Lean against a tree or sit on an old log, for no more than 30 seconds, and you’ve greatly increased your chance of sustaining a tick-bite — particularly in low brush, long grass, woody, tick-infested areas. But it may just as easily jump onto you from the dog or cat, a deer, the rabbit, or horse — depending on life-cycle stage (the tick’s, not yours). While the bandicoot is the natural Australian host, humans act as alternate hosts for all blood-feeding stages — larva, nymph, or adult. These stages can, however, survive for up to a year without a blood meal.

Tacked onto your clothing as you brush by, the tick makes its way down (up) your pants looking for bare skin. Once found, it usually migrates to the warmest, moistest, part: such as the groin or the hairline of your neck. Having found a sweet spot, it begins by injecting an anaesthetic so that you notice much. It then proceeds to project its barbed mouthparts through your skin to form a small crater to feed from. Here it reinforces its hold with a cementum mixed, as it is, with a little blood-thinner — the better to feed from “my precious”. To these basic ingredients is added a variable cocktail of allergen, neurotoxin, and microbial pathogen.

It is this cocktail that makes tick-bites that much more notable, and occasionally life-threatening.

Pathophysiology — immediate, delayed, and postponed

1. ALLERGEN

• Anaphylaxis
• [Sensitisation and subsequent anaphylaxis to red meat]
  2. NEUROTOXIN
• Ascending paralysis
  3. PATHOGEN
• Bacteria

• Borrelia
  • Borelliosis (Lyme disease)
  • Tick-borne relapsing fever
• Francisella tularensis
  • Tularaemia
• Ehrlichia chaffeensis / ewingii
  • Ehrlichiosis
• Rickettsia bacteria
  • Rocky Mountain spotted fever
• Coxiella burnetii
  • Q fever
• Protozoa

• Babesia
  • Babesiosis
• Virus

• Phlebovirus sp.
  • Heartland viral disease
    

Variegated Symptomatology — acute, subacute, chronic

The pathophysiology drives the symptomatology. This include immediate hypersensitivity reactions to tick-saliva antigens, paralysis will often be delayed for a few days as more neurotoxin is secreted, and pathogen-related symptoms may not manifest for days to weeks after the bite according to the respective incubation period.

• Flu-like symptoms
• Fever
• Numbness
• Rash (these vary according to the pathogen transmitted by the tick) — erythema migrans rash that can occur early in Lyme disease may have a characteristic “bull’s eye” appearance
• Confusion
• Weakness
• Pain and swelling in the joints
• Palpitations
• Paralysis
• Shortness of breath
• Nausea and vomiting

Prompt Tick Removal

In the event of multiple nymphs, sitting in a warm bath with an added cupful of sodium bicarbonate is the ideal treatment. Alternatively, a liberal application of permethrin cream should kill them quickly.

Apart from this rare event, most cases involve a single culprit. First disarm and then dislodge this arthropod, in a timely and secure manner:

1. Avoid dousing the tick with any chemicals, or trying to remove it with household tweezers, as this may cause it to secrete more toxin.
2. Freeze the tick with an ether-containing spray (Wart-Off, MediFreze Skin Tag Remover) to instantly disarm it. Wait for around 10 minutes for the tick to die and then brush it off.
3. If you are not allergic to ticks, put on gloves and attempt to remove it with fine-pointed forceps placed parallel to the skin surface. Grab the tick firmly but gently as close to the skin as possible, gradually pulling perpendicularly away from the skin (taking care not to crush the tick).
4. Place the tick into a bottle or onto a piece of tape.
5. Check the remaining skin crater to ensure no head-parts remain.
6. Now douse the crater with an antiseptic or soapy water.
7. Use a topical antibacterial cream as wound prophylaxis.
8. Dispose of gloves and instruments carefully and wash hands well.

Systemic Treatment

1. Consider systemic antibiotic treatment for areas endemic for pathogens outlined above e.g. use Doxycycline 100 mg daily for 7 days

Freeze them, don’t squeeze them. Dab them, don’t grab them.

Further Reading

Thousands of Australians claim to be suffering from tick-borne Lyme disease but a new report insists there is no evidence it exists in Australia – ABC News

Tick bite anaphylaxis: Incidence and management in an Australian emergency department – Emergency Medicine Australasia