The annual rate of tick-borne disease cases has been growing each year for the past couple of decades in all areas of the US, but the northeast continues to see the highest rate of tick-borne disease cases in the country. Several factors are responsible for the progressively larger number of tick-borne infections being contracted in the northeast, but two of the most important factors has to do with the expanding tick population, as well as the growing proportion of infected ticks within a given tick population. Although ticks are a major public health threat, their slow-moving terrestrial activity makes them less dangerous to humans than if they were capable of flight. As it happens, however, there does exist multiple tick-like airborne arthropod species that researchers believe may be capable of transmitting Lyme disease and a variety of other diseases to humans. These fly species were thought to have been exceedingly rare in the United States, but recent research shows that these potentially dangerous insects are far more abundant in the northeast than previously thought.

Deer keds are a group of fly species from the Hippoboscidae family of the Diptera order of insects, which includes houseflies, fruit flies, mosquitoes and gnats. Deer keds are native to Europe and Asia, but they were introduced into the eastern US some years ago. These pests closely resemble ticks in appearance and they spend 20 to 25 minutes sucking blood from mammals, mostly deer, horses and cattle, but occasionally humans. Initially, bites are not noticed, similar to tick bites, but local swelling and severe irritation set in after one to three days following a bite. Deer keds have also been known to feed on dogs and they are most active during the fall and winter seasons. These flies are not well known in the US, as it was assumed that they were rare in the country, but a recent nationwide scientific survey has revealed that these insects are more widespread and abundant than previously thought, especially in the northeast.

Several studies have found bacteria that causes Lyme disease, cat scratch fever and anaplasmosis in deer keds, but no studies have found any instances of the insects spreading disease to humans. However, according to Michael Skvarla, extension educator and researcher at the Department of Entomology at Pennsylvania State University, deer keds have the potential to transmit diseases to humans, and infected females may be able to pass the disease on to their larval offspring, which could potentially lead to disease epidemics across the US.

Have you ever heard of deer keds? Have you ever heard of someone sustaining a bite from a deer ked?