During 9-20 Nov 2011, four prisoners in the national prison died with unknown cause and many prisoners developed diarrhea and neuropathy. The Bureau of Epidemiology launched an investigation to identify etiology and source of outbreak, and implement control measures. A case was defined as a prisoner or guard who developed gastrointestinal (GI) symptoms or neurological symptoms during 1 Sep to 31 Dec 2011. Foods, water, blood and urine samples were tested for heavy metals, vitamins B1 and B12. The prison had 33 guards, 3,668 male prisoners and 555 female prisoners. Among 475 prisoners who met the case definition, 307 (64.6%) GI cases, 49 (10.3%) neurological cases and 119 (25.1%) cases with both GI and neurological symptoms were identified. No case was found among the guards. Attack rates among male and female prisoners were 12.6% (462/3,668) and 2.3% (13/555) respectively. No female prisoners developed neuropathy. Eleven male prisoners had severe distal symmetrical peripheral neuropathy. Four men aged 26-47 years died after developing acute dyspnea. The cases rapidly increased after pipeline of the prison damaged on 2 Nov 2011. Blood and urine samples illustrated vitamin B1 deficiency and high arsenic concentration respectively. This outbreak of peripheral neuropathy possibly resulted from arsenic contaminated drinking water. After providing clean water on 24 Nov 2011, the outbreak subsided within 10 days.

In early September 2010, a nurse in Pua District Hospital observed an unusual increase in number of mumps cases and an outbreak investigation was conducted on 5 Oct 2010. This study described epidemiological characteristics of the outbreak as well as secondary attack rates and outcome of MMR vaccination campaign conducted during the outbreak. We reviewed medical records at Pua District Hospital and interviewed the cases’ family members, classmates and teachers. A clinical case was a person with acute parotitis or acute lymphadenitis at preauricular, submandibular or submental area with onset of illness from 1 Jun to 31 Dec 2010. A confirmed case was a clinical case who tested positive for mumps viral IgM by enzyme-linked immunosorbent assay (ELISA), mumps virus by polymerase chain reaction (PCR) or virus isolation. During the investigation period, we also conducted a single mass measles, mumps and rubella (MMR) vaccination campaign, targeting children aged 1-6 years in 10 sub-districts. From 1 Jun to 13 Oct 2010, 129 clinical cases (attack rate = 0.2%) were found in 11 out of 12 sub-districts. Of which, 70.4% were less than six years old children. Among 10 laboratory confirmed cases, six were positive for mumps IgM by ELISA and four positive for mumps virus by PCR, with one case revealed as genotype J. Secondary attack rate among 1-6 years old children was 31.4%. Attack rate among children aged 1-6 years during the pre-vaccination campaign period was 289.4 per 10,000 populations and decreased to 54.3 per 10,000 after the campaign. This investigation supported the Ministry of Public Health to change from using monovalent measles vaccine to MMR vaccine for 9-month old children in June 2010.

Three main tuberculosis (TB) reporting systems were operating in Thailand: notifiable disease surveillance (R506), TB registration and control in Bureau of Tuberculosis (BTB) and TB report for reimbursement in National Health Security Office (NHSO). A cross-sectional study was conducted in Satun Province in July 2011 to determine whether the three systems responded well to the objectives of TB surveillance. Patients diagnosed with TB and received anti-TB drugs at least once in 2010 from three hospitals were compared with TB cases reported in three systems. In the hospitals, 170 TB cases, including 95 new smear positive pulmonary TB cases, were reviewed. Coverage and positive predictive value were 73% and 83% for R506, 87% and 100% for BTB, and 79% and 99% for NHSO respectively. Success rate (82%) of all cases was lower than that was reported in BTB (96%). Median duration from diagnosis to reporting in R506, BTB and NHSO were six, 61 and two days respectively. All systems had sufficient budget, human resources and regular training. In addition, all systems had good capacity to achieve the major objectives of TB surveillance and their specific objectives. However, the systems had total 295 variables which resulted in high workload for reporting. Integrating three systems as one national TB reporting system was recommended to improve coverage, timeliness and success rate.

Oseltamivir is often prescribed to treat influenza patients, yet its effect on viral shedding among Thai young adults infected with influenza A(H1N1)pdm09 virus remained unclear. During May to June 2011, an influenza A(H1N1)pdm09 outbreak was detected in University S, Nakhon Ratchasima Province, Thailand. A prospective observational study was conducted to define duration of viral shedding and immunologic response in infected students undergoing oseltamivir treatment, and identify factors associated with viral shedding. We enrolled all acute respiratory illness (ARI) patients attending the medical center at University S during 3-7 Jun 2011 with laboratory confirmation of influenza A(H1N1)pdm09 infection by real-time reverse transcription polymerase chain reaction (rRT-PCR). Additional throat swabs were collected and tested daily until rRT-PCR results became negative through two consecutive days. Series of serum samples for hemagglutination inhibition (HI) test were also collected from the individuals. Log-rank test was applied in analysis of association between patients’ characteristics and duration of viral shedding. Of 29 sick students enrolled, 45% were males. All were prescribed oseltamivir for five days and none of them were hospitalized. Median duration from onset of symptoms to the last day of viral shedding detected was five days (range 3-9 days). Over 80% of the patients had 4-fold rises of HI titer within 2-3 weeks after onset of symptoms. None of the patients’ characteristics were significantly associated with duration of viral shedding. However, persons with delayed antiviral treatment tended to have longer duration of viral shedding. Early oseltamivir treatment probably reduced risks of severe influenza in young adult patients. However, guidelines on infection control need to emphasize on strict hygiene and prevention measures in treated patients for nine days in order to minimize the risks of influenza transmission.

In July 2011, catastrophic flooding occurred in 65 out of 77 provinces in Thailand, affecting 9.5 million and caused 813 deaths. The highest number of death due to floodwater was found in Phichit Province. An investigation was conducted to identify risk factors for flood-related mortality. A matched case-control study was performed. A case was defined as a flood-related death and the matched control was a person residing in the same neighborhood within five years age range. Data on cases were gathered by interview with family members and witnesses while information on controls was obtained through a structured questionnaire. Total 50 flood-related deaths and 100 controls were enrolled. Majority of deaths (56%) were 31-60 years old. About 87% of deaths were males and the cause of all deaths was drowning (100%). Health problems such as central nervous system disorder, psychosis and epilepsy were observed among 34% of the deaths. A common activity at the time of death was fishing (44%). Having health problem (adjusted OR=17.3, 95% CI=1.1-275.5) and male gender (adjusted OR=14.6, 95% CI=1.4-154.2) were identified as independent risk factors of flood-related deaths. Risk communication was initiated with the related ministries and high risk activities in the floodwater were prohibited by the responsible ministries.