REDI-NET T-1A ACTIVE VERTEBRATE TICK FIELD SAMPLING
REDI-NET Consortium
Disclaimer
This work is supported by the US Army Medical Research and Development Command under Contract No.W81XWH-21-C-0001, W81XWH-22-C-0093 and HT9425-23-C-0059. The views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army or Navy position, policy or decision unless so designated by other documentation.
Abstract
To outline steps for properly collecting tick samples actively collected from cattle to evaluate the risk of zoonotic disease transmission by the detection of pathogens from invertebrate DNA (iDNA).
Before start
NOTE: Obey all safety procedures in this SOP.
Cattle are restrained in a squeeze chute for all procedures.
- Never stand in front of the chute until the animal has been completely restrained.
- Always be aware of the location of the gate hinge when standing next to the chute as it is opening and closing.
- Always make sure that all drop-down bars and fold-out panels are closed before the chute is opened.
- Always communicate verbally with the team operating the squeeze chute when you are finished checking the animal so that they know when it is safe to open the chute.
- Always be aware of the fact that the animal can still move somewhat inside the chute. Be aware of where your hands and arms are, and be able to remove them from the chute quickly.
- If you ever feel uncomfortable checking an animal (animal is too worked up or aggressive in the chute), or you are unable to safely access part of the animal in the chute, skip it .
Steps
SAMPLING TEAMS
This SOP assumes that the animals’ owners/handlers/veterinarians are on site to corral cattle, move them through the chute, and operate the chute. The three minute search time assumes at least three study personnel are available for tick collection. If only two individuals are present, increase search time to five minutes.
One person should be assigned to search the head/neck/dewlap region, one person should be assigned to search the legs/belly region, and one person should be assigned to search under the tail and the udder.
Record the ambient temperature outside the barn or enclosure if working indoors.
SAMPLE COLLECTION
Once an animal is completely restrained in the squeeze chute, label a collection tube with the date, collection site, and animal’s ear tag number.
Set a timer for three minutes. (See above note in Step 1.)
Lower the rear drop-down bars to access the tail. Lower the lower fold-out panels to access the legs. If necessary, the front swing arm can be used to pin the animal’s head to one side.
Moving your hands over the animal, feel for bumps on the skin. Ticks will be round or flat, smooth, and somewhat moveable, compared to scabs, burs, and warts.
When you feel a tick, grasp it close to the skin at the mouthparts either using your fingers or forceps. Pull forcefully straight out to remove the tick.
Place the tick into the labeled tube. No more than 10 live ticks should be placed in a vial. All stages should be collected. Place a blade of grass in vial before capping. Close the tube to ensure that no ticks escape.
At the end of the three minute search period, close the drop-down bars and fold-out panels and verbally confirm with the chute operator that you are done.
For each animal, indicate whether ticks were collected from that individual (‘Yes’), whether the animal was checked, but no ticks were found (‘No Ticks Present’), or whether that animal was not checked for ticks (‘No’) on the data collection sheet.
Repeat this process until at least 20% of the animals have been sampled. Ideally, all animals will be sampled, but occasionally this will not be possible due to time or personnel restraints.
Transfer collection tubes to a cooler on ice for transport back to the lab.
TICK STORAGE
If ticks do not need to be kept alive do not need to be kept alive for research purposes:
Place collection tubes into a -20C freezer for at least five hours, and up to 24 hours to kill ticks.
Ticks should then be stored at -80C until they are identified to species and processed for TNA extraction. (Follow the REDI-NET T-3 Tick Storage.)
If ticks are to be kept alive for research purposes:
Place collection tubes into a refrigerator (4C). It is not recommended that ticks remain in the refrigerator for more than two days prior to processing. (Follow the REDI-NET T-3 Tick Storage.)
Proceed with sample testing following the REDI-NET SOP T-2 Tick Processing.
