Experimental infections of horses with Legionella pneumophila.

Sangnae Cho, M. T. Collins, J. S. Reif, A. E. McChesney

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Attempts to infect horses with Legionella pneumophila were undertaken to determine pathogenicity and to evaluate the possibility that horses serve as a reservoir for the organism. A previous study showed that the prevalence of antibodies to L pneumophila in the equine population exceeded 30% of over 600 sera examined. Horses were infected experimentally with the Philadelphia 1 or Bloomington 2 strain of L pneumophila IV or by aerosolization. Signs of clinical illness were restricted to a transient febrile response. A transient decrease in circulating lymphocytes occurred 2 days after inoculation. At necropsy, only moderate generalized lymphadenopathy was noted. Histologically, the lungs contained evidence of a low-grade inflammatory response characterized by focal proliferation of alveolar lining cells, with few neutrophils and eosinophils. Lymph nodes had evidence of reactive hyperplasia. The tissue response to Bloomington 2 strain was slightly more pronounced than that to Philadelphia 1. Attempts to reisolate L pneumophila from blood and nasal or pharyngeal swabs were unsuccessful. The organism was not isolated by culturing tissues obtained at necropsy, nor was it demonstrated by tissue-staining techniques. However, all horses exhibited a marked increase in agglutinating antibodies to L pneumophila serogroups (SG) 1 and 3 as early as 4 days after inoculation. The serologic response was confirmed by indirect immunofluorescence and was shown to consist predominantly of immunoglobulin M by 2-mercaptoethanol treatment. Agglutinating antibodies persisted at least 4 months after infection. On the basis of these studies, the pathogenicity of L pneumophila SG 1 and 3 for the horse appears to be low. There is no evidence to support a role for the horse in the maintenance of these organisms in nature. Horses may be exposed in the environment and maintain a relatively long-lived serologic response to L pneumophila. However, it is also possible that they become infected with other strains of L pneumophila or Legionella-like organisms more pathogenic for horses, or other non-Legionella bacteria, which elicit a cross-reacting serologic response to L pneumophila SG 1 to 4.

Original languageEnglish
Pages (from-to)662-668
Number of pages7
JournalAmerican Journal of Veterinary Research
Volume44
Issue number4
Publication statusPublished - 1983 Apr 1

Fingerprint

Legionella pneumophila
Horses
horses
Infection
infection
serotypes
organisms
Virulence
Antibodies
necropsy
pathogenicity
Legionella
Alveolar Epithelial Cells
immunoglobulin M
lymphatic diseases
antibodies
Mercaptoethanol
Indirect Fluorescent Antibody Technique
eosinophils
blood serum

All Science Journal Classification (ASJC) codes

  • veterinary(all)

Cite this

Cho, S., Collins, M. T., Reif, J. S., & McChesney, A. E. (1983). Experimental infections of horses with Legionella pneumophila. American Journal of Veterinary Research, 44(4), 662-668.
Cho, Sangnae ; Collins, M. T. ; Reif, J. S. ; McChesney, A. E. / Experimental infections of horses with Legionella pneumophila. In: American Journal of Veterinary Research. 1983 ; Vol. 44, No. 4. pp. 662-668.
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abstract = "Attempts to infect horses with Legionella pneumophila were undertaken to determine pathogenicity and to evaluate the possibility that horses serve as a reservoir for the organism. A previous study showed that the prevalence of antibodies to L pneumophila in the equine population exceeded 30{\%} of over 600 sera examined. Horses were infected experimentally with the Philadelphia 1 or Bloomington 2 strain of L pneumophila IV or by aerosolization. Signs of clinical illness were restricted to a transient febrile response. A transient decrease in circulating lymphocytes occurred 2 days after inoculation. At necropsy, only moderate generalized lymphadenopathy was noted. Histologically, the lungs contained evidence of a low-grade inflammatory response characterized by focal proliferation of alveolar lining cells, with few neutrophils and eosinophils. Lymph nodes had evidence of reactive hyperplasia. The tissue response to Bloomington 2 strain was slightly more pronounced than that to Philadelphia 1. Attempts to reisolate L pneumophila from blood and nasal or pharyngeal swabs were unsuccessful. The organism was not isolated by culturing tissues obtained at necropsy, nor was it demonstrated by tissue-staining techniques. However, all horses exhibited a marked increase in agglutinating antibodies to L pneumophila serogroups (SG) 1 and 3 as early as 4 days after inoculation. The serologic response was confirmed by indirect immunofluorescence and was shown to consist predominantly of immunoglobulin M by 2-mercaptoethanol treatment. Agglutinating antibodies persisted at least 4 months after infection. On the basis of these studies, the pathogenicity of L pneumophila SG 1 and 3 for the horse appears to be low. There is no evidence to support a role for the horse in the maintenance of these organisms in nature. Horses may be exposed in the environment and maintain a relatively long-lived serologic response to L pneumophila. However, it is also possible that they become infected with other strains of L pneumophila or Legionella-like organisms more pathogenic for horses, or other non-Legionella bacteria, which elicit a cross-reacting serologic response to L pneumophila SG 1 to 4.",
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Cho, S, Collins, MT, Reif, JS & McChesney, AE 1983, 'Experimental infections of horses with Legionella pneumophila.', American Journal of Veterinary Research, vol. 44, no. 4, pp. 662-668.

Experimental infections of horses with Legionella pneumophila. / Cho, Sangnae; Collins, M. T.; Reif, J. S.; McChesney, A. E.

In: American Journal of Veterinary Research, Vol. 44, No. 4, 01.04.1983, p. 662-668.

Research output: Contribution to journalArticle

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