*Rickettsiosis*, “typhus fever” is a disease that has been known since ancient times. It was first described back in the 5th century AD in Japan. In the Middle Ages, this disease was called “typhus”, since the causative agent of the disease also spread throughout the body through flea bites. This is also one of the few cases where a living tick-like creature is found - this is a rickettsia. The pathogen was discovered in 1909 by scientist Stuart Lewis (USA). Through extensive research, scientists were able to establish that this microorganism has a distinctive feature from other known types of bacteria and viruses. It does not reproduce in laboratory conditions on nutrient media, and immediately after addition it dies. To detect this harmful organism, it is necessary to use sophisticated equipment and certain conditions in which the microorganism begins to multiply. Today, doctors distinguish between several forms of the disease: acute, subacute and chronic. The number of sick people reaches almost hundreds of millions, among them men and women of all ages and professions. From an epidemic point of view, this is one of the most dangerous parasitic diseases. About twenty types of pathogens have been identified for the disease, but this does not pose a particular danger; if every fifth person is sick, it is considered an epidemic, every third person is widely spread, every tenth person is sick, this is already a disease. Germs can be transmitted through the skin and the bites of blood-sucking insects. When mosquitoes bite, they enter human skin cells with lymph, multiply there and cause disease. The pathogenesis of this type of disease has been studied in particular detail. It has been established that pathogens