Efficacy of an avirulent live vaccine against Lawsonia intracellularis in the prevention of proliferative enteropathy in experimentally infected weanling foals.

The research article investigates the effectiveness of a certain vaccine for Lawsonia intracellularis in preventing a condition named proliferative enteropathy in weanling foals. The researchers found that this vaccine, when administered correctly, was able to protect foals from this disease and potentially limit the spread of Lawsonia intracellularis in farms where the disease is common.

Objective and Methodology

• The objective of the research was to assess the effectiveness of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy (a disease affecting the intestines) in weanling foals.
• The method adopted for the research involved the use of 12 healthy weanling foals. The foals were divided into three groups: vaccinated, non-vaccinated, and control.
• The vaccinated group was given a non-disease-causing (avirulent) pig version of the L intracellularis vaccine via an intrarectal route, 60 and 30 days before the experimental challenge.
• On the first day of the experiment, both vaccinated and non-vaccinated foals were exposed to a virulent strain of L intracellularis through nasogastric intubation. The control group was not subjected to this challenge.

Data Gathering and Observation

• The researchers, over a period of 56 days, observed the health of the foals, conducted ultrasonographic examinations of their small intestines, recorded their body weight, and measured the serum concentration of total solids.
• Furthermore, they measured the degree of fecal excretion of L intracellularis and evaluated for seroconversion, a sign of infection after exposure to the bacteria.
• Any foal that fell sick during the study period was provided with antimicrobials and supportive care.

Findings

• The findings showed that none of the foals in the vaccinated group developed the disease after being exposed to the virulent L intracellularis.
• In contrast, three out of four of the foals in the non-vaccinated group developed moderate to severe clinical signs of proliferative enteropathy, including hypoproteinemia and thickening of small intestinal loops.
• Additionally, the team found that the vaccinated foals had significantly less fecal shedding of L intracellularis than the non-vaccinated foals, implying a reduced risk of environmental contamination.
• The serologic responses, a measure of the body’s immune response, were similar for both vaccinated and non-vaccinated foals after the challenge.
• The foals in the control group remained healthy with no signs of the disease, fecal shedding, or seroconversion.

Conclusions

• The study concluded that the intrarectal administration of a commercial avirulent porcine vaccine for L intracellularis can prevent proliferative enteropathy in weanling foals.
• The findings also suggest that it could help reduce environmental contamination with the bacteria on endemic farms, thus offering a broader protective benefit.