Brucellosis in Animal and Man. Excerpt from the WORLD HEALTH ORGANIZATION article - WHO/CDS/EPR/2006.7 3.1.2.2 Infection from a contaminated environment This is difficult to document but probably occurs more frequently than is recognized. Infected animals passing through populated areas or kept in close proximity to housing may produce heavy contamination of streets, yards and market places, especially if abortions occur. Inhalation brucellosis may  then result from exposure to contaminated dust, dried dung etc. Contact  infection may also result from contamination of skin or conjunctivae from  soiled surfaces. Water sources, such as wells, may also be contaminated by  recently aborted animals or by run-off of rain water from contaminated areas. Brucella spp. can survive for long periods in dust, dung, water, slurry, aborted fetuses, soil, meat and dairy products. The precise duration of survival is dependent on many variables such as the nature of the substrate, number of organisms, temperature, pH, sunlight, the presence of other mi- crobial contaminants. Some examples are given in Table 3. 3.1.2.3 Occupational exposure Certain occupations are associated with a high risk of infection with brucel- losis. These include people who work with farm animals, especially cattle, sheep, goats and pigs: farmers, farm labourers, animal attendants, stockmen, shepherds, sheep shearers, goatherds, pig keepers, veterinarians and inseminators are at risk through direct contact with infected animals or through exposure to a heavily contaminated environment. Infection may occur by inhalation, conjunctival  contamination, accidental ingestion, skin contamination especially via cuts or  abrasions, and accidental self-inoculation with live vaccines. The families of farmers and animal breeders may also be at risk as domestic  exposure may be inseparable from occupational exposure when animals are  kept in close proximity to living accommodation. In some areas, the animals  are kept in the yards of houses and may even be brought inside, especially  in severe weather. In the case of recently aborted animals, this has resulted  in infection of entire households. The use of dried dung as a fuel may also  import infection into households. It should be noted that brucellosis often  presents as clusters of cases in a family or tribal group, usually relating to a  common infected food source, and often follows an outbreak in animals. Children can be particularly at risk as they may adopt newborn or sick animals as pets. In some areas they may be the only group presenting with acute symptoms, as older members of the community are likely to be immune or chronically infected. Persons involved in the processing of animal products may be at high risk of exposure to brucellosis. These include slaughtermen, butchers, meat packers, collectors of fetal calf serum, processors of hides, skins and wool, renderers and dairy workers. Direct and environmental contamination may present hazards through inhalation, ingestion, mucous contamination and skin contact or penetration. Staff employed in the maintenance of farm premises, factories or plants used for processing animal products are often overlooked as occupationally exposed groups but may be at considerable risk from environmental contamination. Laboratory staff involved in culturing Brucella are at particular risk. In some countries in which brucellosis is no longer endemic, this potential hazard may be overlooked or considered no longer relevant. Nevertheless, the performance of diagnostic procedures on patients with unsuspected imported disease may lead to culture of organisms which are not correctly identified until laboratory-acquired infection raises the level of suspicion. The use of rapid identification gallery test systems has caused Brucella strains to be misidentified as Moraxella spp, with serious consequences for the staff. Inhalation of aerosols generated by manipulation of cultures presents the greatest hazard, especially if breakage of containers occurs during such processes as centrifugation. The preparation and use of live vaccines is also hazardous as strains such as B. abortus S19 and B. melitensis Rev 1 are not completely avirulent for humans. The rough vaccine strain B. abortus RB 51 appears to be of low pathogenicity but still presents a potential hazard through accidental injection and is rifampicin-resistant. The use of virulent strains to prepare diagnostic antigens should also be avoided where possible. 3.1.2.4 Foodborne transmission This is usually the main source of brucellosis for urban populations. Ingestion of fresh milk or dairy products prepared from unheated milk is the main source of infection for most populations. Cow, sheep, goat or camel milk contaminated with B. melitensis is particularly hazardous as it is drunk in fairly large volume and may contain large numbers of organisms. Butter, cream or ice-cream prepared from such milk also presents a high risk. Soft cheeses prepared from sheep or goats milk by addition of rennet are a particularly common source of infection in Mediterranean and Middle Eastern countries. The cheese-making process may actually concentrate the Brucella organisms, which can survive for up to several months in this type of product. Such cheeses should be stored in cool conditions for at least six months before consumption. Hard cheeses prepared by lactic and propionic fermentation present a much smaller risk. Similarly, yoghurt and sour milk are less hazardous. Brucella dies off fairly rapidly when the acidity drops below pH 4, and very rapidly below pH 3.5. Equipment used in the transport or processing of infected milk or other raw material may contaminate uninfected products unless good hygienic practice is observed. Meat products are less frequently associated with infection, mainly because they are not usually eaten raw. However, this is a not unknown practice among butchers and abattoir workers. Muscle tissue usually contains low concentrations of Brucella organisms but liver, kidney, spleen, udder and testis may contain much higher concentrations. In some countries, dishes prepared from these organs may be eaten raw or undercooked. Fresh blood, either alone or mixed with fresh milk, may also be drunk and presents an obvious potential hazard. In many countries, the consumption of “health foods” has become fashionable. These often include unpasteurized milk or milk products and may pose a particular risk. There is often considerable resistance to accepting that such “healthy” products can be dangerous. Raw vegetables may be contaminated by infected animals and present a hazard. In endemic areaPersons with achlorhydria resulting from disease or through consumption of antacids or H2 antagonists may have an increased risk of acquiring brucellosis through ingestion of contaminated foods. Individuals with immunodeficiency states resulting from disease or treatment with immunosuppressive agents may also be at increased risk of severe brucellosis, although this is difficult to quantify. Voice: Dr. Folorunsho KABIR DAODU, DVM (Ibadan). Zoonotic Consultant  #onaaraTODAYnews!  Medical Director & Veterinarian  Animal Hospital unit #onaaraTODAYhospital Services! 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