Interspecies transmission of Edwardsiella ictaluri in Brazilian catfish (Pseudoplatystoma corruscans) from exotic invasive fish species.

Infections caused by Edwardsiella ictaluri are one of the biggest problems in the catfish industry in North America and have been reported in fishes around the world. E. ictaluri was detected in juvenile pintado Pseudoplatystoma corruscans-a Brazilian catfish-in a farm in Paraná State, Brazil; diseased animals showed ascites and neurological signs of infection, with more than 50% mortality. Exotic invasive species susceptible to this bacterium have been reported in this area. We assessed the susceptibility of pintado to E. ictaluri with experimental infection via intraperitoneal and immersion methods as well as a cohabitation experiment with Nile tilapia Oreochromis niloticus and African walking catfish Clarias gariepinus, 2 exotic invasive species. All pintados challenged by intraperitoneal and immersion routes and those cohabiting with infected C. gariepinus died within 17 d of the challenge. Mortality of Nile tilapia reached 71.42% after the intraperitoneal and 35.71% in the immersion challenges within 28 d, whereas African walking catfish showed zero mortality. Observed clinical signs were comparable to those in the farm and those described in the literature as enteric septicemia of catfish. With this study, we demonstrated the susceptibility of P. corruscans to E. ictaluri, as well as interspecies transmission of this bacterium.

Systematic monitoring of glanders-infected horses by complement fixation test, bacterial isolation, and PCR.

Glanders is an equine zoonosis caused by Burkholderia mallei that is responsible for considerable economic loss. Complement fixation testing (CFT) using warm or cold incubation are recommended by the OIE, but many routinely used detection tests may present misleading results. To increase accuracy of glanders diagnosis and establish an appropriate protocol in collaboration with the National Equine Health Program, seven horses positive for glanders kept in isolation in Brazil were examined fortnightly by CFT, microbiological screening, and molecular testing. Warm and cold serologies with USDA and c.c.Pro antigens, respectively, were performed on 132 samples using the US Department of Agriculture protocol. The warm and cold serologies showed, respectively,12.9% and 17.3% seroreactive, 85.7% and 65.2% non-reactive, 0.8% and 3% inconclusive, and 0% and 2.3% anticomplementary. The agreement of CFT protocols was moderate. Of 213 clinical samples submitted to selective culture (167 nasal swabs, 5 ocular swabs, 3 lymph node punctures, and 38 tissue samples from four horses that died), 1.9% tested positive for B. mallei. Fourteen samples and one nasal swab (7%) tested positive with PCR. Cold CFT with the USDA and c.c.Pro antigens, in combination with PCR to increase sensitivity, may be useful for diagnosis of chronic glanders.