Bovis ISSN 2398-2993

Mycoplasma wenyonii

Synonym(s): M. wenyonii, Eperythrozoon wenyonii

Contributor(s): Ben Strugnell , James Breen




  • Class: Mollicutes.
  • Order: Mycoplasmatales.
  • Family: Mycoplasmataceae.
  • Genus: Mycoplasma.
  • Species: wenyonii.
  • Formerly known as Eperythrozoon wenyonii.
  • Other clinically significant members of this group include:
    •  Myocplasma suis which affects pigs.
    • Mycoplasma haemofelis which affects cats.
    • Although thought to be host-specific, some species have been reported to be zoonotic.


  • Gk: myco - fungus; plasma- form; mycoplasma - a fungus form.

Clinical Effects

Pathological effects

  • Hindlimb edema (hindlimbs 'fill up' with pitting edema to mid-tibia, although affected cows not usually lame).
    • Exactly how this blood borne parasite with a tropism for the erythrocyte membrane causes or contributes to clinical signs of hindlimb and udder edema is not yet understood, research is ongoing.
    • Examination of biopsy samples, from edematous skin, has indicated that the edema may be caused by vasculitis, possibly an Arthus-type reaction with deposition of immune complexes in the vascular endothelium.
    • In some cases, there has been an association with recent vaccination, raising the possibility of immune stimulation by adjuvants and precipitation of immune-mediated pathology.
  • Pyrexia - may result in milk drop, malaise and inappetence.
  • Painful, swollen udders in dairy cows. 
  • Milk drop Investigating milk drop in the herd. Investigating milk drop in the individual cow
  • Lymphadenopathy.
    • Prefemoral lymph nodes are enlarged and easily palpable.
  • Scrotal edema (could have significant effects on male fertility).
  • Diarrhea.
  • Depression.
  • Anemia.
    • A case has been reported (Gladden 2015) of a cow presenting with post-calving vaginal bleeding, which on investigation was found to have a regenerative anemia and tested positive for M wenyonii. This animal had suffered milk drop but had no hind-limb edema. The authors concluded that in this case the anemia was associated with M wenyonii.
Clinical signs in dairy cows gradually resolve but full recovery may take 10 days or longer.


  • No vaccine available.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Ade J, Niethammer F, Schade B et al (2018) Quantitative analysis of Mycoplasma wenyonii and 'Candidatus Mycoplasma haemobos' infections in cattle using novel gapN-based realtime PCR assays. Vet Microbiol 220, 1-6 PubMed.
  • McFadden A, Ha H J, Donald J J et al (2016) Investigation of bovine haemoplasmas and their association with anaemia in New Zealand cattle. N Z Vet J 64(1), 65-68 PubMed.
  • Gladden N (2015) A case report of mycoplasma wenyonii associated immune-mediated haemolytic anaemia in a dairy cow. Cattle practice 23 (2) pp 202.
  • Hoelzle K, Winkler M, Kramer M M et al  (2011) Detection of Candidatus Mycoplasma haemobos in cattle with anaemia. Vet J 187, 408-410 PubMed.
  • Strugnell B W, McAuliffe L, Longmire K & Ellis-Iverson J (2010) Mycoplasma wenyonii associated with clinical signs in milking dairy cows after herd-wide bluetongue vaccination. Cattle Practice 19, 75-81.
  • Yuan C L, Liang A B, Yao C B et al (2009) Prevalence of Mycoplasma suis (Eperythrozoon suis) infection in swine and swine-farm workers in Shanghai, China. Am J Vet Res 70, 890-894 PubMed.
  • dos Santosi A P, dose Santos R P, Biondo A W et al (2008) Hemoplasma infection in HIV-positive patient, Brazil. Emerg Infect Dis 14, 1922-1924 PubMed.
  • Scott R (2008) Distal hind limb and udder oedema of dairy cattle associated with an unidentified haemotrophic bacterium with microscopic characteristics of Mycoplasma (formerly Eperythrozoon) wenyonii. Cattle Practice 16, 50-53.
  • McAuliffe L, Lawes J, Bell S et al (2006) The detection of Mycoplasma (formerly Eperythrozoon) wenyonii by 16S rDNA PCR and denaturing gradient gel electrophoresis. Vet Microbiol 117, 292-296 PubMed.
  • Hofmann-Lehmann R, Meli M L, Dreher U M et al (2004) Concurrent infections with vector-borne pathogens associated with fatal hemolytic anemia in a cattle herd in Switzerland. J Clin Microbiol 42, 3775-3780 PubMed.
  • Welles E G, Tyler J W & Wolfe D F (1995a) Haematologic and semen qualitychanges in bulls with experimental Eperythrozoon infection. Theriogenology 43, 427-437 PubMed.
  • Welles E G, Tyler J W & Wolfe D F & Moore A (1995b) Eperythrozoon infection in young bulls with scrotal and hindlimb edema, a herd outbreak. Theriogenology 43, 557-567 PubMed.
  • Montes A J, Wolfe D F, Welles E G, Tyler J W & Tepe E (1994) Infertility associated with Eperythrozoon wenyonii infection in a bull. JAVMA 204, 261-263 PubMed.
  • Kawaku S, Nakamura Y, Kamio T et al (1990) Enzyme-linked immunosorbent assay for detection of antibodies to Eperythrozoon wenyonii in cattle. Jap J Vet Sci 52, 1297-1300.
  • Smith J A, Thrall M A, Smith J L et al (1990) Eperythrozoon wenyonii infection in dairy cattle. JAVMA 196, 1244-1250 PubMed.
  • Quinlan J F (1985) Suspected Eperythrozoonosis in dairy cows. Irish Vet J 39, 27.
  • Sutton R H, Charleston, W A G & Collins G H (1977) Eperythrozoon wenyonii – a blood parasite of cattle. A first report in New Zealand. New Zealand
    Vet J 25, 8-9.
  • Poole D B R, Cutler R S, Kelly W R & Collins J D (1976) Eperythrozoon wenyoni anaemia in cattle. Vet Rec 99, 481.
  • Kreifer J P & Ristic M (1963) Morphologic, antigenic and pathogenic characteristics of Eperythrozoon ovis and Eperythrozoon wenyoni. Am J Vet Res 24, 488-500.

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