Equine Infectious Anemia: How to Avoid Spreading It
Transmission of disease agents from humans to animals and vice versa is a major item in the news today as the majority of "new diseases" in humans are known to arise by transmission from animal reservoirs. But of equal importance, especially with respect to equine infectious anemia (EIA), is the risk that humans pose for transmitting blood-borne infections to the horse, such as in recent experiences where humans were implicated as the major vectors of EIA virus. These experiences prompt us to review human interactions with the horse and to urge adoption of methods to minimize the risks our actions present.
The major risk with people and EIA virus is contamination of man and/or materials and transfer of infected blood to a second horse.
When collecting a blood sample, owners and veterinarians need to consider three major factors:
- Protecting the horse from surface contaminants;
- Protecting the horse from the collector; and
- Choosing equipment to minimize risk.
Multi-Sample Needles (the gasket prevents backflow)
Needle in the Holder (arrow to mark)
Needle partly inserted into evacuated tube (do not insert tubes beyond marked areas)
Collectively, our preferred methods are as follows:
Site Preparation In preparing to draw a blood sample, pay attention to the skin over the jugular vein at the collection site. If the area is heavily contaminated, a povidone iodine soap and water scrub is recommended. Otherwise, an alcohol swab applied once to the area and allowed to dry will suffice. A single-draw blood collection apparatus utilizing one multi-sample needle and one vacuum blood tube should be used, and the needle then discarded in a sharps container. Should bleeding occur at the site following the venipuncture, the alcohol swab can be used to apply pressure to stop the bleeding. When the blood collection is done properly, no blood contamination of the operator should occur. In cases where there is overt blood contamination of the equipment or operator, take additional safeguards (e.g., handwashing or sanitizing) before handling another horse.
In all cases the operator must use appropriate methods to avoid transmitting blood-borne pathogens. This should include adoption of standard precautions, such as reducing contamination of hands with washing or use of hand sanitizers and/or the use of disposable gloves for each patient.
Remember, one of basic tenets of medical practice is to “First, do no harm.”
Site preparation (Methods: surgical scrub>>clipping & disinfection>>cleaning the area)
- Routine blood collection: usually less than IV prep; often surface just “cleaned”
- The use of alcohol wipes varies widely (without clipping the site, the real benefit of alcohol wipes is debatable)
- No standard practice guidelines exist for horses and would be desirable
- Good technique reduces risk even without surface decontamination
Collector/veterinarian preparation (Reducing hand contamination)
- Adequate washing or decontamination of hands with sanitizers
- Gloved hands (change between donors)
Protection for collector (Gloved hands)
Equipment (Safest: Multi-sample needles (with gasket to prevent backflow) and evacuated glass tubes)
- Single use; No blood contamination of tube, collector or donor if done correctly
- Remove needle without wiping off venipuncture site with bare hand
- Spot of blood at needle exit? (Perspective: 1 drop of blood from an acute case of EIA theoretically has the potential to infect 100,000 horses.) For aesthetic purposes, clean site with a sterile cotton pledget or alcohol wipe, but it's better to leave it there than wipe with bare hand.
Let us explain how risks could potentially differ with other techniques...
- Single collection needles and evacuated glass tubes
- High risk of blood contamination of donor, collector and tubes
- Especially if needle is inserted before tube is put in holder, e.g., fractious donor
- Risk decreases if the needle is in gasket of tube while probing, left in tube until filled, then removed with needle in tube
Even more potential risks:
- Syringes and needles
- Blood from syringe must be discharged into tube for submission to lab
- Aerosols generated
- Probability of lysis of sample increases
- Collector exposed to risks of needles and more blood contamination
- Threat from recapping needles; newer styles with recapping cover
- Greater potential risks associated with disposal
- Risk increases exponentially with non-disposable syringes if used without adequate sterilization between uses
Never reuse disposable syringes or needles, even the large, expensive ones!
About the Author
POLL: Radiographs for Hoof Care