Brucellosis

Tiny germs can make people and animals sick.

These germs live in cows, pigs, goats, and dogs. You can get sick from drinking raw milk.

Eating soft cheese made from this milk can also make you sick. People who work on farms might catch it too. It can make your muscles and joints feel very sore. It can also make you sweat a lot at night. This sickness can last for a long time. It is important to cook meat well. You can stay safe by drinking milk that is treated with heat. This helps kill the tiny germs.

Brucellosis is a sickness caused by tiny germs. These germs are called Brucella. They are small, rod-shaped bacteria.

Some types of these germs live in cattle. Others live in pigs or dogs. One type lives in goats. This type is very strong. It can make people very sick.

People can get sick in a few ways. You might drink raw milk. You might eat soft cheese made from raw milk. Some people catch it at work. This includes farmers and vets. You can also get it from wild animals. This happens if you touch them or eat undercooked meat.

When you are sick, you might feel many things. You may have a fever. You might sweat a lot at night. Your muscles and joints can feel very sore. Some people feel sick to their stomach. They may lose weight or feel weak. This sickness can last for a long time. To stay safe, drink milk that has been pasteurized. This means the milk was heated to kill germs. Always cook meat well.

Brucellosis is a disease caused by tiny living things called bacteria. These germs belong to a group named Brucella. They are very small and shaped like little rods.

People often call this sickness undulant fever or Malta fever. It is a zoonosis, which means it spreads from animals to humans. This disease matters because it can last a very long time. It might stay in a person's body for many months or even years.

There are four main types of these bacteria. B. abortus lives in cattle, while B. canis affects dogs. B. suis lives in pigs and has a medium strength. The most powerful type is B. melitensis, which usually infects goats or sheep.

People usually get sick by drinking unpasteurized milk. This is milk that has not been heated to kill germs. Eating soft cheeses made from raw milk is also a risk. Some people catch it at work by touching animals or breathing in germs.

Doctors have studied this sickness for a long time. It has been known in both animals and humans since the early 20th century. Scientists use special tests to find the germs in a person. They might look for antibodies, which are parts of the body that fight germs. They can also grow the bacteria in a lab using special liquids.

This process is very slow and can take two months. Doctors must be very careful because the germs are highly infectious.

When a person gets sick, they often feel many different things. A common sign is a fever that comes and goes. Many people also have heavy sweating at night. This sweat might even have a strange, moldy smell like wet hay.

Muscles and joints can become very painful. Some people feel sick to their stomach or lose weight. In some cases, the sickness can move to the bones or the liver.

We can prevent this sickness by being careful with food and animals. One of the best ways is to drink pasteurized milk. This means the milk was heated to make it safe. Farmers can also give vaccines to their livestock to keep them healthy.

People who work with animals should wear protective clothing. This includes gloves and other gear to stay safe. Even wild animals like bison and deer can carry these germs. Staying safe means cooking meat well and washing hands often.

Brucellosis is a significant zoonotic disease, meaning it spreads from animals to humans. It is caused by a group of small, rod-shaped bacteria known as *Brucella*. These bacteria are classified as Gram-negative, nonmotile, and nonspore-forming coccobacilli. Because they act as facultative intracellular parasites, they can live inside host cells. This characteristic often leads to chronic infections that may persist for a person's entire life.

There are four primary species of *Brucella* that infect humans. *B. abortus* is primarily a disease of cattle and is considered less virulent than other types. *B. canis* is the species that affects dogs. *B. suis* infects pigs and possesses an intermediate level of virulence. The most invasive and virulent species is *B. melitensis*, which typically infects goats and occasionally sheep.

Transmission occurs through several specific pathways. The most common method is the ingestion of unpasteurized milk or soft cheeses made from infected animals. Many people also contract the disease through occupational exposure. This includes veterinarians, slaughterhouse workers, and laboratory personnel. Humans can also be infected by direct handling of infected animals or through aerosol exposure. Hunters are at risk when field-dressing carcasses or consuming undercooked wild game meat.

In the first stage of infection, bacteremia occurs, which is the presence of bacteria in the blood. This often leads to a classic triad of symptoms: undulant fevers, profuse sweating, and migratory arthralgia and myalgia. The sweating can sometimes have a distinct, foul, or moldy smell similar to wet hay. Gastrointestinal symptoms occur in approximately 70% of cases. These include nausea, vomiting, abdominal pain, and unintentional weight loss. The disease can also cause an enlarged liver or an enlarged spleen.

If the infection is left untreated, it can lead to serious complications called focalizations. These often occur in the bones and joints. Specific conditions include osteomyelitis, which is bone inflammation, or spondylodiscitis of the lumbar spine. Other severe consequences include meningitis, endocarditis, and various neurological disorders known as neurobrucellosis. In men, orchitis is also a common complication.

Diagnosing brucellosis requires several specialized medical tests. Doctors may attempt to isolate the bacteria through blood cultures or bone marrow cultures. However, *Brucella* grows extremely slowly and can take up to two months to appear in a culture. Because the bacteria are highly infectious, this poses a risk to laboratory staff. Clinicians also use serological tests to detect antibodies. These include the Rose Bengal plate test, the Huddleson reaction, and the Wright reaction.

Modern diagnostic tools like the ELISA test measure specific antibodies with high sensitivity. Polymerase Chain Reaction, or PCR, is another fast method used to detect the infection. While PCR is highly specific, some centers report persistent positivity even after successful treatment. Prevention relies heavily on controlling the disease in animal populations. This includes the use of livestock vaccines, such as *B. abortus* strain 19 or *B. melitensis* Rev-1. For humans, the most effective protections are pasteurization and the use of personal protective equipment when handling animals.