Preventive antibiotics
The risk of infectious transmission increases with the duration of tick attachment. It requires between 36 and 48 hours of attachment for the bacteria that causes Lyme to travel from within the tick into its saliva. If a deer tick that is sufficiently likely to be carrying Borrelia is found attached to a person and removed, and if the tick has been attached for 36 hours or is engorged, a single dose of doxycycline administered within the 72 hours after removal may reduce the risk of Lyme disease. It is not generally recommended for all people bitten, as development of infection is rare: about 50 bitten people would have to be treated this way to prevent one case of erythema migrans (i.e. the typical rash found in about 70–80% of people infected). Garden landscaping
Several landscaping practices may reduce risk of tick bites in residential yards. The lawn should be kept mowed, leaf litter and weeds removed and groundcover use avoided. Woodlands, shrubs, stone walls and wood piles should be separated from the lawn by a 3-ft-wide rock or woodchip barrier. Without vegetation on the barrier, ticks will tend not to cross it; acaricides may also be sprayed on it to kill ticks. A sun-exposed tick-safe zone at least 9 ft from the barrier should concentrate human activity on the yard, including any patios, playgrounds and gardening. Materials such as wood decking, concrete, bricks, gravel or woodchips may be used on the ground under patios and playgrounds so as to discourage ticks there.
Most infections are caused by ticks in the nymphal stage, because they are very small and thus may feed for long periods of time undetected. Nymphal ticks are generally the size of a poppy seed and sometimes with a dark head and a translucent body. Or, the nymphal ticks can be darker. (The younger larval ticks are very rarely infected.) Although deer are the preferred hosts of adult deer ticks, and tick populations are much lower in the absence of deer, ticks generally do not acquire Borrelia from deer, instead they obtain them from infected small mammals such as the white-footed mouse, and occasionally birds. Areas where Lyme is common are expanding.Within the tick midgut, the Borrelias outer surface protein A (OspA) binds to the tick receptor for OspA, known as TROSPA. When the tick feeds, the Borrelia downregulates OspA and upregulates OspC, another surface protein. After the bacteria migrate from the midgut to the salivary glands, OspC binds to Salp15, a tick salivary protein that appears to have immunosuppressive effects that enhance infection. Successful infection of the mammalian host depends on bacterial expression of OspC.Tick bites often go unnoticed because of the small size of the tick in its nymphal stage, as well as tick secretions that prevent the host from feeling any itch or pain from the bite. However, transmission is quite rare, with only about 1.2 to 1.4 percent of recognized tick bites resulting in Lyme disease.