Seroprevalence of dengue, Japanese encephalitis and Zika among long-term expatriates in Thailand

BACKGROUND

Travel to Southeast Asia increases the likelihood of acquiring mosquito-borne Flavivirus infections such as dengue (DENV), Japanese encephalitis (JEV) and Zika viruses (ZIKV). Expatriates are long-term travellers who have a higher risk of mosquito-borne illness at their destination country. The purpose of this study was to evaluate the seroprevalence of DENV, JEV and ZIKV infections and the determinants contributing to seropositivity among expatriates living in Thailand.

METHODS

A cross-sectional study was performed from December 2017 to February 2020. Expatriates from non-Flavivirus endemic countries were recruited. 5 mL of blood was collected for DENV 1-4, JEV and ZIKV antibody testing by plaque reduction neutralization test (PRNT50). Individuals with vaccination histories or diagnoses for dengue, Japanese encephalitis, yellow fever and tick-borne encephalitis were excluded.

RESULTS

Among 254 participants, most participants (83.1%) were male, the mean age was 65 years and the median duration of stay in Thailand was 6 years. Seroprevalence rate of any Flavivirus, non-specific DENV, DENV1-4, JEV and ZIKV were 34.3, 30.7, 20.5, 18.1, 18.9, 10.6, 4.7 and 2.8%, respectively. The presence of neutralizing antibodies against DENV1-4 positively correlates with the duration of stay in Thailand. DENV seropositivity was associated with living in urban areas (aOR 2.75, 95% CI 1.36-5.57). Expatriates were unlikely to have detectable anti-JEV antibodies regardless of time spent in a JEV-endemic area. No risk factors were identified that were significantly associated with JEV or ZIKV seropositivity. Only 48.4% received pre-travel counselling services, while only 18.9% visited a travel medicine specialist.

CONCLUSIONS

A high proportion (34.3%) of long-term expatriates living in Thailand were seropositive for flavivirus, mainly from dengue (30.7%). To minimize risk, travel medicine practitioners should provide adequate pre-travel health risk information on mosquito-borne flavivirus infection and offer advice on mosquito bite prevention strategies. Dengue vaccine might be considered in high-risk travellers such as long-term expatriate.

Incidence and spectrum of health problems among travellers to Myanmar

BACKGROUND

The number of international travellers visiting Myanmar increases each year. However, information about pre-travel preparation and incidence of health problems among these travellers is limited.

METHODS

This cross-sectional study was conducted at three international airports in Thailand. Travellers returning from Myanmar completed questionnaires querying demographic profile, pre-travel health preparations and health problems during their stay in Myanmar.

RESULTS

From March 2015 to May 2017, we collected and analysed questionnaires completed by 397 Thai and 467 non-Thai travellers (total: 50.1% men, median age 37 years). Non-Thai travellers were from Europe (59%), Northern America (21.4%), Asia (16.5%) and Australia or New Zealand (3.0%). Approximately 74% of non-Thais sought pre-travel health information; only 36% of Thais did so. Tourism was the main purpose for travel among both Thais (58.4%) and non-Thais (85.2%). Non-Thais were more likely than Thais to travel as backpackers and perform outdoor activities such as trekking, cycling or swimming. The average length of stay in Myanmar among non-Thais was significantly longer than that of Thais (26.58 days vs 7.08 days, P < 0.001). Health problems were reported by 22.9% of non-Thais; the most common was diarrhoea (21.0%) followed by upper respiratory tract symptoms (9.2%), fever (3.4%) and skin problems (3.0%). Only 12.6% of Thais reported health problems, the most common being upper respiratory tract symptoms (7.6%), followed by diarrhoea (3.1%), fever (2.8%) and skin problems (2.0%). Most health problems were mild and self-limited in both groups. Only one Thai and eight non-Thai travellers required a doctor's visit during their trip to Myanmar, and two non-Thais required hospitalization.

CONCLUSIONS

Health problems are not very common among travellers to Myanmar. Overall, health problems were reported among 18.2% of travellers in our study. Most problems were mild, with spontaneous recovery. Only two foreign travellers required hospitalization.

Health problems among Thai tourists returning from India

BACKGROUND

The number of Thai tourists visiting India is increasing each year. Most studies investigating health problems among international travellers to India have focused on travellers from Europe or North America, and the applicability of these studies to Asian travellers is unknown.

METHODS

This cross-sectional study used data collected from Thai tourists who had recently completed a trip to India. A questionnaire on demographic data, travel characteristics, pre-travel health preparation, and health problems during the trip to India was administered. All participants were also invited to answer a follow-up questionnaire 15 days after their arrival.

RESULTS

The study included 1,304 Thai tourists returning from India between October 2014 and March 2015. Sixty-two percent were female. Overall median age was 49 years, and the median length of stay was 10.6 days. Most were package tourists, and 52% (675) reported health problems during their trip. Common health problems were cough, runny nose, and sore throat (31.1%), followed by musculoskeletal problems (21.7%), fever (12.7%), diarrhea (9.8%) and skin problems (6.6%). Other reported problems were related to the eyes/ears (2.1%), animal exposure (1.9%) and accidents (0.8%). We found that several factors may be associated with the incidence of health problems among these tourists, including travelling style and travel health preparation. In the follow-up questionnaire, 16.8% of the participants reported new or additional symptoms that developed after their return to Thailand. Respiratory symptoms were still the most common health problems during this 15-day period.

CONCLUSIONS

Over half (52%) of Thai tourists experienced health problems during their trip to India. The most common health problem was not travellers' diarrhoea, as would be expected from published studies. Rather, respiratory and musculoskeletal problems were common symptoms. This information will be useful in pre-travel assessment and care. Our findings may indicate that health risks among travellers vary by nationality.

Health problems and health care seeking behavior among adult backpackers while traveling in Thailand

Background

Health problems among travelers in developing countries are not uncommon. Little is known about the occurrence of health problems and their impacts among backpackers in Thailand. The objective of this study was to assess the health problems and the health seeking behavior among adult backpackers who visited Thailand.

Methods

This was a cross-sectional questionnaire-based study. Data were collected from foreign adult backpackers in Khao San Road, Bangkok. They were asked about their demographic data, health problems (if any), and health-care seeking behavior if they became ill.

Results

During May to July 2015, 420 backpackers were enrolled in this study. Of these, 51.4 % were male with a median age of 26.4 years. Up to 66.9 % were of European origin, while 17.4 % were North American. Fifty-eight percent sought pre-travel consultation before traveling. In this study, 10.2 % (43/420) of the participants reported at least health problem during travel. Most of them (79.1 %) had single episode of illness. Of this, diarrhea was the most common health problem (30.4 %), followed by abdominal pain (14.3 %), skin problems (8.9 %), respiratory problems (8.9 %), accident-associated injury (7.1 %), and febrile illness (7.1 %). One third of backpackers with health problems spontaneously recovered without any treatment, while nearly a quarter treated themselves with standby medication, and one in five had to buy over the counter medication. Just over 9 % of backpackers with a health problem sought medical care at a hospital. Among travellers with health problems, 72.1 % reported that their health problems did not significantly impact to their trip, while 23.3 % had to delay or postpone their trip for at least 1 day, and 4.7 % had to cancel some trip and/or activity. Longer duration of stay was significantly related to higher occurrence of health problems while traveling.

Conclusions

Approximately 10 % of adult backpackers experienced some health problems during their trip in Thailand. Although most of their health problems were mild, up to 22 % of backpackers with health problems need to seek medical care either in a clinic or in a hospital.

Traveler's Diarrhea in Foreign Travelers in Southeast Asia: A Cross-Sectional Survey Study in Bangkok, Thailand

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 self-administered 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.

Awareness, practices, and health problems of backpackers traveling during flooding in Thailand during 2011

During late 2011, Thailand experienced its worst flooding in 50 years with over 4.6 million people directly affected. During the flooding we conducted a cross sectional survey of backpackers in the Khao San Road area of Bangkok to determine awareness, practices, and their incidence of health problems during the flooding. A total of 422 subjects completed questionnaires which were analyzed. Seventy percent were European and 12.3% were North American. The overall median age was 27 years and the median stay in Thailand was 22 days. Most of the backpackers were aware of the flooding in Thailand; some had sought travel health information prior to their trip from various sources including the internet, their family physician or a travel clinic. However, even in travel clinics specific health advice related to flooding, such as leptospirosis risk/prevention, was rarely given to travelers. Fifteen point four percent of subjects (65/422) had come into contact with floodwater; 30.8% of those (20/65) washed their feet/legs afterward. Our findings indicate most backpackers were inadequately aware of potential health hazards, such as leptospirosis, during the floods.