As a group, ticks are placed along with insects, spiders and mites in a large assemblage of organisms known as arthropods. All arthropods have several pairs of jointed legs and a hard outside covering, or exoskeleton. Ticks differ from insects in not having wings or antennae, and in having four, rather than three, pairs of legs in most stages of their life cycle. It is this life style, the feeding on blood from animals, that makes ticks of importance to human health.
Ticks may transmit several diseases to people and domestic animals. Most of these diseases occur only in specific areas and at low frequency. However, Lyme disease and Rocky Mountain Spotted Fever (RMSF) are exceptions in that large numbers of cases occur in downstate New York. Other diseases such as Babesiosis, occurs mainly on Cape Cod and the eastern end of Long Island; and tick paralysis also occurs in localized areas. There are other diseases transmitted to animals.
Lyme disease is the most common tick-borne disease in the United States and is an increasing national public health problem. In 1989 Lyme disease was known to occur in 43 states and is currently most prevalent in eastern coastal areas from Maine to Virginia. The primary vector to humans is the "deer tick," Ixodes scapularis although other species of Ixodes serve as vectors of Lyme Disease to wild animals and may infect humans. The causal agent is the spirochete (cork-screw shaped bacterium) Borrelia burgdorferi. Lyme Disease is an infection that can produce skin, arthritic, cardiac and neurological symptoms in humans and some animals, especially dogs. At the present time 8 states are reporting over 90% of the cases of Lyme Disease. These are New York, New Jersey, Massachusetts, Connecticut, Rhode Island, California, Wisconsin and Minnesota. New York State has reported 40 percent of the total cases according to records submitted to the Center for Disease Control (CDC) from 1986 to 1988.
DESCRIPTION AND DISTRIBUTION:
The adult deer tick is about the size of a sesame seed (2.5mm), oval-shaped, with 4 pairs of legs and a flattened body before feeding. It is reddish before feeding, but after engorging on blood, it is the size of a small pea and blue-black in color.
In New York State Lyme Disease is endemic in Suffolk, Nassau, Westchester, Rockland, Putnam, Orange, Ulster and Dutchess Counties. Ixodes scapularis has also been collected from Greene, Columbia, Schoharie, Albany, Rensselaer, Washington, Saratoga, Fulton, Essex, Madison and Jefferson Counties. This species of tick does not appear to be a resident in New York City, although the American dog tick (Dermacentor variabilis) the vector of Rocky Mountain Spotted Fever does occur in coastal areas of the city as well as being common on Long Island and other downstate counties.
In infested areas, the deer tick is common wherever deer and field mice frequent. White-tailed deer thrive where suburban lawns intersect with woodland or open field. Fields provide grazing areas, woods provide shelter and browse, and the homeowners provide tasty ornamental plantings. People are frequently establishing home sites in wooded areas, increasing the potential for wildlife/homeowner conflicts. In so doing, people create a habitat that attracts deer, field mice and ticks in their backyards.
On Long Island ticks are often found in beach grass near seashores in addition to the above mentioned areas.
LIFE CYCLE AND BIOLOGY OF THE TICK:
Adult deer ticks are most active in October-November, and again during April-May. They commonly attach to white-tailed deer, dogs, horses, and possibly people if they are active out of doors, in tick-prone areas.
The deer tick passes through four life stages over a period of two years. It is known as a three-host tick which means that it feeds at three different times during its life cycle. All life stages besides the egg must take a blood meal to develop, and the adult female must feed to mature the eggs.
The larval deer tick hatches from the egg, and is very tiny &endash; about the size of the period at the end of a sentence. The larva has only three pairs of legs. Larvae attach to small wild rodents such as the white-footed mouse (Peromyscus leucopus) which serve as a reservoir host of the spirochaete (disease organism). They feed for about 3-4 days then drop from the host, seek a protected site under leaves, etc. to overwinter. The larva molts to the nymph state the following spring.
Larvae usually pick up the spirochaete from the rodent host and once they are infected, deer ticks will carry Lyme disease throughout the remainder of their lives.
Nymphs occur in last spring and summer, and are about the size of a poppy seed. Nymphs may attach to humans, dogs, horses, cattle, rodents, and other small to medium sized animals. When an infected nymph feeds on a rodent, it may transmit the spirochaete to that rodent. The rodent then serves as a reservoir capable of transmitting the disease to other tick larvae. Birds frequenting the forest floor where nymphal ticks are present may also serve as hosts. It is believed that migrating birds may contribute to the spread of the tick.
The nymphal stage "quests" - waiting in ambush on vegetation from ground level to about 18 inches high. When a host brushes against the vegetation, the tick clings to it and searches for a suitable feeding site. Ticks do not fly, jump, or actively pursue a host. Nymphs are the most important vectors of Lyme Disease to humans because they are difficult to detect due to their small size, relatively short feeding period, and because humans are most active outdoors during the summer. The nymph feeds for 5-6 days, drops from the host, and again finds shelter under leaves or other vegetation. By late summer, nymphs molt to the adult stage.
Adults occur in the fall and in the spring where they also my be found questing on vegetation. The female tick is about the size of a sesame seed (2.5mm) and is brick red with a black shield on its back. Males are smaller than females and uniformly dark in color. The adults prefer to feed on deer, but will readily attack humans or dogs, as well as other medium-to-large sized animals. Deer are largely responsible (but not the only animals) for maintaining tick populations. Deer are often present in large numbers in wooded sites and a preferred host on which the female mates and acquires necessary blood for egg development.
Adults feed for 8-10 days swelling to the size of a small pea, and becoming blue-black in color. Adults may transmit Lyme disease to humans, but their larger size and longer feeding period makes them easier to detect before they have the opportunity to do so.
At high risk are people that frequent tick-prone areas. High risk groups include hunter, hikers, backpackers, fishermen, who frequent the out-of-doors. To protect yourself again Lyme disease, avoid tick infested areas whenever possible. When you mush travel outdoors in tick-prone areas:
REMEMBER THAT YOU ARE AT RISK DURING ANY SEASON OF THE YEAR EXCEPT DURING PERIODS OF SUBFREEZING TEMPERATURES.
Ticks are commonly feeding from April through October, with June and July the highest risk months for human exposure. If warm spells occur in winter, however, ticks again become active. Ticks must feed for 10 or more hours before the disease is transmitted. If you find an attached tick, remove it by grasping it with fine tweezers as close to the skin as possible, and gently but steadily pull the tick straight out. If no tweezers is available, grasp the tick with your fingers and a piece of paper or a leaf, as close to the skin as possible, and pull firmly until the tick lets go. Apply a topical antiseptic. Save the tick, your doctor may want to see it.
Check your pets or livestock regularly for ticks. Use tick
collars/dips, and seek medical attention for your pet if you suspect
Lyme disease. Veterinarians in endemic areas should be aware of the
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