Best practices in dengue surveillance: a report from the Asia-Pacific and Americas Dengue Prevention Boards.

BACKGROUND: Dengue 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 FINDINGS: We 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. RESULTS: Presentations 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/SIGNIFICANCE: The 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.

Invasive pneumococcal disease in non-Indigenous people in north Queensland, 2001-2009.

OBJECTIVE: To compare trends in invasive pneumococcal disease (IPD) in non-Indigenous people in north Queensland before and after the introduction of funded pneumococcal vaccines, and to examine the proportion of cases that occurred after vaccine roll-out that could be vaccine-preventable. DESIGN, SETTING AND PARTICIPANTS: In 2005, a 7-valent pneumococcal conjugate vaccine (7vPCV) for non-Indigenous children and a 23-valent pneumococcal polysaccharide vaccine (23vPPV) for non-Indigenous adults aged ≥ 65 years were made freely available. Trends in IPD in the non-Indigenous estimated resident population in north Queensland (about 581 850 in 2006) were compared between the 4 years before (2001-2004) and after (2006-2009) the vaccines were rolled out. MAIN OUTCOME MEASURES: Incidences and serotypes of IPD in non-Indigenous people. RESULTS: After the introduction of the vaccines, there were significant declines for all ages in the average annual incidence of IPD (- 34%; P < 0.05) and 7vPCV serotype IPD (- 77%; P < 0.05). In children aged < 5 years, there was a 91% decline in the incidence of 7vPCV serotype IPD (P < 0.05); in adults aged 15-64 years and ≥ 65 years there were 62% and 77% declines, respectively, in 7vPCV and 23vPPV common-serotype IPD (P < 0.05). There was a 188% increase in 23vPPV-only serotype IPD in adults aged 15-64 years (P < 0.05), whereas there was no significant change in adults aged ≥ 65 years. Serotype 19A was the most frequently identified serotype in 2006-2009, causing 19% of all IPD in those 4 years. CONCLUSIONS: There is circumstantial evidence that 7vPCV has had a powerful indirect effect in preventing IPD in adults in north Queensland; 23vPPV may have had a direct effect in adults aged ≥ 65 years. It is likely that with combined direct and indirect effects, newer conjugate vaccines could prevent more IPD than could be prevented with the two current vaccines.

Acute rheumatic fever in Indigenous people in North Queensland: some good news at last?

OBJECTIVES: To ascertain whether changing from enhanced to routine surveillance had any deleterious impact on notification rates of acute rheumatic fever (ARF) among Indigenous people in north Queensland; and to determine whether initiatives to raise awareness about ARF among medical practitioners during the routine surveillance period were associated with any changes in the numbers of recurrences of the disease among Indigenous people in the region. DESIGN, PARTICIPANTS AND SETTING: Routine surveillance of all cases of ARF, and (to identify unrecognised prior episodes) retrospective checking of the medical records of Indigenous people with notified first cases of ARF from mid 2004 to mid 2009 in north Queensland, which has an estimated resident Indigenous population of about 68 400. MAIN OUTCOME MEASURES: Rate of notifications of ARF during the routine surveillance period (mid 2004 to mid 2009) compared with that in the previous 5 years of enhanced surveillance; proportion of recurrent episodes of ARF that occurred from mid 2004 to the end of 2006 compared with the proportion in the following 2.5 years. RESULTS: There were 203 notifications of ARF in 194 Indigenous people in north Queensland from mid 2004 to mid 2009, and this was a 23% increase in the average annual incidence compared with that in the preceding 5 years. Of the 54 recurrences, 34 (63%) occurred between mid 2004 and the end of 2006 and 20 occurred between the beginning of 2007 and mid 2009 (P < 0.01). Of the 148 episodes that were not recurrences, 69 (47%) occurred in the first 2.5 years and 79 in the more recent 2.5 years (P > 0.05). CONCLUSIONS: Changing from enhanced to routine surveillance in 2004 did not have a negative impact on notifications of ARF. The initiatives to raise awareness about ARF probably contributed to fewer missed cases and therefore to the considerable increase in the number of notifications, and ultimately to fewer recurrences.

Melioidosis in north Queensland, 2000-2009.

There were 176 culture-confirmed cases of melioidosis in north Queensland over the 10 years, 2000-2009. Most (nearly 80%) occurred in the first 4 months of the year. The overall case fatality was 21%, but was 14% in 2005-2009. Of the 173 adult cases, 45% were in Indigenous adults. Both diabetes and alcohol abuse were more prevalent among Indigenous adults with melioidosis than among non-Indigenous adults. The incidences in Indigenous adults were particularly high in the Torres Strait and Northern Peninsula Area, Cape York and Mornington Island, whereas for non-indigenous adults there appears to be a higher risk within Townsville city.

Dengue in north Queensland, 2005-2008.

The dengue vector, the mosquito Aedes aegypti, is present in urban settings in north Queensland, thereby putting the region at risk of outbreaks of dengue. This review describes some features of the 9 outbreaks of dengue that occurred in north Queensland over the 4 years, 2005-2008.

Invasive pneumococcal disease in Indigenous people in north Queensland: an update, 2005-2007.

OBJECTIVE: To examine trends in invasive pneumococcal disease (IPD) in Indigenous people in north Queensland following the introduction of the 7-valent pneumococcal conjugate vaccine (7vPCV). DESIGN: Trends in IPD were compared over three 3-year periods: before the introduction of 7vPCV for Indigenous children (1999-2001), and two consecutive periods after its introduction (2002-2004 and 2005-2007). MAIN OUTCOME MEASURES: Incidences of IPD in Indigenous children and adults in 1999-2001 and 2005-2007; trends in IPD caused by 7vPCV and non-7vPCV serotypes; and trends in indirect protective effects and emergence of non-7vPCV serotype IPD. RESULTS: From 1999-2001 to 2005-2007, there was a 60% decline in IPD, with the virtual elimination of 7vPCV serotype IPD in young (< 5 years) Indigenous children. There is no evidence yet of an increase in non-7vPCV serotype IPD in these children. Although the annual incidence of IPD in Indigenous adults remained virtually unchanged, there was a 75% decline in 7vPCV serotype IPD in these adults (chi2(trend) = 11.65, P < 0.001). However, the incidence of IPD caused by non-7vPCV serotypes more than tripled in adults (chi2(trend) = 7.58, P = 0.006). Serotype 1 IPD has been prominent over the 9 years, but there is no evidence of a recent increase in serotype 19A IPD. CONCLUSIONS: Vaccinating Indigenous children with 7vPCV has protected Indigenous adults in north Queensland through an indirect "herd immunity" effect. However, this benefit has been offset by a recent increase in non-7vPCV IPD in Indigenous adults. Newer pneumococcal conjugate vaccines could prevent, both directly and indirectly, a considerable amount of the persisting IPD in Indigenous people in the region.

Hendra virus infection in a veterinarian.

A veterinarian became infected with Hendra virus (HeV) after managing a terminally ill horse and performing a limited autopsy with inadequate precautions. Although she was initially only mildly ill, serological tests suggested latent HeV infection. Nevertheless, she remains well 2 years after her initial illness. Recently emerged zoonotic viruses, such as HeV, necessitate appropriate working procedures and personal protective equipment in veterinary practice.

Multiple outbreaks of dengue serotype 2 in north Queensland, 2003/04.

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 mosquito-control 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 approximately 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.

Invasive pneumococcal disease in Indigenous people in north Queensland, 1999-2004.

OBJECTIVE: To describe the epidemiology of invasive pneumococcal disease (IPD), and the impact of pneumococcal vaccines on IPD, in Indigenous people in north Queensland. SETTING: North Queensland, 1999-2004; there are about 53 750 Indigenous people in the region, including nearly 6900 children < 5 years and nearly 5650 adults > or = 50 years. MAIN OUTCOME MEASURES: Incidences of IPD in Indigenous children and in Indigenous adults compared between the 3 years before and after the introduction of a 7-valent pneumococcal conjugate vaccine (7vPCV) (1999-2001 versus 2002-2004). RESULTS: Estimated annual incidence of IPD in Indigenous children < 5 years of age declined from 170 to 78 cases per 100 000 in the 3 years following the introduction of 7vPCV in 2001. The annual incidence of vaccine-preventable IPD in Indigenous adults had declined by 86% since a 23-valent pneumococcal polysaccharide vaccine (23vPPV) was introduced to the region in 1996, to 15 cases per 100 000 (95% CI, 8-25) in 2002-2004. CONCLUSION: Although there was a rapid decline in IPD in young Indigenous children, it is unlikely that the incidence will fall much further with the current 7-valent vaccine. There was a suggestion that vaccinating Indigenous children indirectly protected those aged 5-14 years and Indigenous adults > or =15 years of age. Incidence of IPD in Indigenous adults in 2002-2004 was the lowest on record in the region.

The epidemiology of acute rheumatic fever in Indigenous people in north Queensland.

OBJECTIVE: To describe the epidemiology and features of acute rheumatic fever (ARF) in Indigenous people in north Queensland from mid-1999 to mid-2004. METHODS: Enhanced surveillance, including regular reminder letters to relevant clinicians and computer searches of hospital discharge diagnoses, was implemented to capture cases of ARF. RESULTS: Over the five years, 144 episodes of ARF occurred in 133 Indigenous people in seven of the Health Service Districts in north Queensland. The annual incidences of ARF were 61 cases/100,000 Indigenous people in these seven districts, and 54/100,000 throughout north Queensland. The median age of the cases was 12.0 years, and 76% of the cases occurred in children <15 years. More than one-third of the definite cases were recurrences of ARF, and carditis was present in 42% of all cases. CONCLUSIONS: Within north Queensland, the incidences of ARF were greatest in the Cape York and the Torres Strait and Northern Peninsula Area Districts. However, the incidence of ARF in north Queensland is considerably lower than that reported from the Top End of the Northern Territory (NT). Furthermore, there appears to be less chorea and less monoarthritis, but more group A streptococci isolated from throat swabs, in ARF cases in north Queensland compared with those from the Top End of the NT. IMPLICATIONS: There is a need for greater awareness of ARF and its complications among both ARF patients and primary health care workers in the region, and for more reliable mechanisms for recalling patients for their prophylaxis and clinical reviews.

An assessment of the interval between booster doses of Japanese encephalitis vaccine in the Torres Strait.

OBJECTIVE: Japanese encephalitis (JE) emerged for the first time in the Torres Strait, north Australia, in 1995. The inactivated mouse-brain derived JE vaccine was offered to all residents of the outer Torres Strait Islands prior to the 1996 wet season. This study was undertaken to determine the appropriateness of the recommended three-year interval between booster doses of the vaccine. METHODS: JE neutralising antibody was measured in residents of Badu Island for whom 30-36 months had passed since either a previous booster or the completion of the primary immunisation series. RESULTS: Only 70 (32%) of 219 eligible individuals had protective antibodies; 50 (37%) of the adults were immune, compared with 20 (24%) of the children (odds ratio (OR) 1.93; 95% confidence interval (CI) 1.01-3.74). CONCLUSIONS: This low level of immunity suggests that there is little in the way of natural boosting from either JE or other closely related viruses. Given the apparent low level of risk of exposure to the JE virus in the Torres Strait, and the logistical complexities involved in delivering the booster doses, the current recommendation of a three-year interval is not inappropriate. IMPLICATIONS: It would be advantageous to have a JE vaccine that is not only safer but also more immunogenic, so that it might be possible to further increase the booster dose interval.

Impact of hepatitis A vaccination of Indigenous children on notifications of hepatitis A in north Queensland.

OBJECTIVE: To describe the impact of a hepatitis A vaccination program for Indigenous children in north Queensland. DESIGN: Enhanced surveillance of all notified cases of hepatitis A in north Queensland from 1996 to 2003. SETTING: North Queensland; population, 596 500 people, including about 6900 Indigenous children aged under five years. INTERVENTIONS: Hepatitis A vaccine was provided to Indigenous children in north Queensland from February 1999; two doses were recommended (at 18 months and 2 years of age), as was catch-up vaccination up to the sixth birthday. RESULTS: In the 4 years 1996-1999, 787 cases of hepatitis A were notified in north Queensland, 237 (30%) of which were in Indigenous people. The average annual notification rates in Indigenous and non-Indigenous people during this period were 110 and 25 cases per 100 000 persons, respectively. In the first 4 years after introduction of the vaccination program (2000-2003), 66 cases of hepatitis A were notified. Only nine of the 66 (14%) were in Indigenous people. The average annual notification rates in Indigenous and non-Indigenous people in 2000-2003 were 4 and 2.5 cases per 100 000 persons, respectively. CONCLUSION: Hepatitis A seems to have been eradicated from Indigenous communities in north Queensland very soon after the vaccination program began. The rapid decline in notifications in non-Indigenous as well as Indigenous people suggests the program quickly interrupted chains of transmission from Indigenous children to the broader community. To our knowledge this is the first evidence that a hepatitis A vaccination program targeting a high-risk population within a community can reduce disease in the broader community. Hepatitis A vaccine should be provided to other high-risk Indigenous children elsewhere in Australia.

Impact of Haemophilus influenzae type b (Hib) vaccination on Hib meningitis in children in Far North Queensland, 1989 to 2003.

Over the four years 1989 to 1992 there were 28 cases of Haemophilus influenzae type b (Hib) meningitis in children aged under five years in Far North Queensland. Thirteen (46%) of the cases were in Indigenous children, indicating that the rate of the disease was about 3.5 times greater in these children than in non-Indigenous children. However, no cases of Hib meningitis have occurred in Indigenous children in Far North Queensland in the 10 years following the addition of Hib vaccines to the Australian Standard Vaccination Schedule in 1993. There was only one case of Hib meningitis, in a (vaccinated) non-Indigenous child, between 1994 and 2003. About 70 cases of Hib meningitis in children were prevented by Hib immunisation in Far North Queensland between 1994 and 2003; possibly as many as five deaths and 12 cases with neurological sequelae were also prevented.

Uptake of influenza vaccine among Aboriginal and Torres Strait Island adults in north Queensland, 2003.

The uptake of the vaccine in at-risk Aboriginal and Torres Strait Island adults in north Queensland in 2003 was determined using the state-wide computerised immunisation register. The uptake in Aboriginal and Torres Strait Island adults > or = 50 years was 63 per cent, and assuming that a third of Aboriginal and Torres Strait Island adults 15-49 years of age had a medical risk factor, 85 per cent of those at-risk were vaccinated in 2003. There were considerable improvements in vaccine uptake in both age groups in the Cairns, Charters Towers, Mackay and the Tablelands Health Service Districts (HSDs) in 2003, but there were been considerable declines in both age groups in the Innisfail and Mt Isa HSDs in 2003 compared to 2002. There was also a decline in uptake in adults 15-49 years of age in the Townsville HSD.