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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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