Alpha-gal Syndrome (AGS) is an allergic reaction to the alpha-gal sugar molecule, found in most red meat and some animal products. This allergy typically develops after a bite from certain ticks that have fed on mammals containing alpha-gal. Understanding which ticks transmit this sugar is key to preventing AGS. This article identifies the ticks known to carry alpha-gal and cause this allergy.
The Lone Star Tick
The Amblyomma americanum, known as the Lone Star Tick, is the primary tick species linked to Alpha-gal Syndrome in the United States. Females are identifiable by a distinct silvery-white, star-shaped spot on their back, while males have white streaks or spots around the shield’s margins. Unlike some other ticks, Lone Star Ticks are aggressive, actively seeking a blood meal and moving quickly towards potential hosts. Their bites are often painless, allowing them to remain attached for days undetected.
When a Lone Star Tick feeds on a mammal, it ingests alpha-gal from the animal’s tissues. If this tick then bites a human, it can inject alpha-gal into the person’s bloodstream through its saliva. This transfer can trigger an immune response, leading to the development of IgE antibodies against alpha-gal. Subsequent consumption of red meat, which also contains alpha-gal, can then cause an allergic reaction. All life stages—larvae, nymphs, and adults—are capable of transmitting alpha-gal and causing AGS.
Other Tick Species
While the Lone Star Tick is the primary cause of AGS in the U.S., other tick species can also transmit alpha-gal. The Blacklegged Tick (Ixodes scapularis), also known as the deer tick, has been implicated in AGS cases in regions like Maine and Washington. This tick is more widely recognized as a vector for Lyme disease, showing that a single tick bite can transmit multiple conditions.
Beyond North America, other tick species are associated with AGS. In Australia, the Paralysis Tick (Ixodes holocyclus) is a known vector. The Asian Longhorned Tick (Haemaphysalis longicornis), found in Japan and recently established in parts of the eastern U.S., has also been linked to alpha-gal sensitization. The European castor bean tick (Ixodes ricinus) in Europe and other Amblyomma species globally are suspected or confirmed carriers. These varying tick species and their distributions highlight the global presence of alpha-gal syndrome.
Where Alpha-gal Ticks Are Found
The geographical distribution of alpha-gal transmitting ticks is expanding, influencing AGS prevalence. The Lone Star Tick is primarily found across the southeastern, eastern, and central United States, notably in states like Virginia, Tennessee, North Carolina, Arkansas, Oklahoma, and Missouri. Its range has rapidly expanded northward and westward, reaching as far north as New York and Maine, potentially covering the entire eastern U.S. This expansion is attributed to climate change, habitat disruption, and growing deer populations.
The Blacklegged Tick (Ixodes scapularis), while not historically associated with AGS, has caused cases in regions outside the traditional Lone Star Tick range, such as Maine and Washington. This suggests AGS can emerge where only Blacklegged Ticks are prevalent. The Asian Longhorned Tick (Haemaphysalis longicornis), established in the eastern U.S., has not yet been definitively linked to U.S. AGS cases, but is a known vector in Japan. The increasing spread of these ticks means areas previously considered low-risk are now seeing emerging cases.
Protecting Against Alpha-gal Tick Bites
Protecting against alpha-gal tick bites involves preventive measures to reduce exposure and prompt action if a bite occurs. Avoiding tick-infested habitats like tall grass, dense brush, and wooded areas is important. When outdoors, wear protective clothing, including long pants tucked into socks and long-sleeved shirts, to create a physical barrier against ticks.
Use EPA-approved insect repellents on exposed skin and clothing. Repellents containing DEET (at least 20% concentration), picaridin (20% concentration), or permethrin (applied to clothing and gear, not skin) are effective. After outdoor activities, perform thorough tick checks on yourself, children, and pets. Focus on areas like:
Underarms
Ears
Belly button
Behind the knees
Between the legs
Around the waist
In the hair
Showering within two hours of coming indoors can also help wash off unattached ticks.
If a tick is found attached, prompt and proper removal is crucial to minimize disease transmission. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible. Pull upward with steady, even pressure without twisting or jerking the tick. After removal, clean the bite area with soap and water or rubbing alcohol. Avoid using home remedies like petroleum jelly or heat, as these can agitate the tick and potentially increase the risk of infection.