Ticks are small arachnids known for their blood-feeding behavior, and they belong to the subclass Acari. They are ectoparasites, meaning they feed on the blood of a wide variety of hosts, including mammals, birds, and sometimes reptiles. Ticks are important vectors of various diseases, and they are found throughout the world.
There are over 900 known species of ticks in the world, and new species continue to be discovered as scientific research and fieldwork progress. These species belong to various genera within the subclass Acari and are distributed across different regions and ecosystems. It’s important to note that the diversity and distribution of tick species can vary by geographic location, and some species are more common and significant vectors of diseases in specific regions.
Common Ticks Species
- Ixodes scapularis (Black-legged tick or Deer tick): Black-legged ticks are primarily found in the eastern and northern regions of North America. They are vectors for Lyme disease, anaplasmosis, and babesiosis.
- Ixodes pacificus (Western Black-legged tick): Western black-legged ticks are found along the western coast of North America, and they can transmit Lyme disease.
- Amblyomma americanum (Lone Star tick): The Lone Star tick is prevalent in the southeastern and eastern United States. It is known to transmit pathogens responsible for ehrlichiosis and tularemia.
- Dermacentor variabilis (American Dog tick): American dog ticks are widely distributed in North America. They can transmit Rocky Mountain spotted fever and tularemia.
- Rhipicephalus (Boophilus) microplus (Southern cattle tick): Southern cattle ticks are a significant threat to cattle and livestock in many regions. They are known to transmit bovine babesiosis and anaplasmosis.
- Rhipicephalus sanguineus (Brown Dog tick): The brown dog tick can infest dogs and can transmit diseases like canine ehrlichiosis and canine babesiosis.
- Haemaphysalis longicornis (Asian longhorned tick): Originally from East Asia, this tick has been found in North America and other regions. It can transmit various diseases and is a concern for livestock.
Ticks have a fascinating life cycle and feeding behavior that revolves around finding and feeding on a host, reproducing, and developing through various stages. They have a four-stage life cycle, including the egg, larva, nymph, and adult stages.
This life cycle is known as metamorphosis, and it can vary in duration depending on the species and environmental conditions. Ticks require a blood meal to advance from one stage to the next, and their life cycle can take several months to several years. Ticks are obligate blood-feeding ectoparasites, which means they require a host to obtain a blood meal at each stage of their life cycle.
Ticks use various strategies to find hosts. They typically lie in wait in vegetation, such as tall grasses or shrubs, using their specialized sensory structures to detect the presence of a potential host. These sensory structures include Haller’s organs, which can detect temperature, humidity, and host odors, as well as CO2 emissions, vibrations, and heat. When a host passes by, ticks can attach themselves to the host’s skin. Once a tick has found a suitable host, it attaches itself by piercing the host’s skin with specialized mouthparts.
These mouthparts include a barbed hypostome and backward-pointing spines, which help anchor the tick in place. The tick then secretes a cement-like substance to further secure its attachment. Ticks feed by inserting their mouthparts into the host’s skin, and they have specialized structures that allow them to create a feeding canal.
They secrete saliva that contains anticoagulants to prevent the host’s blood from clotting, facilitating the feeding process. Ticks can feed for extended periods, ranging from a few minutes to several days, depending on the species and their life stage.
Tick reproduction usually occurs during the blood-feeding phase. Males and females often find each other on the host, and mating can take place on the host’s body. After mating, females will detach and find a suitable location to lay their eggs, which can range from a few hundred to several thousand eggs, depending on the species.
The female’s reproductive success depends on her ability to find a suitable location and on environmental conditions. The study of ticks is an ongoing area of research, and taxonomic classifications may change as new information becomes available.
Some Common Tick Diseases
- Lyme Disease: Caused by the bacterium Borrelia burgdorferi, which is transmitted primarily by Ixodes ticks. It can lead to a range of symptoms, including fever, joint pain, and neurological problems.
- Rocky Mountain Spotted Fever: Transmitted by American dog ticks and other species, this disease is caused by the bacterium Rickettsia rickettsii. It can lead to severe fever, rash, and organ damage.
- Ehrlichiosis: Several species of ticks can transmit Ehrlichia bacteria. Ehrlichiosis can cause flu-like symptoms, fever, and sometimes severe complications.
- Anaplasmosis: Anaplasma bacteria, transmitted by Ixodes ticks, can cause symptoms similar to Ehrlichiosis, including fever, headache, and muscle aches.
- Babesiosis: Caused by protozoa of the genus Babesia, this disease is transmitted by Ixodes ticks. It leads to symptoms similar to malaria, including fever and anemia.
- Tularemia: Ticks, including the Lone Star tick, can transmit Francisella tularensis, the bacterium responsible for tularemia. Symptoms include fever, skin ulcers, and more severe forms of the disease can affect various organs.
- Southern Cattle Fever: This disease, caused by the protozoan parasite Babesia bovis, is transmitted by the Southern cattle tick and affects cattle, leading to anemia and potential death.
Lyme disease, first identified in the United States in 1975, is caused by the spirochete bacterium Borrelia burgdorferi and is primarily transmitted to humans through the bite of infected black-legged ticks (Ixodes scapularis and Ixodes pacificus). Named after the town of Lyme, Connecticut, where it was initially observed, the disease’s history can be traced back to earlier cases in Europe,
but it gained recognition in the U.S. due to a cluster of cases with similar symptoms. Lyme disease presents a range of symptoms, including fever, fatigue, joint pain, and a characteristic skin rash called erythema migrans. If left untreated, it can lead to more severe complications affecting the heart, joints, and the nervous system. Efforts to combat Lyme disease have primarily focused on prevention, including tick control measures,
If a characteristic bull’s eye rash is present, healthcare professionals should feel confident in diagnosing Lyme disease.
Professor Gillian Leng – deputy chief executive and director of health and social care at the National Institute for Health and Care Excellence (NICE)
public awareness campaigns, and advances in diagnostic testing. Vaccines like LYMErix were developed but faced controversies and were withdrawn from the market. Research into tick ecology and behavior, as well as improvements in surveillance and early diagnosis, have contributed to our understanding of the disease and its transmission.
While eradication is challenging, ongoing research and public health initiatives aim to reduce the incidence of Lyme disease in endemic regions.
Early symptoms of Lyme disease can occur 3-30 days after being bitten by an infected deer tick; symptoms can include:
- Fever
- Chills
- Headache
- Fatigue
- Muscle aches
- Swollen lymph nodes
In about 70-80% of people bitten by a deer tick a bulls-eye rash may also develop. The rash can reach 12 inches in diameter and can be found anywhere on the body. Some of the later symptoms (months after a bite) of Lyme disease can include severe head and neck aches, heart palpations, nerve pain, and joint pain and swelling.
Rocky Mountain spotted fever (RMSF) is a potentially severe and sometimes fatal tick-borne disease caused by the bacterium Rickettsia rickettsii. Although the disease is now associated with the Rocky Mountains, it was first identified in the Bitterroot Valley of Montana in the United States in the late 19th century.
The disease’s name can be misleading, as RMSF is not limited to the Rocky Mountain region but is found throughout the Americas. Early in its history, RMSF had a high mortality rate, but with advances in diagnosis and treatment, including the use of antibiotics like doxycycline, the prognosis for patients has improved significantly.
Eradication efforts have focused on public awareness of tick avoidance, timely diagnosis, and appropriate treatment. While RMSF is still a concern, these advances have contributed to better outcomes for those affected by the disease.
What can I do to avoid deer ticks?
- Remove bird feeders and do not feed wildlife.
- Harvest your garden so that is does not attract wildlife.
- Plant bushes and landscape that is not appealing to wildlife.
- Keep your grass short.
- Clear out overgrown areas and keep wooded areas and dense vegetation trimmed back.
- Don’t place picnic tables or swing sets under trees.
- Wear light-colored clothing, long sleeves and pants tucked into socks when outdoors.
- Use a tick repellent on clothing and boots.
- Inspect yourself, family members and pets for ticks before entering your home.
- Speak with your vet about a safe and effective tick treatment for pets.
- Make sure that pets that spend time outside are treated with an effective tick preventative under the guidance of their veterinarian.
The tick problem is a growing concern in many parts of the world, and several factors contribute to its severity. Climate change is a significant driver of the tick problem. Warmer temperatures, altered precipitation patterns, and extended seasons can create more favorable conditions for tick survival and reproduction.
Ticks are sensitive to temperature and humidity, and a changing climate can expand their geographic range. Human activities such as deforestation, urbanization, and changes in land use can alter ecosystems and bring humans and domestic animals into closer contact with tick habitats. This can increase the risk of tick exposure.
Ticks require hosts to feed on, and the presence of suitable hosts, such as mammals and birds, can influence tick populations. The abundance and distribution of host species can be affected by factors like wildlife management and land use practices. As humans and wildlife continue to interact with tick-prone environments, the risk of tick exposure and the potential for disease transmission to humans and animals also increase.
Ticks can hitch a ride on humans, animals, and cargo during international travel and trade, leading to the introduction of new tick species and the spread of tick-borne diseases to new regions. any people underestimate the risks associated with ticks and may not take adequate precautions when spending time in tick-prone areas. Increased public awareness and education are essential to reducing tick-related problems. Ticks can develop resistance to pesticides and acaricides used for their control, making tick management more challenging.
It’s important to note that not all regions face the same level of tick-related issues, and the specific factors influencing the tick problem can vary. Effective tick control and management strategies involve a combination of public education, habitat management, and responsible use of tick-control measures. Regular tick checks and prompt removal of attached ticks,
along with personal protective measures such as wearing appropriate clothing and using repellents, can help reduce tick-related risks. Research and public health efforts continue to address the growing tick problem, as ticks can transmit a variety of diseases to humans and animals, making their management a critical public health concern.
Further Reading
Sources
- “Blacklegged Deer Ticks” https://www.arrownj.com/blacklegged-deer-ticks
- Sonenshine, D. E. (2018). Biology of Ticks. Oxford University Press.
- Eisen, L. (2018). Pathogen transmission in relation to duration of attachment by Ixodes scapularis ticks. Ticks and Tick-borne Diseases, 9(3), 535-542.
- Centers for Disease Control and Prevention (CDC). (2022). Ticks. Retrieved from https://www.cdc.gov/ticks/index.html
- Pritt, B. S., Mead, P. S., Johnson, D. K. H., et al. (2016). Identification of a novel pathogenic Borrelia species causing Lyme borreliosis with unusually high spirochaetaemia: a descriptive study. The Lancet Infectious Diseases, 16(5), 556-564.
- “The Lone Star Tick May Be Spreading A New Disease Across America” (October 28, 2015) https://www.npr.org/sections/health-shots/2015/10/28/451990557/the-lone-star-tick-may-be-spreading-a-new-disease-across-america
- “We Have No Idea How Bad the US Tick Problem Is” (JUL 4, 2018) https://www.wired.com/story/we-have-no-idea-how-bad-the-us-tick-problem-is/
- “Ticks and Tickborne Diseases of Utah” (July 2023) https://extension.usu.edu/pests/research/ticks-and-tickborne-diseases-of-utah
