Tick-Borne Spotted Fevers

Description

The term Tick-borne Spotted Fevers is a catch-all term used to describe illnesses caused by ticks infected with Rickettsia bacteria. Rickettsial infections are zoonoses – animal infections that can spread to humans – transmitted by Rhipicephalus, Ixodes, Amblyomma, Hyalomma, Haemaphysalis, and Dermacentor ticks who feed on deer, birds, rodents, and dogs. Humans become ill when they get bitten by infected ticks (typically in the immature or nymph stage of their life cycle). Due to climate change, tick populations are moving further north in latitude.

African Tick-Bite Fever, Mediterranean Spotted Fever, and Rocky Mountain Spotted Fever are some of the tick-borne infections that can affect travellers.

Risk

Rickettsia bacteria are present worldwide. Many tick species are moving further north in latitude due to climate change. Infections tend to be seasonal when ticks are most active from spring to fall. Travellers involved in outdoor activities in forested areas are at risk, including campers, hikers, and hunters. Brushing against vegetation or walking in city parks known to have infected ticks can also put a person at risk. Rickettsial infections are not transmitted from person to person.

Symptoms

Rickettsial infections are characterized by flu-like symptoms and a rash that usually appear 5 to 14 days after exposure. Initial symptoms include fever accompanied by headache, muscle pain, and sometimes nausea, vomiting, diarrhea, and cough. A red rash can develop and black tissue, also known as an 'eschar', forms at the site of the tick bite. Some people may not exhibit these symptoms, making spotted fevers difficult to diagnose. Rickettsial spotted fever infections can range from mild to severe and are treated with antibiotics.

In the case of Rocky Mountain Spotted Fever symptoms can be severe and fatal if untreated. Complications can occur as a result of blood vessel damage which causes brain swelling, heart, lung, and kidney failure, and gangrene on fingers and toes.

Prevention

Travellers who participate in hiking, camping, or similar outdoor activities in wooded regions of endemic areas should take measures to prevent tick bites. There is no preventive medication or vaccine against rickettsial infections.

• Use a repellent containing 20%-30% DEET or 20% Picaridin. Re-apply according to manufacturer's directions.
• Wear neutral-coloured (beige, light grey) and breathable garments, including long-sleeved shirts and pants. Tuck pants into socks.
• If available, apply a permethrin spray or solution to clothing and gear.
• When hiking in wooded areas, stay in the middle of the trail and avoid tall grasses and shrubs.
• Use a tarp when sitting on the ground.
• Carefully examine your body, clothing, gear, and pets for ticks before entering a dwelling.
• Promptly remove ticks using tweezers by grasping the tick's head and mouth parts as much as possible and by pulling perpendicular from the skin. See How to: Tick Edition for videos on removing ticks correctly.
• Thoroughly disinfect the bite site with soap and water or disinfectant. If travelling in an endemic area, save the tick in a zip-lock bag or container for up to 10 days (refrigerate live ticks; keep dead ticks in the freezer). Write down the date and location of your contact with the tick. Your healthcare practitioner may advise you to submit the tick for testing.
• If you develop symptoms of a tick-borne disease, contact your healthcare practitioner immediately.
• Apply sunscreen first followed by the repellent (preferably 20 minutes later.)
• More details on insect bite prevention.

Infographics

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Information last updated: April 16, 2020