Studies on oral transmission of Potomac horse fever.
Abstract: Eight normal ponies placed in direct contact with ponies experimentally infected with Ehrlichia risticii for 30 to 90 days did not develop signs of Potomac horse fever. They also did not seroconvert, and they remained susceptible to IV infection. One of 8 ponies that were force fed fresh feces from infected ponies while in direct contact with ponies experimentally infected with E. risticii developed Potomac horse fever and seroconverted. The other 7 remained asymptomatic, did not seroconvert, and were susceptible to IV infection. Six of 9 ponies inoculated with E. risticii via nasogastric intubation and oral drench developed Potomac horse fever and seroconverted. The other 3 remained asymptomatic and did not seroconvert. One of these latter ponies and 2 normal ponies that were inoculated via oral drench only developed Potomac horse fever and seroconverted. The high fever, maximum clinical score for decreased feed intake, depressed mental attitude, decreased borborygmal sounds, severity of diarrhea, and the length of illness of the orally infected ponies was not significantly different from those of IV infected control ponies, although the signs occurred significantly later (P < .05).
Publication Date: 1994-03-01 PubMed ID: 8046681DOI: 10.1111/j.1939-1676.1994.tb03203.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article aimed to explore how Potomac horse fever, caused by the bacteria Ehrlichia risticii, is transmitted orally among horses. The various experiments conducted suggested that the disease is not easily transmitted through simple contact or consumption of feces from an infected horse. However, more direct forms of oral infection, such as nasogastric intubation and oral drench, led to a significant number of horses developing the fever.
The Experiment
- The researchers conducted several tests involving ponies that were in direct contact with experimentally infected ponies for a duration of 30 to 90 days. None of these ponies showed signs of Potomac horse fever or produced antibodies against Ehrlichia risticii, proving they were not infected.
- In the second scenario, some ponies were force-fed fresh feces from infected ponies. Only one pony from this group developed Potomac horse fever and seroconverted, indicating the infection. The rest did not show symptoms or seroconvert, implying they were not infected.
- The third part of the experiment involved infecting ponies with nasogastric intubation and oral drench (methods involving direct intake of the bacteria). In this case, majority of the ponies developed the fever and seroconverted.
- Last but not least, ponies that were only inoculated through the oral drench method also fell sick and seroconverted, thereby confirming the effectiveness of this mode of transmission.
Potomac Horse Fever Symptoms and Severity
- The researchers found that ponies infected orally exhibited similar symptoms and severity of the disease as those infected intravenously (IV). These symptoms include high fever, decreased feed intake, depressed mental attitude, decreased borborygmal sounds, severe diarrhea, and length of illness.
- However, onset of these symptoms was significantly later in orally infected ponies compared to those infected via IV.
Conclusion
- The research concluded that Potomac horse fever is not easily transmitted through casual contact or fecal ingestion from an infected horse. However, more direct methods of oral infection revealed a significant risk of transmission.
- The findings of this study are vital for formulating preventive measures against the spread of Potomac horse fever among horses.
Cite This Article
APA
Palmer JE, Benson CE.
(1994).
Studies on oral transmission of Potomac horse fever.
J Vet Intern Med, 8(2), 87-92.
https://doi.org/10.1111/j.1939-1676.1994.tb03203.x Publication
Researcher Affiliations
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square 19348.
MeSH Terms
- Administration, Oral
- Animals
- Antibodies, Bacterial / analysis
- Bacteremia / veterinary
- Ehrlichia / immunology
- Ehrlichia / isolation & purification
- Ehrlichia / pathogenicity
- Ehrlichiosis / diagnosis
- Ehrlichiosis / transmission
- Ehrlichiosis / veterinary
- Female
- Horse Diseases / diagnosis
- Horse Diseases / microbiology
- Horse Diseases / transmission
- Horses
- Male
Citations
This article has been cited 4 times.- Baird JD, Arroyo LG. Historical aspects of Potomac horse fever in Ontario (1924-2010). Can Vet J 2013 Jun;54(6):565-72.
- Barlough JE, Reubel GH, Madigan JE, Vredevoe LK, Miller PE, Rikihisa Y. Detection of Ehrlichia risticii, the agent of Potomac horse fever, in freshwater stream snails (Pleuroceridae: Juga spp.) from northern California. Appl Environ Microbiol 1998 Aug;64(8):2888-93.
- Mott J, Rikihisa Y, Zhang Y, Reed SM, Yu CY. Comparison of PCR and culture to the indirect fluorescent-antibody test for diagnosis of Potomac horse fever. J Clin Microbiol 1997 Sep;35(9):2215-9.
- Shapiro J, Thomson G. Potomac horse fever in eastern Ontario. Can Vet J 1995 Jul;36(7):448.
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