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What 3 types of ticks can carry lyme disease?

Lyme disease is a serious illness caused by the bacteria Borrelia burgdorferi that is transmitted to humans through the bite of infected ticks. Understanding the types of ticks that can carry this disease is important for prevention and prompt diagnosis and treatment. In North America, there are 3 main types of ticks known to transmit Lyme disease to humans.

Lyme disease was first identified in the 1970s in Lyme, Connecticut, when a cluster of children were diagnosed with juvenile rheumatoid arthritis. Further investigation revealed the true cause to be a bacterial infection transmitted by ticks. Lyme disease is now the most common vector-borne illness in the United States, with over 30,000 cases reported to the CDC each year. However, the true number of people diagnosed is likely 10 times higher, estimated around 300,000.

Lyme disease affects people of all ages and is more common in certain regions, such as the Northeastern and Mid-Atlantic states. It is caused by a spiral-shaped bacteria called a spirochete that is related to the bacterium that causes syphilis. Borrelia burgdorferi is transmitted to humans through the bite of infected blacklegged ticks.

Ticks go through three stages in their lifecycle – larva, nymph, and adult. They can pick up Borrelia when feeding on reservoir hosts like mice or deer during the larval or nymph stage. The bacteria stays in the tick’s gut and is transmitted to humans during subsequent feedings.

Prompt diagnosis and treatment with antibiotics can cure most cases of Lyme. However, lack of awareness and failure to remove ticks properly can delay care. If left untreated, Lyme disease can spread to the joints, heart, and nervous system, leading to serious, potentially disabling symptoms.

Ixodes Scapularis

The blacklegged tick, also known by its scientific name Ixodes scapularis, is the main vector for Lyme disease in the Eastern United States. This species of hard-bodied tick goes through a two-year life cycle and requires 3 blood meals – one per each life stage. Here are some key facts about its role in Lyme disease transmission:

  • Found heavily in the Northeastern and Mid-Atlantic regions of the U.S.
  • Larvae and nymphs prefer to feed on small animals and birds.
  • Adult females feed on larger hosts like deer and humans.
  • Can transmit Lyme bacteria during larval, nymph, or adult stages.
  • Nymphs are most likely to transmit Lyme; very small and hard to detect.
  • Peak activity during summer months.

Of all life stages, the poppy-seed sized nymphs pose the biggest threat to humans as they are abundant but difficult to detect on the body due to their tiny size. Nymphs are responsible for transmitting the majority of Lyme bacteria that cause human infection.

Ixodes Scapularis Range in North America

Ixodes scapularis ticks are found predominantly in the northeastern, mid-Atlantic, and north-central states. The map below shows the approximate range of the blacklegged tick in North America.

States
Maine
New Hampshire
Vermont
Massachusetts
Rhode Island
Connecticut
New York
New Jersey
Pennsylvania
Delaware
Maryland
Virginia
West Virginia
Ohio
Indiana
Illinois
Wisconsin
Minnesota
Iowa
Missouri
Michigan
North Dakota
South Dakota

Areas shaded in red have established I. scapularis tick populations. Areas in orange have reported I. scapularis ticks but do not have fully established populations. Unshaded states are outside of the blacklegged tick’s range.

Ixodes Pacificus

On the West Coast of the United States, the western blacklegged tick (Ixodes pacificus) is the primary vector for Lyme disease. It is found in the following states:

  • Oregon
  • Washington
  • California
  • Nevada
  • Idaho
  • Utah

This species has a similar life cycle and behavior as the eastern blacklegged tick. Nymphs are most active during the spring and early summer months. Key differences include:

  • Found in drier chaparral and woodland habitats of the Pacific Coast.
  • Peak activity during the rainy season from November to April.
  • Transmit a less pathogenic form of the Lyme bacteria.
  • Thought to be less efficient at transmitting Lyme to humans.

Lyme disease cases from ticks in this region are less frequent, although incidence has increased in recent years. Additional research is needed on the transmission efficiency of I. pacificus ticks.

Reported Cases of Lyme Disease Carried by I. pacificus

State Reported Cases (2018)
Oregon 17
Washington 30
California 167
Nevada 4
Idaho 2
Utah 25

This table shows reported cases of Lyme disease in states within the range of Ixodes pacificus ticks in 2018 (latest CDC data). California has the highest reported cases, while incidence in other western states is much lower compared to some eastern states.

Amblyomma Americanum

The lone star tick, Amblyomma americanum, is another species capable of transmitting Lyme disease to humans, although less efficient than blacklegged ticks. These ticks are found throughout southeastern and eastern states with expanding range due to changing climate and habitats. Key facts:

  • Aggressive biter that feeds on humans, livestock, other mammals.
  • All three life stages (larva, nymph, adult) will bite humans.
  • Found in wooded areas, especially those with dense underbrush.
  • Most active during summer months of June-August.
  • Saliva may induce an allergic reaction, causing red meat allergy in some individuals.

Research shows the lone star tick is a poor vector for Lyme disease transmission compared to blacklegged ticks. However, its wide distribution and aggressive biting behavior increase the risk of infections in certain areas where it overlaps with Ixodes tick ranges.

Distribution of the Lone Star Tick

The current range of Amblyomma americanum ticks covers the Southeastern and Eastern states listed below:

States
Oklahoma
Texas
Arkansas
Louisiana
Mississippi
Alabama
Georgia
Florida
South Carolina
North Carolina
Tennessee
Kentucky
Virginia
West Virginia
Maryland
Delaware
New Jersey
Pennsylvania
New York
Connecticut
Rhode Island
Massachusetts

Range includes states shaded in red. The lone star tick has expanded northward in recent decades, increasing overlap with blacklegged tick populations.

Protecting Yourself from Tick Bites

Now that we’ve reviewed the main tick species that can transmit Lyme disease, it’s important to know how to protect yourself from tick bites. Here are some tips when outdoors in tick habitats:

  • Wear light-colored clothing to spot ticks easily.
  • Tuck pant legs into socks to keep ticks off skin.
  • Apply EPA registered insect repellent such as DEET.
  • Stay in the center of trails; avoid high grass and brush.
  • Perform daily tick checks on yourself, children, and pets.
  • Shower soon after being outdoors to wash off unseen ticks.
  • Talk to your vet about tick prevention products for dogs.

Catching and removing ticks quickly can prevent transmission of Lyme bacteria. If you develop a bullseye rash, fever, or other symptoms after a tick bite, see your doctor right away to get tested and treated for Lyme. Prompt antibiotic treatment is crucial for preventing complications.

Conclusion

Lyme disease is a growing public health concern as tick populations flourish across North America. Knowing the regional ticks capable of carrying Lyme – primarily Ixodes scapularis in the East, Ixodes pacificus in the West, and Amblyomma americanum in the Southeast – is key for diagnosis and prevention. While tick bites cannot be prevented completely, using protective clothing and repellents, checking regularly for ticks, and removing them swiftly can reduce your risk. Speak to your doctor right away about testing and treatment if Lyme disease is suspected. Increased awareness and preventative actions by individuals, combined with expanded research and surveillance by public health authorities, will help address the rising incidence of Lyme disease.