Equine Infectious Anemia (EIA)

The clinical signs are often nonspecific and of variable severity. Clinical signs in an acute case can range from fever and decreased appetite to severe anemia and sudden death. It is often difficult to differentiate EIA from other diseases.  Incubation period is a week to 60 days or longer.  Additional clinical signs in an acute case can include:

• Jaundice (yellow discoloration of mucous membranes)
• rapid breathing, rapid heart rate
• swelling of limbs
• bleeding from the nose, or red/purple spots on mucous membranes
• blood-stained feces

Horses that survive the acute phase of the disease become chronic, in-apparent carriers.  Some carriers may develop recurrent flare-ups, often following another stress – illness or strenuous work. While donkeys and mules have the ability to contract this virus, most remain non-clinical.

*For further information, documents and references please open the EIA Documents and references tab. 

Samples to collect

• Serum should be collected and submitted to an EIA APHIS-Approved Laboratory using a VS Form 10-11 or another VS approved EIA form, alternatively, you may submit electronically via VSPS (https://vsapps.aphis.usda.gov/vsps/) - which is free for veterinarians and laboratories to use - or another, VS approved, electronic EIA submission system.

  For questions, or supplies of paper VS 10-11s, please contact your APHIS-VS District office 

• VS 10-11 Instructions (2020).  Note that VS 10-11 forms are only available to accredited veterinarians and there are no approved fillable pdfs of the form for submissions. 

Post Mortem Lesions

• Spleen, liver and abdominal lymph nodes may be enlarged. Mucous membranes can be pale. In chronic cases, emaciation may also be noted. However horses that die between clinical episodes may have no gross lesions.

*For further information, documents and references please open the EIA Documents and references tab.

Natural transmission of EIA is by blood feeding flies (horse flies and deer flies) and is limited to relatively short distances. This virus is frequently transmitted via unclean or re-used needles and syringes, blood transfusions and contaminated instruments (IV sets, dental instruments, tattoo equipment).  Mares can transmit the virus to foals in utero, and, less likely, transmission can occur via milk or semen.

*For further information, documents and references please open the EIA Documents and references tab. 

There is no treatment for EIA. Because infected animals become lifelong carriers they must be permanently isolated and quarantined or euthanized.

*For further information, documents and references please open the EIA Documents and references tab. 

• VSG 15201.1 Approval of Labs to Conduct EIA Testing (Made effective in 2019)
• VSG 15201.1 Official Documents:
  
  • EIA Laboratory Monthly Data Report TEMPLATE (MS-Excel file, Aug 2020)
    
  • VS 10-16 Application to Conduct EIA Testing
  • VS 10-15 (Director’s) Agreement to Conduct EIA Testing
  • VS 10-17 Laboratory Inspection Checklist for EIA Labs (Oct 2020)
• VSG 15201.1 Outreach, Training and Explanatory Information:
  
  • FAQ 15201.1 (2019)
  • 15201.1 Requirements Actions (2020)
  • EIA Lab Approval Webinar recording
    
  • NVAP Outreach
• Current List of Approved EIA Laboratories
• List of Approved EIA Test Forms
  
• Further Information and Historical References:
  • EIA Concept for Federal Regulation (2016)
  • EIA Discussion Group  (2015)
  • EIA Fact Sheet  (2009)
  • EIA Uniform Methods and Rules (2007)
  • APHIS EIA Info (2006)
    
  • Status Report on EIA  (1996)

Reducing exposure to biting flies through management practices may reduce the spread of infection. To prevent iatrogenic spread, never reuse needles, syringes or IV sets, use only new, clean needles with injectable medicines and use only licensed and approved blood products. Blood transfusions should be performed only by licensed veterinarians using donor horses tested negative for EIA and other blood-borne infections like equine piroplasmosis.

Surveillance and testing are the best methods of prevention. Since EIA control efforts began over 40 years ago the reactor rate has fallen from 4% to .004% in 2017 among tested animals. USDA recommends testing every equid annually.

There is no vaccine approved for use in the U.S.

*For further information, documents and references please open the EIA Documents and references tab. 

1. Call your veterinarian
2. Move suspected horse at least 200 yards away from other horses
3. Reduce exposure to biting flies

*For further information, documents and references please open the EIA Documents and references tab.

• 2020 Summary of Equine Infectious Anemia Cases in the United States
  
• 2019 Summary of Equine Infectious Anemia Cases in the United States
• 2018 Summary of Equine Infectious Anemia Cases in the United States
• 2017 Summary of Equine Infectious Anemia Cases in the United States
  
• 2016 Summary of Equine Infectious Anemia Cases in the United States 
  
• 2015 Summary of Equine Infectious Anemia Cases in the United States 
  
• 2014 Summary of Equine Infectious Anemia Cases in the United States
• 2013 Summary of Equine Infectious Anemia Cases in the United States
• 2012 Summary of Equine Infectious Anemia Cases in the United States
• 2011 Summary of Equine Infectious Anemia Cases in the United States
• 2010 Summary of Equine Infectious Anemia Cases in the United States
• 2009 Summary of Equine Infectious Anemia Cases in the United States
• 2008 Summary of Equine Infectious Anemia Cases in the United States
• 2007 Summary of Equine Infectious Anemia Cases in the United States