Ticks, which share the animal kingdom’s Arthropoda phylum with crustaceans such as lobster and arachnids like spiders, pack a mighty punch for so small a creature. Ticks account for the majority of vector borne infections to people. Ticks transmit a greater variety of infectious illnesses to humans in the U.S. than any other arthropod. Ticks also transmit more diseases to domestic animals than any other arthropod. They can survive in nature for many years without food.
Deer Ticks – The most common carrier for Lyme Disease in the U.S., the deer tick in its nymph stage feeds on humans. The deer tick is principally found in the Northeast (from Maryland to Maine) and Northern Midwest (especially in Wisconsin and Minnesota), to a lesser extent in the South and along the coastal areas of California, Oregon and Washington. On the Pacific Coast, particularly in Northern California, the disease is transmitted by the western black-legged tick, and in the Southeastern states possibly by the black-legged tick.
The deer tick is also the species responsible for Human Granulocytic Ehrlichiosis and Babesiosis. Very small and hard to see, the deer tick is dark in color. Before reaching adulthood, it is as small as a poppy seed. As an adult, it is the size of a pinhead.
Rocky Mountain Wood Tick – This tick is most commonly associated with Rocky Mountain spotted fever, anaplasmosis and what is known as tick fever, is found principally in mountainous areas.
American Dog Tick – Another common vector for Rocky Mountain spotted fever, anaplasmosis and tick fever, the American dog tick in the adult stage attacks humans. It is found in all states east of the Rocky Mountains and is well established in Idaho, Washington and Oregon.
Brown Dog Tick – This most common tick in the U.S. infests human and pet habitats-which are often but not necessarily the same areas. Associated with Human Granulocytic Ehrlichiosis and tick paralysis, it only occasionally bites humans.
Lone Star Tick – Another vector of Rocky Mountain spotted fever, as well as tularemia and tick paralysis, the Lone Star tick in the adult stage will attack humans.
Ticks occur in two basic types, hard and soft, with a life cycle of four stages- egg, larva, nymph and adult. The life history varies considerably in different types of ticks.
Sucking blood is the mode of feeding- hence the term blood meal- for the larva, nymph, and adult states. The larvae, nymphs, and adults of soft ticks each feed on hosts many times, while the hard tick feeds on blood only once during each of the three stages. Some ticks spend their whole life cycle on one host, while with others, each stage feeds on a different host. Dogs and small children commonly bring ticks into the home from outdoors. Walking in the woods or in fields exposes adults. For the most part, ticks do not normally infest homes, as do fleas. However, ticks are more dangerous to humans and harder to find on the body.
Most active from April through October in the U.S., ticks can transmit diseases to humans and attack animals until the first frost. Requiring humidity and moderate temperature to flourish, in the absence of a host or proper conditions, ticks will simply await proper conditions. Some ticks are highly fecund- capable of producing many offspring. A single tick can lay more than 18,000 eggs.
Being larger than the deer tick associated with Lyme Disease, dog ticks and wood ticks are easier to spot on the body.
Human Health Impact
Human tick-borne diseases are found in almost every state. The national Centers for Disease Control and Prevention, which reports that tick-borne disease is on the rise in the U.S., believes that available statistical data vastly underestimate the true incidence of tick-borne disease because only a small fraction of cases are seen or recognized by medical professionals. Blood testing is necessary to accurately diagnose all tick-borne diseases.
The bacteria that cause Lyme Disease, Human Granulocytic Ehrilichioisis and Babesiosis can all be carried by the deer tick. This means that a single bite by this species can potentially transmit more then one of the diseases.
Lyme Disease – The best known, Lyme Disease, is a bacterial infection transmitted by the bite of an infected deer tick. Taking its name from the town of Lyme, Conn., the disease is a chronic debilitating condition that may cause musculo-skeletal, cardiac and central nervous system disorders. A circular rash or skin lesion may be the first sign. The red blotch or circular “bull’s eye” pattern may show at three to thirty days after a bite by an infected tick. The rash does not always occur at the bite site and may show at the armpit, groin or back of the knee. Other symptoms include fatigue, neck stiffness, muscle aches and flu-like symptoms such as headaches, chills, fever, dizziness, sore throat, cough and hoarseness. Later stage symptoms may not appear until weeks, months or years after a tick bite and can include memory loss, difficulty concentrating, and changes in mood and sleeping habits.
For more information about Lyme Disease visit the American Lyme Disease Foundation.
Rapid reforestation in northeastern states is the main factor in the surge in Lyme Disease over the last 17 years, according to the American Lyme Disease Foundation (ALDF). Travel may be the reason that the disease is now reported in almost every state, ALDF suggests. Lyme Disease continues to be a rapidly emerging infectious disease, accounting for more than 90% of all vector-borne illness reported to the U.S. by the CDC. In 1996, the CDC reported 16,455 cases in the U.S. and between 1982 and 1996, more than 99,000 cases.
Treatment is easy and effective if detected early. Antibiotics are administered under a physician’s supervision. If undetected, however, a serious long-term disability can result.
Human Granulocytic Ehrlichiosis – Human Granulocytic Ehrilichiosis, a particularly severe disease transmitted by the deer tick in the same regions as Lyme Disease, have been reported primarily in the South Central and South Atlantic states- particularly in Oklahoma, Missouri, and Georgia. Since 1986 to 1996, the CDC recorded 320 cases.
Symptoms are similar to those of Lyme Disease and include rash, fatigue, neck stiffness, muscle aches and flu-like symptoms such as headaches, chills, fever, dizziness, sore throat, cough, hoarseness and sleep disturbances. Symptoms show about a week after a tick bite.
Treatment generally requires hospitalization and antibiotics administered by a physician to cure the disease and prevent serious complications. Without treatment, it can cause overwhelming infection, toxic shock and death. Death occurs in 5% of cases.
Babesiosis – An emerging disease in the U.S. that is often mistaken for malaria, Babesiosis is transmitted by the deer tick. It can cause serious, even life-threatening illness, and is occasionally fatal.
Most cases occur in New England and New York, but since 1990, cases have been reported in Wisconsin and Minnesota. From 1967 to 1996, the CDC recorded about 450 cases, mostly among older individuals.
Symptoms, which may appear one to three weeks after a bite, include flu-like fatigue, loss of appetite, fever, drenching sweats, general achiness and headache. Illness can range from mild infection to severe hemolytic anemia, renal failure and severe hypertension. Treatment is with antibiotics under a physician’s supervision.
Rocky Mountain Spotted fever – Transmitted by many species of ticks, including dog ticks, brown dog ticks and wood ticks (all larger than the deer tick and easier to spot) Rocky Mountain spotted fever is now a misnomer since it occurs in almost every state in the U.S., Canada, Mexico, Central and South America.
Rocky Mountain spotted fever was first reconfirmed in 1896 in the Snake River Valley of Idaho and was originally called “black measles” because of the characteristic rash. By the early 1900s, the disease spread to parts of the United States as far north as Washington and Montana and as far south as California, Arizona, and New Mexico.
The highest incidence of Rocky Mountain spotted fever is among children five to nine years old. In 1997, 831 cases over all ages were reported to the CDC. In the last three decades, more than 22,000 cases have been recorded.
Symptoms typically include headache, fever, restlessness and loss of appetite. After the third day of infections, a skin rash may show and may spread over the entire body. Some cases may involve nausea, vomiting, diarrhea or abdominal pain. Undiagnosed, Rocky Mountain spotted fever can cause central nervous system disorders, respiratory, kidney, or liver failure and in some cases, death. Treatment includes antibiotics under a physician’s supervision.
For more information about Rocky Mountain Spotted Fever, please visit Center for Disease Control (Rocky Mountain Spotted Fever).
Tularemia – Caused by the bacteria Francisella tularensis, Tularemia is normally transmitted to humans by contact with animals (particularly game animals), and by the bites of flies and ticks. If the bacteria enter through a wound on the skin, a skin eruption will slightly appear at the sight of entry. Symptoms most likely include swollen lymph nodes, fever, chills and headache. Pneumonia may also develop.
Animal Health Impact
Tick bites and blood feeding annoy and harm animals, and can even cause them debilitating or fatal illnesses. The tick is the number-one cause of infectious disease in animals.
Anaplasmosis is a blood parasite that invades red blood cells of infected animals. The animal’s immune system then begins to attack the red blood cells and the animal eventually suffers acute anemia. It is a disease that, at times, has been disastrous to the cattle industry. Transmission among animals is generally by ticks (Dermacentor andersoni in western North America), but transmission by biting flies, mosquitoes, hypodermic needles, dehorning, castrating and ear tagging can occur. The disease does not affect humans.
Environmental Control – Spray yards if ticks are seen, and consider spraying during summer tick season. Keep weeds or grass well mowed. Restrict access of wild animals into the yard.
Limit Exposure – Carefully plan excursions into fields and woods during the months of May, June or July to limit exposure to ticks. If possible, stay away from heavy woods and areas with standing water.
Wear long pants tucked into socks. Ticks travel upward until their path is blocked. Clothing with collars and cuffs is recommended, since ticks often lodge in these areas of fabric. Wear long sleeved shirts with collars and cuffs (tucking the shirt into pants) when venturing into fields and forests. Light colored clothing makes it easier to spot ticks
Dress children in loose fitting, light colored clothes to spot ticks more easily. Choose long pants and long sleeved shirts with collars and cuffs. Tuck shirts into pants and pants into socks or boots.
Insect Repellents – Use insect repellents from April through October, until the first frost for effective control of ticks. Sprays clothes or apply to exposed skin as directed on the label. Read the label to determine whether the repellent should be applied to skin or clothing.
Adults should apply repellent to young children. Follow all child safety precautions on labels. Of course, always keep insect repellents out of the reach of children.
For safe and effective use, read and follow product label directions and cautions. Apply repellent only to exposed skin and/or clothing as directed on the product label. Do not apply under clothing. Use only enough to cover exposed skin and/or clothing. Saturation of clothing or frequent reapplication to skin is unnecessary for effectiveness. Do not apply repellent to eyes or mouth, nor over cuts, wounds or irritated skin.
On returning indoors, wash treated skin with soap and water. This is particularly important when repellents are used repeatedly. If any reaction to a repellent is suspected, wash the treated skin and seek medical attention. Show the product to a health professional for proper identification.
Checking for Ticks – Always visually inspect yourself and your children for ticks after outdoor activities. Before returning indoors, inspect clothing, especially under collars and cuffs. Further inspect behind knees, under armpits, around the scalp, nape of the neck and behind ears.
Removing and Disposing of Ticks – A tick should be removed immediately with tweezers by grasping the tick as close as possible to the skin and slowly pulling it away. Do not remove ticks with vaseline, hot objects such as matches or cigarettes or by other methods. These methods can increase the chance of a host tick injecting bacteria into the person. Be sure to kill and dispose of any detected ticks. Do not brush a tick into the grass, where it can colonize and continue to pose a health risk. Wash hands after contact.
If Bitten – If bitten by a tick, treat the bite site with a topical antibiotic and over the next few weeks watch for any rash or flu like symptoms. Consult a physician about any questions.
Animals – Insecticidal products such as tick sprays, collars, dips, pour ons, shampoos, and other forms all may prove effective for pets and other animals. When animals have been running in yards, fields and woods during tick season inspect them on their return and remove any ticks. Wear light colored clothes for your own protection to facilitate detection should ticks move from the animal to you.
In the Home – Products used for flea control in the home will usually control ticks as well. These include total release foggers, direct sprays and powders. Be sure to follow label directions.