Tufts infectious disease researcher Dr. Heidi Telford. [Photo/Mark Blazis]
Worthy of much acclaim herself, Heidi has developed a technique to help determine from which species ticks get infected.
They’re both now analyzing every tick that our bird banding team studying Lyme disease at the Auburn Sportsmen’s Club took off mist-netted migrating birds this past spring. They’ll determine whether the ticks were infected by those birds — or by something else.
This spring, we captured one robin that had 15 deer ticks on it. But we’ve captured many other species of birds carrying ticks on the vulnerable, exposed skin around their eyes and at the corners of their mouths — especially low-foragers like towhees, song sparrows, thrushes, and many different warblers that are parasitized by ticks.
We’ve found that most ticks occur in low, thick vegetation inhabited by mice and deer. Canopy birds seldom are parasitized. The ticks know where the blood they critically need can be most readily sucked.
What Telford’s lab at Tufts does with our specimens is truly amazing. A generation ago, their discoveries would have been impossible.
According to Telford, who has a knack for simplifying just about everything that’s scientifically complex, the lab basically grinds up the ticks, amazingly extracting their DNA to determine what the infected ticks fed on.
As it turns out, some tick-parasitized birds, like common yellowthroats and house wrens, can carry the Lyme disease in their blood while other birds like gray catbirds don’t. Deer don’t either. How is it possible for an animal to be bitten by these ticks and not be infected?
Some species, Telford explains, have complimentary proteins, which can find a specific bacteria in the blood and kill it. So, despite a deer in late fall possibly having dozens of infected ticks on it — and being bitten by all of them — it will never become infected with Lyme disease or cause a problem for anyone eating it.
Coincidentally, federal endangered plant botanist Tom Rawinski sent me a photo of a rabbit, its neck grossly covered with very large, engorged ticks. Telford looked at them and immediately identified them the rabbit ticks as Ixodes dentatus — relatives of deer ticks, Ixodes scapularis. “They transmit Lyme disease between rabbits but rarely bite people. They feed on songbirds, particularly in the fall when the larvae are out.”
I asked Dr. Telford if rabbits and other tick-bitten species suffer Lyme disease. Considering we’re still trying to get a handle on ticks and people, it’s not surprising that we don’t really know everything about other animals’ Lyme problems. “Rabbits suffer more from blood loss and secondary bacterial infection from heavy tick infestation although one disease, tularemia, is transmitted by ticks and can be devasting to them, proving fatal within seven days.”
It’s likely, though, that all animals on first exposure to Lyme disease bacteria would show signs of Lyme disease. “Mice, for example, have joint swelling and heart inflammation that’s detectable by histopathology three weeks after getting infected. But both of their symptoms resolve very quickly. The mice simultaneously have many other parasites from fleas to tapeworms, roundworms, as well as amoebas and viruses. Amazingly, some of their reactions can prove beneficial — even canceling out a severe disease. For example, a roundworm might induce a cellular immune response that overrides a viral infection.”
I asked Dr. Telford why rabbit ticks don’t bite people very often here. He said, “They’re capable of biting people, and in a Maryland study, we found that for every rabbit tick bite on a human, there were four deer tick bites. We just don’t know how or why a specific species of tick decides which host is the right one to bite and suck. If we did, we might be able to develop new repellents. This would be worthwhile research — but tough to get research money to look at the problem.”
Telford’s second big grant is now allowing his lab to study the deer tick encephalitis virus that is also spread by deer ticks. This disease is separate from equine encephalitis and has been recognized since the 1930s in Asia where it originated.
Telford has actually been studying this disease for decades and wonders why we don’t see more cases. It’s a good thing that it occurs so rarely as 10-30% of those infected die, and over 50% of those who survive are debilitated by permanent nerve damage often marked by paralysis. There is no cure, but those who have gone to Mass General Hospital early when presenting symptoms have more often than not done well.
Summer is a bad time to get bitten by ticks. From July through September, we can be bitten by the tiny, hard-to-see nymphal form of the deer ticks. Far fewer people get infected by adult ticks, which emerge in colder weather, partly because we’re more clothed then and also because the adults are much bigger, far more noticeable, and therefore much more likely to be removed.
Telford also shared that it’s only a matter of time before the long horn tick, which is now in New Jersey, becomes a threat to us in New England. Some bird species can carry the disease. Additionally, we now have to worry about diseases spread by the lone star tick. Telford has observed that the explosion of turkeys in New England directly parallels the spreading occurrence of lone star ticks. The turkeys may well have helped spread them and may be doing so most notably now in Cape Cod and the Islands.
Considering how our dogs can get debilitating Lyme disease, I asked Dr. Telford about our wild, native canids: foxes, coyotes, and wolves. “Nobody knows. It’s very hard to determine much about wild animals’ infections given that at any one time they have multiple infections that may cause observed lesions and disease. We could do experimental infections on hand-reared wild animals, but that might prove little since in the wild, other infections might actually negate the effects of Lyme.”
Telford offered a tip to hunters. Many of us will hang a deer to dress it out or age it in our back yards. Ticks will inevitably precipitate from that carcass, possibly infecting our property — or crawling up to bite and infect us or our pets. He recommends anyone hanging a deer carcass should place a tarp sprayed heavily with Raid underneath it to kill all ticks that do fall off.
We’re so lucky to have brilliant scientists like the Telford working on behalf of our community to counter health threats from ticks. Sam’s helping develop our first Lyme disease vaccine and his proving that reduction in deer populations reduces the incidence of Lyme disease are just a part of a brilliant resumé that one could almost predict from his youth.
Sam Telford’s father, Dr. Sam Telford, Jr., was an internationally famous parasitologist, who pioneered the discovery of the life cycles of several infectious disease carriers. So, Tufts’ Sam (Telford III) grew up in the tropics, living in numerous countries that included Panama, Pakistan, and Burma.
Telford recollects, “Up until the age of 17, I lived only two years in the United States.” He grew up studying reptiles and mammals with his scientist father. He might have been a zoologist or ecologist, but realized there wasn’t much of a financial future in those fascinating studies. His lucky break and start to a career of discovery and fame came in 1984 at Harvard, when Dr. Andrew Spielman needed a mammal trapper to start collecting ticks.
We can look forward to the Telfords continuing the critically important battle against tick-borne and other diseases, and generously sharing their lab discoveries and advisories with us here in the Worcester Telegram & Gazette.
—Contact Mark Blazis at markblazissafaris@gmail.com.