Raw diary major cause of brucellosis

Brucellosis is a highly infectious disease that is transmitted from animals to humans. It is caused by the bacterial genus Brucella. The bacteria are transmitted from animals to humans by consumption of infected food products, direct contact with an infected animal, or inhalation of aerosols. 

According to Dr Fiona Mutesi Magololo, the medical services technical lead at TASO Mulago, the disease has existed through the ages, known as Mediterranean fever, Malta fever, gastric remittent fever, and undulant fever. 

“Humans are accidental hosts, but brucellosis continues to be a major public health concern worldwide and is the most common animal-borne infection. The organism causes more than 500,000 infections per year worldwide,” she says.

The prevalence of Brucellosis in Uganda has been reported as follows; 11-20 percent for humans, 17 percent in goats and 14 percent in cattle. 

The disease in animals is characterised by abortions or reproductive failure.

While animals typically recover and will be able to have live offspring following the initial abortion, calves born from later pregnancies may be weak and unhealthy. The bacteria can survive outside the animal in the environment for several months, particularly in cool, moist conditions and remains infectious to other animals that ingest it. The bacteria also colonise the udder and contaminate the milk.

Causes and risk factors

According to the World Health Organisation (WHO), brucellosis is a bacterial disease caused by various Brucella species, which mainly infect cattle, swine, goats, sheep and dogs. Humans generally acquire the disease through direct contact with infected animals by eating or drinking contaminated animal products or by inhaling airborne agents. Most cases are caused by ingesting unpasteurised milk or cheese from infected goats or sheep.

“The disease is also considered an occupational hazard for people who work in the livestock sector. People who work with animals and are in contact with blood, placenta, foetuses and uterine secretions have an increased risk of contracting the disease. This method of transmission primarily affects farmers, butchers, hunters, veterinarians and laboratory personnel. However, human-to-human transmission is very rare,” WHO states. 

Brucella is spread through consumption of or close contact with infected animal products. The organisms are shed in large numbers in the animal’s urine, milk, placental fluid, and other fluids. 

The bacteria can also enter through a cut or wound on the skin if the person touches an animal infected with the disease or touches its aborted foetus.

Dr Magololo says Brucellosis is found in many domestic animals as well as camels, reindeer, rabbits and some wild animals that exist in herds. 

“Humans have only a limited risk from wild animals, mainly because of lack of proximity and infrequent use of milk and meat products from these animals,” she adds.

Signs and symptoms

According to Dr Franklin Wasswa, a general physician at Entebbe Grade B Hospital, there is usually an overlap of symptoms, especially with malaria or typhoid but the commonest symptoms of brucellosis include anorexia, fatigue, malaise, irregular fever, headache, weakness, profuse sweating, chills and weight loss, among others.

Bone and joint symptoms include pain in several joints, low back pain, spine and joint pain, and, rarely, joint swelling or occasionally the bacteria localises in the joints, causing arthritis.

“Headache, depression, and fatigue are the most frequently reported neuropsychiatric symptoms. Genitourinary infections with brucellae have been reported and include inflammation of one or both testicles (orchitis), urinary tract infection (UTI), and damage of the part of the kidney that filters blood,” Dr Magololo says.

Neurologic symptoms of brucellosis can include weakness, dizziness, unsteadiness of gait, and urinary retention. Cough and a feeling that you cannot get enough air into your lungs develop in up to 19 percent of persons with brucellosis. 

Treatment

The disease may be suspected based on clinical signs such as abortions, but confirmation is made through blood tests, then with prescribed laboratory tests to isolate and identify the bacteria.

Dr Magololo says in many patients, symptoms may range from mild to severe and the incubation period of the disease can vary ranging from one week to two months. 

She adds that initial care for brucellosis is supportive. However, appropriate precautions such as wearing of mask, gloves, and eye protection should be taken while handling body fluids of a person suffering from the disease. 

Antimicrobial regimens are the mainstay of therapy. Depending on what other systems are involved, more specialised care may be needed. 

Complications

Left untreated, brucellosis presents major risk factors for the development of focal complications as symptom duration is greater than 30 days before diagnosis. The most common complications include osteoarthritis, liver abscess, damage to the central nervous system by brucellosis (Neurobrucellosis), inflammation of the inside lining of the heart chambers and heart valves (Endocarditis), among other complications. 

Prevention

Prevention of brucellosis is based on surveillance and the prevention of risk factors. The most effective prevention strategy is the elimination of infection in animals.

Avoid potential sources of infection. This may involve avoiding infected animals, using stricter precautions when dealing with a potentially infected animal, and avoiding consuming potentially contaminated foods such as unpasteurised milk and milk products, as well as raw or undercooked meats.

For farmers and ranchers, immunisation of cattle against the disease is necessary. Reliable hygiene may prevent infection, especially when practiced by individuals likely to have close contact with goats, sheep, cows, camels, pigs, reindeer, rabbits, or hares. 

“Vaccination is not an option for patients; the vaccine is for animals but not for humans. However, immunisation of at-risk animals reduces the number of infected animals and, therefore, the reservoir of infection,” Dr Magololo says.

In order to reduce the risk of Brucella among livestock, Dr Halid Kirunda, the director of research at Mbarara Zonal Agricultural Research Development Institute, says vaccination of heifers between the age of four and 10 months (the animal should not be pregnant) with the Strain 19 (S-19) vaccine is one of the most effective ways of preventing the disease.

He also remarks that the disease can be prevented by using artificial insemination (since the bulls carry the bacteria from one female to another), using long arm gloves and boots during insemination and other practices that might involve touching fluids from livestock, and proper hygiene by washing hands after touching animals or their meat and milk. 

“It is important that people cook their meat at the right temperatures and for some time. The milk should also be boiled up to 100 degrees celsius in order to kill the bacteria before it is consumed,” he adds. 
Human brucellosis is best prevented by controlling the infection in animals. Pasteurisation of milk from infected animals is an important way to reduce infection in humans.

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