3 to 9.2% in a commercial plasma collection center. Of the 281 people who donated the antibody-positive units, 62 (22.1%) had documented seroconversion during these 5 months. An epidemiologic study of 54 seropositive and 58 seronegative donors was carried out. The HIV serologic status did not change in any of these donors after repeat testing. Only 13.0% of the seropositives and 15.5% of the seronegatives had any of the known risk factors for AIDS. There was a direct relationship between frequency of plasma donation and the risk of being seropositive. A survey of employees disclosed the frequent re-use of disposable blood collection equipment. We conclude that HIV transmission had probably occurred in this plasma collection center.

PIP: This report provides the results of a study of plasma donor clients from records abstracted between June-October 1986. The purpose was to identify risk factors for HIV infection among donors at the National Center for Blood Transfusions. Screening for HIV among donors began in May 1986. 54 Seropositive donors were identified and located from 281 and 58 seronegative donors were randomly selected. 16 employees of the plasma collection center were locatable and also included in the study. The results were that seroprevalence increased between June-October from 6.3% to 9.2%. The total donations were 3201 of which 294 were seropositive. Of 281 seropositive clients, 62 (22%) had seroconversion (a prior seronegative donation). Seroconversions increased from 1.6% in July to 50% in October. On retesting of the 112 study participants, no change in status was found. The groups were similar and both groups had relatively low risk factors for (13% for HIV seropositive and 15.5% for HIV seronegative donors). The rate of seropositivity increased with the frequency of plasma donations from 19.6% for those donating 1-3 times/month to 88.9% for those donating 10 times/month. Of the 16 employees, 1 died who was HIV seropositive; 5 were directly involved in plasma collection and reported reuse of saline solution and intravenous tubing. The results lead the authors to suggest that HIV was transmitted in the collection process. Support for this suggestion comes from the number of seroconversions; the risk factors among the seropositive donors had no known risk factors. Although not statistically significant, male seropositive donors had greater contract with prostitutes in Mexico City, but prostitutes had shown in the past 2 years a seropositivity rate of 1%. More demonstrative evidence comes from the increased rate of seropositivity with frequency of donation, and the employee reports of reutilization of blood collection materials. Other studies have postulated plasma donor site risk. Regardless of the expense of intravenous equipment, it is suggested that the risk of HIV transmission precludes reuse of materials. At present, all blood is collected from volunteer donors with disposable equipment. Other countries need to assess the safety of blood donor centers, particularly with paid donors.

Infections in British clinical laboratories, 1984-5.

During 1984-5 this continuing survey showed that 41 infections occurred in the staff of 193 laboratories, representing 23,043.5 person years of exposure. The community was the probable source of two cases each of hepatitis A and B, one of tuberculosis, two of campylobacter enteritis, and 12 of Norwalk viral diarrhoea. Occupational exposure was the probable cause of six hepatitis B infections (affecting haematology, biochemistry, and microbiology staff), three of tuberculosis (affecting mortuary and morbid anatomy workers), seven shigella, three salmonella (including one typhoid) and one pseudocholera infection (all in microbiology medical laboratory scientific officers), and a streptococcal infection in a mortuary technician. An episode of hepatitis of uncertain cause affected a carrier of hepatitis B. The incidence of reported infections of all types was 178 per 100,000 person years (91 for infections of suspected occupational origin). The highest incidence was in morbid anatomy and mortuary workers, followed by microbiology medical laboratory scientific officers.

Infections in British clinical laboratories 1980-81.

This survey through the Association of Clinical Pathologists was continued and extended for 1980-81, with the help of the Institute of Medical Laboratory Sciences. Hepatitis maintained a low attack rate of 26/100 000 person-years, including only three cases of hepatitis B probably attributable to laboratory work (attack rate 9). Nineteen cases of tuberculosis (attack rate 56) included 14 of probable occupational origin (attack rate 41) half of which involved post-mortem or mortuary work. Thirteen bacterial infections of the bowel (attack rate 38, predominantly shigellosis) involved almost exclusively microbiology MLSOs, with 10 attributed to laboratory work (attack rate 29). The seven other infections included 4 of occupational sepsis in morbid anatomy and post-mortem workers. There appears to be scope for improvement in bacteriological bench techniques particularly at the faeces bench and for reduction in the hazards of tuberculosis and sepsis for morbid anatomy and mortuary workers.

Infections transmitted by large and small laboratory animals.

Although zoonotic spread of infectious disease continues to occur in laboratory animals used in biomedical research, reported outbreaks have been minimized with the advent of rigorous veterinary and husbandry procedures, the use of commercially reared animals, and the institution of appropriate personnel health programs. Maintaining animals in modern facilities with appropriate safeguards against introduction of vermin and biologic vectors is also important in preventing zoonotic disease in personnel. Nevertheless, established zoonotic agents, newly discovered microorganisms, or new animal species not previously recognized as carriers of zoonotic microorganisms are encountered, and the potential for spread of infectious disease from animals to humans still exists. Active dialogue between veterinarians and physicians regarding the potential of zoonotic disease, the species of animals that are involved, and the methods of diagnosis, is an indispensable component of a successful preventive health program involving personnel who deal with laboratory animals.

Laboratory-acquired malaria, leishmaniasis, trypanosomiasis, and toxoplasmosis.

Because of renewed interest in parasitic diseases, increasing numbers of persons in clinical and research laboratories have the potential for exposure to parasites and therefore are at risk for acquiring parasitic infections. In this review of laboratory-acquired parasitic infections, we concentrate on protozoan diseases that frequently have been reported to be laboratory acquired: malaria, leishmaniasis, trypanosomiasis (American and African), and toxoplasmosis. These diseases can be severe, even fatal, and may be difficult to diagnose. Many laboratorians who have acquired these diseases did not recall having had an accident. Of those with recognized accidents, needlestick injuries were the most common. Laboratories should have established protocols for handling specimens that may contain viable organisms and for responding to laboratory accidents.

Percutaneous exposure resulting in laboratory-acquired leptospirosis -- a case report.

A screw-capped glass tube containing a Leptospira culture accidentally broke and the laboratory worker who was handling the tube sustained a cut on his hand. The wound was flooded with the culture. The culture was that of strain MG 347 belonging to serovar Australis recovered from a patient, and it had undergone 52 passages in Ellinghausen McCullough Johnson Harris medium. The laboratory worker developed a headache 21 days after the accident and became febrile the next day. He was hospitalized for 5 days and was treated initially with doxycycline and later with ciprofloxacin. A blood sample collected on the second day of illness, after starting doxycycline therapy, yielded leptospires and the isolate, HZ 651, was identified as serovar Australis. Monoclonal antibody patterns and randomly amplified polymorphic DNA fingerprinting patterns of the isolate and strain MG 347 were identical, thus indicating that HZ 651 and MG 347 were clonal.

Laboratory-acquired brucellosis.

Brucellosis is endemic in Saudi Arabia and hospital laboratories are handling increasing numbers of specimens for diagnosis. We report four cases of laboratory-acquired brucellosis.

Brucellosis: imported and laboratory-acquired cases, and an overview of treatment trials.

Following the successful eradication of Brucella abortus infection in cattle, human brucellosis in England and Wales has become an uncommon imported disease. Culture of the organism presents a major laboratory hazard, and difficulties in identification may occur using a biochemical test-strip method. An overview of recent treatment trials of brucellosis indicates that regimens combining streptomycin and doxycycline are associated with a higher success rate (judged by the frequency of treatment failure and relapse following therapy) than combinations of rifampicin and doxycycline.

Echo 11 conjunctivitis.

We describe a case of Echo 11 virus infection producing a moderately severe conjunctivitis in a laboratory worker who had handled infected material. This virus has previously been known to cause systemic disease, sometimes fatal, in children.

A case report of fowl plague keratoconjunctivitis.

A case of human fowl plague keratoconjunctivitis occurred after accidental laboratory exposure. The conjunctivitis was characterised by follicle formation and a mucopurulent discharge, and ran a self-limiting course over two weeks. The keratitis was of an unusual type and consisted of small intraepithelial opacities, which appeared after one week and resolved completely over the next three weeks. The infection, confirmed by viral culture, was produced by Dutch strain (Hav 1 Neq 1) of fowl plague virus.

Infection of laboratory workers with hantavirus acquired from immunocytomas propagated in laboratory rats.

Hantavirus has been isolated in cell culture from rat immunocytomas used and stored at a research laboratory in the U.K. where there was evidence of a laboratory-acquired infection leading to haemorrhagic fever with renal syndrome. Both transplantation into LOU/M/Wsl rats and storage of passaged immunocytomas at -70 degrees C over a period of 8-10 years had not eliminated the virus. The isolates were identified as Hantavirus by means of serum obtained from patients with hantavirus infection as well as polyclonal serum derived from laboratory animals. This paper identifies a potential source of hantavirus infection in laboratories. The importing of rats, rat immunocytomas and anti-immunocytoma serum in relation to the potential risks of laboratory-acquired hantavirus infection is discussed.

Past and present hazards of working with infectious agents.

Over 4,000 cases of laboratory-associated infection have been recorded. Some of the agents involved often in the past have been less frequently the cause of such infection in recent years, and some agents are more likely to infect those working with them than others. Pipetting, the use of a needle and syringe, and spills have been most frequently involved in accidents resulting in infection, but in the majority of cases no recognized accident occurred. In these instances, infectious aerosols, produced in various ways, are probably the most frequent causes of laboratory-associated infection. The introduction of protective devices and emphasis on safe procedures seem to be reducing the risk of accidental infection. Although work with tumor viruses and recombinant DNA research may not be as hazardous as was originally feared, continued caution and surveillance is advised.

Cutaneous larva migrans, an occupational disease.

Creeping skin eruption is known to follow exposure to canine and feline hookworm larvae found in contaminated soil encountered in humid, tropical and subtropical regions. A little known hazard of similar infections exists among veterinarians and laboratory workers exposed to Strongyloides larvae from horses located in temperate climates. The evolving clinical picture is described in detail. Continued exposure may lead to a state of hypersensitivity to the parasitic protein resulting in severe hyperimmune reactions. The invasiveness of Strongyloides larvae through intact skin and the pathologic changes associated with infection were demonstrated in a rabbit.

Zoonoses of occupational health importance in contemporary laboratory animal research.

In contemporary laboratory animal facilities, workplace exposure to zoonotic pathogens, agents transmitted to humans from vertebrate animals or their tissues, is an occupational hazard. The primary (e.g., macaques, pigs, dogs, rabbits, mice, and rats) and secondary species (e.g., sheep, goats, cats, ferrets, and pigeons) of animals commonly used in biomedical research, as classified by the American College of Laboratory Animal Medicine, are established or potential hosts for a large number of zoonotic agents. Diseases included in this review are principally those wherein a risk to biomedical facility personnel has been documented by published reports of human cases in laboratory animal research settings, or under reasonably similar circumstances. Diseases are listed alphabetically, and each section includes information about clinical disease, transmission, occurrence, and prevention in animal reservoir species and humans. Our goal is to provide a resource for veterinarians, health-care professionals, technical staff, and administrators that will assist in the design and on-going evaluation of institutional occupational health and safety programs.

Accidental inoculation blastomycosis.

The pathogenesis of blastomycosis as a primary pulmonary infection has been well established and widely accepted. The rate cases of primary cutaneous inoculation are in all documented instances related to "laboratory" accidents. A case of inoculation with a culture suspension of Blastomyces Dermatitidis is herein reported. A slow healing chancre remained active for about eight months.

[Laboratory infections]. / Laboratuvar enfeksiyonlari.

Infection constitutes an important professional hazard for health care workers. Since the past decades infections acquired during laboratory work have caused morbidity and even mortality among laboratory employees. In this article the importance of laboratory acquired infections and some guidelines for protection are stated.