Effect of low‐dose Piscirickettsia salmonis infection on haematological‐biochemical blood parameters in Atlantic salmon (Salmo salar)

• Published in: Journal of fish biology Vol. 101; no. 4; pp. 1021 - 1032
• Main Authors: Isla, Adolfo, Sánchez, Patricio, Ruiz, Pamela, Albornoz, Romina, Pontigo, Juan P., Rauch, María Cecilia, Hawes, Christopher, Vargas‐Chacoff, Luis, Yáñez, Alejandro J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2022; Wiley Subscription Services, Inc
• Subjects: Blood; Blood cells; Carbohydrates; Carnivorous animals; Fish; Freshwater fishes; haematocrit; Haemoglobin; Haemolysis; Hematocrit; Hemoglobin; Hepatotoxicity; Hypoxia; Infections; Iron; Iron deficiency; L-Lactate dehydrogenase; Lactate; Lactate dehydrogenase; Lactic acid; LDH; Leukocytes; Magnesium; Marine fishes; Nutrient deficiency; Osmoregulation; Parameters; Piscirickettsia salmonis; Salmo salar; Salmon; Signs and symptoms; Symptoms; white blood cell
• ISSN: 0022-1112; 1095-8649
• DOI: 10.1111/jfb.15167

Piscirickettsia salmonis is the etiological agent of Piscirickettsiosis, a severe disease that affects Atlantic salmon (Salmo salar) farmed in Chile and many other areas (Norway, Scotland, Ireland, Canada and the USA). This study investigated the effects of low‐dose P. salmonis infection (1 × 102 CFU/ml) on Atlantic salmon. In this study, we challenged fish with an isolated representative of the EM‐90 genogroup via intraperitoneal injection for 42 days. Infected fish displayed decreased haematocrit and haemoglobin levels at day 13 post‐infection, indicating erythropenia, haemolysis and haemodilution. Conversely, their white blood cell counts increased on days 13 and 21 post‐infection. Additionally, their iron levels decreased from day 2 post‐infection, indicating iron deficiency and an inability to retrieve stored iron before infection. Their magnesium levels also decreased at day 28 post‐infection, possibly due to osmoregulatory problems. Also, we observed an increase in lactate dehydrogenase activity on days 5, 21, and 28 post‐infection, suggesting early symptoms of hepatotoxicity. Later analyses determined a decrease in plasma glucose levels from day 2 post‐infection. This may be attributed to the hypoxic conditions caused by P. salmonis, leading to an excess utilization of stored carbohydrates. Our results suggest that the blood parameters we studied are useful for monitoring the physiological status of Atlantic salmon infected with P. salmonis.