Brucellosis

BRUCELLOSIS :• Undulant fever• Malta fever• Mediterranean fever

Identification

• A systemic bacterial disease of acute onset, with irregular fever of variable duration; headache; weakness; profuse sweating; chills; arthralgia; depression; weight loss and generalized aching.

• Osteoarticular complications occur in 20%–60% of cases.

• Genitourinary involvement is seen in 2%–20% of cases.

• The case-fatality rate of untreated brucellosis is 2% or less and usually results from endocarditis caused by Brucella melitensis infections.

• Part or all of the original syndrome may reappear as relapses.

• A neurotic symptom complex is sometimes misdiagnosed as chronic brucellosis.

• Laboratory diagnosis is through appropriate isolation of the infectious agent from blood, bone marrow or other tissues, or from discharges.

• Current serological tests allow a precise diagnosis in over 95% of cases, but it is necessary to combine a test (Rose Bengal and seroaglutination)detecting agglutinating antibodies (IgM, IgG and IgA) with others detecting non-agglutinating antibodies (Coombs–IgG or ELISA-IgG) developing in later stages.

Infectious agents

• Brucella abortus, biovars 1–6 and 9• B. melitensis, biovars 1–3• B. suis, biovars 1–5• B. canis.

• Reservoir• Cattle, swine, goats and sheep.

Occurrence• Worldwide, especially in Mediterranean countries (Europe and Africa),

Middle East, Africa, central Asia, central and South America, India, Mexico.

• Sources of infection and responsible organism vary according to geographic area. Brucellosis is predominantly an occupational disease of those working with infected animals or their tissues,especially farm workers, veterinarians and abattoir workers; hence it is more frequent among males.

• Sporadic cases and outbreaks occur among consumers of raw milk and milk products (especially unpasteurized soft cheese) from cows, sheep and goats.

Mode of transmission

• Contact through breaks in the skin with animal tissues, blood, urine, vaginal discharges, aborted fetuses and especially placentas.

• ingestion of raw milk and dairy products (unpasteurized cheese) from infected animals.

• Airborne infection occurs in pens and stables for animals, and for humans in laboratories and abattoirs.

Incubation period

• Variable and difficult to ascertain; usually 5–60 days; 1–2 months commonplace; occasionally several months.

Period of communicability

• No evidence of person-to-person communicability.

Susceptibility

• Severity and duration of clinical illness vary. Duration of acquired immunity uncertain.

Methods of control

• The control of human brucellosis rests on the elimination of the disease among domestic animals.

Preventive measures1) Educate the public (especially tourists) regarding the risksassociated with drinking untreated milk or eating productsmade from unpasteurized milk.

2) Educate farmers and workers in slaughterhouses, meat processing plants and butcher shops as to the nature of the disease and the risk in handling carcases and products from potentially infected animals.

3) Educate hunters to use protective outfits (gloves, clothing) in handling feral swine and to bury the remains.

4) Search for infection among livestock by serological testing and by ELISA or testing of cows’ milk eliminate infected animals.

5) Pasteurize milk and dairy products from cows, sheep and goats.

6) Exercise care in handling and disposal of placenta, discharges and fetuses. Disinfect contaminated areas.

Control of patient, contacts and the immediate environment

1) Report to local health authority: Case report obligatory in most countries.

2) Immmunization of contacts: Not applicable.

3) Investigation of contacts and source of infection: Trace infection to the common or individual source, usually

infected domestic goats, swine or cattle, or raw milk or dairy products from cows and goats. Test suspected animals and remove reactors.

4) Specific treatment: A combination of rifampicin (600–900mg daily) or streptomycin (1 gram daily), and doxycycline(200 mg daily) for at least 6 weeks is the treatment of choice.

In severely ill toxic patients, corticosteroids may be helpful.Tetracycline should preferably be avoided in children under7 to avoid tooth staining.

Trimethoprim-sufamethoxazole is effective, but relapses are common (30%). Relapses occur in about 5% of patients treated with doxycycline and rifampicin and are due to sequestered rather than resistant organisms.

Epidemic measures

• Search for common vehicle of infection, usually raw milk or milk products, especially cheese, from an infected herd.

• Recall incriminated products.

• stop production and distribution unless pasteurization is instituted.

International measures

• Control of domestic animals and animal products in international trade and transport.

• WHO Collaborating Centres.