The Uninfected Ixodes Scapularis Human Tick Challenge Model

This will be an, single centre, experimental study. The design of the study is similar to a human challenge trial, with the important exception that the subjects in this study are not experimentally infected with a pathogen, but are exposed to well-characterized laboratory-reared uninfected nymphal Ixodes scapularis ticks.

Seven healthy human volunteers of >18 years old who have no history of known tick-bites or tick-borne diseases will be recruited. Subjects will undergo three to four tick challenges, consisting of five to six days per challenge with two weeks between the consecutive challenges. The total duration of participation is approximately five months for each subject. By making use of ticks from a laboratory-reared tick colony that have been, and are being, used in xenodiagnosis and tick challenge models in the USA and that are well tolerated minimizing the risks of the tick challenges. Regardless, the tick challenge can cause some discomfort because of possible local reactions and because the dressing must be kept dry for five to six days. The risk of infection with a tick-borne pathogen is negligible due to the fact that these ticks are exhaustively tested for various known tick-borne pathogens. Finally, risks are considerated of development of a red meat allergy or other allergic reactions negligible because no clear associations are known of I. scapularis ticks and red meat allergy. No serious adverse events (such as human infections or red meat allergy) have resulted from more than >100 challenges in the United States using this tick colony. There are no direct benefits of participation.