Twenty years of HIV surveillance in the Pacific--what do the data tell us and what do we still need to know?

BACKGROUND: Most Pacific Island countries and territories (PICTs) provide some level of HIV testing for their populations and record demographic data for diagnosed cases of HIV and AIDS. These routine HIV data are usually held within the national Department/Ministry of Health or National AIDS Council. Summary HIV data can illustrate important trends in HIV infection over time and by age, gender and exposure. For some countries no other data are available to illustrate the extent and distribution of HIV infection in the region.
METHODS: Annual HIV and AIDS data were requested from all PICT reporting authorities disaggregated by year, age group, sex and exposure. Data were grouped to provide regional and sub-regional totals. Descriptive statistics were reported, including age-adjusted rates and trends.
RESULTS: The first cases of HIV in the Pacific were reported in the mid-1980s in all three sub-regions (Melanesia, Micronesia and Polynesia). Many early cases were acquired either by men who have sex with men (MSM) or by recipients of blood products. Some early cases migrated from outside the region. Since then numbers have increased, with 12,169 HIV cases reported across the Pacific to December 2004, including 2,335 AIDS cases and 617 AIDS-related deaths. The majority have been observed in Papua New Guinea (PNG)--11,139 HIV, 1,926 AIDS and 353 AIDS deaths). Other countries with relatively high HIV rates are New Caledonia, French Polynesia, Guam and Kiribati. Fiji, despite a high case count (182), has a mid-range rate of HIV infection due to its large population. Zero or very few cases have been reported in many other PICTs. Nearly two thirds of HIV cases have been diagnosed in the predominant risk group--young, sexually active adults. The ratio of male to female cases is 1.1 to 1 (2.5 to 1 excluding PNG), much lower than in countries like Australia (14.2) and New Zealand (5.5) where MSM predominates exposure. Rates of observed cases in women and young people are increasing with heterosexual contact being an increasingly important mode of spread. Other exposures include injecting drug use (mostly imported), perinatal transmission (rising more recently with increased heterosexual risk) and blood exposures. DISCUSSION: Apart from Papua New Guinea (PNG), which is currently experiencing an exponential increase in HIV infection, observed rates for most of the Pacific are currently low, and are either static or rising very slowly. Low observed HIV prevalence in pregnant women lends some support for this observation. However these data do not reflect the total HIV disease burden due to variable access to and uptake of testing, and incomplete notification. Several factors make the Pacific vulnerable to rapid spread such as close proximity to countries with high HIV prevalence, increasing migration, both in and outward, and expanding economic links with other regions. High levels of STIs and risk behaviours across the Pacific indicate significant potential for rapid spread where HIV is introduced. Efforts are currently under way to improve routine screening, complement with targeted surveillance surveys of at-risk and vulnerable groups. This expanded monitoring of HIV trends is designed to guide increasing efforts to prevent and control HIV in the region.