The Centre for Health Protection urges people to be vigilant against typhus and other rickettsial diseases. There have been 18 cases of spotted fever and 20 of scrub typhus so far this year.

Last year there were 13 cases of spotted fever, eight in 2006 and 12 in 2005. For scrub typhus the centre recorded 15 cases last year, 20 in 2006 and 30 in 2005.

Spotted fever is transmitted by ticks, a vector which is usually found in scrubby areas or on rodents and stray animals. Scrub typhus is transmitted by trombiculid mites which are found in vegetated areas or on rodents.

Most patients had been engaged in outdoor activities around the time of infection, such as hiking in rural areas. Symptoms of the two diseases are similar with patients developing fever, chills, headache, muscle pain and body rash.

Both are characterised by a primary skin ulcer corresponding to the bite site of the arthropod. Lymph nodes near the ulcer can be swollen and painful. The disease can cause severe complications and can be fatal. The average incubation period of the two diseases is one to two weeks. Click here for details.