Infectious

Brucellosis (Undulant fever—Malta fever—Mediterranean fever)

Identification-
Identification- a systemic bacterial disease of acute or insidious onset; with fever, headache, weakness, profuse sweating, chills, arthralgia, depression, weight loss, and generalized aching.
localized suppurative infections of organs
chronic localized infections
subclinical disease
The disease may last days, months, or occasionally a year or more if not adequately treated.

Identification-

Osteoarticular complications occur in 20%-60%.
Genitourinary involvement seen in 2%-20%.
Neurobrucellosis occurs in 3%-7%.
The case fatality rate of untreated brucellosis is 2%.
Part or all of original syndrome may reappear as relapses.
A neurotic symptom complex is sometimes misdiagnosed as chronic brucellosis.

Identification-

laboratory diagnosis
Isolation of infectious agent from blood, bone marrow, or other tissues, or discharges.
Serological tests (Rose Bengal and sero agglutination) with other tests (Coombs –IgG or ELISA-IgG) .These methods do not apply to B.canis.



Epidemiology
Infectious agent. Brucella abortus, biovars 1-6 and 9; B.melitensis biovars 1-3; B.suis biovars 1-5; and B.canis.

Epidemiology

Occurrence.
Worldwide, especially Mediterranean countries (Europe and Africa), the Middle East, Africa, central Asia, central and South America, India, and Mexico.
Sources of infection and responsible organism vary according to geographical area.
Cases are increasingly documented in non-endemic areas due to international travel

Epidemiology

Brucellosis is an occupational disease
Another major risk factor for cases and outbreaks is consumption of raw or unpasteurized milk and milk products

Epidemiology

Isolated cases of infection with B. canis occur in animal handlers .The disease is often unrecognized and unreported.
Rare cases of marine-associated brucella species reported.
Brucellosis remains among the most common laboratory acquired bacterial infections.

Epidemiology

Reservoir
Cattle, swine, goats and sheep.
Dog
Coyotes
Marine mammals


Epidemiology
Mode of transmission
Contact through breaks in the skin

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

Airborne infection.

Accidental self-inoculation with vaccine.

Epidemiology
Incubation period:
Commonly 1-2 months

Epidemiology

Period of communicability
Rare person to person transmission.

Epidemiology

Susceptibility –
severity and duration of clinical illness vary.
Duration of acquired immunity uncertain


Preventive measures
Preventive measures
Health education of the public

Health education of farmers and workers in slaughterhouses, meat processing plants and butcher shops

Health education of hunters

Preventive measures

• Search for infection among livestock by serological testing and by ELISA or testing of cows "milk (ring test); eliminate infected animals (segregation and /or slaughtering).Infection among swine usually requires slaughter of the herd. in high prevalence area immunize young goats and sheep with live attenuated Rev-1strain of B.melitensis ,and immunize calves and sometimes adult animals with strain 19 ,B.abortus .Since 1996 ,strain RB51 of B.abortus has largely replaced strain 19 for immunization of cattle .RB51 was designed to be less virulent for human when accidentally injected .

Preventive measures

• Rev-1 is resistant to streptomycin, and RB51 is resistant to Rifampicin. This must be taken in consideration when treating human cases of animal vaccine infection.
• Pasteurize milk and dairy products from cows, sheep and goats. Boiling milk is effective when pasteurization is impossible. Do not eat meat from animals that appear ill.
• Exercise care in handling and disposable of placenta, discharges and fetuses. Disinfect contaminated areas.

Control measures

Control of patients, contacts and immediate environment

Report to local health authority –obligatory in most countries. Class 2.

Isolation: Draining and secretion precautions if there are draining lesions; otherwise none.
Concurrent disinfection: Of purulent discharges.
immunization of contacts : Not applicable


Control measures
Specific treatment: combination of doxycycline (200mg daily) and Rifampicin (600-900mg daily) or streptomycin (1gm daily) for at least 6 weeks. Relapses occur in 5%-15% of cases due to sequestered rather than resistant organisms. Monotherapy should be avoided as relapses can be as high as 50%. Arthritis may occur in recurrent cases.

Control measures

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
Disaster implications: None

Control measures

International measures:
Control of domestic animals and animal products in international trade and transport .WHO collaborating centers provide support as required

Control measures

Measures in the case of deliberate use:
The potential to infect humans and animals through aerosol exposure, combined with a low infectious dose of 10-100 organisms, is such that Brucella species may be as a potent biological weapon.