Ticks and the diseases they carry, region by region: what CDC, Canada, the NHS and NSW say

This page reports what the official source says. It is not legal advice: ask the office named here. It is not medical advice and gives no steps for bites. Each agency's page covers that. The guide on bites and stings in tree work sets out the wider list of animals and insects, and the guide to health hazards is the hub for this section.

United States

The CDC page Where Ticks Live (July 30, 2025) lists tick species with the diseases each can spread. It adds that a tick living in an area "does not necessarily mean it transmits a specific disease in that area". The table follows the page.

Tick	Where, and diseases named
American dog tick	Widespread east of the Rocky Mountains; a related species lives west of them. Diseases: Tularemia, Rocky Mountain spotted fever.
Asian longhorned tick	20 states as of April 12, 2024. Diseases: CDC says its role in spreading disease in the United States is still being studied.
Blacklegged tick	Widely across the eastern United States. Diseases: Anaplasmosis, babesiosis, Lyme disease, hard tick relapsing fever, ehrlichiosis, Powassan virus disease.
Brown dog tick	Listed by CDC as affecting the entire United States. Diseases: Rocky Mountain spotted fever in the southwest and along the Mexico border.
Gulf Coast tick	Mainly the southeast, with pockets in the northeast, midwest and southwest. Diseases: Rickettsia parkeri rickettsiosis, a spotted fever.
Lone star tick	Northeast, South and Midwest. Diseases: Bourbon virus, ehrlichiosis, Heartland virus, tularemia; linked by CDC to STARI and, with growing evidence, to alpha-gal syndrome.
Rocky Mountain wood tick	Rocky Mountain states and southwestern Canada, 4,000 to 10,500 feet. Diseases: Rocky Mountain spotted fever, Colorado tick fever, tularemia.
Western blacklegged tick	Pacific coast, particularly northern California. Diseases: Anaplasmosis, Lyme disease, hard tick relapsing fever.

CDC's page on alpha-gal syndrome describes it as a potentially life-threatening allergy that can occur after a tick bite. It says red meat such as beef and pork, dairy and some medicines contain alpha-gal, and that reactions range from mild to severe. The page does not name a tick species, so the lone star link above comes from the Where Ticks Live page.

Canada

The Public Health Agency of Canada's Lyme disease page (dated 2026-07-03) names the blacklegged tick, also called the deer tick, and the western blacklegged tick as the ticks whose bites can spread Lyme disease. It does not list regions. It sends readers to their provincial or territorial public health authority for local information.

United Kingdom

The NHS page on Lyme disease says ticks are found all over the United Kingdom, in woods, long grass and sometimes urban parks and gardens. It says ticks that may cause Lyme disease are found all over the country, and that high-risk places include grassy and wooded areas in southern England and the Scottish Highlands. It also says not all ticks in England carry the bacteria that cause Lyme disease.

New South Wales

The Sydney Children's Hospitals Network, part of NSW Health, publishes a tick bites factsheet written for families. It says ticks are common in humid, wet places such as forests and bushland, and that tick saliva can cause paralysis, trigger severe allergic reactions and cause other allergies to develop. It describes tick paralysis as a condition that can affect children. The factsheet names no disease by tick species, and this page has not read a separate NSW Health page for adults.

What the table shows

The four sources do not describe the same thing. CDC lists species and diseases by region. Canada names two ticks and defers to the provinces. The NHS names a risk by landscape. The New South Wales factsheet describes the effects of tick saliva. A comparison by disease is therefore not possible from these pages.