Symptoms
The incubation period (i.e. the time between infection and outbreak) of brucellosis can vary considerably. It can range from 5 days to several months and years. However, it is important to know that patients can be contagious for others during the entire incubation period.
Brucellosis can be reflected in many different symptoms. In 90% of cases, infection is subclinical, i.e. without the slightest sign of disease. The fact that brucellosis is then actually present can only be determined by the detection of antibodies (antibodies against the pathogen) in the blood.
In 10% of cases, however, an acute or chronic course can also occur, either insidiously (sub-acute) or suddenly (acute) with severe fever, headaches, nausea, night sweats, fatigue and fever-free intervals of varying length. Chronic brucellosis usually affects patients whose disease has not been treated long enough or in whom the disease has simply not been detected. In this case, the main focus is on unspecific symptoms such as loss of performance, depression, sweating, inflammation of the spine and inflammation of the eyes (uveitits).
Often there is also an additional infection of bones, joints, liver or even the spleen. This often leads to the formation of inflammation foci, from which new pathogens are released again and again, so that the disease persists. Especially the infestation of the heart and its valves can have life-threatening consequences. One speaks of chronic brucellosis if the symptoms persist for at least 1 year.
Diagnosis
The diagnosis of brucellosis is often difficult and is based mainly on the determination of antibodies or DNA sequences (by PCR) from the blood. Alternatively, blood cultures can also be helpful, but are usually very difficult. If there is a suspicion of advanced infection with organ and tissue infestation, other tissues and fluids such as urine, cerebrospinal fluid, spleen, liver and bone marrow can also be examined for brucella.
Brucellosis is usually treated for 6 to 12 weeks with an antibiotic combination therapy of rifampicin and doxycycline in adults, alternatively cotrimoxazole in children or if doxycycline is not tolerated. In order to prevent a chronification of brucellosis, a therapy duration of up to 12 weeks is recommended. If neurological failures or the infestation of several internal organs are added, additional drugs such as amoxicillin or chloramphenicol may be considered. The duration of therapy should also be extended to at least 12 weeks. The impact or failure of the therapy is checked by regular blood tests.
Forecast
The course and prognosis of brucellosis depend on various factors such as the type of infection, severity, individual previous illnesses, etc. If the therapy is carried out properly, the prognosis of brucellosis is generally very good. Only in rare cases (up to 5%) does a chronicity of the disease occur, where fever intervals and organ infestation can still occur several years after initial infection. However, the lethality (mortality rate) is very low (2%). Only patients with a severe brucella melitensis infection (Malta fever) with an inflammation of the heart valves (endocarditis) are affected by a higher mortality rate.