Evaluation of the national Notifiable Diseases Surveillance System for dengue fever in Taiwan, 2010-2012

Background

In Taiwan, around 1,500 cases of dengue fever are reported annually and incidence has been increasing over time. A national web-based Notifiable Diseases Surveillance System (NDSS) has been in operation since 1997 to monitor incidence and trends and support case and outbreak management. We present the findings of an evaluation of the NDSS to ascertain the extent to which dengue fever surveillance objectives are being achieved.

Methodology

We extracted the NDSS data on all laboratory-confirmed dengue fever cases reported during 1 January 2010 to 31 December 2012 to assess and describe key system attributes based on the Centers for Disease Control and Prevention surveillance evaluation guidelines. The system’s structure and processes were delineated and operational staff interviewed using a semi-structured questionnaire. Crude and age-adjusted incidence rates were calculated and key demographic variables were summarised to describe reporting activity. Data completeness and validity were described across several variables.

Principal Findings

Of 5,072 laboratory-confirmed dengue fever cases reported during 2010–2012, 4,740 (93%) were reported during July to December. The system was judged to be simple due to its minimal reporting steps. Data collected on key variables were correctly formatted and usable in > 90% of cases, demonstrating good data completeness and validity. The information collected was considered relevant by users with high acceptability. Adherence to guidelines for 24-hour reporting was 99%. Of 720 cases (14%) recorded as travel-related, 111 (15%) had an onset >14 days after return, highlighting the potential for misclassification. Information on hospitalization was missing for 22% of cases. The calculated PVP was 43%.

Conclusions/Significance

The NDSS for dengue fever surveillance is a robust, well maintained and acceptable system that supports the collection of complete and valid data needed to achieve the surveillance objectives. The simplicity of the system engenders compliance leading to timely and accurate reporting. Completeness of hospitalization information could be further improved to allow assessment of severity of illness. To minimize misclassification, an algorithm to accurately classify travel cases should be established.

In Taiwan, around 1,500 cases of dengue fever are reported annually. Surveillance and outbreak preparedness are important activities aimed at reducing the burden of dengue fever worldwide. A national web-based Notifiable Diseases Surveillance System (NDSS) for dengue fever has been established since 1997 in Taiwan to monitor trends, and support case and outbreak management. We evaluated this surveillance system based on the Centers for Disease Control and Prevention guidelines and operational staff interviews to ascertain the extent to which stated objectives are being achieved. The results indicate that the NDSS for dengue fever surveillance works well, is easy to use, and can be used to accurately identify cases. The findings have informed recommendations to improve surveillance and its use in outbreak response, including efforts to improve data completeness. Comprehensive surveillance exemplified by the NDSS for dengue fever in Taiwan is necessary for establishing a clear picture of the local burden and distribution of dengue fever to effectively support public health response.

A human metapneumovirus outbreak at a community hospital in England, July to September 2010

We describe an outbreak of human metapneumovirus (hMPV) which occurred in July-September 2010 at a community hospital in the East of England. Based on the medical and nursing records, cases were retrospectively defined as suspected if they had had an influenza-like illness (ILI), and probable if they had had an ILI and an epidemiological link to a laboratory-confirmed case. Of a total of 17 symptomatic inpatients, five were classified as probable cases, five were laboratory confirmed and seven were suspected. The attack rate was 29.4% for confirmed and probable cases combined. The median age of symptomatic inpatients was 85 years-old (range 68-96) and the majority (16/17) of symptomatic inpatients had an underlying medical condition. Control measures introduced appeared to restrict further exposure of susceptible patients to infection although modelling suggested that up to four of 10 confirmed and probable cases (40%) could have been prevented through more timely diagnosis and recognition of an outbreak. These findings suggest that there should be increased awareness of hMPV infection within healthcare settings, particularly when the population at risk has a high prevalence of underlying co-morbidities.

A human metapneumovirus outbreak at a community hospital in England, July to September 2010

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Use of antiviral drugs to reduce household transmission of pandemic (H1N1) 2009, United Kingdom

TOC Summary: Early treatment of primary case-patients and prophylaxis of household contacts provides effective protection.

The United Kingdom implemented a containment strategy for pandemic (H1N1) 2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (<48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.

Surveillance of community genital Chlamydia trachomatis testing in the East of England, 2008-2010

BACKGROUND

Widespread testing for chlamydia is expected to result in a reduction in prevalence. In 2008, coverage indicators introduced by the Department of Health (DH) required collection and submission of all tests performed outside of genitourinary medicine clinics. No mechanism existed to collect community-based tests conducted outside of the National Chlamydia Screening Programme. The Health Protection Agency Regional Epidemiology Unit in the East of England (EoE) set up a new system to routinely collect and submit these tests on behalf of the regional Primary Care Organizations (PCOs).

METHODS

Testing data were requested from all laboratories commissioned to undertake chlamydia testing by EoE PCOs. Data were imported into a bespoke Structured Query Language server database and automated data processing routines were run. Data fulfilling national criteria were submitted for inclusion in the DH indicators.

RESULTS

High-quality data were submitted to set deadlines with minimum impact on laboratories. Completeness of data variables varied by laboratory and by variable type. After complex data processing, 96% of laboratory reported tests in the 15-24 year age range were eligible for submission.

CONCLUSIONS

This centralized method of data collection provides high-quality data, allowing for further analysis, which can be used to inform improvements in health care. These methods could be transferred to any of the hundreds of organisms for which similar laboratory data exist.

Pandemic Influenza A (H1N1) 2009 and mortality in the United Kingdom: risk factors for death, April 2009 to March 2010

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Pandemic Influenza A (H1N1) 2009 and mortality in the United Kingdom: risk factors for death, April 2009 to March 2010

This paper describes the epidemiology of fatal pandemic influenza A(H1N1) cases in the United Kingdom (UK) since April 2009 and in particular risk factors associated with death. A fatal case was defined as a UK resident who died between 27 April 2009 and 12 March 2010, in whom pandemic influenza A(H1N1) infection was confirmed by laboratory or recorded on death certificate. Case fatality ratios (CFR) were calculated using the estimated cumulative number of clinical cases as the denominator. The relative risk of death was estimated by comparing the population mortality rate in each risk group, with those not in a risk group. Across the UK, 440 fatal cases were identified. In England, fatal cases were mainly seen in young adults (median age 43 years, 85% under 65 years), unlike for seasonal influenza. The majority (77%) of cases for whom data were available (n=308) had underlying risk factors for severe disease. The CFR in those aged 65 years or over was nine per 1,000 (range 3 - 26) compared to 0.4 (range 0.2 to 0.9) for those aged six months to 64 years. In the age group between six month and 64 years, the relative risk for fatal illness for those in a risk group was 18. The population attributable fractions in this age group were highest for chronic neurological disease (24%), immunosuppression (16%) and respiratory disease (15%). The results highlight the importance of early targeted effective intervention programmes.

Health impact of the Buncefield oil depot fire, December 2005: Study of accident and emergency case records

BACKGROUND

On Sunday 11th of December 2005, an explosion occurred at the Buncefield oil depot, Hertfordshire, resulting in a large fire that blazed for several days. Two Accident and Emergency (A&E) departments were placed on stand-by to receive casualties. A simple surveillance system was put in place during the acute phase of the incident, but this was not adequate to fully examine the health impact of the fire.

METHODS

Retrospective study of A&E records at Hemel Hempstead and Watford A&E departments for the period that the fire burnt.

RESULTS

Two hundred and forty-four people attended A&E as a result of the fire: 187 were members of the emergency services; 17 were oil depot workers; and 40 were members of the public. The most common presenting complaints were respiratory symptoms (n = 66) and injuries (n = 38). Twenty-five (21%) individuals were referred for medical follow-up. There were no fatalities.

CONCLUSION

There was a significant impact on local health services, with many emergency service personnel attending A&E asymptomatically. Alternative health service provision for these individuals, possibly near to the scene of the incident, should be considered. This incident has also highlighted an urgent need to develop surveillance systems that enable real-time monitoring of the acute public health impact of major incidents.

Outbreak of tuberculosis in a junior school in south-eastern England

Several tuberculosis outbreaks in schools have been reported in the last decade, usually following transmission from an infectious staff member.

What happens to people diagnosed with tuberculosis? A population-based cohort

We examined different patient outcomes following diagnosis of tuberculosis (TB). Incident cases were reported to the enhanced surveillance system in the East of England, between 2000 and 2003. For the 575 cases reported in 2001 and 2002, outcomes were assessed 1 year after initiating treatment. The crude clinical incidence rate of TB was 6.0 cases/100,000 person-years (pyr) [95% confidence interval (CI) 5.7-6.4], highest in the 25-29 years age group (14.9, 95% CI 12.9-17.1 cases/100,000 pyr) and among Black Africans (328.6, 95% CI 286.9-374.6 cases/100,000 pyr). Patients born abroad were 2.35 (95% CI 1.03-5.32) times more likely to be lost to follow-up than those born in the United Kingdom. Age at diagnosis (OR 1.05, 95% CI 1.04-1.07) and pulmonary disease (OR 2.73, 95% CI 1.21-6.15) were independently associated with mortality. Elderly patients and those with pulmonary TB appear to have worse outcomes despite treatment. Foreign-born patients may need closer follow-up to ensure favourable outcomes.

Legionnaires' disease: when an 'outbreak' is not an outbreak

During August 2006, there was a large increase in non-travel related legionella cases throughout England and in the Netherlands.

Outbreak of low pathogenicity H7N3 avian influenza in UK, including associated case of human conjunctivitis

On 26 April 2006, the veterinary authorities in the United Kingdom reported that there had been an outbreak of avian influenza type A/H7 among a 35 000-bird housed poultry flock in eastern England, United Kingdom.

Tetanus immunisation policy in England and Wales--an overview of the literature

Current UK policy on immunisation for tetanus has changed in the light of evidence that five doses of vaccine probably provides sufficient protection as long as high-risk wounds are managed with tetanus immunoglobulin. This paper reviews the evidence base for tetanus immunisation policy in England and Wales: the epidemiology of tetanus, vaccination coverage and response to tetanus toxoid, and population immunity to tetanus. The paper highlights gaps in our current knowledge of tetanus vaccination and policy implementation, and makes recommendations for further investigations.

Monitoring the uptake of HIV testing among first attendees at GUM clinics in the East of England region

This study was conducted to determine the extent to which genitourinary medicine clinics in the East of England region are monitoring the uptake of HIV testing. Ninety-four per cent of GUM clinics in the region offer HIV testing to all new patients. The uptake varied around the region, but all clinics are able to monitor uptake and the majority of clinics can audit uptake. The overall regional uptake has already exceeded the target for 2004.

Prevention of perinatal hepatitis B transmission in a health authority area: an audit

The aim of this audit was to provide baseline measurement of antenatal hepatitis B virus (HBV) screening uptake, coverage of HBV vaccination in infants born to high- and low-risk HBsAg carrier mothers, completion of post-vaccination serological testing, outcome for vaccinated infants, and an assessment of the factors that influenced the effectiveness of the whole programme. Methods included identifying HBV positive pregnancies by laboratory results, and follow up of at-risk infants by a GP survey. Uptake of antenatal HBV screening was 99.9%. Thirty-one HBV positive pregnancies were identified, and twenty-nine infants were followed up. The overall HBV vaccination completion rate was 93%. Fifty per cent of eligible infants were tested for hepatitis carriage, the majority of whom were high-risk infants. None had acquired HBV infection and all had gained adequate immunity. We conclude that, although the local screening programme has been implemented effectively, there is inconsistency in the follow up of infants at high and low risk of acquiring HBV.

Use of ivermectin, given orally, to control scabies in homes for the elderly mentally ill

Outbreaks of scabies in two homes for the elderly mentally ill in the UK and the use of an oral agent, ivermectin, as a control measure are described. The difficulties of diagnosis and control in this setting are discussed.