I. scapularis has a two-year life cycle, during which time it passes through three stages: larva, nymph, and adult. The tick must take a blood meal at each stage before maturing to the next. Deer tick females latch onto a host and drink its blood for four to five days. After she is engorged, the tick drops off and overwinters in the leaf litter of the forest floor. The following spring, the female lays several hundred to a few thousand eggs in clusters. Transtadial (between tick stages) passage of Borrelia burgdorferi is common. Vertical passage (from mother to egg) of Borrelia is uncommon.
Ticks are very hardy creatures and I. scapularis is no exception. Expect them to be active even after a moderate to severe frost, as daytime temperatures can warm them enough to keep them actively searching for a host. In the spring, they can be one of the first invertebrates to become active. Deer ticks can be quite numerous and seemingly gregarious in areas where they are found.
As Disease Factor
Ixodes scapularis is the main vector of Lyme disease in North America. It can also transmit other Borrelia species, including Borrelia miyamotoi.
Ixodes ticks also can transmit Ehrlichia, a gram-negative obligate intracellular bacteria that is responsible for Ehrlichiosis.
Ticks that transmit Borrelia burgdorferi to humans can also carry and transmit several other parasites, such as Theileria microti and Anaplasma phagocytophilum, which cause the diseases babesiosis and human granulocytic anaplasmosis, respectively. Among early Lyme disease patients, depending on their location, 2%–12% will also have HGA and 2%–40% will have babesiosis.
Co-infections complicate Lyme symptoms, especially diagnosis and treatment. It is possible for a tick to carry and transmit one of the co-infections and not Borrelia, making diagnosis difficult and often elusive. The Centers for Disease Control’s emerging infectious diseases department did a study in rural New Jersey of 100 ticks, and found 55% of the ticks were infected with at least one of the pathogens.
Ticks of Domestic Animals
Ticks of domestic animals directly cause poor health and loss of production to their hosts by many parasitic mechanisms. Ticks also transmit numerous kinds of viruses, bacteria and protozoa between domestic animals. These microbes cause diseases which can be severely debilitating or fatal to domestic animals, and may also affect humans. Ticks are especially important to domestic animals in tropical and subtropical countries. Here the warm climate enables many species of ticks to flourish. Also the numerous wild animals in warm countries provides a reservoir of ticks and infective microbes that spread to domestic animals. Farmers of livestock animals use many methods to control ticks and there are related treatments to reduce infestation of companion animals. Veterinarians and animal health agencies work at private, national and international scales to reduce the harm caused by ticks and their associated diseases.