188 EDWIN R. SQUIERS AND WARREN A. WISTENDAHL Vol. 76

BRIEF NOTE Transovarial transmission by Derma- centor andersoni was not observed, while TRANSMISSION EXPERIMENTS transstadial transmission occurred spar- WITH BAB ESI A MICROTI (GRAY ingly. The hamsters were infested at STRAIN) USING DERM ACEN TOR 1 parasitaemias ranging from 8% to 71% ANDERSON I STILES AS A VECTOR. in order to determine if the parasite load had any effect in Babesia infectivity to , but this factor did not influence Interest in has been infectivity. Out of 21 transstadial stimulated recently by the observation of and 13 transovarial transmission at- a number of Babesia infections in humans tempts, two instances of stage-to-stage (Scholtens et al, 1968; Fitzpatrick et at, transmission from the nymph to the 1968; Western et al, 1970; Anderson et al, adult occurred (table 1). Adult ticks 1974). The ticks of the genus which had fed on infected hamsters as are very common in the United States nymphs were placed on clean hamsters 7 and, as the larvae and nymphs of these days after molting and infection was ticks commonly feed on rodents (Bishopp detected in the hamsters 4 days after and Trembley, 1945), we considered them infestation. likely candidates as vectors of Babesia Transmission was not observed in microti and we undertook to determine if, groups 1 and 3 (table 1). It is possible in fact, Dermacentor andersoni could that the ingested parasites, if they in- transmit Babesia microti. fected the ticks either did not reach the The ticks were fed on Golden Syrian salivary glands or the ovaries. There is hamsters. Feeding was carried out within also the possibility that the parasites were a chamber constructed from a plastic cap not infective for these ticks. In order to which had its lip placed against the ham- determine which situation occurred, week- ster's abdomen and a hole cut in the old nymphs, fed on infected hamsters as other end. The cap was held in place with larvae, were ground in physiological saline an adhesive tape belly band. The ticks and injected intra-muscularly into a were placed in the chamber through the hamster. The blood of the hamster was hole in the cap and then a plastic lid was monitered for parasites by the Giemsa placed over the hole and secured with method for 1 month, but the hamster did a water-proof adhesive tape band. not develop . Extracts of week- old eggs and larvae from ticks which had !Note received April 13, 1976 (#76-37). fed on infected hamsters as adults were No. 4 TRANSMISSION OF BABERIA 189

TABLE 1 Attempts of transstadial (Groups 1 and 2) and transovarial {Group 3) transmission of Babesia microti (Gray Strain) by larval (Group 1), nymphal (Group 2) and adult ticks (Group 3) fed on infected hamsters.

Feeding on Feeding uninfected hamsters No. of Group on infected - - transmissions* hamsters No. of Instar hamsters

1 Larvae Nymphs 4 0 Adults 5 0 2 Nymphs Adults 7 2 Larvae 5 0 3 Adults Larvae 9 0 Nymphs 4 0

*Transmission was indicated by babcsiosis in clean hamsters on which adult ticks fed. also prepared and injected into hamsters. Babesia microti is scapular is (Per- The hamster which received the ground sonal Communication).—U. EDWARD larvae did not develop the disease during GENGA AND JULIUS P. KREIER. a month of observation. The hamster Department of Microbiology, The Ohio which received the ground eggs died in 3 State University, Columbus, Ohio 43210. days apparently from egg toxicity (Stein- LITERATURE CITED haus, 1942). Anderson, A. E., P. B. Cassady and G. R. Since the two instances of transstadial Healy. 1974. Babesiosis in man: Sixth docu- transmission occurred between nymphs mented case. Amer. J. Clin. Path. 62: 612- 618. and adults, and as Dermacentor ander- Bishopp, F. C. and H. L. Trembley. 1945. soni is a three-host tick, the adults of Distribution and hosts of certain North which usually infest large , it is American ticks. J. Parasitol. 31: 1-56. probable that D. andersoni is not an im- Fitzpatrick, J., C. Kennedy, M. McGeon, D. Oreopoulos, J. Robertson and M. Sayannuna. portant vector for the transmission of 1968. Human case of piroplasmosis (babesio- Babesia microti among rodents. As the sis). Nature 217: 861-862. adults of this tick often feed on humans, Scholtens, R., E. Graff, G. R. Healy and N. it is possible that this tick may be a Gleason. 1968. A case of human babesiosis vector for the transmission of rodent in a man in the United States. Amer. ]. Trop. Med. Hyg. 17: 810-813. babesiosis to humans. Epidemiological Steinhaus, E. A. 1942. Note on a toxic prin- and laboratory work by Andrew Spielman cipal in eggs of the tick Dermacentor ander- (Dept. of Tropical Health, Harvard soni Stiles. Pub. Health Rep. 57: 1310-1312. School of Public Health, Boston) on Western, G. W., G. Benson, N. Gleason, G. R. Healy and M. Schultz. 1970. Babesiosis Nantucket Island, Massachusetts indi- in a Massachusetts resident. New Eng. J. cates that the major vector there for Med. 283: 854-856.