01693nas a2200193   4500008004100000245012400041210006900165260000800234300001100242490000700253520110000260100001501360700001601375700001501391700001401406700001701420700001801437856004401455       2000                        eng d00aInfection of aquatic insects with trematode metacercariae carrying Ehrlichia risticii, the cause of Potomac horse fever0 aInfection of aquatic insects with trematode metacercariae carryi  cJul  a619-250 v373 aWe provide evidence of Ehrlichia risticii Holland, the agent of Potomac horse fever, in trematode stages found in aquatic insects collected from a pasture stream in northern California, using nested polymerase chain reaction (PCR) amplification and sequence analyses of the 16S rRNA, 51 kDa major antigen and groEL heat shock protein genes. E. risticii was detected in metacercariae found in the immatures and adults of the following insects: caddisflies (Trichoptera), mayflies (Ephemeroptera), damselflies (Odonata, Zygoptera), dragonflies (Odonata, Anisoptera), and stoneflies (Plecoptera). The prevalence of E. risticii was 31.9% (n = 454 individuals) in aquatic insects (13 of 17 species were positive). Prevalence within orders was as follows: 43.5% (n = 207) in caddisflies, 15.2% (n = 92) in mayflies, 13.9% (n = 115) in damselflies, 10.0% (n = 10) in dragonflies, and 80.0% (n = 30) in stoneflies. This study demonstrates a broad intermediate host range for trematodes that act as vector for E. risticii. Insects are likely to play an important role in the epidemiology of this disease.1 aChae, J, S1 aPusterla, N1 aJohnson, E1 aDerock, E1 aLawler, S, P1 aMadigan, J, E  uhttps://odonatas.myspecies.info/node/68