a. General. Leptospirosis is a bacterial disease of wildlife and domestic animals, and occurs in man only incidentally after exposure to these species or to an environment contaminated by them. This disease is an occupational hazard to rice field workers, farmers, and military troops. It is an acute and often severe infection affecting the liver or other organs. Symptoms include meningeal irritation and hepatic disturbance. The most common reservoirs are rats, dogs, and cattle and swine. The incidence of leptospirosis is higher than usually supposed. The Leptospira icterohemorrhagiae found rats causes the most severe illness. These organisms can remain in culture contaminated soil for 43 days, and in urine contaminated soil for 15 days.
b. Modes of Transmission. There have been outbreaks among swimmers who have been exposed to water contaminated by the urine of domestic or wild animals such as cattle, dogs, swine, rodents, deer, foxes, reptiles, and amphibia (frogs). The disease can occur through contact of abraded skin with water, moist soil, or vegetation contaminated with the urine of infected animals. Leptospirosis is an occupational hazard for sugar cane field and rice workers, sewer workers, veterinarians, miners, dairymen, fish workers, farmers, animal husbandmen, abattoir workers, and military men. It is more apt to occur in those areas of the world where agriculture is less mechanized than North America, or where more intimate contact with livestock occurs.
It is also a recreational hazard to campers, bathers, and sportsmen in infected areas. Person-to-person transmission is rare. The organisms may be excreted in the urine up to 11 months. The most common form of transmission in the US is from animal bites, close contact with the animal's droplets, transmission by aerosolized urine, infected carcasses/tissues, and by ixodial ticks. Since pets (dogs) have assumed a greater role in peoples' lives, the possibility of infection is ever present.
c. Signs and Symptoms. In the first or leptospiremic phase lasting from 4 to 9 days, the victim has chills, usually a frontal headache, severe muscle aches, a high spiking temperature (102°F or more), anorexia, nausea and vomiting, and conjunctival suffusion. The second or immune phase lasts from 6 to 12 days with meningeal irritation, hepatic disturbance (jaundice or hepatic enlargement), skin rash (erythematous lesions), and myocarditis. There may be renal manifestations, such as proteinuria or hematuria.
d. Treatment. The administration of penicillin G (penicillin) dihydrostreptomycin, or tetracycline hydrochloride within the first few days seems to decrease severity. The primary supportive care is to hospitalize the patient, provide bed rest, and give meticulous fluid and electrolyte therapy.
(1) Preventive measures.
(a) Provide boots and gloves for workers in occupations that are susceptible to the disease.
(b) Drain potentially contaminated water and soil.
(c) Provide public education explaining how the disease is transmitted, explaining how to provide protection if working in area where the disease may be prevalent, and apprising the public of the possibility of contacting the disease when swimming or wading in potentially contaminated waters.
(d) Control rodents, especially in rural and recreational habitations. Before harvest, fire cane fields.
(e) Isolate infected domestic animals in order to prevent the contamination of the working, living, and recreational areas.
(f) Isolate and test new stock; know the vaccination history.
(g) Control runoff from feedlots and barnyards.
(h) Provide adequate water treatment and disinfection.
(i) Prevent disease by immunizing farm and pet animals.
(j) Immunize workers. (Human immunization has been provided for workers in Japan, Spain and Italy.)
(2) Patient control (contacts and immediate environment).
(a) Notify the local health authority when the disease is contacted.
(b) Investigate to determine where the disease was contacted; close suspected pools or swimming holes.
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