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.

Risk perception of health problems among travelers visiting a travel clinic in Bangkok, Thailand

BACKGROUND

Effective pre-travel consultations cannot be achieved only through individual risk assessment and advice on vaccinations and chemoprophylaxis. Travelers' perceptions of the risk of health problems represent another key factor in successful risk communication and co-operation with pre-travel advice. The objective of this study was to determine perception of travel-related health risks among Thais and westerners visiting the Thai Travel Clinic for consultation before visiting developing countries.

METHODS

A novel pictorial scale questionnaire-based study was conducted with both Thai and western travelers who visited the Thai Travel Clinic for pre-travel consultation. All participants were approached before and after completing the consultation, and were asked about their demographic data and perceptions of travel-related health risk. The perceptions of risk before and after consultation were compared using the McNemar test, and were also compared with the actual estimated risk.

RESULTS

During May to November 2019, 594 travelers (330 Thais and 264 Westerners) were enrolled and completed the pictorial scale questionnaires. Most Thai travelers visited Africa/South America (63%), and 20% had previously received counseling. Westerners were mostly backpackers (37.5%), traveling for > 30 days (71.6%), while 43.6% had previously received counseling. Overall, the westerners (n = 264) changed their risk perceptions slightly after counseling in contrast with the Thais. The change in perception of most health problems was observed statistically significant (p-value < 0.05) after receiving pre-travel consultation among both groups of travelers. Risk perception among western travelers after consultation compared with estimated actual risk showed accurate risk perception toward most of health problems especially in travelers who had previously received counseling in ones' home countries.

CONCLUSIONS

Risk perception of health problems plays an important role in successful risk communication and their response to pre-travel advices. Differences in risk perceptions were evident between the two groups. Therefore, this highlight the importance of obtaining pre-travel advice in one's home country before travelling. Raised awareness of the risks should be emphasized during consultations for underestimated health risks, especially for rabid animal exposure and sexually transmitted diseases.

Case Report: A Cluster of Plasmodium falciparum Malaria Cases among Thai Workers in Gembu, Nigeria

Although falciparum malaria is an important risk among travelers to sub-Saharan Africa, many travelers remain unaware of this risk. In October 2015, we found a cluster of imported Plasmodium falciparum malaria cases among Thai gem mine workers in Nigeria; none had received malaria chemoprophylaxis or information regarding malaria risk. The index case developed fever and visited our hospital on arrival day in Thailand after his 3-week stay in Nigeria. Plasmodium falciparum was found in his blood. He recovered completely 3 days post-admission. After we requested he contact his colleagues in Nigeria regarding malaria risk, we found that three of his five colleagues currently had fever, were diagnosed with malaria, and were being treated in a local hospital. Two were successfully treated in Nigeria. Although their blood films were negative for malaria, we could confirm that they recently had malaria because the polymerase chain reaction (PCR) was still positive for P. falciparum. Tragically, the last febrile case died in Nigeria 6 days post-admission, after developing jaundice and alteration of consciousness. The two colleagues without fever symptoms were also tested by PCR, which was negative for malaria. In conclusion, we found that four of six workers had malaria in this cluster, which was equal to 66.7% attack rate. There is an urgent need to raise awareness of malaria among workers in highly endemic areas. Clinical practice for travelers who are ill on their return should not only focus on individual cases but also consider potential disease clusters.

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.

Outcomes of hospitalized diabetic foot patients in a multi-disciplinary team setting: Thailand's experience

Aims

The aims of this study were to evaluate the outcomes of treatment among hospitalized patients with diabetic foot ulcers, the risk factors for non-healing ulcers, and the rate of major amputation among Thai patients.

Methods

A retrospective study of hospitalized diabetic foot patients treated at Theptarin Hospital during the period of 2009–2013. The complete healing rate was assessed at 12 months after admission.

Results

During the study period, 232 patients (123 males and 109 females) with 262 admissions were included (mean age 65.6 ± 11.9 years, mean duration of diabetes 17.2 ± 9.9 years) with a mean follow-up of 17.5 ± 16.7 months. Major amputations were performed in 4.2% of the patients and peripheral vascular disease (PVD) was a predictive factor (OR 5.25; 95% CI [1.43–19.29]; p-value 0.006). Complete healing (including minor amputations) was achieved in 82.1% of the admissions. Only DFU of the heel was a statistically significant (OR 3.34; 95% CI [1.11–10.24]; p-value 0.041) predictor of non-healing ulcers. Three patients (1.1%) died during hospitalization.

Conclusions

Management of diabetes-related foot ulcers with a multidisciplinary approach resulted in a limb salvage rate that was greater than 90% and a complete healing rate that was greater than 80%. Successful management of diabetic foot ulcers might be possible in Thailand utilizing this approach.