Communicable Diseases Network Australia: National Arbovirus and Malaria Advisory Committee annual report 2004-05

This report describes the epidemiology of mosquito-borne disease in Australia for the mosquito-borne disease season 1 July 2004 to 30 June 2005. Ross River virus (RRV) infections (45%), Barmah Forest virus (BFV) infections (30%) and malaria (19%) were the most common mosquito-borne diseases reported in 2004-05. The Northern Territory had the highest rate of RRV notifications and the peak notification rate (in February 2005) was 54 per cent less than the previous season. The Northern Territory also reported the highest BFV notification rate this season, peaking in April 2005, which was the second highest reported BFV notification rate since 1998. National RRV and BFV notification rates were highest in the 45-49 year age group. There were 799 notifications of malaria in 2004-05 of which none were reported as locally acquired. This was the third highest reporting season for malaria notifications since 1998. In contrast to previous years in which Plasmodium vivax was the predominant species, Plasmodium falciparum was reported as the infecting species in 57 per cent of the malaria notifications and Plasmodium vivax for 34 per cent of cases. Children in the 5-9 year age group had the highest number of cases compared to previous years in which the peak number of cases tended to be in young adult age groups. There were four cases of Kunjin virus (KUNV) and two cases of Murray Valley encephalitis virus (MVEV) reported in 2004-05. Sentinel chicken surveillance data for flaviviruses and sentinel pig surveillance data for Japanese encephalitis virus are reported. There were 188 notifications of dengue virus infection (DENV) in 2004-05, of which 46 per cent (n=86) were reported as having been acquired overseas. Dengue serotype 4 was the most frequently reported type, accounting for 32 per cent of cases (n=60).