The Bite of the Chigger

D. E. Larsen, DVM

I came to the end of the gravel on this side road off of Pleasant Valley Road. There was just a dirt path in front of me. I say path because it would probably not meet any criteria to qualify as a road. I took a deep breath and continued on, finally breaking out into a pasture whittled out of the young forest. 

On the far corner were several ramshackle travel trailers that served as the family living quarters. I pulled up to these trailers. Kids and chickens were running everywhere. Finally, Annie stepped out of the far trailer.

“I am glad you found us,” Annie said. “We are moving back to Missouri, and we have this little heifer that needs a health certificate to make the trip.”

“You are sort of hidden back in these trees,” I said. “It must have taken a little work to clear this pasture.” 

“It was done before we came,” Annie said. “We have lived here a couple of years, but can’t make a go of it. Time to go home, I guess.”

“Let’s look at this heifer,” I said. “I have to give her a brucellosis vaccine and a quick exam. The rest is just paperwork. Do you want any other vaccines for her?”

“No, we just want that piece of paper,” Annie said.

Annie and her family group left Sweet Home not long after that visit. They faded into my memory like so many others. And it was several years later that events reawakened my memory of that day.

Marilyn had Tiger in the clinic for a routine exam. Marilyn had quite a group of cats, indoor-only cats, and outdoor cats, and then a small group of cats that were allowed to come in and out of the house. Tiger was one of those cats that came in and out of the house as he pleased. Marilyn lived on another road system, but her home was not far up the hill from Annie’s settlement.

As I worked through the exam, I noticed a row of little white bugs attached to Tiger’s ear margins. I looked closely at these bugs and scraped a couple of them onto a microscope slide.

“I have noticed those every Spring for the last couple of years,” Marilyn said. “They only seem to be on the outdoor cats, and they don’t seem to cause much of a problem.”

“Maybe we should send them to the lab and find out what they are,” I suggested. 

“I don’t think so,” Marilyn said. “They will be gone in a few weeks, and they don’t seem to cause much of a problem. I would rather not spend the money on the lab.”

Over the next couple of years, I would see other cats with these bugs on their ear margins. They all seemed to come from the Pleasant Valley area.

Finally, Susan came in with Rudy, a large black cat. The white bugs on his ear margins really stood out against his black hair. 

“Doc, I have noticed these things on his ears for several years,” Susan said. “This year, there are a lot of them, and they are bothering him.”

“I can put some ear mite ointment on them,” I said. “That will take care of the problem for now. But I have seen several cats from your area with this same problem. Maybe we should send some of these little guys to the lab and find out what we are dealing with.”

“Yes, that would be good,” Susan said. “Even if we can’t do anything with them other than treat them, it would be good to know what they are.”

I scraped most of the bugs off one ear into a blood vial to send to the lab. Then I applied some ear mite lotion to the ear flaps. Ruddy’s ear margins were a little eroded, but with the bugs gone, that should resolve in short order.

The diagnostic lab called when they received my sample.

“We are going to send these critters over to Oregon State’s Entomology Department for identification,” the secretary said. “It is hard to say how long it will be before you have any results.”

“That’s fine,” I said. “There is no urgent situation here.”

Surprisingly, it was just two days later that I got a call from Randy. Randy was a graduate student in the Entomology Department.

“Doctor Larsen, I am looking at your sample that you sent to the Diagnostic Lab a couple of days ago,” Randy said. “This is exciting stuff. Can you give me any background on Ruddy, the cat that you collected these from.”

“Not much, Ruddy is a pretty typical cat, indoors and outdoors, at his choosing,” I said. “I see these bugs on the ear margin of outdoor cats, most of them from the Pleasant Valley area, every spring for the last few years.”

“These bugs, as you call them, are larval chiggers,” Randy said. “What is interesting here is that chiggers of this species are rarely reported in Oregon. I would like to write this case up for publication if that is okay with you. I could give you credit in the paper.”

“That’s fine with me,” I said. “I really have no need for any credits, I won’t be doing any research in my career. You are free to use any information on the lab request. And if you need more information, just call.”

The fact that I was just now seeing chiggers and in an area associated with Annie’s settlement, makes one wonder if they were the source. Missouri is a hotbed for chiggers.

Photo Credit: Photo by Lisa Fotios from Pexels

Information Link:   https://en.wikipedia.org/wiki/Trombiculidae