- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Arachnida
- Order: Ixodida
- Family: Ixodidae
- Genus: Amblyomma
See also list of arachnids.
What is the lone star tick and where is it commonly found?
What diseases can Lone Star ticks transmit to humans?
What is alpha-gal syndrome and how is it caused?
What is the life cycle of the lone star ticks?
lone star tick, (Amblyomma americanum), species of North American hard tick capable of transmitting a number of diseases to humans and other animals. They are typically found in wooded areas with white-tailed deer across the eastern, southeastern and midwestern United States. While lone star ticks do not spread Lyme disease, they are vectors for a number of pathogens and are particularly associated with alpha-gal syndrome, which causes an allergic reaction to meats including beef, pork, and lamb.
Physical description
Lone star ticks are arachnids and have eight legs as nymphs and adults; the young larval stage has only six legs. Their body forms a single region, unlike the segmented bodies of their spider cousins. Adults are brown, reddish brown, or tan in color. The lone star tick gets its common name from its characteristic white spot on the dorsal shield of females. Males often have varied white streaks and spots on their dorsal shields or lack markings altogether. Adult females are generally larger than males, averaging 4–6 mm (0.16–0.24 inch) but reaching up to 16 mm (0.63 inch) when feeding. Adult males average between 2–5mm (0.08–0.2 inch). Nymphs are roughly the size of the head of a pin, while the tiny larva are about the size of a poppy seed. Like other ticks, the adults may be distinguished from their close relatives, the mites, by the presence of a sensory pit (Haller’s organ) on the end segment of the first of four pairs of legs.
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Natural history
Lone star ticks are parasites and feed on the blood of different animal hosts throughout their roughly two-year life cycle. They have four developmental stages: egg, six-legged larva (or “seed tick”), eight-legged nymph, and adult. They progress to the next developmental stage only after consuming a blood meal. Both larvae and nymphs can survive up to 6 months without feeding on a host, and adults can survive up to two years without feeding if the environmental conditions are optimal. Unlike mosquitoes, biting midges, fleas, and most other blood-feeding arthropods, which can obtain a blood meal within a few minutes, ticks usually feed for several days or even weeks, during which time they significantly increase in size to accommodate the blood consumed.
After hatching, the larval tick “quests” to find its first host, waiting on an object such as like a blade of grass until a host comes into contact. When a lone star larva encounters a host, it attaches and feeds on the host’s blood for several days before detaching, leaving its mouthparts behind, digesting its meal, and molting into a nymph. Nymphs repeat the process, and when they detach from their host they molt into adults. Adult males die after mating with one or more females. Females lay their mass of eggs on the soil one or two weeks after their last blood meal and die shortly thereafter. A single female can produce 3,000 to 8,000 eggs.
Larva and nymph lone star ticks typically attach onto rodents and other small mammals and birds, while adults attach to larger hosts including humans and deer, a strategy that can help reproductive tick populations spread to new locations. In some regions they are known to feed on wild turkeys, earning them the nickname “turkey tick” or “turkey mite.” Adults aggressively seek hosts, locating them by sensing carbon dioxide and movement vibrations, and readily feed on humans. Tick bites often go unnoticed because tick saliva has a number of active compounds that alter or block the host’s pain, itch, and immune responses, and modulate blood coagulation and wound healing.
Diseases
Alpha-gal syndrome
One unique illness associated with lone star tick bites in the United States is alpha-gal syndrome (other ticks can cause the syndrome elsewhere in the world). Lone star ticks have alpha-gal, a sugar molecule also found in the tissues of all non-primate mammals, in their saliva. When alpha-gal is passed to a human through the tick’s saliva, the person’s immune system sometimes responds by producing antibodies against it. Now sensitized to alpha-gal, the affected person will have an allergic reaction when consuming products from other non-primate mammals such as beef, pork, and lamb, as well as dairy products, gelatin, or even medical products such as snake antivenin (typically made with horse plasma) or porcine heart valves. People with alpha-gal syndrome can still consume poultry and fish. The syndrome is considered a type of food allergy, and the reaction cause life threatening anaphylaxis. There is no cure. However, a complete avoidance of mammalian meats and products for a period of time can lead to a decline in the levels of the responsible antibodies, and some people may eventually be able to consume such products without a reaction.
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Southern tick-associated rash illness (STARI)
Lone star tick bites can cause Southern tick-associated rash illness (STARI) in humans. STARI causes a round lesion or rash, sometimes with a bull’s-eye appearance much like the characteristic rash of Lyme disease, that appears within a week of the bite. Though the rash is sometimes the only symptom, other symptoms may include headache, fever, muscle or joint pain, and fatigue. Though the exact pathogen responsible has not been identified, scientists have ruled out Borrelia burgdorferi, the bacterium primarily responsible for Lyme disease.
Tularemia
Lone star tick bites may also cause potentially fatal illnesses such as tularemia, which can also be transmitted through mosquito bites or contact with infected animals. The disease is caused by the bacterium Francisella tularensis. Several species and genera of ticks are vectors for the disease, and may be largely responsible for perpetuating it wild animal populations. In addition, the bacterium is transmitted from the adult tick to the egg, and both larvae and nymphs are infectious and form an insect reservoir of infection. Symptoms from tick transmission often include a skin ulcer at the bite site, along with swollen lymph nodes and flulike symptoms. Fever can persist for two or three weeks.
Ehrlichiosis
Lone star tick bites can transmit ehrlichiosis, a disease caused mainly by the bacteria Ehrlichia canis, E. chaffeensis, E. ewingii, and E. muris eauclairensis, to humans and other animals, especially dogs. It primarily infects white blood cells and can range from mild to life-threatening if not treated promptly. Initial symptoms are similar to those of STARI, though ehrlichiosis may also cause gastrointestinal distress. In more severe cases, patients may experience confusion, respiratory issues, bleeding problems, or a rash—especially in children. If left untreated, the illness can progress to life-threatening complications involving the heart, lungs, kidneys, or brain.
Since 2000 the incidence of the disease in these regions has increased dramatically, from about 200 cases reported annually to nearly 2,000 in 2023 alone. This increase is likely associated with the growing population of the lone star tick, the primary vector for E. chaffeensis and E. ewingii.
Heartland and Bourbon viruses
Heartland virus, discovered in 2009, and Bourbon virus, discovered in 2014, are very rare; the latter is not conclusively known to be transmitted by ticks. They both are associated with flulike symptoms and gastrointestinal distress.