Babesiosis is a parasitic infection of red blood cells. It is usually spread by the bite of certain types of ticks. In 2012, the first reported human case believed to be acquired in Australia was reported in a resident of New South Wales. People with symptoms usually require treatment for several days. Avoid ticks to prevent infection.
Babesiosis is an infection of people and animals caused by the Babesia parasite.
Babesiosis can be severe and life-threatening, especially for people with other illnesses, the elderly, and particularly for people who do not have a spleen.
Babesia parasites are usually spread by the bite of an infected tick. Because Babesia parasites infect red blood cells, the infection can rarely be spread through a blood transfusion from an infected donor, or from an infected mother to her baby during childbirth. Ticks in the Ixodes family are the most common tick linked to babesiosis transmission, although the tick vector has not been identified for all Babesia species and strains.
People who test positive for Babesia infection should refrain from donating blood indefinitely.
Babesia infection has been reported worldwide, with most cases reported from the north-east of the United States or from Europe.
In 2012, a case of severe babesiosis was reported in an individual from the south coast of New South Wales. This was the first reported human case of babesiosis believed to have been acquired in Australia. Note: this person had not travelled overseas for many years but recalled having been bitten by ticks near home. This person also had underlying medical conditions.
The Babesia parasite causing the infections was identified directly and was found to be closely related to the strain most commonly associated with human babesiosis in North America (Babesia microti). It is not known which type of tick was responsible for transmitting the infection in this case.
In Australia, some strains of Babesia parasites cause infections in cattle (called Bovine babesiosis or 'tick fever'). The infection is primarily transmitted by the cattle tick (Rhiphicephalus (Boophilus) microplus) and involves strains different to those that cause human infections.
It is not known how common it is for the Babesia parasites that cause human disease to infect ticks in NSW. It is assumed to be rare, given that only one human case has been reported. It is possible that other cases may have occurred in the past but were not recognised, particularly as most infections cause no symptoms.
In people who have symptoms of babesiosis, the active infection is primarily diagnosed by examining a blood sample under a microscope (using thick and thin films) and seeing the Babesia parasites in red blood cells.
People who are diagnosed with Babesia infection but who do not have symptoms of babesiosis may not require treatment. These people should have their blood monitored to ensure they become free of the parasite.
People with symptoms of babesiosis who have Babesia infection confirmed usually require a 7 to 10 day course of anti-parasitic medicines (usually atovaquone plus azithromycin, or clindamycin plus quinine). Doctors should seek advice from an infectious diseases physician when considering the diagnosis and treatment of Babesia infections.
Ticks tend to live in coastal areas in NSW. People are at greatest risk when they visit habitats where ticks live such as forests and other densely vegetated areas, especially areas with high grass and abundant leaf litter.
Ticks can be found all year but the risk of tick bites is generally increased during the warmer months when people are more likely to visit tick areas. If tick affected areas cannot be avoided, some practical measures to reduce the risk of tick bites include the following:
Ticks in the nymph stage are tiny (about the size of a sesame seed) but are important in the transmission of babesiosis. Tick nymphs attached while biting may not be noticed and they can be difficult to detect. It is important to examine the skin closely for any small ticks that may be attached.
Follow the Department of Health and Aged Care advice here: Management of tick bites in Australia
Babesiosis is not a notifiable infection in NSW and so cases are not required to be reported to public health units. As this is a novel infection in Australia, doctors are encouraged to discuss cases of active infection believed to have been acquired locally with their public health units.
For further information please call your local Public Health Unit on 1300 066 055