2012-05-19
Tick testing using PCR method
Castor bean tick (Ixodes ricinus) is a small, temporarily parasitizing arachnid, feeding with blood of many wild and domestic animals and humans. His life cycle is rather complicated: egg, larva, nymph, ephebic tick (imago). It feeds once in every cycle stage. Tick feeds only during worm season of the year (from March to November), and winters afterwards. Duration of bloodsucking is from two days to one week. Ticks are found in the forests, parks and scrubs.
Morphological, physiological and biochemical feature of ticks differ from other insects, And therefore they can transmit viral, rickettsial and bacterial diseases. The most common and well-known tick-borne diseases are Lyme disease and tick-borne encephalitis.
Lyme disease is caused by human pathogenic agent, Borellia burgdorfery sensulata, belonging to Spirocheta family. It is very long spiral bacteria, possessing linear chromosome and up to 20 mini-chromosomes. Bacterium access tick with blood, e.g., from mice, and remains in its alimentary tract or access other organs. When ticks sucks blood at least 24-48 ours, bacteria from tick’s alimentary tract through insect’s saliva pass into person’s bloodstream. According to research data, in Lithuania approximately 6,9% of ticks are infected B. burgdorferi s.l., and in various regions infectiousness rates from 0% to 33%.
In order to learn if bloodsucking tick is infected with borellia, it should be examined. Only intact and whole tick could be examined, and therefore tick should be removed very carefully. Tick is removed using pincers or special device; available in drugstores (dense fabric or sheet of paper also could be used). Tick should be grasped as close to the skin as possible and gently moved to and fro in order to untack it and slowly pull it until skin surface forms “pavilion”. Tick should be held in this position for a few seconds, rotated it counterclockwise and carefully removed. Bite place should be disinfected with alcoholic solution. Removed alive tick should be put into vial together with leaf of grass; vial is closed with cotton and gauze and stored in refrigerator. Tick should be delivered to laboratory as soon as possible till it is alive. Removed tick also could be put into small container with 40%-96% ethyl alcohol. Tick prepared in such a manned could be stored longer.
In SORPO medical research center tick will be removed in professional and ably way. In the laboratory of SORPO medical research center B. burgdorferi is determined using molecular method of polymerase chain reaction (PCR). B. burgdorferi DNA fragment is amplified. When “positive” result is obtained, it means that tick was infected with Lyme disease causative agent B. burgdorferi.
Ticks for testing are accepted every day. Test is performed twice a week.