14 World Health • SlstYeor, No. 4, July-August 1998
Brucellosis: a widespread public health problem
Ottorino Cosivi & Aristarhos Seimenis
Brucellosis can be prevented in humans by limiting or, ideally, eliminating the disease in the animal population and by avoiding contact with infected animals and consumption of raw milk and milk products
O
f all the zoonoses that have both public health and eco- nomic implications, brucel- losis (also known as Mediten-anean fever, remittent fever, Malta fever and undulant fever) is the most widespread. The first clinical de- scription of it dates back to 1860, and the cause of the disease was discov- ered in 1887, when a British an-ny doctor, David Bruce, identified the microbe, which was named after him. Later, in 1905, infected goats and their milk were identified as a source of infection in humans.The risk to humans
The incubation period for brucellosis is usually one to three weeks, but sometimes it may be several months.
Symptoms of the illness vary from mild and self-limiting to severe, though they are seldom life-threaten- ing. Onset can be sudden or insidi- ous, and can be accompanied by persistent or intermittent fever. The general symptoms resemble those of many other febrile diseases, but brucellosis also affects the bones and
A West African "Peul" woman milking a goat in northern Senegal Health education con discour- age people from drinking untreated milk which may carry the Bruce/fa microbe.
Photo WHO/FA0/1 Balderi
muscles, producing generalized aches and pains, and is associated with exhaustion and depression. The duration of the disease can vary from a few weeks to several months. Laboratory tests are needed to con- firm the clinical diagnosis.
Brucellosis is transmitted through contaminated untreated milk and milk products, and through direct contact with infected cattle, sheep, goats, pigs, camels, buffaloes, wild ruminants and, most recently, seals.
Animal carcasses and aborted fetuses are also sources of the disease.
Millions of individuals are at risk worldwide, especially in countries where infection in animals has not been brought under control, proce- dures for heat treatment of milk (such as pasteurization) are not routinely applied, and standards of hygiene in animal husbandry are low.
In countries around the Mediten-anean, efforts are being made to control the disease in ani- mals, but brucellosis persists in sheep
and goats, causing widespread infection in humans. In these coun- tries the annual incidence of brucel- losis in people varies from less than 1 to 78 cases per 100 OOO popula- tion. In confined endemic areas where no animal control measures are applied more than 550 cases per 100 OOO population have been re- ported.
Reported cases do not tell the full story, however. Although human brucellosis is a notifiable disease in many countries, the true incidence is thought to be between 10 and 25 times as high as the reported figures. Very often the disease remains unrecognized as a result of inaccu- rate diagnosis, and is thus reported as a different disease, or as "fever of unknown origin". A recent human survey conducted in Saudi Arabia found that almost 20% of the popu- lation had had the infection and the disease was still active in over 2% of those examined. Similar figures can be expected from most countries in
World Health • SlstYear, No. 4, July-August 1998 15
Collecting fresh milk in Pakistan. Heat treatment ensures that milk and milk products ore safe. Photo WHO/FAO/G. Bizzorri
A veterinarian in Afghanistan examines a goat as port of on effort to ensure that the livestock remain healthy.
which the disease in endemic in the animal population, and a higher prevalence should be expected in occupationally exposed groups such as veterinarians, farmers and slaughter-house workers.
Strategies for brucellosis control
The disease can be prevented in humans by limiting or, ideally, elimi- nating the disease in the animal population and by avoiding contact with infected animals and consump- tion of raw milk and raw milk prod- ucts. Brucellosis control pro- grammes in animals include testing for the disease, slaughtering infected animals and vaccinating animals at risk. In several countries these programmes have been successful, resulting in a major reduction of the incidence in humans. Proper heat treatment of milk or milk products is important for effective prevention of brucellosis in humans. However, social and economic constraints can impede the wider application of such measures. Health education is essen- tial for the success of any prevention and control activities, and should form an integral part of all phases of public health and animal health brucellosis pro-grammes.
Antimicrobials (drugs that de- stroy or inhibit microbes) are effec- tive against brucellosis, but only if several of them are used at once over a period of several weeks.
Antimicrobial-resistant strains of
Photo WHO/FAO/M. Griffin
Brucella have been reported but their clinical implications are not yet fully understood. Some of the commonly used antimicrobials for brucellosis treatment, such as rifampicin and streptomycin, are also preferred drugs for the treatment of tuberculo- sis. The current emergence of strains of tuberculosis bacteria that are resistant to a number of such drugs makes it increasingly important to find an alternative treatment for brucellosis, using antimicrobial agents not employed for tuberculosis.
Animal brucellosis, also known as Bang's disease, causes serious economic losses in developing coun- tries. It provokes spontaneous abor- tions, infertility, and milk and meat production losses, and makes it necessary to place restrictions on trade in animals and animal prod- ucts. This impairs economic devel- opment, particularly in the case of smail-scale livestock owners, one of the most vulnerable groups in many rural populations.
Brucellosis and WHO
Brucellosis in humans and animals is increasing in many parts of the world, including the Mediterranean region, western Asia and parts of Africa, eastern Europe and Latin America. A number of WHO pro- grammes are aimed at strengthening brucellosis surveillance and control activities at national, regional and global levels. In collaboration with the Food and Agriculture
Organization of the United Nations
and the Office international des Epizooties, WHO is promoting a regional control programme in the eastern Mediterranean area. The Mediterranean Zoonoses Control Programme of WHO is coordinating a study to evaluate new treatment regimens for human brucellosis.
WHO and the United Nations Development Programme are collab- orating with the Palestinian
Authority in a programme for the control of human and animal brucel- losis in the West Bank and Gaza Strip. WHO's Regional Office for the Americas has launched an initia- tive for bovine brucellosis elimina- tion in Latin American countries.
The Organization also provides information material for travellers and consumers, covering dietary precautions and such measures as heat treatment of milk and derived products. Currently WHO is prepar- ing guidelines for the integrated surveillance of brucellosis, and promoting research on new brucel- losis vaccines for both humans and animals. •
Dr Ottorino Cosivi is o Scientist with the Zoonotic Diseases Unit, Division of Emerging and other Communicable Diseases SuNeillance and Control, World Health Organization, I 2 I I Geneva 27,
Switzerland. Dr Aristorhos Seimenis is Director of the WHO Mediterranean Zoonosis Control Programme, P.O. Box 66074, Athens, GR-15510 Greece.
