Dengue fever, caused by the mosquito-borne dengue virus (DENV), has been endemic in Myanmar since 1970 and it has become a significant public health burden. It is crucial that circulating DENV strains are identified and monitored, and that their transmission efficiency and association with disease severity is understood. In this study, we analyzed DENV-1, DENV-2, DENV-3, and DENV-4 serotypes in 1235 serum samples collected in Myanmar between 2017 and 2019. Whole-genome sequencing of DENV-1–4 demonstrated that most DENV-1–4 strains had been circulating in Myanmar for several years. We also identified the emergence of DENV-3 genotype-I in 2017 samples, which persisted through 2018 and 2019. The emergence of the strain coincided with a period of increased DENV-3 cases and marked changes in the serotype dynamics. Nevertheless, we detected no significant differences between serum viral loads, disease severity, and infection status of individuals infected with different DENV serotypes during the 3-year study. Our results not only identify the spread of a new DENV-3 genotype into Yangon, Myanmar, but also support the importance of DENV evolution in changing the epidemic dynamics in endemic regions.

The dengue virus (DENV) has been endemic in Myanmar since 1970, causing outbreaks every 2–3 years. DENV infection symptoms range from mild fever to lethal hemorrhage. Clinical biomarkers must be identified to facilitate patient risk stratification in the early stages of infection. We analyzed 45 cytokines and other factors in serum samples from the acute phase of DENV infection (within 3–5 days of symptom onset) from 167 patients in Yangon, Myanmar, between 2017 and 2019. All of the patients tested positive for serum DENV nonstructural protein 1 antigen (NS1 Ag); 78.4% and 62.9% were positive for immunoglobulin M (IgM) and G (IgG), respectively; and 18.0%, 19.8%, and 11.9% tested positive for serotypes 1, 3, and 4, respectively. Although the DENV-4 viral load was significantly higher than those of DENV-1 or DENV-3, disease severity was not associated with viral load or serotype. Significant correlations were identified between disease severity and CCL5, SCF, PDGF-BB, IL-10, and TNF-α levels; between NS1 Ag and SCF, CCL5, IFN-α, IL-1α, and IL-22 levels; between thrombocytopenia and IL-2, TNF-α, VEGF-D, and IL-6 levels; and between primary or secondary infection and IL-2, IL-6, IL-31, IL-12p70, and MIP-1β levels. These circulating factors may represent leading signatures in acute DENV infections, reflecting the clinical outcomes in the dengue endemic region, Myanmar.

Rotavirus vaccine was planned to be introduced in the National Immunization Program of Myanmar in 2020. Reported potential association of a small increased risk of intussusception after rotavirus vaccination in some countries is a major safety concern and it is mandatory to collect baseline information before vaccine introduction. Retrospective study reviewed medical records of intussusception cases for past 3 years (2015–2018) and prospective, active study was conducted from August 2018 to January 2020 at three tertiary children hospitals where pediatric surgical facility is present. Brighton Level 1 Criteria was used for confirmation of intussusception among children 3days after onset) is significantly associated with requirement of surgery (61/85, 71.8%), which in turn is significantly associated with longer hospital stay (296/452, 65.5%) (p < 0.05). Intussusception occurrence is most frequent between 5-7 months age group which is old enough to be vaccinated under the schedule that has now been introduced in Myanmar. More than half of the cases were treated by surgery and late arrival to hospital enhances requirement of surgery and poor outcome. Findings of this baseline surveillance provide important facts for public health officials in balancing risks and benefits of rotavirus vaccine introduction, defining targeted age and dosage scheduling and facilitate monitoring system in post-vaccination.

During the 2015 dengue season in Myanmar, there was an unusual increase in occurrence of adult dengue cases. To identify circulating serotypes and clinical profiles of adult dengue during the outbreak, blood samples were collected from clinically suspected dengue patients admitted to Yangon General Hospital during July to September 2015. Among 75 samples tested for NS1Ag and immunoglobulins IgG/IgM, 33 (44.0%) were serologically confirmed, including 11 (33.3%) primary and 22 (66.7%) secondary infection. The mean age was 20.8 years (range 13-49 years). There were 77.3% (17/22) of secondary infection and 45.5% (5/11) of primary infection developed into severe types of dengue infection. Bleeding manifestations occurred in 13 (39.4%) patients, with gastrointestinal bleeding as the most common form. Out of the 33 samples serologically confirmed, dengue virus was detected in six (18.2%) and all were serotype 1 which has been the predominant serotype in Myanmar since 2009. These findings contributed information on the recent adult dengue outbreak and aided to bridge the knowledge gap concerning adult dengue in Myanmar. Further molecular research should be conducted on serotype negative samples.