ENTOMOLOGY

LOUSE BORNE DISEASES 295Mastigophora: Spirochaetacea: SpirochaetidaeSpiroschaudilwnia carten (Mackie) is the cause of ASIATIC RE­LAPSING FEVER. Mackie (1907) in India was the first to investigatethe transmission of relapsing fever by lice. He found a striking coincidencebetween the cases of fever among Indian school children and theprevalence of lice (Pediculus corporis). Mackie found the spirochaete in14 per cent of the lice from the boys and 2.7 per cent of the lice fromthe girls. He noted that the spirochaetes multiplied within the gut ofthe lice and that they could be found in the ovary, testis and Malpighiantubules of the insects, but did not find them in the ova laid by infectedinsects. Bisset (1914) only found Spirochaetes in the gut and coelomiccavity of the lice. The organism, Spiroschaudinrntia carteri Mackie, isconsidered as a biological species not morphologically separable from S.recurrenti8.Spiro8chaudwwa berbera (Sergent and Foley) is the cause ofNORTH AFRICAN RELAPSING FEVER. Following up Mackie'swork, Sergent and Foley (1908) in Algeria carried out experiments withlice and obtained positive results by the inoculation of a monkey (Cynomolguscynocephalus) with a single, crushed, infected louse (Pediculu8corporis). Pediculus humanus has also be,en recorded as an intermediatehost. Nicolle, Blaizot and Conseil (1912), also working in North Africa,found that when body lice were fed upon infected blood, the spirochaetesdisappeared rapidly from the insects' intestinal tract within 24 hours.On the eighth to tenth day, typical, active spirochaetes reappeared in thelice. Thousands of lice were allowed to bite monkeys and a man withonly negative results. Infection was obtained in one of the authors bycrushing an infected louse on excoriated skin, the incubation period of thefever being five days. They determined in one experiment that the infectivityof the lice was hereditarily transmitted. Eggs laid 12 to 20 daysafter the parent lice had fed on relapsing fever blood were placed at 28°C. and began to hatch on the seventh day. The young larval lice andsome unhatched eggs were now crushed and inoculated into a monkeywhich subsequently developed relapsing fever. The spirochaetes werenot discoverable mieroscopica~ in the eggs. As the result of the workof Sergent, Foley, Nicolle, Blaizot, Conseil and others, it is proven thatthe liee are infect~e, though inconstantly, up to five days after aninfective meal, and constantly on the sixth day, although during thisperiod spirochaetes are absent; on the eighth to ninth days the spirochaetesmayor may not be present and infectivity is exceptional. Afterthe spirochaetes become fully developed in the lice infectivity vanishes.They may be infective up to the fifteenth day. The apyrexial stage ofthe spirochaete in man and the developmental ~r granule stage in the