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SUBJECT: EPIDEMIOLOGY OF BRUCELLOSIS IN JORDAN Epidemiology of Brucellosis in Jordan August 1990 SUMMARY: Brucellosis has been increasingly recognized as an important public health problem in Jordan. Disease transmission occurs predominately in the rural village areas, and usually is due to consumption of unpasteurized dairy products. INCIDENCE: Prior to 1985, human brucellosis was seldom reported in Jordan, although it was known to be widely enzootic in livestock. Clinicians then began to recognize brucellosis as improved diagnostic capabilities by several laboratories indicated that brucellosis was the cause of almost 25 percent of human fevers of unknown origin. According to the Ministry of Health, the annual reported incidence of human brucellosis increased from 20 cases in 1985 to 893 in 1986 and 1,278 cases in 1987. There is no difference in the occurrence of brucellosis between males and females. The disease occurs among all age groups with the highest incidence in young adults, ages 20-29. HUMAN POPULATION-AT-RISK: The population of Jordan is almost 3 million, half of whom are villagers or bedouin who often live in close proximity with their livestock. Most human cases occur among this rural group and outbreaks in cities or towns are usually traced to an unlicensed backyard dairies and street vendors. INFECTIOUS AGENT: Only Brucella melitensis has been reported in Jordan. Sensitivity patterns in Jordan show little or no resistance to cholamphenicol, streptomycin, rifampicin, ofloxacin, tetracycline, or gentamicin. Resistance has been demonstrated against tobramicin, cephradine, erythromycin, and co-trimoxazole. RESERVOIR: Brucella melitensis is enzootic in sheep and goats, and also cattle, in Jordan. Sheep and goats are the primary source of infection for humans. Recent surveys found infection rates of over 10 percent in sheep and goats. The prevalence among cattle is estimated at 2 percent in Jordan. LIVESTOCK POPULATION: There are the following approximate numbers of livestock in Jordan: cattle 35,000 (includes 20,000 dairy cattle) camels 14,000 sheep 1,100,000 goats 500,000 Most of the larger dairy cattle farms sell their milk to processing plants which provide safe (pasteurized and inspected) dairy products to the urban areas. Most of the sheep and goats are held in small herds which graze the open marginal grasslands. The sheep and goats are raised for meat, fiber, and dairy products. Although raw goat, sheep, and camel (a cultural favorite of the bedouin) milk is consumed, most of the goat and sheep milk is used for cheese. Many brucellosis outbreaks have been traced to consumption of these raw cheese products. TRANSMISSION: Humans usually become infected through consumption of unpasteurized dairy products. Direct contact with infected material (such as during manual assistance during lambing) plays only a minor role in Jordan. Transmission increases in the spring and summer, peaking in June-July. CONTROL: Ministry of Health: In early 1986, a nationwide campaign of health education was initiated. The emphasis was on the safe consumption of dairy products and identification of non-licensed salespersons. All dairy products in Jordan are required to be pasteurized and licensed. Dairy products purchased in stores in the larger towns are usually licensed (and safe for consumption). Ministry of Agriculture, Animal Health Division: Control programs have been initiated as the incidence of human brucellosis and the economic impact of brucellosis livestock production have been recognized. Effort to reduce the level of infection in sheep and goats have been done through immunization with the live attenuated vaccine, B. melitensis Rev. 1, at between 3-6 months of age and reimmunization annually. Immunization efforts have been hampered by the lack of adequate corrals an fences, as well as difficulties in communicating with many widely distributed shepherds. In addition, many shepherds are unwilling to have their sheep and goats immunized. With cattle, there is a testing and eradication program which has been more successful due to the small number of herds. Some restrictions have also been imposed along the open borders with neighboring countries (all of whom also have a high prevalence of brucellosis).
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