AIDS Cases in NSW and Victoria

Keywords: Poisson process

Description

The pattern of growth of AIDS in Australia is characteristic of countries where infection with HIV is predominantly seen in homosexual and bisexual men, recipients of blood and blood products, people who use drugs intravenously, and their sexual partners. The first case of AIDS diagnosed in Australia was in New South Wales in December 1982. Of the total 1187 cases diagnosed to 31 December 1988 (from data available in mid-1989), 764 cases were diagnosed in New South Wales, the state with the largest population in Australia, and 238 cases were diagnosed in Victoria, the second largest state. Research into the probably course of the epidemic in Australia shows significant regional differences in course of the epidemic, with the epidemic in New South Wales appearing to be more advanced than in the rest of the country. In Australia, zidovudine (AZT) was introduced in June 1987 and could be given to those individuals infected with the virus but not yet diagnosed as suffering from an AIDS-defining condition. Solomon, Doust and Wilson (1989) found evidence that the widespread availability of zidovudine from this data was associated with a flattening of the increase in the rate of diagnosis of new cases of AIDS.

Data

The table gives the yearly incidence of cases of AIDS in New South Wales and Victoria. AIDS is a notifiable disease in Australia, and the effect of reporting delays has been minimal. For example, for data on AIDS cases diagnoses (and ever reported) before the end of 1988, approximately 95% were reported within 6 months (Solomon et al, 1989).

Table 1 Observed number of cases of AIDS (yearly data) in New South Wales and Victoria, Australia
	New South Wales	Victoria
1982	1	0
1983	3	3
1984	28	7
1985	79	11
1986	158	36
1987	236	74
1988	259	107

Source

Solomon, P. J., and Wilson, S. R. (1990). Accommodating change due to treatment in the method of back projection for estimating HIV infection incidence. Biometrics, 46, 1165-1170.

Solomon, P. J., Doust, J. A., and Wilson, S. R. (1989). Predicting the course of AIDS in Australia and evaluating the effect of AZT: a first report. NCEPH Working Paper Number 3. Australian National University, Canberra.