The Amblyomma maculatum, or Gulf Coast tick, is gaining attention due to its expanding geographical range and its role in transmitting pathogens. It represents a health concern for both humans and animals in its native and newly established habitats.
Identifying the Gulf Coast Tick and Its Habitat
The Gulf Coast tick, Amblyomma maculatum, has distinct physical characteristics. Adult males have a reddish-brown body with white, web-like patterns across their dorsal shield. Adult females display bright, white markings on their dorsal shield, which is the hard plate covering part of their back. Both sexes have flat eyes and spurs on their fourth coxa, and their legs are typically yellow-orange. A notable feature of Gulf Coast ticks, compared to other species like the American dog tick, is their longer and thinner mouthparts.
The historical distribution of the Gulf Coast tick includes the southeastern coastal states along the Gulf of Mexico and southern Atlantic coast, stretching from Texas to South Carolina, and extending inland by approximately 100-150 miles. However, its range is expanding northward, with established populations now reported in states like Maryland, Delaware, New Jersey, and even Connecticut. These ticks prefer dry environments, such as grass prairies, coastal uplands, shrublands, and open woodlands, including fields and roadsides. While adults are most active from late spring through fall, activity can vary by region, with some coastal populations showing adult activity peaking in August.
Diseases Associated with the Gulf Coast Tick
The Gulf Coast tick transmits Rickettsia parkeri, the bacterium causing Rickettsia parkeri rickettsiosis. This illness is a type of spotted fever rickettsiosis that shares similarities with Rocky Mountain spotted fever but is generally considered less severe. Symptoms typically appear within 2 to 10 days after a tick bite, with a median incubation period of about 5 days.
Patients often develop an eschar, a dark, scab-like lesion, at the site of the tick bite, which is a distinguishing feature of Rickettsia parkeri rickettsiosis. Several days after the eschar appears, other symptoms may develop, including fever, headache, and muscle aches. A rash can also appear on the trunk and extremities. While gastrointestinal symptoms are uncommon, some patients may experience mildly elevated levels of hepatic transaminases and mild leukopenia.
Beyond Rickettsia parkeri rickettsiosis, the Gulf Coast tick has also been associated with other conditions. It can cause tick paralysis, a serious medical condition resulting from a neurotoxin in the tick’s saliva that is injected into the host during feeding. Symptoms of tick paralysis typically begin with ataxia and paralysis in the feet and can progress upwards in the body. If the tick is removed promptly, symptoms usually subside within a day or two.
In laboratory settings, these ticks have also been shown to be capable of transmitting Ehrlichia ruminantium, the pathogen that causes Heartwater, a fatal disease in ruminants, though this disease is not present in the United States.
Preventing Bites and Tick Removal
Preventing bites from the Gulf Coast tick involves several practical measures to reduce exposure. When in areas where ticks are common, such as grasslands or wooded edges, wearing protective clothing can help. This includes long sleeves and long pants, with pant legs tucked into socks to create a barrier. Choosing light-colored clothing can make it easier to spot ticks that may have latched on.
Using insect repellents is another effective strategy. Products containing DEET can be applied to exposed skin, while permethrin-treated clothing and gear can offer added protection, as permethrin kills ticks upon contact. After spending time outdoors, it is important to perform a thorough tick check on yourself, children, and pets, paying close attention to warm, hidden areas like underarms, behind ears, and in the belly button. Showering within two hours of coming indoors can help wash off unattached ticks, and placing clothes in a dryer on high heat for at least one hour can kill any lingering ticks.
If a Gulf Coast tick is found attached, prompt and proper removal is important. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible, ideally near its head or mouthparts. Pull upward with steady, even pressure, avoiding twisting or jerking the tick, as this can cause the mouthparts to break off and remain in the skin.
If mouthparts do remain, they can often be left alone to heal, but medical advice can be sought. After removing the tick, clean the bite area and your hands thoroughly with rubbing alcohol, an iodine scrub, or soap and water. The removed tick can be disposed of by placing it in alcohol, a sealed bag, wrapping it tightly in tape, or flushing it down the toilet.