Risk of infection is highly variable within the region. The risk of food and water-borne infections is low in most of Australia and New Zealand; immunization coverage is also generally high in those countries. Vector-borne infections and gastrointestinal infections are common in travelers to other islands.
Vector-borne infections: Malaria is transmitted on Papua New Guinea, Vanuatu, and the Solomon Islands. Dengue has caused recurring epidemics on many of the islands and in northern Australia. Japanese encephalitis (JE) is found in Papua New Guinea and the Torres Strait and far northern Australia. JE infections have occurred in the western Pacific islands (e.g., Guam). Lymphatic filariasis is widely distributed on many of the Pacific islands, including American Samoa, Cook Islands, Fiji, French Polynesia, Kiribati, Niue, Samoa, Tonga, Tuvalu, Vanuatu, and Wallis and Futuna. Other vector-borne infections include scrub typhus (in northern Australia and Papua New Guinea and on some of the western and southern islands), murine typhus, spotted fever due to Rickettsia australis (Queen-sland tick typhus), and Murray Valley encephalitis (recurring epidemics are re-ported, especially in southeastern Australia; rare cases occur in Papua New Guinea). Ross River fever (epidemic polyarthritis) causes sporadic cases and outbreaks in Australia and on a number of the Pacific islands.
Food- and water-borne infections: Risk of hepatitis A is high on many of the Pacific islands. Gastrointestinal infections due to bacteria, viruses, and parasites (including Entamoeba histolytica) have been common on some of the islands, including Papua New Guinea. Typhoid fever is uncommon in Australia; outbreaks have occurred on some of the islands. Cases of eosinophilic meningitis due to Angiostrongylus cantonensis have been reported from many of the islands. Occasional cases of cholera occur in Australia.
Airborne and person-to-person transmission: The annual incidence of tuberculosis per 100,000 population is estimated to be 100-300 for the Pacific islands, and 0-25 for the rest of the region. The influenza transmission season in Australia typically occurs April through September. Periodic outbreaks of measles have occurred on islands with inadequate immunization coverage.
Sexually transmitted and blood-borne infections: The prevalence of HIV in adults is 0.1%-<0.5% in most of the region; it is higher (1%-<5%) in Papua New Guinea and some of the Pacific islands. The prevalence of chronic infection with hepatitis B is ≥8% on many of the Pacific islands. The prevalence of hepatitis C is 1%-2.4% in most of the area.
Zoonotic infections: Sporadic cases and outbreaks of Q fever* occur in Australia (rarely in New Zealand). Most of the islands are reported to be rabies free, although bat rabies exists in some of these areas. Fatal cases of Hendra virus (closely related to Nipah virus) infection occurred in Australia in 1994. Fruit bats, widely distributed in Australia and the South Pacific, may be the natural host.
Soil- and water-associated infections: Buruli ulcer (caused by Mycobacterium ulcerans) increased in incidence in Australia in the 1990s, with the development of new foci on Phillip Island and in a district southwest of Melbourne. Most cases are in Victoria and Queensland. Cases of melioidosis have been reported from Papua New Guinea, Guam, and Australia; risk may exist on other islands. Leptospirosis is common on some of the islands. Sporadic cases of histoplasmosis have been documented. Hookworm infections and strongyloidiasis are common on some of the Pacific Islands.
Other hazards: High attack rates of ciguatera poisoning from eating large reef-dwelling fish have been reported on some of the islands. Venomous snakes and spiders are a risk in many areas. Screening of blood before transfusion is inadequate in hospitals on many of the islands.
