Environmental Engineering Reference
In-Depth Information
spores as a weapon of war or act of terrorism. Although rare, meningitis
is a relatively deadly, and as consequence, “scary” disease. Anthrax, a
disease primarily associated with animals, has been developed into a
highly dangerous germ warfare agent. Release of even a small quantity of
anthrax spores would create an episode of deaths and injury of nightmarish
proportions.
Until the beginning of the 20th century, TB was a
major cause of death in the U.S., as well as many other countries. Due to
advances in diagnosis, prevention, and treatment, the prevalence of TB
declined dramatically. It is, however, still an important disease in the U.S.,
with 20,000 cases and a few thousand deaths reported each year. While the
incidence rate has now stabilized, it had been increasing in the U.S. since
1970 due to the influx of immigrants from countries where TB is still com-
mon; the development of resistance by the causal organism to a variety of
antibiotics; and increases in susceptible populations. (immunocompromised
individuals such as AIDS patients and individuals living under poor sanitary
conditions, such as the homeless and alcoholics).
Tuberculosis is a chronic infection of the lungs but may also affect the
intestines, kidneys, lymph nodes, bones, and joints. The causal organism,
b.
Tuberculosis.
is a slender, rod-shaped, nonmotile, nonspore-
forming bacillus. It is relatively resistant to the effects of drying and may
remain alive in dust and dried sputum in dark places for weeks or months.
Since it has no natural existence outside an infected individual, humans are
the most important reservoir of infection, with exposure to aerosols being
the most common mode of transmission. Studies have shown that exposure
to one aerosol droplet may be sufficient to cause infection.
Outbreaks of TB have occurred in hospitals, nursing homes, homeless
shelters, correctional facilities, and residential AIDS care centers. Individuals
in such environments are at a much higher risk of exposure and infection
than in other environments where the infection rate is much lower. Because
the risk of TB infection in patients and staff in health-care facilities can be
relatively high, the Occupational Safety and Health Administration (OSHA)
has proposed an occupational exposure standard for TB which is scheduled
to go into effect in the year 2000.
Mycobacterium tuberculosis,
Legionnaires' disease was initially identified
after a major investigation of an outbreak of a pneumonia-like illness (by
the Centers for Disease Control) that affected approximately 220 individuals
at a state American Legion convention at the Hotel Bellevue in Philadelphia,
PA, in 1976. The disease was characterized by symptoms of fever, cough,
shortness of breath, chest pain, headache, myalgia, diarrhea, and confusion.
It is a progressive pneumonia with a fatality rate of approximately 15%.
Nearly 10% of reported cases of Legionnaires' disease are associated
with outbreaks affecting several or more individuals, but in most cases it
c.
Legionnaires' disease.
