Abstract. The effect of origin and destination country on traveler's diarrhea incidence rates in Southeast Asia is poorly understood, and research generally only addresses diarrhea in travelers from the developed world. This study evaluated the attack rate and effects of traveler's diarrhea by origin and destination and analyzed key risk factors. A selfadministered questionnaire was provided to foreign travelers departing Southeast Asia from Suvarnabhumi Airport, Bangkok, Thailand. It evaluated traveler demographics, relevant knowledge and practices, experiences of diarrhea, and the details and consequences of each diarrheal episode. A total of 7,963 questionnaires were completed between April 2010 and July 2011. Respondents were 56% male (mean age 35) with a mean and median duration of stay of 28 days and 10 days, respectively. Most respondents were from Europe (36.8%) or East Asia (33.4%). The attack rate of traveler's diarrhea was 16.1%, with an incidence rate of 32.05 per 100 person months. Travelers' origin and destination countries significantly related to diarrhea risk. Oceanians had the highest risk (32.9%) and East Asians the lowest (2.6%). Vietnam and Indonesia were the highest risk destinations (19.3%). Other significant factors were youth, trip duration, number of countries visited, and frequently drinking beverages with ice.

Abstract. Acute liver failure is an atypical manifestation of dengue with a high mortality. We performed a retrospective cohort study at the Hospital for Tropical Diseases, Bangkok, Thailand. In total, 1,926 patients with serologically confirmed dengue were enrolled in the study from 2011 to 2015. Of these, six patients presented with acute liver failure, four died, and two survived. The incidence of dengue-associated acute liver failure was 0.31%. Dengue-associated acute liver failure was most common among young adults (median age, 29 years). The median duration from onset of fever to development of acute liver failure was 7.5 days. Patients with the severe stage of dengue had a higher risk of developing acute liver failure (P < 0.001). The baseline risk factors associated with the development of acute liver failure were an age of ≤ 40 years (odds ratio [OR] = 1.5, 95% confidence interval [CI] = 1.1-2.0, P < 0.05), a > 10% ratio of atypical lymphocytes (OR = 2.3, 95% CI = 1.8-3.0, P < 0.001), and a platelet count of < 50,000 mm 3 (OR = 2.8, 95% CI = 2.2-3.6, P < 0.001). The incidence of acute liver failure in patients with dengue was quite low, but its impact on morbidity, mortality, and poor clinical outcomes was significant. In summary, this study indicates that various baseline risk factors are associated with acute liver failure in patients with dengue.

About one third of the foreign backpackers in Southeast Asia had experienced diarrhea during their trip. Their current practices related to the risk of travelers' diarrhea were inadequate and should be improved.

Live attenuated Shigella sonnei vaccine candidate WRSS1, previously tested in U.S. and Israeli volunteers, was evaluated in a population of adult Thai volunteers in which the organism is endemic. In a randomized placebo-controlled, double-blind design, inpatient participants received a single oral dose of 1.6 × 104 CFU of WRSS1. The vaccine was generally well tolerated, with equal numbers of vaccinees and placebo controls showing mild symptoms. Only 3 of 13 vaccinees (23%) had culture-positive stools, while a total of 9 vaccinees were positive by PCR. Lack of vaccine shedding in volunteers correlated with lack of clinical symptoms and immune responses, just as the duration of fecal shedding correlated directly with stronger immune responses. Two months following immunization, 10 vaccinees and 10 newly recruited naive controls received a challenge dose of 1,670 CFU of virulent S. sonnei strain 53G. This dose had previously demonstrated a 75% attack rate for dysentery in Thai volunteers. However, in this study the attack rate for dysentery in naive controls after challenge was 20%. Based on clinical record summaries, 3 vaccinees and 5 naive controls experienced clinically relevant illness (diarrhea/dysentery/fever/shigellosis), and a 40% vaccine efficacy was calculated. When these data are compared to those for the performance of this vaccine candidate in more naive populations, it is clear that a single oral dose of WRSS1 at 104 CFU failed to achieve its full potential in a population in which the organism is endemic. Higher doses and/or repeated immunizations may contribute to improved vaccine shedding and consequent elevation of protective immune responses in a population in which the organism is endemic. (The study has been registered at ClinicalTrials.gov under registration no. NCT01080716.)

Abstract. In Thailand, the burden of liver abscess, a life-threatening infectious disease, has not been thoroughly evaluated. We developed a predictive scoring system to estimate survival of patients with liver abscess using information from the 2008-2013 Nationwide Hospital Admission Data to evaluate the burden of liver abscess in Thailand. All patients with primary diagnosis of pyogenic liver abscess (PLA) and amoebic liver abscess (ALA) were included. Epidemiological data, baseline characteristics, hospital course, and survival were analyzed. Overall, 11,296 admissions comprising 8,423 patients from 844 hospitals across Thailand were eligible for analysis. The mean age was 52 ± 17 years and 66.1% of patients were male. ALA was significantly prevalent in southern and western border regions of Thailand, and PLA occurred nationwide. The highest incidence of liver abscess occurred in the rainy season (June-November, P < 0.01). The median length of hospital stay was 8 days (interquartile range = 4-13 days), and mean direct cost of hospitalization was 846 ± 1,574 USD. The overall inhospital mortality rate was 2.8%. Incidence of ALA decreased over the 5-year study period, whereas PLA incidence increased (P < 0.01). Using multivariable Cox regression methods with stepwise variable selection, we developed a final model with five highly significant baseline parameters associated with increased 60-day mortality: older age, PLA, underlying chronic kidney disease, cirrhosis, and human immunodeficiency virus infection. Range of estimated probability of 60-day survival was 95-16% at cumulative risk score 0-13. This simplified score is practical, and may help clinicians prioritize patients requiring more intensive care.

BackgroundEach year millions of travelers visit Southeast Asia where rabies is still prevalent. This study aimed to assess the risk of rabies exposure, i.e., by being bitten or licked by an animal, among travelers in Southeast Asia. The secondary objective was to assess their attitudes and practices related to rabies.Methodology/Principal FindingsForeign travelers departing to the destination outside Southeast Asia were invited to fill out the study questionnaire in the departure hall of Bangkok International Airport. They were asked about their demographic profile, travel characteristics, pre-travel health preparations, their possible exposure and their practices related to rabies during this trip. From June 2010 to February 2011, 7,681 completed questionnaires were collected. Sixty-two percent of the travelers were male, and the median age was 32 years. 34.0% of the participants were from Western/Central Europe, while 32.1% were from East Asia. Up to 59.3% had sought health information before this trip. Travel clinics were the source of information for 23.6% of travelers. Overall, only 11.6% of the participants had completed their rabies pre-exposure prophylaxis, and 15.3% had received only 1–2 shots, while 73.1% had not been vaccinated at all. In this study, the risk of being bitten was 1.11 per 100 travelers per month and the risk of being licked was 3.12 per 100 travelers per month. Among those who were bitten, only 37.1% went to the hospital to get post exposure treatment. Travelers with East Asian nationalities and longer duration of stay were significantly related to higher risk of animal exposure. Reason for travel was not related to the risk of animal exposure.ConclusionsTravelers were at risk of being exposed to potentially rabid animals while traveling in Southeast Asia. Many were inadequately informed and unprepared for this life-threatening risk. Rabies prevention advice should be included in every pre-travel visit.

Since rabies is a preventable disease as long as one has the appropriate knowledge, attitude, and practice, it is essential to promote prevention activities for the Japanese population in Thailand to avert serious consequences of this disease.

Background:The role of hepatitis B surface antigen (HBsAg) levels in predicting the risk of developing hepatocellular carcinoma (HCC) has remained unclear. The aim of this study was to obtain the most up-to-date estimated measure of the association between HBsAg levels and the development of HCC in patients. Methods:We performed a systematic review by searching for relevant studies on PubMed, Scopus, ProQuest and the Cochrane Central Register of Controlled Trials from January 2002 to November 2017. We presented the effects of HBsAg levels at each cut-off value as the odds ratios (ORs) at 95% confidence interval (CI). We also investigated HCC and its potential risk factors including HBeAg, and HBV DNA. We registered our protocol with the International Prospective Register of Systematic Reviews (PROSPERO) with the registration number CRD42018081138. Results:We selected 10 studies representing 12 541 cases. At the 100 IU/ml cut-off, the OR for HCC at the high HBsAg level versus the low level was 4.99 (95% CI, 3.01–8.29) with high inconsistency (I2=79%). At the 1,000 IU/ml threshold, the pooled OR for HCC at the high HBsAg versus the low level was 2.46 (95% CI, 2.15–2.83) with low variance. We also found correlations between the risk of HCC and male gender (OR=2.12), hepatitis B e-antigen positivity (OR=2.99), or hepatitis B (HBV) viral load ≥ 2,000 IU/ml (OR=4.37). Conclusion:Our study revealed that HBsAg levels ≥ 100 IU/ml, and notably >1,000 IU/ml, are associated with an increased risk of HCC development.