Academic journal article Central European Journal of Public Health

Influence of the Environment and Occupational Exposure on the Occurrence of Q Fever

Academic journal article Central European Journal of Public Health

Influence of the Environment and Occupational Exposure on the Occurrence of Q Fever

Article excerpt

SUMMARY

Q fever, which is caused by Coxiella burnetii, is a worldwide zoonotic infectious disease and ruminants are the main reservoir for human infections. Humans become infected primarily by inhaling aerosols that are contaminated with C. burnetii. Ingestion (particularly drinking raw milk) and person-to-person transmission are minor routes. Animals shed the bacterium in urine and faeces, and in very high concentrations in birth by-products. The bacterium persists in the environment in a resistant spore-like form which may become airborne and transported long distances by the wind. Q fever is considered primarily an occupational disease of workers in close contact with farm animals or processing their products, however, it may occur also in persons without direct contact. To prevent the introduction and spread of Q fever infection, preventive measures should be implemented including immunisation with currently available vaccines of domestic animals and humans at risk.

Key words: Q fever, Coxiella burnetii, environmental contamination, occupational exposure, preventive measures

INTRODUCTION

Q fever was first described in 1 937 by Edward Holbrook Derrick (1898- 1976), while he was the director of the Laboratory of Microbiology and Pathology at the Queensland Health Department in Brisbane (Australia). In 1935, he was instructed to investigate a febrile illness among abattoir workers in Brisbane (1).

The disease is caused by the obligate intracellular bacterium Coxiella burnetii, which lives in the macrophages of the host but may survive outside the cell and can have two distinct antigenic phases I and ?. Animals and humans develop antibody responses to both phases (2, 3). C. burnetii remains viable for months to years in the environment contaminating water and soil. Highlevel resistance to UV radiation, heat, desiccation, pressure, osmotic and oxidative stress, and disinfectant agents has been demonstrated (4-6).

Q fever is an infectious disease that occurs in all geographic and climatic zones, where the conditions support natural C. burnetii infection and circulation (7). Infected domestic animals (cattle, sheep, and goats but also pet animals, especially cats and dogs), frequently with persistent and subclinical coxiellosis, are the main source of C. burnetii infection in humans, who become infected by direct contact with these animals, by environmental contamination (from animal excrements), and (indirectly) through processing or consuming animal products (8-11).

Though Q fever can be considered primarily an occupational disease of workers in close contact with farm animals or processing animal products, it may occur also in visitors to areas at risk, travellers to areas with Q fever occurrence, even in innocent bystanders, etc. An uncontrolled transfer and movement of domestic animals seems to be responsible for the spread of disease (12).

Because human infection is not limited only to people in contact with animals, we would like to point to the importance of both profession and the environment as important risk factors associated with transfer of Q fever and recommend protective measures aimed at prevention of the development and spread of disease.

Occurrence in Slovakia and European Countries

In Slovakia, Q fever has been known since 1954 when outbreaks occurred among agricultural workers who contracted the infection from sheep and among workers of a textile plant who were exposed to contaminated imported cotton. Until the eighties of the 20th century the waves of epizootics and small epidemics appeared in factories processing cotton, wool, and hides, in a sheep farm, and on various agricultural premises. Large-scale vaccination of cattle carried out in the 1970s and 1980s, together with improved veterinary control of domestic animal transport within the country, could explain a decrease in the occurrence of human Q fever in Slovakia (7, 11). An exception was the explosive epidemic of Q fever in 1993 that affected 113 humans (13). …

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