Effect of water temperature and flow rate on the transmission of microsporidial gill disease caused by Loma salmonae in rainbow trout Oncorhynchus mykiss

Two studies were designed to quantify the effect of water temperature and flow rate on the transmission potential of the important salmonid gill pathogen, Loma salmonae. Using survival analysis, increased water temperature and low flow rates were determined as risk factors for the transmission of microsporidial gill disease caused by L. salmonae in rainbow trout Oncorhynchus mykiss. Fish were experimentally infected with L. salmonae via a cohabitation exposure model and monitored for the development of branchial xenomas. On any given day, fish held at 11degreesC and 15degreesC had a hazard ratio equal to 0.80 and 0.68, respectively, for the development of branchial xenomas compared with fish held at 19degreesC. From the flow rate trial, fish housed in a low flow tank (0.83 L/min) had an increased chance of developing branchial xenomas when compared to fish in tanks at normal (1.67 L/min) and high (2.5 L/min) flow rates with hazard ratios reported as 0.69.PT: J; CR: BARKER DE, 2000, AQUACULTURE, V187, P261 BEAMAN HJ, 1998, THESIS U PRINCE EDWA BEAMAN HJ, 1999, J AQUAT ANIM HEALTH, V11, P237 BEBAKWILLIAMS J, 2002, J FISH DIS, V25, P715 BECKER JA, 2002, J FISH DIS, V25, P673 BODENSTEINER LR, 2000, J AQUAT ANIM HEALTH, V12, P209 CLEVES MA, 2002, INTRO SURVIVAL ANAL GEORGIADIS MP, 2001, PREV VET MED, V48, P287 GUTIERREZ RG, 2002, STATA J, V1, P22 HEDRICK RP, 1998, J AQUAT ANIM HEALTH, V10, P107 KENT ML, 1995, CAN VET J, V36, P98 KLEINBAUM DG, 1986, SURVIVAL ANAL SELF L, P4 MAGOR BG, 1987, CAN J ZOOL, V65, P751 PENNELL W, 1996, PRINCIPLES SALMONID RAMSAY JM, 2001, J FISH DIS, V24, P453 RENO PW, 1998, J AQUAT ANIM HEALTH, V10, P160 ROSS RM, 1995, AQUACULT ENG, V14, P29 SEDGWICK SD, 1990, TROUT FARMING HDB SHAW RW, 1998, DIS AQUAT ORGAN, V33, P151 SHAW RW, 2000, DIS AQUAT ORGAN, V43, P49 SPEARE DJ, 1998, CONTEMP TOP LAB ANIM, V37, P55 SPEARE DJ, 1998, J FISH DIS, V21, P345 SPEARE DJ, 1998, J FISH DIS, V21, P93 SPEARE DJ, 1999, J FISH DIS, V22, P277; NR: 24; TC: 6; J9: FISH PATHOL; PG: 8; GA: 815FNSource type: Electronic(1