BRUCELLOSIS Razia Kausar1 DVM, 10th Semester, FVS,UAF Department


Sami Ullah Khan  and Razia Kausar1

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                                    DVM, 10th Semester, FVS,UAF

of Anatomy, FVS,UAF1

Brucellosis is an infectious, contagious and economically
important disease of primarily animals but also has zoonotic importance. OIE
has declared it as second most important zoonotic disease after rabies.
Although it has been eradicated from many developed countries like Australia,
Canada, Japan, New Zealand and European countries but it still has endemicity
in Africa, Mediterranean, parts of Asia and Latin America. In Pakistan,
prevalence of animal Brucellosis was reported only 0.33-0.65% in 1967 but
recent studies have shown increased prevalence many folds. Due to its increased
prevalence in Pakistan, there are severe hazards to human health either through
direct contact or through consumption of contaminated milk and dairy products, so
it is necessary to conduct surveillance and to devise control programs for
Brucellosis accordingly.

Objective of this article is to highlight the zoonosis,
etiology, transmission, clinical manifestations, and prevalence in Pakistan, of
Brucellosis in humans. For this purpose, knowing its features related to
animals, is an important aspect. There is also a need to know bioterrorism
potential of Brucellosis. At the end, control strategies will be discussed to
stop the increment of its prevalence in Pakistan. Being a veterinarian, it’s
our responsibility to highlight all the zoonotic threats and their control to
save not only animals’ but also human’s lives.

Causative Agent :Brucellosis is caused by Brucella abortus in cattle, Brucella
melitensis in goats, Brucella ovis in
sheep and Brucella suis in swine/pig.
In Horse, disease is caused by Brucella
abortus. In a study conducted by University of Agriculture, seroprevalence
of brucellosis in horses was found nearly 20%. 

In humans, disease is mainly caused by B. melitensis, called
“undulant fever”, “Mediterranean fever” or “Malta fever”. There are certain
measures which can be taken to prevent and treat infection in humans even in
persistence of infection in domestic animals.

 Transmission: Brucellosis is milk borne
disease, transmitted to human population due to persistence of infection in
domestic animals, expansion of International travel and lack of hygienic
measures in animal husbandry. People dealing with meat i.e. slaughter-house
workers, slaughter-men, butchers, meat packers, processors of hides, skin and
wool and veterinarians, are more susceptible, called occupational risk. In this
aspect, families of farmers and animal breeders are also at higher risk. Organism
gets entry through direct contact with infected animals or materials with skin abrasions.
Human-to-human transmission, from lactating mothers to their breastfed infants
is rare but blood donation and tissue transplantation have higher significance.
Transmission through inhalational route can be there due to contaminated dust
and dried dung. Contaminated water by recently aborted fetus or run-off rain
water from endemic areas can be source of spread for Brucellosis in human

Ingestion of fresh milk and dairy products like
butter, cream or ice-cream and cheese, is main source of transmission to human
populations. In contrast, meat products are less frequently associated with
transmission due to their consumption after proper cooking. Raw vegetables can
also be contaminated by infected animals and be a hazard. Travelling to endemic
areas and consuming contaminated foods, import the pathogen to disease-free
region. Similarly, import of animals from endemic countries, becomes source of
introducing disease in a country. Cattle, sheep, goat and camel are main
reservoirs for Brucellosis in Pakistan.

Diagnosis: In humans as well as in animals, clinical picture of
brucellosis is not specific or evident and diagnosis needs to be supported by
laboratory tests. Disease is manifested by acute or sub-acute febrile illness
usually marked by an intermittent or remittent fever that’s why called
“undulant fever” in humans. Fever is accompanied by headache, malaise,
anorexia, prostration, arthralgia and back-pain. Patients feel better in the
morning but symptoms worsen with the progression of a day.

Signs and Symptoms: A research, conducted on humans regarding symptoms,
has shown that 93% patients infected with Brucellosis had fever, 95% had lack
of energy (prostration), 87% had sweats, 91% had aches (pain),   86% had back pain, 81% had headache, 78% had
lack of appetite, and 65% had weight loss. Other sign and symptoms observed were
abdominal pain, constipation, arthritis, cough, testicular
pain/epididymo-orchitis, sleep disturbance, lymphadenopathy, splenomegaly, and
hepatomegaly. Respiratory complications including hilar & para-tracheal
lymphadenopathy, interstitial pneumonitis, bronchopneumonia, lung nodules,
pleural effusions, and empyema, have been reported in people working in
abattoirs due to inhalational route of transmission. In men, most pronounced
complications are orchitis and epididymitis. Endocarditis is major
cardiovascular complication reported in 2% people and can involve both native
and prosthetic valve, most often involving aortic valve than mitral valves.

In a case report from Morocco, complication of CNS
i.e. meningitis was seen, resembling Tuberculosis meningitis. In this report,
human patient admitted at emergency had chronic headache for 9 months with some
episodes of vomiting and intermittent fever. Tuberculosis is endemic in Morocco
but results of lumber puncture, Magnetic Resonance Imaging (MRI) and especially
serology confirmed the neuro-brucellosis, one of clinical manifestations of

Brucella can involve any of the organ system of human
body so diagnosis in human is difficult based on clinical picture. Due to wide
variety of clinical manifestations other complications include osteo-articular,
gastrointestinal, hepatobiliary, cutaneous and ophthalmic which can be seen in

Brucella is not only a zoonotic problem but also a
potential agent of Bioterrorism “intentional use or threatened use of
biological agents to hurt people, create fear or disrupt society”. Whenever, we
talk about the zoonosis “transfer of disease from animals to human” and
bioterrorism “defined earlier”, then the importance of veterinarian, as an
asset for any crisis or public health team, becomes obvious. Veterinarians have
extensive knowledge of microbiological, chemical and physical health hazards of
food animals. So veterinarians have to play major role in conducting surveillance
and devising control programs for Brucellosis.

Brucella belongs to “Category B” as a biological
weapon. Two species B. melitensis and
B. suis are potential source of
bio-terrorism and have been developed experimentally as biological weapons by
state sponsored programs but no application in a bioterrorist attack has been
reported so far. They both have higher stability in aerosol form and low
infectious dose rate. These features make them suitable for the purpose of
bio-terrorism. Chances of attack to human and animal populations are higher in
areas with low endemic rate. The organism can be obtained from natural sources
so Health and veterinary authorities should be aware of this potential source
of infection. In Pakistan, the expected prevalence of Brucella suis is negligible but B.
melitensis has higher prevalence in animals as well as humans.

Researches have been conducted in different areas of
Pakistan, for knowing the prevalence of human brucellosis. For this purpose,
serological diagnostic tests like Rose Bengal
Precipitation Test (RBPT), Standard Plate Agglutination Test (SPAT) and Serum
Tube Agglutination Test (STAT) are considered authentic but PCR (molecular
test) and ELISA are also conducted as confirmatory tests. A research conducted
in Bhimber, a district of Azad Kashmir, in a year of 2013 has shown 9.33%,
7.33% and 6% prevalence of human Brucellosis by RBPT, SPAT and STAT,
respectively. It was also concluded that prevalence was higher in females than
in males. Similar study was conducted in District Swat, KPK in a year of 2016,
which had shown 3.66%, 2% and 2.66% prevalence of B. melitensis in human by SPAT, STAT and PCR diagnostic tests,

Prevention and control: Brucellosis in
human, can only be prevented effectively by elimination of animal reservoirs.
As described earlier, this elimination necessitates an interaction between the
medical authorities concerned with public health and veterinary authorities. This
collaboration is first step in devising control programs, indicating concept of
“One-world, One-health”. For successful outcomes, all sections of community
need to be involved but provision of specialist expertise is responsibility of
medical and veterinary authorities. They are responsible for diagnosis,
treatment, surveillance and devising control programs accordingly.

Prevention of disease
in human must be based on elimination of direct and indirect contact to
infected animals and their products, which is main source of spread. This can
be achieved by personal hygiene, adoption of safe working practices, protection
of the environment and food hygiene. Use of vaccination for human has little
part in prevention of human disease. Personal hygiene includes wearing
protective clothing, disinfection of clothes after use, disinfection of
footwear, treating body cuts and wounds with antiseptics, protection of eyes by
rinsing and using eye drops, use of respirators to avoid respiratory
contamination, and serological examination after a specific period. Farm
sanitation/ adoption of safe working practices include fulfilling biosecurity
recommendations, wearing protective clothing to avoid contact with contaminated
material e.g. aborted foetus, disinfection of farm premises, incineration of
collected material in leak-proof container, vehicle tyre dipping at farm

Food hygiene include milk
hygiene and meat hygiene. Milk and its products are source of contamination so
boiling or high temperature pasteurization of milk is necessary for control of
Brucellosis in human. If pasteurization facilities are not available, heating
at 80-85 °C for several minutes is necessary to make milk safe for consumers. Transmission
of Brucella through meat is
impossible in Pakistan due to thorough or over-cooking of meat. Meat
preservation methods like drying, salting and smoking can’t kill the organism.
Never consume under-cooked meat.

Brucellosis control
in animals is directly linked with Brucellosis control in humans. There are
three types of control measures in animals:

Quarantine strategies at farm and
country level.

Sanitation and biosecurity measures at

Herd immunity through

There are three strains for vaccination programs i.e. Strain-19 (S-19), RB-51
and Rev-1. Strain-19 is used in Pakistan for vaccination which is imported
because still there is no manufacturing of Brucella vaccine in Pakistan.
Brucella vaccine is live, shouldn’t be used in pregnant animals. One of its
properties is that it should be non-pathogenic for humans.

is concluded that Veterinary department has parallel importance to the medical
department when we talk about zoonotic diseases and public health. These both
authorities have to work in collaboration, involving whole community through
public health education and training of workers, to minimize the zoonosis,
potential threats and to devise control strategies for any outbreak. The
emerging concept of “one-world, One-health” has made, importance of
veterinarians, obvious.