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Outbreak investigation is an essential function of public health professionals. It is an opportunity to gain new knowledge of diseases and to discover the weaknesses of current public health practices and systems. Unfortunately, most outbreaks are not investigated. This chapter will present the principles and important points about outbreak investigation. The reader will learn about how to detect outbreaks from routine official surveillance and unofficial sources. The reader can assume oneself as an investigator who has to organize the team, review previous knowledge, and prepare the technical and management aspects, before starting the investigation. The reader will learn about the major ten steps in the investigation, with examples, which starts by confirming the existence of the outbreak, verifying the diagnosis, gathering case information, descriptive epidemiology, formulating and testing the hypothesis when necessary, conducting environmental surveys to supplement epidemiological evidence, providing timely on-site reporting of the findings, with practical recommendations to local and national responsible authorities, and communicating risk to health professional community and public. The reader is reminded about the need to follow-up on the recommendations and continue vigorous surveillance of the health problem. The chapter ends by forecasting more joint international investigations to control emerging diseases and new problems. After reading this chapter, the reader should be clear that outbreak investigation is an interesting, challenging, and important task requiring a competent investigator who combines sound scientific knowledge and good management.

Rapeepong Suphanchaimat,1,2 Natthaprang Nittayasoot,1 Panithee Thammawijaya,1 Pard Teekasap,3 Kumnuan Ungchusak1 1Division of Epidemiology, Department of Disease Control, Ministry of Public Health, Nonthaburi, 11000, Thailand; 2International Health Policy Programme, Ministry of Public Health, Nonthaburi, 11000, Thailand; 3Stamford International University, Bangkok, 10110, ThailandCorrespondence: Rapeepong Suphanchaimat Email rapeepong@ihpp.thaigov.neBackground: Thailand experienced the first wave of Coronavirus Disease 2019 (COVID-19) during March–May 2020 and has been facing the second wave since December 2020. The area facing the greatest impact was Samut Sakhon, a main migrant-receiving province in the country. The Department of Disease Control (DDC) of the Thai Ministry of Public Health (MOPH) considered initiating a vaccination strategy in combination with active case finding (ACF) in the epidemic area. The DDC commissioned a research team to predict the impact of various vaccination and ACF policy scenarios in terms of case reduction and deaths averted, which is the objective of this study.Methods: The design of this study was a secondary analysis of quantitative data. Most of the data were obtained from the DDC, MOPH. Deterministic system dynamics and compartmental models were exercised. A basic reproductive number (R0) was estimated at 3 from the beginning. Vaccine efficacy against disease transmission was assumed to be 50%. A total of 10,000 people were estimated as an initial population size.Results: The findings showed that the greater the vaccination coverage, the smaller the size of incident and cumulative cases. Compared with a no-vaccination and no-ACF scenario, the 90%-vaccination coverage combined with 90%-ACF coverage contributed to a reduction of cumulative cases by 33%. The case reduction benefit would be greater when R0 was smaller (∼ 53% and ∼ 51% when R0 equated 2 and 1.5, respectively).Conclusion: This study reaffirmed the idea that a combination of vaccination and ACF measures contributed to favourable results in reducing the number of COVID-19 cases and deaths, relative to the implementation of only a single measure. The greater the vaccination and ACF coverage, the greater the volume of cases saved. Though we demonstrated the benefit of vaccination strategies in this setting, actual implementation should consider many more policy angles, such as social acceptability, cost-effectiveness and operational feasibility. Further studies that address these topics based on empirical evidence are of great value.Keywords: COVID-19, vaccine, active case finding, reproduction number, Thailand

The entire H5N1 highly pathogenic avian influenza viral genomes were identified in the frozen autopsy specimens: the trachea, lung, colon, and intestinal feces from a patient who died of the disease in 2006. Phylogenetic analysis of the viral genomes showed that these viruses belonged to clade 1 and were the reassortants generated from the reassortment of the viruses within the same clade. The sequencing data from the autopsy specimens revealed at least 8 quasispecies of the H5N1 viruses across all 4 specimen types. These sequences were compared to those derived from the virus isolates grown in Madin Darby canine kidney (MDCK) cells. The virus isolates from the trachea, lung, and fecal specimens showed 27 nucleotide substitutions, leading to the changes of 18 amino acid residues. However, there was no change in the amino acid residues that determined the viral virulence. The changes were more commonly observed in the lung, particularly in the HA and NA genes. Our study suggested that the adaptation changes for the viral fitness to survive in a new host species (MDCK cells) might involve many genes, for example, the amino acid substitution 177G or 177W adjacent to the receptor-binding residues in the HA1 globular head and the substitution M315I in PB2. However, a mutation changes near the receptor binding domain may play an important role in determining the cell tropism and is needed to be further explored.

Ungchusak, Heymann and Pollack address the critical global issue of public health surveillance. They describe how epidemiologists collect and use surveillance data to detect unusual events or outbreaks and to guide control programmes. Drawing on their combined international experience, the authors explain the vital role that data play in alerting authorities to respond to outbreaks such as Severe Acute Respiratory Syndrome, Ebola, Zika virus and Avian influenza. They point to the importance of sharing information globally while ensuring equal benefits to providers of data, coordinating surveillance activities across sectors, building capacity for surveillance and coordinating national surveillance activities. The authors emphasise the need for enhanced global cooperation to prepare for future public health emergencies of international concern.

The complete genomic sequences of H5N1 highly pathogenic avian influenza (HPAI) viruses were directly obtained from lung, trachea, and colon tissues and an intestinal fecal sample of a patient by using the next-generation sequencing technique. This is the first report on complete H5N1 viral genomes from human autopsy specimens.

Thailand faced an outbreak of H5N1 avian influenza in poultry and in humans in early 2004. By the end of the same year, more than 62 million birds had died or been culled and 17 human cases, with 12 dead, had been detected. Among the human cases, most people were infected via direct contact with ill or deceased poultry, or when living in households with abnormal poultry deaths. One family cluster with probable human-to-human transmission was identified in September 2004. Recognizing the threat of avian and pandemic influenza, the Thai Government endorsed a three-year national strategic plan for 2005-7 with a total budget of 120 million US dollars. In accordance with the national strategic plan, the institutional response was implemented to improve the bio-security of poultry raising, including active surveillance and rapid control of animal and human outbreaks via grassroots participation. The country also started its minimum stockpiling for essential drugs and supplies, with a surge capacity to care for patients if a pandemic should occur.

SUMMARYWe investigated an outbreak ofShigella sonneiinfections in Denmark and Australia associated with imported baby corn from one packing shed in Thailand. We reviewed nationwide surveillance and undertook case finding, food trace-back and microbiological investigation of human, food and environmental samples. A recall of baby corn and sugar snaps was based on descriptive epidemiological evidence. In Denmark, we undertook a retrospective cohort study in one workplace. In total, 215 cases were laboratory-confirmed in Denmark, and 12 in Australia. In a multivariable analysis, baby corn was the only independent risk factor. Antibiotic resistance and PFGE outbreak profiles in Denmark and Australia were indistinguishable, linking the outbreaks. Although we did not detectS. sonneiin baby corn, we isolated high levels of other enteric pathogens. We identified a packing shed in Thailand that supplied baby corn to Denmark and Australia, and uncovered unhygienic practices in the supply chain. This outbreak highlights the importance of international communication in linking outbreaks and pinpointing the source.

Outbreaks of H5N1 avian influenza show strong seasonality. It is not clear where the source of virus originates from in each new outbreak season. This study sought to understand the nature of viral resurgence in recent outbreak seasons in Thailand, where the epidemic is relatively well controlled. In such a situation, indigenous viruses surviving the inter-outbreak season would have to pass through a bottleneck. In order to look for evidence of the bottleneck effect, viral genome sequences from recent outbreaks in the country were analysed. H5N1 avian influenza viruses were isolated from six outbreaks in the rainy season and winter of 2007 through to early 2008. Most of the outbreaks were in the Yom-Nan River basin in the southern part of the northern region of the country. Sequences of these viral isolates were identified as clade 1, genotype Z, similar to viruses from previous years in the central region of the country. The sequences clustered into two groups, one of which was closely related to viruses isolated from the same area in July 2006. These analyses indicated that there was a strong bottleneck effect on the virus population and that only a few lineages remained in the area. In addition, evidence of reassortment among these viruses was found. These indicated re-emergence of viruses from a small pool of indigenous sources that had been silently perpetuated over the dry summer months. Therefore, an approach to eradicate H5N1 avian influenza from the area by eliminating these local reservoirs may be feasible and should be seriously considered.

The International Health Regulations (IHR) 2005 present a challenge and opportunity for global surveillance and control of infectious diseases. This article examines the opportunity for regional networks to address this challenge. Two regional infectious disease surveillance networks, established in the Mekong Basin and the Middle East, are presented as case studies. The public-private partnerships in the networks have led to an upgrade in infectious disease surveillance systems in capacity building, purchasing technology equipment, sharing of information, and development of preparedness plans in combating avian influenza. These regional networks have become an appropriate infrastructure for the implementation of the IHR 2005.

Highly pathogenic avian influenza A (subtype H5N1) is threatening to cause a human pandemic of potentially devastating proportions. We used a stochastic influenza simulation model for rural Southeast Asia to investigate the effectiveness of targeted antiviral prophylaxis, quarantine, and pre-vaccination in containing an emerging influenza strain at the source. If the basic reproductive number ( R 0 ) was below 1.60, our simulations showed that a prepared response with targeted antivirals would have a high probability of containing the disease. In that case, an antiviral agent stockpile on the order of 100,000 to 1 million courses for treatment and prophylaxis would be sufficient. If pre-vaccination occurred, then targeted antiviral prophylaxis could be effective for containing strains with an R 0 as high as 2.1. Combinations of targeted antiviral prophylaxis, pre-vaccination, and quarantine could contain strains with an R 0 as high as 2.4.

background During 2004, a highly pathogenic avian influenza A (H5N1) virus caused poultry disease in eight Asian countries and infected at least 44 persons, killing 32; most of these persons had had close contact with poultry. No evidence of efficient person-to-person transmission has yet been reported. We investigated possible person-to-person transmission in a family cluster of the disease in Thailand. methods For each of the three involved patients, we reviewed the circumstances and timing of exposures to poultry and to other ill persons. Field teams isolated and treated the surviving patient, instituted active surveillance for disease and prophylaxis among exposed contacts, and culled the remaining poultry surrounding the affected village. Specimens from family members were tested by viral culture, microneutralization serologic analysis, immunohistochemical assay, reverse-transcriptase–polymerase-chainreaction (RT-PCR) analysis, and genetic sequencing. results The index patient became ill three to four days after her last exposure to dying household chickens. Her mother came from a distant city to care for her in the hospital, had no recognized exposure to poultry, and died from pneumonia after providing 16 to 18 hours of unprotected nursing care. The aunt also provided unprotected nursing care; she had fever five days after the mother first had fever, followed by pneumonia seven days later. Autopsy tissue from the mother and nasopharyngeal and throat swabs from the aunt were positive for influenza A (H5N1) by RT-PCR. No additional chains of transmission were identified, and sequencing of the viral genes identified no change in the receptor-binding site of hemagglutinin or other key features of the virus. The sequences of all eight viral gene segments clustered closely with other H5N1 sequences from recent avian isolates in Thailand. conclusions Disease in the mother and aunt probably resulted from person-to-person transmission of this lethal avian influenzavirus during unprotected exposure to the critically ill index patient.

Thailand's comprehensive national response to the HIV/AIDS epidemic has been extensively documented since the beginning of epidemic. Substantial progress in the fight against HIV/AIDS has been made because awareness of the problem was raised. Top-level political commitment and multisectoral strategies mobilized funds and human resources to implement the control program at all levels. Behavioral change resulting in increased condom use in brothels on a national scale rose from virtually nil to more than 95%. This was accompanied by a 90% reduction of the sexually transmitted disease rate. In parallel, the rate of new HIV infections dropped by 80%. Despite these achievements, there remains an urgent need to continue efforts to ensure universal and unfailing condom use. Further, Thailand needs to establish pragmatic innovative approaches to reduce transmission, especially among injection drug users, women, and youth, as well as to develop effective strategies for implementation of antiretroviral treatment. Further strategies also need to consider the changing cultural, social, and economic characteristics of the Thai populations.

Dengue fever is a mosquito-borne virus that infects 50-100 million people each year. Of these infections, 200,000-500,000 occur as the severe, life-threatening form of the disease, dengue haemorrhagic fever (DHF). Large, unanticipated epidemics of DHF often overwhelm health systems. An understanding of the spatial-temporal pattern of DHF incidence would aid the allocation of resources to combat these epidemics. Here we examine the spatial-temporal dynamics of DHF incidence in a data set describing 850,000 infections occurring in 72 provinces of Thailand during the period 1983 to 1997. We use the method of empirical mode decomposition to show the existence of a spatial-temporal travelling wave in the incidence of DHF. We observe this wave in a three-year periodic component of variance, which is thought to reflect host-pathogen population dynamics. The wave emanates from Bangkok, the largest city in Thailand, moving radially at a speed of 148 km per month. This finding provides an important starting point for detecting and characterizing the key processes that contribute to the spatial-temporal dynamics of DHF in Thailand.

The first International Emerging Infections Programs (IEIPs) was launched in October of 2001, with the opening of offices within the Ministry of Public Health complex in Nonthaburi, Thailand. The surveillance approach adopted by IEIP in Thailand differs somewhat from routine surveillance in most countries. Provinces are selected for surveillance on the basis of several criteria, including the representativeness of the population of Thailand, accessibility from Bangkok, feasibility of capturing the majority of hospitalizations through the public health system, availability of basic laboratory facilities, existence of epidemiologic capacity, and interest and commitment from local public health authorities. Between 1995 and 2001, the reported incidence of leptospirosis in Thailand increased by more than 100-fold, leading to widespread concern and calls for urgent control efforts. On 25 March 2002, the Bureau of Epidemiology was called to investigate a cluster of gastroenteritis cases among foreign tourists at a resort hotel in southern Thailand. In early 2002, outbreaks of hand, foot, and mouth syndrome were increasingly reported in Bangkok and six other provinces of Thailand. The vision of the IEIPs as a network of centers of excellence in infectious disease control is beginning to assume a realistic shape with the early growth of the IEIP-Thailand and the plan for a second IEIP in Africa. The establishment in Sa Kaeo Province of active, population- based, syndromic surveillance has the potential to provide uniquely valuable data to guide national and international public health decisions, though this potential will not be fully realized for several years.

The primary goal of this paper is to estimate the population size for a births only model when the capture probabilities vary with behavior response and time (or sampling occasion). A Bayesian framework is developed from the births only models for the capture–recapture experiment. We propose a unified approach for estimating the population size on each sampling occasion for four specified models using the Gibbs sampler, a Markov chain Monte Carlo method. The proposed methodology is illustrated with a simulation study and HIV serosurveillance data of Thailand. The results show that Gibbs sampler provides a reasonable estimate of population size when compared with the classical technique.

An anonymous, self-administered behavioral survey was conducted in Royal Thai Army (RTA) conscripts from 19 provinces throughout Thailand in May 1996. All (to a maximum of 350) Thai men who entered the RTA in each province were selected. Data from 5474 men were included in this analysis. High-risk behaviors were reported nationwide; however, some regional differences were found. Men from the upper North were more likely to have had a commercial sex worker (CSW) as their first sexual partner (42%) than men from any other region. However, in the past year, reported sex with CSWs in the upper North (41%) was similar to or lower than those in other regions. Consistent condom use with CSWs was higher in the North than in any other region. Condom use at first sex with CSWs increased with later years at first sex in all regions. These data suggest that past higher-risk behavior among young men in the upper northern part of Thailand may have contributed to the concentration of the HIV epidemic in that region. Risk behaviors, particularly unprotected sex, appear to be decreasing nationwide.The HIV behavioral risk factors associated with temporal and regional trends in HIV prevalence were investigated in a 1996 survey of 5474 Royal Thai Army conscripts from 19 provinces. 89% of respondents were 21 years of age and 77% were single. HIV prevalence was highest among men from the upper north (4.3%), followed by 2.6% in the central region, 2.4% in Bangkok, and 1.2% in the southeast. The median age at first intercourse was 17 years. Among sexually experienced men, a significantly higher proportion of those from the upper north (42%) had their first such encounter with a commercial sex worker (CSW). However, sex with CSWs during the year preceding the survey was similar or less frequent among men from the upper north (41%) compared with other regions. Also, significantly more men from the upper north (62%) used condoms every time with a CSW. Overall, 10% (range, 8-12%) reported having had sex with a man and 13% reported symptoms of a sexually transmitted disease (STD). Men whose sexual initiation occurred after 1990 were more likely to use condoms with a CSW partner. The decrease in sexual risk factors documented in this survey is consistent with national declines in HIV prevalence, especially in the upper northern region, after 1992. The increase in condom use with CSWs coincides with the 100% condom campaign initiated in 1991, intensified STD control efforts, and the emergence of AIDS deaths. Sex with non-CSW female partners, where condoms are rarely used, and homosexual sex require attention as situations where HIV risk may persist.

To the Editor: The unprecedented epizootic of avian influenza A (H5N1) in Asia poses a serious threat of causing the next global influenza pandemic. H5N1 viruses, to which humans have little or no immunity, have demonstrated the capacity to infect humans and cause severe illness and death (1–4). Fortunately, these viruses have not yet demonstrated the capacity for efficient and sustained person-to-person transmission, although limited person-to-person transmission was the cause of at least 1 family cluster of cases (5). Since family clusters of H5N1 illness may be the first suggestion of a viral or epidemiologic change, we have been monitoring them with great interest. Through our regional contacts and public sources, we have monitored family clusters and other aspects of H5N1 in Southeast Asia. A cluster was defined as >2 family members with laboratory-confirmed H5N1 or >2 family members with severe pneumonia or respiratory death, at least one of which had confirmed H5N1. To determine if family cluster events had increased over time, we divided the number of cluster events by the total number of days in 2 discrete periods and calculated rate ratios (RR) and 95% confidence intervals (CI). To determine whether the increase in family clustering was attributable to an increase in the number of cases, we divided the number of family units with >2 laboratory-confirmed cases by the total number of family units in the period. Percentage of deaths was also compared. From January 2004 to July 2005, 109 cases of avian influenza A (H5N1) were officially reported to the World Health Organization (WHO) (6). During this time, 15 family clusters were identified (Table). Of the 11 (73%) clusters that occurred in Vietnam, 7 were in northern Vietnam. Cluster size ranged from 2 to 5 persons, and 9 (60%) had >2 persons with laboratory-confirmed H5N1. Cluster 6 in Thailand was well documented and was likely the result of limited person-to-person transmission (5). For the other clusters, epidemiologic information was insufficient to determine whether person-to-person transmission occurred. In at least 3 clusters in Vietnam (Table; clusters 5, 7, and 11), >7 days occurred between the onset of the first and the next case, suggesting that simultaneous acquisition from a common source was unlikely. In cluster 11, 2 nurses assisted in the care of the index case-patient and subsequently were hospitalized with severe pneumonia; 1 had laboratory-confirmed H5N1. Table Family clusters of influenza A (H5N1) in Southeast Asia, January 2004–July 2005* Family clusters were slightly more likely to have occurred between December 2004 and July 2005 than in the first year of the outbreak (9 clusters in 243 days or 3.7 per 100 days vs. 6 clusters in 365 days or 1.6 per 100 days, respectively; RR 2.3, 95% CI 0.8–6.3). The difference was similar when the periods were limited to the same 8 months, 1 year apart (RR 1.8, 95% CI 0.6–5.4). Twenty-five (61%) of the 41 patients in the 15 family clusters died; the 7 persons who recovered or were not ill experienced secondary cases. Family clusters are still occurring; however, they do not appear to be increasing as a proportion of total cases. The proportion of families that were part of a cluster was similar from December 2004 to July 2005 to the proportion in the first year (6/55, 11% vs. 3/41, 7%, respectively, p = 0.7). However, the proportion of deaths dropped significantly, from 32 of 44 (73%) during December 2003 to November 2004, to 23 of 65 (35%) during December 2004 to July 2005 (p

BACKGROUND: The first human infections with influenza A(H1N1)pdm09 virus were confirmed in April 2009. We describe the clinical and epidemiological characteristics of influenza A(H1N1)pdm09-associated pneumonia deaths in Thailand from May 2009-January 2010. METHODS: We identified influenza A(H1N1)pdm09-associated pneumonia deaths from a national influenza surveillance system and performed detailed reviews of a subset. RESULTS: Of 198 deaths reported, 49% were male and the median age was 37 years; 146 (73%) were 20-60 years. Among 90 deaths with records available for review, 46% had no identified risk factors for severe influenza. Eighty-eight patients (98%) received antiviral treatment, but only 16 (18%) initiated therapy within 48 hours of symptom onset. CONCLUSIONS: Most influenza A(H1N1)pdm09 pneumonia fatalities in Thailand occurred in adults aged 20-60 years. Nearly half lacked high-risk conditions. Antiviral treatment recommendations may be especially important early in a pandemic before vaccine is available. Treatment should be considered as soon as influenza is suspected.

The incidence of new HIV infections in Asia and the Pacific will soon pass that in Africa and is projected to increase into the next century. The AIDS epidemic arising from these infections will have enormous consequences for the health and socioeconomic development of a region encompassing more than half the world's population.

Our objective was to estimate HIV seroconversion rates among commercial sex workers (CSWs) between 1990 and 1991 and to identify the behavioral, demographic, and reproductive determinants of these rates. This study has a prospective (n = 240 with 15 cases) and a cross-sectional component (n = 271 with 34 cases). In November 1990, HIV-negative female CSWs from 24 brothels in Khon Kaen city were interviewed and were followed prospectively for up to 1 year. In March, June, and September 1991, additional HIV-negative CSWs were enrolled and prospectively followed. HIV seroconversion rates were calculated, and the Cox regression model was used to estimate the relative risks of HIV seroconversion from demographic, sexual practice, and reproductive factors, adjusted for the effects of the others, among 232 of the 240 without missing data. Seroprevalence rates were also calculated for the 271 participants enrolled between March and December 1991, and relative risks of HIV seroprevalence were calculated for demographic, sexual practice, and reproductive risk factors among 184 of the 271 without missing data. The average seroprevalence was 12.5% (95% confidence interval 9.6-15.4%). With 1,947 person-months of observation obtained from 240 participants who were uninfected at baseline and seen at least twice during the course of the study, the cumulative incidence of HIV seroconversion between November 1990 and December 1991 was 9.4% (95% confidence interval 5.4-13.4%), and the average incidence rate of HIV seroconversion was 9.2 per 100 person-years (95% confidence interval 4.6-13.9 per 100 person-years). In the multivariate analysis, later date of enrollment into the study, having3 months experience as a CSW, and use of injectable contraceptives were the only risk factors that remained significant, with relative risks of 2.1 (95% confidence interval 1.2-3.7) for enrollment 3 months later, 3.8 (95% confidence interval 1.0-14.4) for3 months experience as a CSW versus3 months experience, and 3.9 (95% confidence interval 1.3-11.8) [corrected] for use of injectable contraceptives. In multivariate analysis of the cross-sectional data with 184 participants, of whom 21 were HIV seropositive, risk of HIV seropositivity increased significantly with current syphilis infection (odds ratio 5.8, 95% confidence interval 1.1-31.0). The results of this study will contribute to a better understanding of the risk factors of infection with HIV and thus allow for better targeting of group-specific interventions, particularly for CSWs and their clients. Further investigation of a possible association between injectable contraceptive use and HIV infection is needed.

It was estimated that 4.8 million people in Asia were already infected with HIV. Many countries including India, Myanmar, Thailand, Cambodia, some part of Vietnam and China is experienced a severe HIV epidemic. All categories of HIV risk behaviors and factors are known to exist in most countries of the region but with different degree. Experiences and lessons from some countries such as Thailand suggested that to effectively prevent HIV, it is necessary to have a national AIDS program, adequate budget from the country, and with partnerships from all government and non-government sectors. There are five important strategies which should be implemented with wide coverage: STDs service, condom promotion in all sex establishments, HIV screening for blood supply, HIV surveillance and information dissemination through mass media. With this prevention strategies, there is evidence of decrease of STDs and declining of HIV infection among young Thai male. Because HIV is the effect from poverty, inequality of socioeconomic development, National AIDS program should not neglect the opportunity to reform the unfavorable social or economic situation. Asian countries can and must strengthen their collaboration for joint HIV control program with full commitment and contribution.J Epidemiol, 1996 ; 6 : S125-S128.

We examine the emergence, development, and value of regional infectious disease surveillance networks that neighboring countries worldwide are organizing to control cross-border outbreaks at their source. The regional perspective represented in the paper is intended to serve as an instructive framework for others who decide to launch such networks as new technologies and emerging threats bring countries even closer together. Distinct from more formal networks in geographic regions designated by the World Health Organization (WHO), these networks usually involve groupings of fewer countries chosen by national governments to optimize surveillance efforts. Sometimes referred to as sub-regional, these “self-organizing” networks complement national and local government recognition with informal relationships across borders among epidemiologists, scientists, ministry officials, health workers, border officers, and community members. Their development over time reflects both incremental learning and growing connections among network actors; and changing disease patterns, with infectious disease threats shifting over time from local to regional to global levels. Not only has this regional disease surveillance network model expanded across the globe, it has also expanded from a mostly practitioner-based network model to one that covers training, capacity-building, and multidisciplinary research. Today, several of these networks are linked through Connecting Organizations for Regional Disease Surveillance (CORDS). We explore how regional disease surveillance networks add value to global disease detection and response by complementing other systems and efforts, by harnessing their power to achieve other goals such as health and human security, and by helping countries adapt to complex challenges via multi-sectoral solutions. We note that governmental commitment and trust among participating individuals are critical to the success of regional infectious disease surveillance networks. Keywords: regional networks; disease surveillance; trust; pandemics; cross-border; SARS; International Health Regulations (Published: 25 January 2013) Citation: Emerg Health Threats J 2013, 6 : 19913 - http://dx.doi.org/10.3402/ehtj.v6i0.19913

The intent of the HIV sentinel surveillance program in Thailand, as in other countries, is to provide early warning of pending epidemics so that public health of ficials can intensify prevention and control activities to protect their communities. While the intention is clear, questions remain as to how sentinel groups should be selected and if they predict future HIV occurrence. Every six months, serum is collected in Thailand from a sample of six sentinel groups in all provinces of Thailand for determining the prevalence of HIV infection. Among the sentinel groups, the HIV epidemic is rapidly increasing in female sex-workers, males at STD clinics, and females at antenatal clinics, increasing less rapidly among blood donors, and remaining high among IV drug addicts. Two sentinel groups were found to be useful for predicting the future spread of the epidemic to women attending clinics: lower-class female sex-workers and males attending STD clinics.

Up to 65% of travelers to less developed countries report health problems while traveling. International travel is an increasing concern for health practitioners. To date, there have not been any published analyses of mortality amongst foreign nationals visiting Thailand. Our objectives are to examine the magnitude and characterize the deaths among foreign nationals in Chiang Mai, a popular tourist province in Thailand.The study commenced with a review of the Thai death registration. Death certificates were retrieved, reviewed, and classified by the causes of death. Basic statistics and proportionate mortality ratio (PMR) were used to describe the pattern of deaths. Standardized mortality ratio (SMR) was used to assess the excess mortality risk among foreign nationals.Between January 1, 2010 and May 31, 2011, there were 1,295 registered deaths in Chiang Mai City, of which 102 records (7.9%) were foreign nationals. Median age of decedents was 64 years (range 14-102 y). Female-to-male ratio was 1 : 5.4. The highest mortality was among Europeans (45.1%). Most of the deaths were natural causes (89.2%) including 36 cardiac diseases (PMR = 35.3) and 20 malignancy diseases (PMR = 19.6). Deaths due to external causes were low. The SMRs range between 0.15 and 0.30.Communicable diseases and injuries were not the leading causes of death among foreign nationals visiting Chiang Mai, Thailand. It is essential that travelers are aware of mortality risk associated with their underlying diseases and that they are properly prepared to handle them while traveling.

To determine HIV seroconversion rates among female commercial sex workers (CSW) in Chiang Mai, Thailand.A three-round multi cross-sectional study was used at approximately 3-month intervals.In December 1989, 38 brothels (60%) in Chiang Mai were randomly selected. All 518 female CSW in the brothels were interviewed about their sociodemographics, sexual practices, condom use, history of sexually transmitted diseases (STD) and other risk factors. Blood was tested for Venereal Disease Research Laboratory (VDRL)-reactivity and HIV-1 antibody. The same brothels, which were all still operating, were revisited in March and July 1990 and 431 and 320 CSW, respectively, were interviewed and blood-tested. Pelvic examination, cervical, urethral and rectal cultures for gonococcus were added to the study in March 1990, although rectal culture was dropped from the study in July 1990.There were 5.2% [95% confidence interval (CI), 4.1-10.6] and 3.6% (95% CI, 1.5-5.4) per woman-month HIV seroconversion rates for the December-March and March-July periods, respectively. Of the CSW, 71.6-77.0% reported histories of at lest one STD. Condom-use rates among these CSW were reported to be 85.8-91.8%. High rates of positive cervical (11.2-12.3%) and urethral (8.8-11.4%) cultures for gonococcus were also found in the CSW.The fact that high HIV seroconversion rates and high STD prevalence rates occur despite high rates of reported condom use suggests that more aggressive education programs are needed in Thailand.In Thailand, health workers interviewed and drew blood samples from 518 female prostitutes working out of 38 brothels in Chiang Mai in December, 1989. They revisited the brothels, which were all still operating, and surveyed 431 and 320 female commercial sex workers in March and July, 1990, respectively. Researchers aimed for this 3-round multi cross- sectional study to determine HIV seroconversion rates among female prostitutes. HIV seroprevalence rates were 35.7%, 37.8%, and 42.6% in December, 1989, and March and July, 1990, respectively. 48.5% and 52.5% of prostitutes available on the 2nd and 3rd rounds, respectively, were new recruits. Newly recruited workers had much lower HIV seroprevalence rates than those previously working in the brothels (between 1st and 2nd round, 25.4% vs. 49.5% and between 2nd and 3rd round, 37.7% vs. 48%; p .05). The estimated HIV seroconversion rates in the December-March interval was 5.2% and 3.6% for the March-July interval. Around 90% of the workers used contraception, particularly oral contraceptives. Most (60.2-64.4%) were no more than 20 years old and were of Thai origin. Most workers (71.6-77%) had a history of sexually transmitted diseases (STDs), especially gonorrhea (45.6-63.4%) and genital ulcers (45.3- 47.2%). Positive cervical and urethral cultures for gonococcus were high (11.2-12.3% and 8.8-11.4%, respectively). Most (85.8-91.8%) used condoms for last night sex services. The high HIV seroconversion rates and high STD rates, despite high condom use, coupled with a high turnover rate suggest the need for more aggressive education programs aiming for 100% condom use rate to control the transmission of HIV and other STDs among commercial sex workers in Thailand.

SUMMARYAlthough pneumonia is a leading cause of death from infectious disease worldwide, comprehensive information about its causes and incidence in low- and middle-income countries is lacking. Active surveillance of hospitalized patients with pneumonia is ongoing in Thailand. Consenting patients are tested for seven bacterial and 14 viral respiratory pathogens by PCR and viral culture on nasopharyngeal swab specimens, serology on acute/convalescent sera, sputum smears and antigen detection tests on urine. Between September 2003 and December 2005, there were 1730 episodes of radiographically confirmed pneumonia (34·6% in children aged

BackgroundData on the incidence, seasonality and mortality associated with influenza in subtropical low and middle income countries are limited. Prospective data from multiple years are needed to develop vaccine policy and treatment guidelines, and improve pandemic preparedness.MethodsDuring January 2005 through December 2008, we used an active, population-based surveillance system to prospectively identify hospitalized pneumonia cases with influenza confirmed by reverse transcriptase-polymerase chain reaction or cell culture in 20 hospitals in two provinces in Thailand. Age-specific incidence was calculated and extrapolated to estimate national annual influenza pneumonia hospital admissions and in-hospital deaths.ResultsInfluenza was identified in 1,346 (10.4%) of pneumonia patients of all ages, and 10 influenza pneumonia patients died while in the hospital. 702 (52%) influenza pneumonia patients were less than 15 years of age. The average annual incidence of influenza pneumonia was greatest in children less than 5 years of age (236 per 100,000) and in those age 75 or older (375 per 100,000). During 2005, 2006 and 2008 influenza A virus detection among pneumonia cases peaked during June through October. In 2007 a sharp increase was observed during the months of January through April. Influenza B virus infections did not demonstrate a consistent seasonal pattern. Influenza pneumonia incidence was high in 2005, a year when influenza A(H3N2) subtype virus strains predominated, low in 2006 when A(H1N1) viruses were more common, moderate in 2007 when H3N2 and influenza B co-predominated, and high again in 2008 when influenza B viruses were most common. During 2005-2008, influenza pneumonia resulted in an estimated annual average 36,413 hospital admissions and 322 in-hospital pneumonia deaths in Thailand.ConclusionInfluenza virus infection is an important cause of hospitalized pneumonia in Thailand. Young children and the elderly are most affected and in-hospital deaths are more common than previously appreciated. Influenza occurs year-round and tends to follow a bimodal seasonal pattern with substantial variability. The disease burden varies significantly from year to year. Our findings support a recent Thailand Ministry of Public Health (MOPH) decision to extend annual influenza vaccination to older adults and suggest that children should also be targeted for routine vaccination.

Background. Population-based estimates of the incidence of invasive pneumococcal disease are unavailable for Thailand and other countries in Southeast Asia. We estimated the incidence of pneumococcal bacteremia cases requiring hospitalization in rural Thailand. Methods. Blood cultures were performed on samples from hospitalized patients in 2 rural provinces where active, population-based surveillance of community-acquired pneumonia is conducted. Blood cultures were performed at clinician discretion and were encouraged for all patients with suspected pneumonia and all children aged