Hispid cotton rats (Sigmodon hispidus) as a source for infecting immature Dermacentor variabilis (Acari: Ixodidae) with Rickettsia rickettsii

K L Gage, W Burgdorfer, C E Hopla
Journal of Medical Entomology 1990, 27 (4): 615-9
Hispid cotton rats (Sigmodon hispidus Say and Ord) were susceptible to infection with Rickettsia rickettsii Wolbach under laboratory conditions and were capable of serving as sources for infecting ticks with rickettsiae. Cotton rats developed rickettsemias that could be detected for as long as 6 h following intraperitoneal inoculation of 10(5) plaque-forming units (PFUs) of R. rickettsii (Morgan strain). An estimate of the median infectious dose (ID50) was made by inoculating six groups (eight animals per group) with serial dilutions of 10(1) to 10(6) PFUs. In this experiment, cotton rats became infected after exposure to relatively few organisms (ID50 = 37 PFUs). None of the 48 cotton rats succumbed to infection, and only 6 of the 48 rats failed to seroconvert. Dermacentor variabilis (Say) larvae were fed on rickettsemic cotton rats to determine whether this species could serve as a source for infecting ticks with R. rickettsii. A small percentage (0.9-3.0%) of larval ticks that fed on three of the four cotton rats had R. rickettsii in their tissues when examined as nymphs. A fourth cotton rat died 7 d after inoculation with R. rickettsii and infected a much higher percentage of ticks (64.0%) than the other three animals.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"