PREVALENCE AND ASSOCIATED RISK FACTORS OF INTESTINAL PARASITES IN HUMANS AND DOMESTIC ANIMALS ACROSS BORDERS OF THAILAND AND LAO PDR: FOCUS ON HOOKWORM AND THREADWORM.

Hookworm and threadworm infections are major public health problems in developing countries. A cross sectional study comprising 843 participants (346 males and 497 females) was conducted in three populations: i) Thai residents (TR) of Ubon Ratchathani Province, Thailand; ii) Laotian immigrant workers (LI) in the same province; and iii) Laotian residents (LR) in Champasak Province, Lao PDR. Participants were interviewed based on a structured questionnaire regarding their health status. Stool samples from participants and 300 samples from domestic animals (277 dogs and 23 cats) living in the participants households were collected and examined for parasitic infection using a formalin-ether concentration and a Harada-Mori filter paper culture techniques. Approximately one-third of TR and LI populations and domestic animals in Thailand were positive for parasitic infections, while almost half of LR population and domestic animals were positive. We confirmed by PCR and DNA sequencing a case of Ancylostoma ceylanicum infection in a Thai man. We also observed infections of other parasites, such as Taenia spp and Opisthorchis viverrini. Multivariate analysis indicated that risk factors for hookworm infection were population group and walking barefoot. Factors associated with threadworm infection were population group, adult male, lack of previous antiparasitic treatment and of knowledge of parasitic infection, and failure to wash hands after contact with domestic animals. Our results highlight the high prevalence of both hookworm and threadworm infections especially among LI population and domestic animals in both countries. Our findings emphasize the need for public health intervention to control the spread of parasitic infections in Thailand and Lao PDR.

Co-circulation of the dengue with chikungunya virus during the 2013 outbreak in the southern part of Lao PDR.

BACKGROUND: During the 2013 outbreak, 4638 infection cases and 32 deaths have been recorded in the southern part of Laos. In recent years, the chikungunya virus (CHIKV) emerged in the part of the country bordering Cambodia. Dengue virus (DENV) and CHIKV are transmitted by common mosquito vectors. Both diseases have similar clinical presentations; therefore, CHIKV infections might go undiagnosed in DENV-endemic areas. Thus, rapid detection and accurate diagnosis are crucial for differentiating between the two viruses (DENV and CHIKV). In this study, we demonstrated that CHIKV and two serotypes of DENV are circulating in Laos. In addition, we encountered patients that had been concurrently infected with multiple DENV serotypes or DENV and CHIKV. METHODS: Plasma samples were collected from 40 patients with suspected DENV infections during an outbreak between July and August 2013. The reverse transcription polymerase chain reaction was performed to detect the four DENV serotypes and CHIKV using specific primers. Specifically, the complete envelope gene sequences of the viruses were sequenced and subjected to phylogenetic analysis. RESULTS: Forty acute-phase plasma samples from patients with suspected dengue infections were tested for the presence of DENV viral RNA using molecular methods. Among the 40 samples, 14 samples were positive for DENV, 2 samples were positive for both viruses (DENV-2 and DENV-3), whereas DENV-1 and DENV-4 were not detected during the study period. We also encountered 10 samples that were positive for CHIKV. Of the 10 CHIKV-positive samples, 3 samples were co-infected by DENV-2, and 2 samples were co-infected by DENV-3. Phylogenetic analysis revealed that the 2013 dengue outbreak in Laos involved DENV-2 genotype Asian I and DENV-3 genotype II. Moreover, the Laotian CHIKV strains grouped together with those isolated during outbreaks on the Indian Ocean Islands within the East Central South African genotype. CONCLUSIONS: These findings revealed that two serotypes (DENV-2 and DENV-3) and CHIKV were detected. Furthermore, infection of multiple DENV serotypes and CHIKV was also observed in the 2013 dengue outbreak. This is the first documented evidence of co-infection with CHIKV and one of two DENV serotypes.