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Diagnosis of leptospirosis
Last reviewed: 03.07.2025
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Diagnosis of leptospirosis is based on the study of the epidemiological anamnesis. It is necessary to take into account the patient's profession (agricultural worker, hunter, veterinarian, exterminator), as well as contact with wild and domestic animals. It is necessary to pay attention to whether the patient swam in open water bodies, since the contamination of water with leptospires in some regions is extremely high.
The diagnosis of leptospirosis is established on the basis of characteristic clinical symptoms: acute onset, hyperthermia, myalgia, facial flushing, combined liver and kidney damage, hemorrhagic syndrome, acute inflammatory changes in the blood.
[ Laboratory diagnostics of leptospirosis
Laboratory diagnostics of leptospirosis involves the use of bacterioscopic, bacteriological, biological and serological studies. In the first days of the disease, leptospira are detected in the blood using dark-field microscopy, later in the urine sediment or cerebrospinal fluid.
More reliable results can be obtained by sowing blood, urine or cerebrospinal fluid on nutrient media containing blood serum, although this method takes time, since, as already mentioned, leptospires grow rather slowly. Primary sowings of blood, urine, and organ tissues suspected of containing leptospires are recommended to be kept at a temperature of 37°C for the first 5-6 days, and then at 28-30°C.
The biological method involves infecting animals: mice, hamsters and guinea pigs, but recently this method has gained many opponents who consider it inhumane.
The most informative are serological methods, in particular the microagglutination reaction recommended by WHO. A positive result is considered to be an increase in the antibody titer of 1:100 or higher. The Dutch modification of leptospira RAL is also used. Antibodies appear late, not earlier than the 8th-10th day of illness, so it is advisable to examine paired sera taken at intervals of 7-10 days.
Differential diagnosis of leptospirosis
Differential diagnostics of leptospirosis is carried out with viral hepatitis and other infectious diseases, in which jaundice is observed (malaria, yersiniosis). Unlike viral hepatitis, leptospirosis begins acutely, with a high temperature, against which jaundice occurs. The patient can name not only the day, but also the hour of the disease. In icteric forms of leptospirosis, increasing anemia is characteristic. Against the background of jaundice, hemorrhagic syndrome and phenomena of renal failure develop. In the presence of meningeal syndrome, it is necessary to differentiate leptospirotic meningitis from serous and purulent meningitis of other ethnology, in the presence of hemorrhagic syndrome - from hemorrhagic fever, in renal failure - from HFRS.
Differential diagnostics of leptospirosis with anicteric forms is carried out with influenza and rickettsiosis.