Enterocolitis caused by Ehrlichia sp. in the horse (Potomac horse fever).
Abstract: Potomac horse fever was reproduced in 15 ponies by transfusion of whole blood originally from two natural cases and subsequently from ponies infected by the transfusions. Incubation periods varied from 9 to 15 days. Affected ponies developed varying degrees of fever, diarrhea, anorexia, depression, and leukopenia. Eleven affected ponies were killed, three died in the acute phase of the disease, and one did not show clinical signs. The most consistent post-mortem findings were fluid contents in the cecum and large colon, and areas of hyperemia (of inconstant degree and distribution) in mucosae of both small and large intestines. Multifocal areas of necrosis occurred in mucous membranes. Ehrlichial organisms were most common in the cytoplasm of epithelial cells, macrophages, and mast cells of the large colon.
Publication Date: 1986-07-01 PubMed ID: 3750739DOI: 10.1177/030098588602300418Google Scholar: Lookup
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- Journal Article
Summary
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This research shows how Potomac Horse Fever was artificially induced in ponies by transfusion of infected blood, studying its symptoms, duration, and post-mortem effects. The study also investigates how Ehrlichial organisms, the bacteria causing the disease, commonly inhabit cells of the large colon.
Methodology and Results
- The study was conducted on 15 ponies, which were infected with “Potomac Horse Fever” through blood transfusion. This blood was obtained from two previously reported cases of the disease as well as blood from ponies that were infected by the transfused blood.
- The incubation period of the disease, which is the time from being infected to the onset of symptoms, varied between 9 to 15 days.
- Once infected, the ponies exhibited several symptoms including fever, diarrhea, anorexia (a lack or loss of appetite), depression and leukopenia (a decrease in the number of white blood cells).
Mortality and Post-mortem Analysis
- Out of the 15 infected ponies, 11 were euthanized for further research, while three others died during the acute phase of the disease. One pony, however, did not exhibit any symptoms at all.
- Post-mortem examinations revealed that the most consistent abnormalities were detected in the cecum and large colon, which had fluid contents. Additionally, varying degrees of hyperemia (an excess of blood in vessels supplying an organ or other body part) were noticed in some parts of the small and large intestines.
- Multifocal areas, or areas occurring in multiple locations, of necrosis were also observed in mucous membranes, implying that tissues in those areas had died.
Disease Mechanism
- An important finding of this study was that Ehrlichial organisms, the bacteria causing this disease, were most common in the cytoplasm of certain kinds of cells in the pony. These were the epithelial cells that line the large colon, macrophages which are a type of immune cell, and mast cells which are involved in inflammatory processes.
- This suggests that these cells could be prime targets for the bacteria, leading to the symptoms and abnormalities witnessed in the infected ponies.
Cite This Article
APA
Cordes DO, Perry BD, Rikihisa Y, Chickering WR.
(1986).
Enterocolitis caused by Ehrlichia sp. in the horse (Potomac horse fever).
Vet Pathol, 23(4), 471-477.
https://doi.org/10.1177/030098588602300418 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Cecum / pathology
- Colon / pathology
- Ehrlichia / ultrastructure
- Enterocolitis / microbiology
- Enterocolitis / pathology
- Enterocolitis / veterinary
- Female
- Horse Diseases / microbiology
- Horse Diseases / pathology
- Horses
- Intestinal Mucosa / pathology
- Intestine, Small / pathology
- Male
- Rickettsiaceae Infections / pathology
- Rickettsiaceae Infections / veterinary
- Stomach / pathology
Citations
This article has been cited 11 times.- Thirumalapura NR, Livengood J, Beeby J, Wang W, Goodrich EL, Goodman LB, Erol E, Tewari D. Improved molecular detection of Neorickettsia risticii with a duplex real-time PCR assay in the diagnosis of Potomac horse fever. J Vet Diagn Invest 2023 Jan;35(1):62-66.
- Uzal FA, Arroyo LG, Navarro MA, Gomez DE, Asín J, Henderson E. Bacterial and viral enterocolitis in horses: a review. J Vet Diagn Invest 2022 May;34(3):354-375.
- Lin M, Bachman K, Cheng Z, Daugherty SC, Nagaraj S, Sengamalay N, Ott S, Godinez A, Tallon LJ, Sadzewicz L, Fraser C, Dunning Hotopp JC, Rikihisa Y. Analysis of complete genome sequence and major surface antigens of Neorickettsia helminthoeca, causative agent of salmon poisoning disease. Microb Biotechnol 2017 Jul;10(4):933-957.
- Durán MC, Marqués FJ. Detection of Neorickettsia risticii, the agent of Potomac horse fever, in a Gypsy Vanner stallion from Manitoba. Can Vet J 2016 Mar;57(3):293-5.
- Heller MC, McClure J, Pusterla N, Pusterla JB, Stahel S. Two cases of Neorickettsia (Ehrlichia) risticii infection in horses from Nova Scotia. Can Vet J 2004 May;45(5):421-3.
- McConnico RS, Argenzio RA, Roberts MC. Prostaglandin E2 and reactive oxygen metabolite damage in the cecum in a pony model of acute colitis. Can J Vet Res 2002 Jan;66(1):50-4.
- Pusterla N, Madigan JE, Chae JS, DeRock E, Johnson E, Pusterla JB. Helminthic transmission and isolation of Ehrlichia risticii, the causative agent of Potomac horse fever, by using trematode stages from freshwater stream snails. J Clin Microbiol 2000 Mar;38(3):1293-7.
- Larsen J, Dolvik NI, Teige J Jr. Acute post-treatment enterocolitis in 13 horses treated in a Norwegian surgical ward. Acta Vet Scand 1996;37(2):203-11.
- Biswas B, Vemulapalli R, Dutta SK. Detection of Ehrlichia risticii from feces of infected horses by immunomagnetic separation and PCR. J Clin Microbiol 1994 Sep;32(9):2147-51.
- Rikihisa Y, Johnson GC, Burger CJ. Reduced immune responsiveness and lymphoid depletion in mice infected with Ehrlichia risticii. Infect Immun 1987 Sep;55(9):2215-22.
- Rikihisa Y, Pretzman CI, Johnson GC, Reed SM, Yamamoto S, Andrews F. Clinical, histopathological, and immunological responses of ponies to Ehrlichia sennetsu and subsequent Ehrlichia risticii challenge. Infect Immun 1988 Nov;56(11):2960-6.
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