# Predictive Model of Lyme Disease Epidemic Process Using Machine Learning Approach
## 2 Background  
### Lyme Disease Epidemiology  
Lyme disease is caused by bacteria that belong to the _Spirochaetaceae_ family of the _Borrelia_ genus. These are gram-negative spirochetes, able to move quickly with the help of flagella. More than 20 Borrelia genospecies belonging to _Borrelia burgdorferi sensu lato_ are currently distinguished by differences in DNA nucleotide sequences with a complex genomic structure. The pathogenic genospecies are _B. burgdorferi_ ss, _B. garini_, _B. afzelli_, _B. bavariensis_, and a new genospecies, _B. mayonii_, has recently been identified, the significance of which is being studied [9; 10]. The division of the pathogen into genomic groups is of clinical importance [11]. Thus, _B. burgdorferi_ ss is associated with a predominant lesion of the joints, _B. garini_--with the development of meningoradiculitis, _B. afzelli_--with skin lesions. The pathogenicity of other Borrelia to humans requires further study. All genotypes are unevenly distributed within the world nosoareal of this infection. _B. burgdorferi_ sl and _B. mayonii_ mainly circulate in the USA, while _B. afzelli_, _B garini_, _B. burgdorferi_ ss, and _B bavariensis_ circulate in Europe [9]. The natural reservoir of Borrelia in nature is wild animals--rodents, marsupials, deer, birds, etc. Dogs and farm animals--sheep, goats, and cattle--can also be reservoirs. Ixodid ticks support the circulation of the pathogen in nature. The principal epidemiological significance as a vector of borelia in Europe is the ticks _Ixodes ricinus_, _I. persulatus_, in the USA--_I. scapularis_, _I. pacificus_ are vectors of _B. burgdorferi_ sl in the western coastal areas. In addition, pathogens can transmit some types of ticks from the genera _Amblionma_, _Dermancettor_, _Haemphysalis_, and _Ripiccephalus_[12]. Transphase transmission of Borrelia has been established in vectors--independently living stages: larva--nymph--imago. Transphase transmission is carried out by 5% of female ixodid ticks, in which Borrelia penetrate the salivary glands and the reproductive apparatus. However, the infectivity of larvae from such females is very high and reaches 60-100%. From 7-9 to 24-50% of ticks in the epidemic focus can be infected simultaneously by two or three different Borrelia. On average, in Europe, 12% of nymphal and 15% of imago _I. ricinus_ ticks are infected with _B. burgdorferi_ sl, and 2-3% of people develop Lyme borreliosis after a tick bite [12]. An infected person is not a source of the pathogen for humans. Infection of a person occurs mainly due to the suction of a tick, in the saliva of which the causative agent of Lyme disease is located. Ticks are often attached to a person's clothing in a forest or meadow when in contact with tall grass. Ticks can be brought into dwellings (tents, buildings), remaining on clothes and things, with a bouquet, fresh hay, firewood, and animals (for example, dogs), and only after a few days go to humans. It takes 1-2 h from the moment a tick crawls onto a person's clothes until the start of bloodsucking. The suction of the tick is usually painless. Saliva contains analgesic, vasodilating, and anticoagulant substances. Ticks most often stick in places with thin skin and abundant blood supply (neck, chest, armpits, inguinal folds, in children--the scalp). A person feels itching at the site of tick suction only after 6-12 h and later. The blood saturation of female ixodid ticks can last up to six to eight days. Transmission of Borrelia is also possible by rubbing tick feces, scratching the skin, and/or the mechanical transfer of Borrelia into microtraumas of the skin and/or conjunctiva of the eyes when ticks are accidentally crushed during their removal from animals (dogs). The incubation period for Lyme disease is two to 30 days, usually 10 to 14 days. With the saliva of an infected tick, Borrelia gets into the skin and multiplies within a few days, then spreads to other areas of the skin and internal organs (heart, brain, joints, etc.).