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.

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

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%.

BCG vaccination reduces risk of infection with Mycobacterium tuberculosis as detected by gamma interferon release assay.

AIMS: To investigate whether BCG vaccination, in addition to a reduction of active tuberculosis, leads to a reduction of Mycobacterium tuberculosis infection during an outbreak of tuberculosis. METHODS: Pupils (n=199) of a Junior School exposed to a pupil with active pulmonary tuberculosis were screened using a gamma interferon release assay for detection of M. tuberculosis infection (ex vivo ELISPOT assay). Relative risk of M. tuberculosis infection and pulmonary tuberculosis associated with BCG vaccination were calculated and adjusted for exposure risk. RESULTS: Twenty-nine percent of children with previous BCG vaccination had a reactive gamma interferon release assay compared with 47% of unvaccinated children (unadjusted RR 0.61, 95%CI 0.39, 0.96). The protective effect of BCG vaccination persisted following adjustment for other risk factors for infection like ethnicity and proximity to the source case reflected in membership of class and activity groups (corrected relative risk 0.26, 95%CI 0.09, 0.69 and risk reduction of 74%, 95%CI 31%, 91%). A higher proportion of unvaccinated children (11%) were diagnosed with active pulmonary tuberculosis compared with 5% of vaccinated children (RR 0.51 95%CI 0.15, 1.70). CONCLUSION: BCG vaccination was associated with a reduction of M. tuberculosis infection diagnosed by gamma interferon release assay testing in school children during a point source outbreak.