How can ticks become infected with the Lyme bacteria?
Ticks have a three stage lifecycle – larva, nymph and adult – usually over two to three years, and they feed only once during each stage. Larvae are rarely infected with Lyme bacteria when they are newly hatched, but may become infected during their first feed, usually taken on a small mammal such as a field mouse or bank vole, or a ground feeding bird, e.g. a blackbird or pheasant. If the feeding host carries the Lyme bacteria (i.e. it is a “reservoir host”) the larva can take in the infection during its blood meal. It then drops off the host, returning into the undergrowth for many months until it matures into a nymph, when it will again seek a blood meal. If an infected nymph feeds on an uninfected animal or bird, it can transmit the infection, and this second host then becomes a “reservoir host”. In this way, the infection is maintained in nature. If the nymph is uninfected this second feed provides another opportunity for it to acquire the infection. Following the feed the nymphs