It is a skin infection caused by a single-celled parasite that is transmitted by sandfly bites.
Robert Killick-Kendrick (20 July 1929 – 22 October 2011) was a British parasitologist with interests in the vectors of infectious diseases, in particular phlebotomine sandflies
This is the mechanism by which many Rickettsiae are maintained in their arthropod hosts through generations, which occurs also in aedes mosquito vector of the yellow fever virus and in phlebotomine sandflies that transmit pappataci fever.