Status of eradication of smallpox (and control of measles) in West and Central Africa.
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Biomedical subjects
Publications and source records attributed to J D Millar.
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Jet injection has met with great success in the rapid and effective mass administration of several immunizing agents. The recent development of a jet injector nozzle specifically designed for intradermal inoculation suggested the possible extension of jet injector methodology to mass smallpox vaccination. A total of 156 volunteer subjects, 16 unvaccinated and 140 vaccinated more than 5 years previously, received either undiluted smallpox vaccine by the multiple-pressure technique, or 0.1 ml of various dilutions of smallpox vaccine by jet injector using the new nozzle. Cutaneous and serological responses in revaccinees revealed that jet injection of diluted vaccine with a titre of 10(7) TCID(50)/ml was as effective as multiple-pressure inoculation of undiluted vaccine. Among the small number of primary vaccinees, jet injection of diluted vaccine with a titre of 10(6) TCID(50)/ml appeared as effective as multiple-pressure inoculation of undiluted vaccine. No complications of vaccination occurred.The findings confirm the utility of the intradermal nozzle for jet injection of smallpox vaccine. In view of the speed of administration and the economy of vaccine, it is suggested that there is a distinct role for jet injection in global smallpox eradication efforts. Further studies on larger numbers of unvaccinated subjects and on persons with significant residual vaccinial immunity are needed to define the optimal concentration of vaccine for mass vaccination by jet injection.
Primary vaccination by intradermal jet injection, using diluted smallpox vaccine, was compared with multiple-pressure vaccination in 625 Jamaican children. The cutaneous and antibody response patterns were evaluated. The primary take rates among those jet vaccinated were 97% or more in those receiving vaccines with a titre of 10(6.3) TCID(50)/ml and 10(7.0)TCID(50)/ml, and 96% in those vaccinated by multiple pressure, using undiluted vaccine. The primary take rates in subjects receiving jet-injected vaccine with titres of 10(6.0) TCID(50)/ml and 10(5.0) TCID(50)/ml were 90% and 62%, respectively. Among subjects tested who developed Jennerian vesicles, all but 3 demonstrated seroconversion. In those who failed to develop primary Jennerian vesicles, there was also a failure of neutralizing-antibody development. Vesicle and scar sizes were generally smaller in the jet-vaccinated subjects than in those vaccinated by the multiple-pressure technique. Infants tolerated jet vaccination without difficulty. Vaccinial complications did not occur in any subject. The intradermal jet injection of 0.1 ml of vaccine with a titre 10(6.3) TCID(50)/ml or higher is recommended as a highly effective method for achieving successful primary smallpox vaccination. The method appears best suited for use in mass smallpox-vaccination programmes.
Smallpox vaccinations were performed in a well-vaccinated prison population by multiple-pressure technique and by intradermal jet injection using serial dilutions of vaccine. A total of 140 subjects were divided into groups, and each group was vaccinated by the multiple-pressure technique or by jet injection using 1 of 3 vaccine dilutions with the following calculated titres: ID-Jet 1 = 10(7.0) TCID(50)/ml, ID-Jet 1a = 10(6.3) TCID(50)/ml, ID-Jet 2 = 10(6.0) TCID(50)/ml. Clinical observations were made at intervals during the first week after vaccination. Prevaccination and post-vaccination serum samples were obtained immediately before and 30 days after the vaccination. Results based on clinical and serological evaluations indicated that smallpox vaccination by jet injection with the ID-Jet 1 vaccine was at least as efficacious as vaccination by the standard multiple-pressure technique.
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This review seeks to assist industrial hygienists in the prevention of Legionnaires' disease caused by Legionella bacteria. Breathing water droplets contaminated with Legionella bacteria, in which the organism has been permitted to amplify, causes this disease. Possible sources of transmission include nearly all manmade building water systems. Legionella organisms, found in most natural water sources but at very low concentrations, can thrive under conditions of warmth in these manmade systems. Primary prevention of Legionnaires' disease requires prevention of amplification of Legionella in water systems. This, in turn, requires familiarity with the system and all its components, and effective maintenance and water treatment. However, good maintenance and water treatment regimens alone cannot assure that amplification will not occur somewhere in the system. Systematic microbiological testing for Legionella and appropriate interpretation of the testing results can be powerful assets in prevention by enabling the detection and control of amplification. The occurrence of a confirmed or suspected case of Legionnaires' disease in a building occupant may indicate transmission within the facility; this poses an immediate crisis for the facility manager. An aggressive intervention is indicated to search for previously unknown additional cases of illness, to detect potential sources of transmission, and to decontaminate any suspected sources of transmission on an emergency basis. Once adequate remediation has been achieved and confirmed by microbiological testing, on-going control measures are essential with periodic microbiological investigation to assure continuing prevention of amplification.
We constructed a mathematical model to describe the spread of smallpox after a deliberate release of the virus. Assuming 100 persons initially infected and 3 persons infected per infectious person, quarantine alone could stop disease transmission but would require a minimum daily removal rate of 50% of those with overt symptoms. Vaccination would stop the outbreak within 365 days after release only if disease transmission were reduced to <0.85 persons infected per infectious person. A combined vaccination and quarantine campaign could stop an outbreak if a daily quarantine rate of 25% were achieved and vaccination reduced smallpox transmission by > or = 33%. In such a scenario, approximately 4,200 cases would occur and 365 days would be needed to stop the outbreak. Historical data indicate that a median of 2,155 smallpox vaccine doses per case were given to stop outbreaks, implying that a stockpile of 40 million doses should be adequate.
A custom-built controlled-rate freezing machine is described. It operates by automatically raising and lowering the sample carrier in a static column of liquid nitrogen vapour. It is controlled by a computer-assisted thermocouple feedback system that operates a stepper motor driving the sample carrier. The cooling protocol is divided into three phases: cooling from +5 to -5 C, initiation of ice nucleation, and cooling from -5 to -80 C. Experiments are described to validate the device over a range of different cooling rates. A freezing protocol is established to cool samples in plastic straws over a range of rates up to 80 C/min, with rapid and consistent absorption of the latent heat.
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Occupational safety and health is 1 of 15 areas addressed in the Public Health Service's Objectives for the Nation. This area represents 104 million working men and women and the deaths, diseases, and injuries that result from exposures to hazards in their work environment. Characteristics of public health practice are compared with characteristics of occupational safety and health practice. The National Institute for Occupational Safety and Health (NIOSH), created by the Occupational Safety and Health Act, is discussed. NIOSH has developed a list of 10 leading work-related diseases and injuries. The list is headed by occupational lung diseases. Twenty Objectives for the Nation in the area of occupational safety and health are reviewed, and the status of NIOSH efforts toward their attainment is discussed. Five categories of objectives are covered: (a) improved health status, (b) reduced risk factors, (c) improved public and professional awareness, (d) improved service and protection, and (e) improved surveillance and evaluation. The potential for achieving these objectives is discussed, with special attention given to the lack of a data base for monitoring progress. A major conclusion is that surveillance in occupational safety and health needs to be strengthened.