The last time I spoke to Shannon LaDeau at the Cary Institute of Ecosystem Studies, in February, we were in the middle of our first classically cold winter in several years, thanks to a wonky polar vortex.
I asked Shannon if all the deep freezes might lead to a down year for ticks and tick-borne illnesses. She reminded me that blacklegged ticks, the buggers responsible for Lyme disease, are well-adapted to cold weather. However, to pass pathogens to us, the ticks must feed on an infected animal, typically a deer or a white-footed mouse. If the brutal cold affected them, we could frolic with less concern.
Unfortunately, it appears we will not have a carefree tick season. LaDeau and her colleagues are starting their annual tick counts in Millbrook, and there isn’t any hard data yet on the deer and mice populations, but “the ticks so far do not seem to be showing any signs of suffering from winter effects,” she said last week.
The federal Centers for Disease Control and Prevention says that emergency room visits for tick bites are three times what was reported at the same time last year.
That’s especially bad news considering a report that LaDeau and the Cary Institute just put out with researchers at SUNY Albany: Ticks in the Hudson Valley are becoming more likely to carry more than one pathogen, increasing the chances that you could get multiple diseases from just a single bite.
The Cary Institute has been studying ticks for more than 30 years. It has decades of data and ticks placed in cold storage in anticipation of additional funding and improved technology. For the recent study, the researchers screened 10 years’ worth of nymphal blacklegged ticks — the poppy-seed ones that are so difficult to detect — for 16 pathogens.
They found that about 10 percent were carrying more than one pathogen, but that the rate had increased over the years. The most prevalent pathogens were those that cause Lyme disease and babesiosis, a malaria-like disease that can be devastating for some but has little effect on others. (I found out seven years ago that I had it only because it came up in a test when I gave blood.)
If there’s good news, it’s that diseases such as the Powassan virus, which can cause brain inflammation and meningitis, only showed up in a single tick, and the bacteria (Bartonella henselae) that cause “cat scratch disease” didn’t show up at all. The researchers also didn’t find any ticks with alpha-gal, a molecule that can cause allergic reactions to red meat.
That’s not surprising, because lone star ticks are most likely to cause alpha-gal syndrome. While they have been found on Long Island, they are not prevalent in the Hudson Valley and haven’t been found at Cary. But the researchers did find a few ticks carrying pathogens responsible for Rocky Mountain Spotted Fever, which usually isn’t found in blacklegged ticks.
What’s causing these changes? It’s not clear, but LaDeau has some hypotheses. If nymphs carry more than one pathogen, it’s likely they picked them up from the animal they bit, because they’re probably too young to have had multiple meals. That would suggest deer and white-footed mice can also carry multiple pathogens, possibly from having been bitten repeatedly over years. Contracting one pathogen might also make hosts more vulnerable to infection from a different pathogen. “There are some lab studies that suggest that that’s possible,” said LaDeau.
If you find a tick has been feasting on you for at least 12 hours, get tested for multiple infections. LaDeau worries that the prevalence of Lyme disease in the Hudson Valley has made doctors less likely to test for other infections or to start patients right away on an antibiotic such as doxycycline, which is not the best strategy for other infections. For instance, treating babesiosis requires anti-malarial drugs.
It’s also worth noting that Pfizer recently announced that its Lyme vaccine, which has completed Phase 3 trials, is 70 percent effective and has no reported safety concerns. A vaccine would be welcome news here — I know people who have had Lyme disease who avoid touching grass in the spring and summer. “People find comfort in thinking they will have protection, but it’s only for one tick-borne disease, and it won’t mean that you won’t be bitten,” and need to be tested, said LaDeau.
