RATIONALE FOR SURVEILLANCE
Brucellosis is the most widespread zoonosis transmitted from animals (cattle, sheep, goats, pigs, camels and buffaloes), through direct contact with blood, placenta, foetuses or uterine secretions, or through consumption of infected raw animal products (especially milk and milk products). Human brucellosis due to Brucella melitensis has serious public health consequences in areas where sheep and goat are raised. Brucellosis has an important worldwide impact on human health and the animal industry. In most countries brucellosis is a notifiable disease. Control measures are based on prevention. Surveillance is a key element for management of prevention and control programmes.
RECOMMENDED CASE DEFINITION
An illness characterized by acute or insidious onset, with continued, intermittent or irregular fever of variable duration, profuse sweating particularly at night, fatigue, anorexia, weight loss, headache, arthralgia and generalized aching. Local infection of various organs may occur
Laboratory criteria for diagnosis
• Isolation of Brucella spp. from clinical specimen or
• Brucella agglutination titre (e.g., standard tube agglutination tests: SAT>160) in one or more serum specimens obtained after onset of symptoms or
• ELISA (IgA, IgG, IgM), 2-mercaptoethanol test, complement fixation test, Coombs, fluorescent antibody test (FAT), and radioimmunoassay for detecting antilipopolysaccharide antibodies; and counterimmunoelectrophoresis (CIEP)
Suspected: A case that is compatible with the clinical description and is epidemiologically linked to suspected or confirmed animal cases or contaminated animal products.
Probable: A suspected case that has a positive Rose Bengal test.
Confirmed: A suspected or probable case that is laboratory-confirmed.
RECOMMENDED TYPES OF SURVEILLANCE
Routine surveillance must be undertaken, particularly among high-risk groups (farmers, shepherds, workers in slaughterhouses, butchers, veterinarians, laboratory personnel).
Mandatory early case-based reporting by health care providers or laboratory to upper levels of the public health sector as welt as to the appropriate level of the animal health sector. In endemic countries where investigation of all reported cases may not be feasible, a representative proportion of reported cases should be investigated routinely.
RECOMMENDED MINIMUM DATA ELEMENTS
Case-based data for investigation and reporting
• Case classification
• Unique identifier, age, sex, geographical information, occupation and ethnic group if appropriate
Date of clinical onset, date of reporting
• Exposure history
• Number of cases by case classification (probable/confirmed), age, sex, geographical area, occupation
RECOMMENDED DATA ANALYSES, PRESENTATION, REPORTS
Graphs: Number of probable/confirmed cases by month.
Tables: Number of probable/confirmed cases by age, sex, month, place.
Maps: Number of probable/confirmed cases by place.
PRINCIPAL USES OF DATA FOR DECISION-MAKING
• Estimate the magnitude of the problem in humans and animals
• Monitor the distribution of the disease in humans and animals
• Monitor and evaluate impact of prevention activities in humans, and of control/elimination measures in animals
• Identify populations at risk
• Identify potentially contaminated products of animal origin
• Identify potentially infected animal sources (herds or flocks)
The surveillance activities of both public health and animal health sectors must be fully coordinated and integrated. Administrative arrangements between the two sectors must be established to facilitate immediate cross-notification of cases, as well as joint investigations.
Surveillance and control programmes must be promoted in goat-raising areas.
See Regional Communicable Disease contacts on section "Communicable disease contacts in Regional Offices".
Headquarters: 20 Avenue Appia, CH-1211 Geneva 27, Switzerland
Communicable Diseases Surveillance and Response (CSR)
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Tel: (41 22) 791 2531/4687/2111
Fax: (41 22) 791 48 93/07 46 attn CSR