What are ticks? - briefly
Ticks are small arachnids that attach to mammals, birds, or reptiles to feed on their blood. They act as vectors, transmitting bacteria, viruses, and protozoa that cause disease.
What are ticks? - in detail
Ticks are obligate ectoparasites belonging to the subclass Acari, order Ixodida. They are arachnids, closely related to spiders and mites, and possess four pairs of legs in the adult stage. Their bodies consist of a capitulum, which houses the mouthparts, and an idiosoma, containing the organs and the dorsal shield.
The life cycle includes egg, larva, nymph, and adult stages. Each active stage requires at least one blood meal to advance. Larvae, often called seed ticks, have six legs and typically feed on small mammals, birds, or reptiles. After engorgement, they molt into six‑legged nymphs, which seek larger hosts. Adult females attach to mammals, including humans, and ingest sufficient blood to lay thousands of eggs.
Key physiological traits:
- Sensory organs: Haller’s organ on the first pair of legs detects carbon dioxide, heat, and host movement.
- Salivary secretions: Contain anticoagulants, anti‑inflammatory agents, and immunomodulators that facilitate prolonged feeding.
- Cuticle: Expands dramatically during engorgement, allowing the tick to increase its weight up to 100 times.
Disease transmission is a primary concern. Ticks serve as vectors for a range of pathogens, including:
- Borrelia burgdorferi (Lyme disease)
- Rickettsia spp. (spotted fever group)
- Anaplasma phagocytophilum (human granulocytic anaplasmosis)
- Babesia microti (babesiosis)
- Powassan virus
Transmission occurs when the pathogen migrates from the tick’s midgut to its salivary glands during feeding. The duration of attachment correlates with infection risk; many agents require several hours of attachment before transmission.
Identification relies on morphological features observable under magnification:
- Scutum: Hard dorsal shield present in males and partially in females.
- Festoons: Rectangular grooves on the posterior margin of the idiosoma in many species.
- Genital aperture: Located ventrally in females, providing a reliable sex marker.
Control measures focus on prevention and removal:
- Environmental management: Maintain low vegetation, apply acaricides in high‑risk zones, and treat host animals with approved tick‑kill products.
- Personal protection: Wear long sleeves, apply repellents containing DEET or permethrin, and conduct thorough body checks after exposure.
- Tick removal: Grasp the mouthparts with fine tweezers, pull upward with steady pressure, and disinfect the bite site.
Understanding the biology, life cycle, and vector capacity of these arachnids underpins effective public health strategies and reduces the incidence of tick‑borne illnesses.