Tick

subclass Acari, order Parasitiformes, suborder Ixodida

ticks taxonomy

ticks

oval, dorsoventrally flattened, unsegmented arthropods. Adults and nymphs have 4 pairs of legs, larvae have 3 pairs.

Ixodidae (hard ticks) – most medically important
Argasidae (soft ticks) – also medically relevant
Nuttalliellidae – not of veterinary/medical significance, found only in Africa

Name the three families of ticks and indicate their medical relevance.

Scutum
Dorsally visible capitulum
near 4th pair of legs genital pore

What distinguishes hard ticks (Ixodidae) from soft ticks (Argasidae)?

absent scutum
hidden capitulum
genital pore near capitulum
leathery cuticle

soft ticks distinguishing shit

One-host: Rhipicephalus (Boophilus) decoloratus
Two-host: Hyalomma marginatum
Three-host: Ixodes spp.

How many host types exist in hard tick life cycles? Give examples.

multiple nymphal instars, feed quickly, and females undergo several gonotrophic cycles, laying eggs in batches after each blood meal.

life cycle of soft ticks

Questing is host-seeking behavior.
Ambushers: Wait on vegetation (e.g., cattle ticks)
Hunters: Actively seek hosts (e.g., dog ticks)

What is "questing" in ticks, and what are the types?

Sensory palps locate the site. Chelicerae incise the skin. The hypostome, with backward spines, anchors the tick. Some secrete cement-like saliva.

Describe the process of blood-feeding in ticks.

Hard ticks: 1 gonotrophic cycle; lay thousands of eggs; mating usually on-host
Soft ticks: Multiple cycles; lay hundreds per batch; mating often off-host

How do reproduction patterns differ between hard and soft ticks?

Ornate, large, with festoons and long palps. 3-host ticks. Vectors of Ehrlichia chaffeensis, Rickettsia spp. (e.g., A. americanum - lone star tick).

What are the key features and pathogens associated with Amblyomma spp.?

Inornate, no eyes/festoons, long palps. 3-host ticks. Transmit Borrelia burgdorferi (Lyme disease), Babesia spp., tick-borne encephalitis virus.

Describe Ixodes spp. and the diseases they transmit.

Borrelia duttonii (relapsing fever in humans), African swine fever virus.

What diseases are associated with Ornithodoros spp.?

Infests ear canals of animals and humans; larvae/nymphs are parasitic, adults non-parasitic.

What is the significance of Otobius megnini (Spinose ear tick)?

Anemia, dermatoses, allergic reactions, wounds, toxicosis, and tick paralysis (via neurotoxin in saliva).

What are direct effects of tick infestations on hosts?

D. andersoni, D. variabilis, A. americanum, I. holocyclus, I. rubicundus, R. evertsi.

Name tick species associated with tick paralysis.

Transstadial
Transovarial
Co-feeding
Sexual transmission

What are the transmission routes for tick-borne pathogens?

Transstadial

Pathogen persists after molting

Transovarial

Pathogen passed to offspring

Co-feeding

Transfer among ticks feeding close together

Sexual transmission

Pathogen in spermatophore

Lyme disease (Borrelia burgdorferi)

What is the leading tick-borne disease in areas without malaria or dengue?

Amblyomma americanum (lone star tick)

What tick is associated with red meat allergies?

Hyalomma spp.

Which tick transmits Crimean–Congo hemorrhagic fever?

Zero-grazing, pasture rotation, acaricide dips/sprays, impregnated ear tags, limited vaccines (e.g., Bm86-based).

What are common methods for controlling cattle ticks?

Manual removal, protective clothing, repellents, avoiding grassy areas, and controlling ticks on animals.

How can humans prevent tick bites?