Studies on the transmission of Toxoplasma gondii. II. Note on the experimental transmission by the tick Amblyomma cajennense

Deane, M.P.

Revista Brasileira de Malariologia E Doencas Tropicais. Publicacoes Avulsas 10: 551-555


ISSN/ISBN: 0034-7256
PMID: 13848246
Document Number: 9960
This paper describes one experiment in which transmission of Toxoplasma gondii was obtained with the tick Amblyomma cajennense, possibly, through the bite. Having received some batches of A. cajennense (captured on horses sent to the Instituto Butanta, S. Paulo), the Author separated the engorged females to obtain eggs and the nymphs were allowed to develop to adult stage. Later on, 6 adult specimens that had passed through the last moult in laboratory, were placed on the belly of a clean mouse and protected by a plastic capsule and adhesive tape. Next day the mouse was inoculated with toxoplasms and, 5 days later, was dying of acute toxoplasmosis. Under their "protection", 5 of the 6 ticks were found so firmly attached to the mouse's skin that to take them out it was necessary to use ether and forceps, although none seemed to be engorged. One of the ticks was ruptured while being pulled out and was immediately triturated in saline and inoculated into the peritoneal cavity of a clean mouse. In smears made of the triturated material no blood cells or toxoplasms were found, but the inoculated mouse died in 7 days, of acute toxoplasmosis. Of the original lot, 2 ticks were triturated in saline, and inoculated into clean mice, one in the 7th day and the other in the 10th day after being taken from the corpse of the infected mouse; one of the mice, inoculated in the 10th day, died of acute toxoplasmosis 10 days later. The remaining 2 ticks, 17 days after being taken from the infected mouse, were placed on a clean mouse and "protected" in the way already described. Next day, one of the ticks was walking around under the plastic capsule and was taken away; the other was attached to the mouse's skin and thus stayed for 7 consecutive days. On the 8th day the tick was loose under the capsule and was taken away. Here again, the tick had apparently taken very little food - if any. The mouse was kept under observation and 6 days after, a small but deep necrotic area was noticed in the skin, on the spot where the tick had been attached. On the 26th day the mouse was found dead and its liver heavily parasitized by toxoplasms. Commenting on these results the Author feels sure that transmission occurred through the tick Amblyomma cajennense, since in three years work on toxoplasmosis there never was any evidence of spontaneous infection among the mice, although repeated and careful examinations have been made. As for the mechanism of transmission, the Author thinks it probably occurred through the bite, but cannot, obviously, exclude the possibility of contamination by feces or coxal fluid of the tick. The tick responsible for the transmission was found dead and dry, and thus could not be dissected. In smears of the other ticks no toxoplasms or any other similar organisms were found.

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Studies on the transmission of Toxoplasma gondii. II. Note on the experimental transmission by the tick Amblyomma cajennense