Acute flaccid paralysis incidence and Zika virus surveillance, Pacific Islands.

PROBLEM: The emergence of Zika virus has challenged outbreak surveillance systems in many at-risk, low-resource countries. As the virus has been linked with Guillain-Barré syndrome, routine data on the incidence of acute flaccid paralysis (AFP) may provide a useful early warning system for the emergence of Zika virus. APPROACH: We documented all Zika virus outbreaks and cases in 21 Pacific Islands and territories for the years 2007 to 2015. We extracted data from the Global Polio Eradication Initiative database on the reported and expected annual incidence of AFP in children younger than 15 years. Using a Poisson probability test, we tested the significance of unexpected increases in AFP in years correlating with Zika virus emergence. Data were analysed separately for each Pacific Island country and territory. LOCAL SETTING: In most Pacific Island countries, early warning surveillance for acute public health threats such as Zika virus is hampered by poor health infrastructure, insufficient human resources and geographical isolation. RELEVANT CHANGES: Only one example was found (Solomon Islands in 2015) of a significant increase in reported AFP cases correlating with Zika virus emergence. LESSONS LEARNT: We found no conclusive evidence that routinely reported AFP incidence data in children were useful for detecting emergence of Zika virus in this setting. More evidence may be needed from adult populations, who are more likely to be affected by Guillain-Barré syndrome. Reporting of AFP may be deficient in regions certified as polio-free.

Early warning epidemic surveillance in the Pacific island nations: an evaluation of the Pacific syndromic surveillance system.

OBJECTIVE: The Pacific Syndromic Surveillance System (PSSS), launched in 2010, provides a simple mechanism by which 121 sentinel surveillance sites in 21 Pacific island countries and areas perform routine indicator- and event-based surveillance for the early detection of infectious disease outbreaks. This evaluation aims to assess whether the PSSS is meeting its objectives, what progress has been made since a formative evaluation of the system was conducted in 2011, and provides recommendations to enhance the PSSS's performance in the future. METHODS: Twenty-one informant interviews were conducted with national operators of the system and regional public health agencies that use information generated by it. Historic PSSS data were analysed to assess timeliness and completeness of reporting. RESULTS: The system is simple, acceptable and useful for public health decision-makers. The PSSS has greatly enhanced Pacific island countries' ability to undertake early warning surveillance and has contributed to efforts to meet national surveillance-related International Health Regulation (2005) capacity development obligations. Despite this, issues with timeliness and completeness of reporting, data quality and system stability persist. CONCLUSION: A balance between maintaining the system's simplicity and technical advances will need to be found to ensure its long-term sustainability, given the low-resource context for which it is designed.

Understanding human - bat interactions in NSW, Australia: improving risk communication for prevention of Australian bat lyssavirus.

BACKGROUND: Australian bat lyssavirus (ABLV) infects a number of flying fox and insectivorous bats species in Australia. Human infection with ABLV is inevitably fatal unless prior vaccination and/or post-exposure treatment (PET) is given. Despite ongoing public health messaging about the risks associated with bat contact, surveillance data have revealed a four-fold increase in the number of people receiving PET for bat exposure in NSW between 2007 and 2011. Our study aimed to better understand these human - bat interactions in order to identify additional risk communication messages that could lower the risk of potential ABLV exposure. All people aged 18 years or over whom received PET for non-occupation related potential ABLV exposure in the Hunter New England Local Health District of Australia between July 2011 and July 2013 were considered eligible for the study. Eligible participants were invited to a telephone interview to explore the circumstances of their bat contact. Interviews were then transcribed and thematically analysed by two independent investigators. RESULTS: Of 21 eligible participants that were able to be contacted, 16 consented and participated in a telephone interview. Participants reported bats as being widespread in their environment but reported a general lack of awareness about ABLV, particularly the risk of disease from bat scratches. Participants who attempted to 'rescue' bats did so because of a deep concern for the bat's welfare. Participants reported a change in risk perception after the exposure event and provided suggestions for public health messages that could be used to raise awareness about ABLV. CONCLUSIONS: Reframing the current risk messages to account for the genuine concern of people for bat welfare may enhance the communication. The potential risk to the person and possible harm to the bat from an attempted 'rescue' should be promoted, along with contact details for animal rescue groups. The potential risk of ABLV from bat scratches merits greater emphasis.

Cross sectional survey of human-bat interaction in Australia: public health implications.

BACKGROUND: Flying foxes (megachiroptera) and insectivorous microbats (microchiroptera) are the known reservoirs for a range of recently emerged, highly pathogenic viruses. In Australia there is public health concern relating to bats' role as reservoirs of Australian Bat Lyssavirus (ABLV), which has clinical features identical to classical rabies. Three deaths from ABLV have occurred in Australia. A survey was conducted to determine the frequency of bat exposures amongst adults in Australia's most populous state, New South Wales; explore reasons for handling bats; examine reported practices upon encountering injured or trapped bats or experiencing bat bites or scratches; and investigate knowledge of bat handling warnings. METHODS: A representative sample of 821 New South Wales adults aged 16 years and older were interviewed during May and June 2011, using a computer assisted telephone interview (CATI) method. Frequencies, proportions and statistical differences in proportion were performed. Using an α-value of 0.05 and power of 80%, it was calculated that a sample size of 800 was required to provide statistical significance of +/- 5% for dichotomous variables. RESULTS: One-hundred-and-twenty-seven (15.5%) respondents indicated that they had previously handled a bat, being 22% (48/218) rural and 13% (78/597) urban respondents (χ2 = 9.8, p = 0.0018). Twenty one percent of males (63/304) had handled bats compared with 12% (64/517) of females (χ2 = 10.2, p = 0.0014). Overall, 42.0% (n = 345) of respondents reported having seen or heard a warning about handling bats. If faced with an injured or trapped bat, 25% (206/821) indicated that they would handle the bat, with 17% (36/206) saying that they would use their bare hands. For minor scratches, 14% (117/821) indicated that they would ignore the injury while four respondents would ignore major scratches or bites. CONCLUSIONS: Previous human-bat interactions were relatively common. Bat exposures most frequently occurred with sick or injured bats, which have the highest risk of ABLV. On encountering an injured or sick bat, potentially high risk practices were commonly reported, particularly among rural males. It is important to understand why people still handle bats despite public health warnings to inform future communication strategies.

Australia's polio risk.

Australia, like all polio-free countries and regions, remains at risk of a wild poliovirus importation until polio is eradicated globally. The most probable route of importation will be through a traveller arriving in Australia either by air or sea from a polio-endemic or re-infected country. While the overall risk of an imported wild poliovirus infection leading to transmission within Australia is assessed as being low, some areas of the country have been identified as at increased risk. Local areas with relatively high arrivals from polio endemic countries, areas of low vaccination coverage and the potential for transmission to occur when these 2 factors are combined, were identified by this review as Australia's main polio risk. The risk of an importation event leading to locally acquired cases is mitigated by generally high polio vaccination coverage in Australia. This high coverage extends to residents of the Torres Strait Islands who are in close proximity to Papua New Guinea, a country identified as at high risk of poliovirus transmission should an importation occur. In 2012, all states and territories had vaccination coverage of greater than 90% at 1 year of age and all exceeded 93% at 2 years of age. Population immunity to wild poliovirus type 1, which remains the major cause of paralysis globally, has been estimated at 82%. This is sufficient to prevent outbreaks of this type in Australia. Of the 211 eligible non-polio acute flaccid paralysis (AFP) cases classified between 2008 and 2011, 91% (193) were vaccinated against polio at least once. High quality surveillance for AFP, which is supplemented by sentinel enterovirus and environmental surveillance activities, gives confidence that an imported case would be detected and appropriate public health action would ensue.

Review of Australia's polio surveillance.

With eradication almost within reach, the importance of detecting every poliomyelitis case has taken on additional significance. The selected surveillance strategy must be effective and efficient. A review of polio surveillance in Australia was conducted to consider whether current strategies were optimal. Document review and semi-structured key informant interviews were used to conduct the review. Interviews were recorded, transcribed and thematically analysed. The review was an iterative process with feedback on the findings sought from interviewees. Since Western Pacific Regional polio-elimination status was certified, one imported adult case was detected in 2007 in Australia, with no evidence of further transmission, and no Australian paediatric cases identified. Respondents reported that: it was not possible to prevent importations; paediatric cases were more likely to be identified than adult cases; and there may be a low level of suspicion among clinicians. Case detection and outbreak mitigation were considered key reasons to undertake polio surveillance. While Australia has not achieved one of the key World Health Organization (WHO) surveillance targets, this did not compromise Australias polio-free status. Identified issues with polio surveillance were the potential for an importation with high attendant investigation and containment costs, low stool sample collection rates, and the opportunity to improve safeguards around the importation and laboratory storage of biological samples containing poliovirus. The review found strong support for ongoing polio surveillance, particularly to detect imported cases and to demonstrate commitment to maintaining a polio-free region. Existing polio surveillance strategies were considered appropriate for Australia.

'Silent' and 'noisy' areas: acute flaccid paralysis surveillance at subnational level, Australia, 2001-2015.

Background: Acute flaccid paralysis (AFP) surveillance rates are used as an indicator of surveillance sensitivity to detect poliomyelitis with an expected rate of ≥1 case per 100 000 population in children under 15 years of age. Methods: The Australian AFP detection rates at sub-national (statistical local area) level were analysed using χ2 goodness of fit tests and exact Poisson probabilities for the combined years 2001-2015 to detect 'silent areas', which may require improved AFP detection efforts, and areas with greater than expected rates, which may indicate unexplained clusters such as those due to enterovirus infection. Results: Eight (n=8/87, 9%) local areas had AFP surveillance detection rates that were less than expected, and eighteen local areas (n=18/87, 21%) had rates that were greater than expected. However, based on available evidence, it is unlikely that these indicated previously unidentified, enterovirus clusters. Conclusions: While Australia has regularly met the national AFP surveillance performance indicators, at the subnational level nine per cent of local areas demonstrated statistically significant lower AFP detection rates. All countries, even those with relatively small populations, should actively identify silent AFP areas to prompt surveillance improvements.

The remarkable adaptability of syndromic surveillance to meet public health needs.

The goal of syndromic surveillance is the earlier detection of epidemics, allowing a timelier public health response than is possible using traditional surveillance methods. Syndromic surveillance application for public health purposes has changed over time and reflects a dynamic evolution from the collection, interpretation of data with dissemination of data to those who need to act, to a more holistic approach that incorporates response as a core component of the surveillance system. Recent infectious disease threats, such as severe acute respiratory syndrome (SARS), avian influenza (H5N1) and pandemic influenza (H1N1), have all highlighted the need for countries to be rapidly aware of the spread of infectious diseases within a region and across the globe. The International Health Regulations (IHR) obligation to report public health emergencies of international concern has raised the importance of early outbreak detection and response. The emphasis in syndromic surveillance is changing from automated, early alert and detection, to situational awareness and response. Published literature on syndromic surveillance reflects the changing nature of public health threats and responses. Syndromic surveillance has demonstrated a remarkable ability to adapt to rapidly shifting public health needs. This adaptability makes it a highly relevant public health tool.

Historical data and modern methods reveal insights in measles epidemiology: a retrospective closed cohort study.

OBJECTIVES: Measles was endemic in England during the early 1800s; however, it did not arrive in Australia until 1850 whereas other infectious diseases were known to have arrived much earlier-many with the First Fleet in 1788-leading to the question of why there was a difference. DESIGN: Ships surgeons' logbooks from historical archives, 1829-1882, were retrospectively reviewed for measles outbreak data. Infectious disease modelling techniques were applied to determine whether ships would reach Australia with infectious measles cases. SETTING: Historical ship surgeon logbooks of measles outbreaks occurring on journeys from Britain to Australia were examined to provide new insights into measles epidemiology. PRIMARY AND SECONDARY OUTCOME MEASURES: Serial intervals and basic reproduction numbers (R(0)), immunity, outbreak generations, age-distribution, within-family transmission and outbreak lengths for measles within these closed cohorts. RESULTS: Five measles outbreaks were identified (163 cases). The mean serial interval (101 cases) was 12.3 days (95% CI 12.1 to 12.5). Measles R(0) (95 cases) ranged from 7.7-10.9. Immunity to measles was lowest among children ≤10 years old (range 37-42%), whereas 94-97% of adults appeared immune. Outbreaks ranged from 4-6 generations and, before 1850, were 41 and 38 days in duration. Two outbreaks after 1850 lasted longer than 70 days and one lasted 32 days. CONCLUSIONS: Measles syndrome reporting in a ship surgeon's logs provided remarkable detail on prevaccination measles epidemiology in the closed environment of ship voyages. This study found lower measles R(0) and a shorter mean clinical serial interval than is generally reported. Archival ship surgeon log books indicate it was unlikely that measles was introduced into Australia before 1850, owing to high levels of pre-existing immunity in ship passengers, low numbers of travelling children and the journey's length from England to Australia.

Sustaining surveillance: evaluating syndromic surveillance in the Pacific.

Prior to the 2009 H1N1 pandemic, the Pacific Island Countries and Territories (PICTs) had agreed to develop a standardised, simple syndromic surveillance system to ensure compliance with International Health Regulations requirements (rapid outbreak detection, information sharing and response to outbreaks). In October 2010, the new system was introduced and over the next 12 months implemented in 20 of 22 PICTs. An evaluation was conducted to identify strengths and weaknesses of the system, ease of use and possible points for improvement. An in-country quantitative and qualitative evaluation in five PICTs identified that the most important determinants of the system's success were: simplicity of the system; support from all levels of government; clearly defined roles and responsibilities; feedback to those who collect the data; harmonisation of case definitions; integration of data collection tools into existing health information systems; and availability of clinical and epidemiological advice from external agencies such as the World Health Organization and the Secretariat of the Pacific Community. Regional reporting of alerts, outbreaks and outbreak updates has dramatically increased since implementation of the system. This syndromic system will assist PICTs to detect future influenza pandemics and other emerging infectious diseases and to rapidly contain outbreaks in the Pacific.

A review of the epidemiology and surveillance of viral zoonotic encephalitis and the impact on human health in Australia.

Human encephalitis in Australia causes substantial mortality and morbidity, with frequent severe neurological sequelae and long-term cognitive impairment. This review discusses a number of highly pathogenic zoonotic viruses which have recently emerged in Australia, including Hendra virus and Australian bat lyssavirus which present with an encephalitic syndrome in humans. Encephalitis surveillance currently focuses on animals at sentinel sites and animal disease or definitive diagnosis of notifiable conditions that may present with encephalitis. This is inadequate for detecting newly emerged viral encephalatides. Hospital-based sentinel surveillance may aid in identifying increases in known pathogens or emergence of new pathogens that require a prompt public health response.