BackgroundDengue fever is a virus infection that is spread by the Aedes aegypti mosquito and can cause severe disease especially in children. Dengue fever is a major problem in tropical and sub-tropical regions of the world.Methodology/Principal FindingsWe invited dengue experts from around the world to attend meetings to discuss dengue surveillance. We reviewed literature, heard detailed reports on surveillance programs, and shared expert opinions.ResultsPresentations by 22 countries were heard during the 2.5 day meetings. We describe the best methods of surveillance in general, the stakeholders in dengue surveillance, and the steps from mosquito bite to reporting of a dengue case to explore how best to carry out dengue surveillance. We also provide details and a comparison of the dengue surveillance programs by the presenting countries.Conclusions/SignificanceThe experts provided recommendations for achieving the best possible data from dengue surveillance accepting the realities of the real world (e.g., limited funding and staff). Their recommendations included: (1) Every dengue endemic country should make reporting of dengue cases to the government mandatory; (2) electronic reporting systems should be developed and used; (3) at minimum dengue surveillance data should include incidence, hospitalization rates, deaths by age group; (4) additional studies should be completed to check the sensitivity of the system; (5) laboratories should share expertise and data; (6) tests that identify dengue virus should be used in patients with fever for four days or less and antibody tests should be used after day 4 to diagnose dengue; and (7) early detection and prediction of dengue outbreaks should be goals for national surveillance systems.

Objectives To determine the distribution of virus infection during an outbreak of Japanese encephalitis (JE) in the Torres Strait, and to describe the environmental factors facilitating the outbreak. Design Human and porcine serological surveys for JE virus activity throughout the Torres Strait, and mosquito and household surveys on the island of Badu. Setting The island of Badu (where the clinical cases occurred) and the other islands of the Torres Strait, Australia, during April‐May 1995. Results The serological surveys identified recent JE virus infection among residents or domestic pigs on at least nine outer Torres Strait islands. A JE virus, confirmed by nucleotide sequencing, was isolated from two asymptomatic Badu residents. Virus isolations and mosquito surveys implicated Culex annulirostris as the major vector involved in the outbreak. There was prolific Cx. annulirostris breeding in a variety of water bodies close to and within the Badu community. Over half (53%) of the households kept pigs in pens, and many (63%) of the pigpens were situated near standing water; in 56% of these “wet” pigpens Cx. annulirostris was breeding. Conclusions There was evidence of widespread JE virus activity throughout the outer islands of the Torres Strait. We suggest that migratory birds and/or wind‐blown mosquitoes could have imported the virus into the Torres Strait from a focus of viral activity, possibly in Papua New Guinea, thereby initiating the outbreak. A combination of environmental factors, with large numbers of domestic pigs in close proximity to human dwellings and mosquito breeding sites, undoubtedly facilitated the outbreak on Badu.

Objective To describe the circumstances of two cases of Japanese encephalitis (JE) in north Queensland in 1998, including one acquired on the Australian mainland. Design Serological surveillance of sentinel pigs for JE virus activity; serological surveys of humans and pigs and viral cultures of mosquito collections. Setting Islands in the Torres Strait and communities in the Northern Peninsula Area (NPA) and near the mouth of the Mitchell River in Cape York, Queensland, In the 1998 wet season (December 1997‐May 1998). Results Sentinel pigs in the Torres Strait began to seroconvert to JE virus in February 1998, just before onset of JE in an unvaccinated 12‐year‐old boy on Badu island. By mid‐April, most sentinel pigs had seroconverted. Numerous JE viruses were isolated from Culex annulirostris mosquitoes collected on Badu. In early March, a person working at the mouth of the Mitchell River developed JE. Serological surveys showed recent JE virus infection in 13 young pigs on a nearby farm, but not in 488 nearby residents. In NPA communities, sentinel pigs seroconverted slowly and JE viruses were isolated from three, but none of 604 residents showed evidence of recent infection. Nucleotide sequencing showed that 1998 JE virus isolates from the Torres Strait were virtually identical not only to the 1998 isolate from an NPA pig, but also to previous (1995) Badu isolates. Conclusions JE virus activity was more widespread in north Queensland in the 1998 wet season than in the three previous wet seasons, but ecological circumstances (eg, less intensive pig husbandry, fewer mosquitoes) appear to have limited transmission on the mainland. Nucleotide sequencing indicated a common source for the 1995 and 1998 JE viruses. Circumstantial evidence suggests that cyclonic winds carried infected mosquitoes from Papua New Guinea.

In December 1998, a 37‐year‐old Queensland woman died from a rabies‐like illness, 27 months after being bitten by a flying fox (fruit bat). Molecular techniques enabled diagnosis of infection with Australian bat lyssavirus (ABL), the second human case to be recognised and the first to be acquired from a flying fox. It must be assumed that any bat in Australia could transmit ABL; anyone bitten or scratched by a bat should immediately wash the wounds thoroughly with soap and water and promptly seek medical advice.

Objectives: To describe the various investigations and responses to multiple outbreaks of dengue serotype 2 that occurred in north Queensland in 2003/04. Methods: Details about each case were collated so as to target mosquitocontrol responses including control of mosquito breeding sites, interior spraying of selected premises, and a novel ‘lure and kill’ approach using lethal ovitraps. Phylogenetic analyses were undertaken to determine the genetic relatedness of viruses isolated during the outbreaks. Results: Except for a two‐month hiatus in mid‐2003, the outbreaks continued for 16 months and included 900 confirmed cases, with three severe cases and one death. The available evidence suggests that the mosquito‐control measures were effective, but delays in recognising the outbreaks in Cairns and the Torres Strait coupled with intense mosquito breeding contributed to the extensive nature of the outbreaks. Phylogenetic analyses showed that there had been only two major outbreaks, one that spread from Cairns to Townsville, the other from the Torres Strait to Cairns; both were initiated by viraemic travellers from Papua New Guinea. Conclusions: Phylogenetic analyses were essential in understanding how the outbreaks were related to each other, and in demonstrating that dengue had not become endemic. Further innovative approaches to dengue surveillance and mosquito control in north Queensland are necessary. Implications: Dengue outbreaks have become more frequent and more severe in north Queensland in recent years, raising the possibility that dengue viruses could become endemic in the region leading to outbreaks of dengue haemorrhagic fever.