Survival of Rickettsia conori in nymphal Rhipicephalus sanguineus ticks at different temperatures
Injeyan, H.S.; Sweatman, G.K.; Matossian, R.M.
Journal of Medical Entomology 8(4): 372-378
1971
ISSN/ISBN: 0022-2585 PMID: 5159249 Document Number: 43853
The following is substantially the authors' abstract. The availability of Rickettsia conori tonymphs of Rhipicephalus sanguineus (Latr.) feeding on infected guineapigs was observed at different intervals throughout the engorgement period, and the survival of the rickettsiae in nymphs from the time of engorgement to ecdysis was demonstrated at different temperatures. The presence of rickettsiae in the nymphs was determined by observing the clinical and serological responses of guineapigs into which known numbers of triturated nymphs were injected. A moderately heavy single dose of rickettsiae produced a 4- to 6-day fever in guineapigs, while infective concentrations of rickettsiae circulated for three days, as shown by the injection of their blood into other guineapigs. The engorgement period of the nymphs was 72 h or a little longer. Nymphs that were allowed to feed for only 24 h on a guineapig at the time of peak fever and rickettsaemia did not apparently imbibe rickettsiae. Only some of the nymphs that fed for a further 12 h acquired rickettsiae, while feeding periods of 48-72 h gave adequate rickettsial uptake. Rickettsia conori lived in engorged ticks at 15 degrees C, a temperature too low for nymphal ecdysis, and appeared well adapted to temperature conditions (20-35 degrees C) suitable for ecdysis. The strongest clinical and serological response was produced when adult ticks resulting from nymphs that had been held at 35 degrees C from the time of engorgement until the moult were injected into a guineapig.