Dengue virus transmission risk in blood donation: Evidence from Thailand.

Individuals infected with dengue virus (DENV) often show no symptoms, which raises the risk of DENV transfusion transmission (TT-DENV) in areas where the virus is prevalent. This study aimed to determine the evidence of DENV infection in blood donors from different geographic regions of Thailand. A cross-sectional study was conducted on blood donor samples collected from the Thai Red Cross National Blood Center and four regional blood centers between March and September 2020. Screening for DENV nonstructural protein 1 (NS1), anti-DENV immunoglobulin G (IgG), and IgM antibodies was performed on residual blood from 1053 donors using enzyme-linked immunosorbent assay kits. Positive NS1 and IgM samples indicating acute infection were verified using four different techniques, including quantitative real-time (q) RT-PCR, nested PCR, virus isolation in C6/36 cells, and mosquito amplification. DENV IgG seropositivity was identified in 89% (938/1053) of blood donors. Additionally, 0.4% (4/1053) and 2.1% (22/1053) of Thai blood donors tested positive for NS1 and IgM, respectively. The presence of asymptomatic dengue virus infection in healthy blood donors suggests a potential risk of transmission through blood transfusion, posing a concern for blood safety.

Persistence of Wild-Type Japanese Encephalitis Virus Strains Cross-Neutralization 5 Years After JE-CV Immunization.

BACKGROUND: The live-attenuated Japanese encephalitis (JE) vaccine (JE-CV; IMOJEV) induces a protective response in children. A shift in circulating JE virus strains suggests that a genotype shift phenomenon may occur throughout Southeast Asia. We assessed the neutralization of wild-type (WT) JE virus isolates at distal time points after vaccination. METHODS: We analyzed serum samples from a subset of 47 children who had received a JE-CV booster after an inactivated JE vaccine primary immunization. We measured antibody titers (50% plaque reduction neutralization test) using a panel of WT JE strains at baseline, then after the booster at 28 days and 6 months in all subjects present at the time points and in a subset at year 5. Three additional recent isolates were tested at year 5. RESULTS: Of 47 subjects, 43 (91.5%) subjects had JE neutralizing antibody titers ≥10 (reciprocal serum dilution) against the homologous strain before JE-CV boost; all were seroprotected up to year 5 after the JE-CV boost. Baseline WT seroprotection ranged between 78.7% and 87.2%; all subjects were seroprotected against the 4 WT strains at 28 days and 6 months; year 5 seroprotection ranged between 95.7% and 97.9%. Similar rates of protection against 3 additional WT isolates were observed at year 5. CONCLUSIONS: The long-term immune responses induced after a JE-CV booster dose in toddlers were able to neutralize WT viruses from various genotypes circulating in Southeast Asia and India. CLINICAL TRIALS REGISTRATION: NCT00621764.

Dengue hemorrhagic fever and the kidney.

Dengue virus infection (DVI)/dengue hemorrhagic fever (DHF) is a common febrile illness with a variety of severities. The mortality rate is high in dengue shock syndrome (DSS), caused by circulatory failure due to plasma leakage resulting in multi-organ failure. However, acute kidney injury (AKI) is rarely reported. In areas of endemic DVI, the prevalence of AKI due to DVI has been reported to be as high as 6.0 % in children with AKI, and 0.9 % in children with DVI who were admitted to a hospital. The mechanism of AKI in DVI is not clear. It may result from (a) direct injury as in other infectious diseases, (b) an indirect mechanism such as via the immune system, since DHF is an immunological disease, or (c) hypotensive DSS, leading in turn to reduced renal blood supply and renal failure. The mortality rates of DF/DHF, DSS and DHF/DSS-related AKI are <1 %, 12-44 %, and >60 %, respectively. Kidney involvement is not actually that rare, but is under-recognized and often only reported when microscopic hematuria, proteinuria, electrolyte imbalance, or even AKI is found. The prevalence of proteinuria and hematuria has been reported as high as 70-80 % in DVI. A correct diagnosis depends on basic investigations of kidney function such as urinalysis, serum creatinine and electrolytes. Although DVI-related renal involvement is treated supportively, it is still important to make an early diagnosis to prevent AKI and its complications, and if AKI does occur, dialysis may be required. Fortunately, in patients who recover, kidney function usually completely recovers as well.

Listeriosis: Is It a Rare Disease in Thailand?

The prevalence of Listeria monocytogenes infection has been characterized as rare in Thailand. Within one month, 3 cases of listeriosis were seen at Vachira Phuket Hospital in Phuket, Thailand. Two cases were neonates with septicemia, of which one made an uneventful recovery and the other expired. The third case was an eleven-year-old boy with meningitis who also succumbed to his illness. All isolated L. monocytogenes were sensitive to ampicillin. An outbreak investigation revealed no L. monocytogenes contamination in tested food sources in Phuket.

Risk Factors for Severe Enteroviral Infections in Children.

OBJECTIVE: To study the risk factors associated with severe enterovirus infection among hospitalized pediatric patients with hand, foot, and mouth disease (HFMD) at King Narai Hospital, Lopburi, Thailand. MATERIAL AND METHOD: We reviewed all of the suspected enterovirus infection cases aged less than 15 years admitted to King Narai Hospital between 2011 and 2013. Cases were classified into mild and severe enterovirus infection. Risk factors for severe enterovirus infection were analyzed using univariate and multivariate logistic regressions. RESULTS: During the study period, 156 patients met the case definition for further analysis. Of those 156 patients, 131 (84.0%) were classifed as mild cases, and 25 (16.0%) as severe cases with five (3.2%) deaths. The most common manifestations among the severe cases were seizures, pneumonia, meningoencephalitis, meningitis, and hyperglycemia. Of the 31 identifiable cases, 12 were caused by enterovirus 71 (EV71), 12 by coxsackievirus A16 (CA16), four by both, and three by other enterovirus. The clinical manifestations that were significantly related to severe enterovirus infection in univariate analysis were age of less than one year, highest body temperature greater than 39.0 degrees C, duration of fever greater than three days, absence of skin lesions, diarrhea, dyspnea, and hyperglycemia. The clinical manifestations that were significantly related to severe enterovirus infection by both univariate and multivariate analyses were absence of oral lesions, seizures, and drowsiness/lethargy. CONCLUSION: The major pathogens of severe disease were EV71 and CA16. High-risk factors significantly related to severe enterovirus infection in both univariate and multivariate analyses were absence of oral lesions, seizures, and drowsiness/lethargy. Early recognition of children at risk and prompt treatment is important to mitigate the deterioration of patients with enterovirus infection.

Seroepidemiology of Dengue Virus Infection in HIV-Infected Children in Comparison to Healthy Children.

BACKGROUND: Dengue infection is the most common arboviral infection in the world while the HIV/AIDS epidemic remains a global concern. The pathogenesis of both diseases is rather on the contrary and it is generally observed that dengue diseases are uncommon in children with AIDS. OBJECTIVE: To study the seroprevalence of dengue virus infection in HIV-infected children compared to healthy children. MATERIAL AND METHOD: A cross-sectional seroprevalence of dengue virus was conducted at King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Eighty-six HIV-infected children aged less than 15 years and one hundred age-matched healthy children were enrolled. HIV-infected children were classified in categories by CDC 1994 criteria. Neutralizing antibodies to all four dengue serotypes (DEN1, DEN2, DEN3, and DEN4) were measured by plaque reduction neutralization test (PRNT). RESULTS: Fifty out of 86 (58%) HIV-infected children and 65 out of 100 (65%) healthy, HIV-negative children had positive neutralizing antibody against dengue virus by PRNT There were no significant differences between these two groups (p > 0.05). Most children had neutralizing antibody against DEN2. In HIV-infected children, a monotypic PRNT50 pattern was found in 26 children (30%) and multitypic pattern was found in 24 children (28%). Most children had neutralizing antibody against DEN2. There were no significant differences in dengue seroprevalence between these two groups. CONCLUSION: HIV-infected children and healthy children had no different seroepidemiology of dengue virus infection.

Clinical efficacy and safety of a novel tetravalent dengue vaccine in healthy children in Asia: a phase 3, randomised, observer-masked, placebo-controlled trial.

BACKGROUND: An estimated 100 million people have symptomatic dengue infection every year. This is the first report of a phase 3 vaccine efficacy trial of a candidate dengue vaccine. We aimed to assess the efficacy of the CYD dengue vaccine against symptomatic, virologically confirmed dengue in children. METHODS: We did an observer-masked, randomised controlled, multicentre, phase 3 trial in five countries in the Asia-Pacific region. Between June 3, and Dec 1, 2011, healthy children aged 2-14 years were randomly assigned (2:1), by computer-generated permuted blocks of six with an interactive voice or web response system, to receive three injections of a recombinant, live, attenuated, tetravalent dengue vaccine (CYD-TDV), or placebo, at months 0, 6, and 12. Randomisation was stratified by age and site. Participants were followed up until month 25. Trial staff responsible for the preparation and administration of injections were unmasked to group allocation, but were not included in the follow-up of the participants; allocation was concealed from the study sponsor, investigators, and parents and guardians. Our primary objective was to assess protective efficacy against symptomatic, virologically confirmed dengue, irrespective of disease severity or serotype, that took place more than 28 days after the third injection. The primary endpoint was for the lower bound of the 95% CI of vaccine efficacy to be greater than 25%. Analysis was by intention to treat and per procotol. This trial is registered with ClinicalTrials.gov, number NCT01373281. FINDINGS: We randomly assigned 10,275 children to receive either vaccine (n=6851) or placebo (n=3424), of whom 6710 (98%) and 3350 (98%), respectively, were included in the primary analysis. 250 cases of virologically confirmed dengue took place more than 28 days after the third injection (117 [47%] in the vaccine group and 133 [53%] in the control group). The primary endpoint was achieved with 56·5% (95% CI 43·8-66·4) efficacy. We recorded 647 serious adverse events (402 [62%] in the vaccine group and 245 [38%] in the control group). 54 (1%) children in the vaccine group and 33 (1%) of those in the control group had serious adverse events that happened within 28 days of vaccination. Serious adverse events were consistent with medical disorders in this age group and were mainly infections and injuries. INTERPRETATION: Our findings show that dengue vaccine is efficacious when given as three injections at months 0, 6, and 12 to children aged 2-14 years in endemic areas in Asia, and has a good safety profile. Vaccination could reduce the incidence of symptomatic infection and hospital admission and has the potential to provide an important public health benefit. FUNDING: Sanofi Pasteur.

DENGUE: GLOBAL THREAT.

Dengue is a mosquito-borne viral disease, which is currently an expanding global problem. Four closely related dengue serotypes cause the disease, which ranges from asymptomatic infection to undifferentiated fever, dengue fever (DF), and dengue hemorrhagic fever (DHF). DHF is characterized by fever, bleeding diathesis, and a tendency to develop a potentially fatal shock syndrome. Dengue infection with organ impairment mainly involves the central nervous system and the liver. Consistent hematological findings include vasculopathy, coagulopathy, and thrombocytopenia. Laboratory diagnosis includes virus isolation, serology, and detection of dengue ribonucleic acid. Successful treatment, which is mainly supportive, depends on early recognition of the disease and careful monitoring for shock. A severity-based revised dengue classification for medical interventions has been developed and validated in many countries. There is no specific dengue treatment, and prevention is currently limited to vector control measures. The world's first, large-scale dengue vaccine efficacy study demonstrated its efficacy and a reduction of dengue disease severity with a good safety profile in a study of more than 30,000 volunteers from Asia and Latin America.

ASSOCIATION BETWEEN MANNOSE-BINDING LECTIN GENE POLYMORPHISMS AND SUSCEPTIBILITY TO DENGUE VIRUS INFECTION: A PRELIMINARY REPORT.

Mannose-binding lectin (MBL) can bind with a wide range of pathogens and can activate through lectin pathway or enhances opsonophagocytosis. MBL is encoded by the MBL2 gene and single-nucleotide polymorphisms (SNPs) in the promoter and exon have functional effects on serum levels of MBL. MBL deficiency has been shown to predispose to infectious diseases. We assess whether or not, the variant MBL alleles are associated with susceptibility to dengue infection. Patients with confirmed dengue infection who were admitted to King Chulalongkorn Memorial Hospital during a calendar year were studied. Controls were patients without dengue infection. Deoxyribonucleic acid (DNA) was extracted from 50 µl of peripheral blood mononuclear cell (PBMC) using the DNA Blood Mini Kit. The SNPs in the promoter (-221 X/Y) and exon 1 (codon 54 A/B) of MBL2 gene were genotyped by using 2 separate cycling reactions of the TaqMan allele discrimination system. Serum levels of MBL were determined by double-antibody sandwich ELISA. Chi-square was used for statistical analysis. Serum MBL levels and genotypes were determined in 110 dengue patients (mean age 18.1 years; 62 males and 48 females) and 42 controls (mean age 25.8 years; males: females = 1:1). Our study showed that YB haplotype is associated with low serum levels of MBL. There was no association between MBL2 gene polymorphisms and susceptibility to dengue infection. The higher frequency of YB in dengue patients than in controls suggesting the likelihood of an association. Further studies are warranted.

DENGUE VIRUS VIRULENCE AND DISEASES SEVERITY.

The dengue virus is the causative agent of a wide spectrum of clinical manifestations, ranging from mild acute febrile illness to classical dengue fever, dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS). DHF and DSS are the potentially fatal forms of dengue virus infection, which has become an intractable public health problem in many countries. The pathogeneses of DHF/ DSS are not clearly understood. One hypothesis concerning virus virulence and the immune enhancement hypothesis has been debated. Although dengue disease severity has been associated with evidence of genetic differences in dengue strains, virus virulence has been difficult to measure because of the lack of in vivo and in vitro models of the disease.

DENGUE WITH CENTRAL NERVOUS SYSTEM INVOLVEMENT.

Dengue has spread to new geographic areas affecting both children and adults, and it has become a global threat. Dengue with central nervous system involvement includes febrile seizures, encephalopathy, encephalitis, aseptic meningitis, intracranial hemorrhages, intracranial thrombosis, subdural effusions, mononeuropathies, polyneuropathies, Guillain-Barré syndrome, and transverse myelitis. These manifestations may be associated with co-infections, co-morbidities, or complications of prolonged shock. It is important to consider dengue as a cause for the above neurological presentations, particularly in endemic territories for dengue disease.

DENGUE VACCINES.

The uniqueness of the dengue viruses (DENVs) and the spectrum of disease resulting from infection have made dengue vaccine development difficult. Several vaccine candidates are currently being evaluated in clinical studies. The candidate currently at the most advanced clinical development stage, a live-attenuated tetravalent vaccine based on the chimeric yellow fever-dengue virus (CYD-TDV), has progressed to Phase 3 efficacy studies. Several other live-attenuated vaccines, as well as subunit, DNA, and purified inactivated vaccine candidates are at earlier stages of clinical development. Additional technological approaches, such as virus-vectored and Virus-Like Particles (VLP)-based vaccines are under evaluation in preclinical studies.

HEMOSTATIC STUDIES IN DENGUE PATIENTS.

The pathogenesis of hematologic changes in dengue patients is not clearly understood. Consistent hematological findings include vasculopathy, thrombocytopenia, and coagulopathy. There are evidences suggesting that dengue virus causes pathophysiological changes that involve all of the consistent hematologic findings resulting in vasculopathy, reduction in platelet number as well as platelet dysfunction, and reduction of several coagulation factors. Laboratory evidences of disseminated intravascular coagulation (DIC) are also demonstrated in all degrees of severity in dengue patients. Only in severe dengue cases is profound DIC aggravated, leading to uncontrolled bleeding and death. A study to determine the extent of the activation of endothelial cells and the hemostatic system in correlation with clinical severity and also to detect the best prognostic factor for severe dengue showed plasma von Willebrand factor antigen (VWF:Ag) to be the best indicator of progression to severe dengue.

RISK FACTORS FOR SEVERE HAND, FOOT AND MOUTH DISEASE.

We studied risk factors associated with severe hand, foot and mouth disease (HFMD) caused by enteroviruses among patients aged less than 15 years admitted to King Narai Hospital, Lopburi, Thailand during 2011-2013. Cases were divided into either mild or severe. Severe cases were those with encephalitis, meningitis, myocarditis, pneumonia, pulmonary edema or respiratory failure. Risk factors for severe infection were evaluated using univariate and multivariate logistic regression analysis. One hundred eighteen patients met the case definition of HFMD. Of these, 95 (80.5%) were classified as mild cases, and 23 (19.5%) as severe cases; there were 5 deaths (4.2%). Of the 23 severe cases, 9 were infected with coxsackievirus A16 (CA16), 8 with enterovirus 71 (EV71) and 4 with both EV71 and CA16. The most common presentations among the severe caseswere: seizures (74%), pneumonia (39%), encephalitis (39%), and meningitis (13%). The clinical manifestations significantly related to severe HFMD on univariate analysis were highest body temperature 39.00C, duration of fever 23 days, absence of skin lesions, diarrhea, dyspnea, seizures and hyperglycemia. The clinical manifestations significantly related to severe HFMD on both univariate and multivariate analyses were age less than 1 year, absence of oral lesions and drowsiness/lethargy. Clinicians should be aware of these factors. Early recognition of severe cases is important to increase the rates of successful outcomes and reduce mortality.

Dengue: a global threat.

Dengue, a mosquito-borne viral disease, is currently an expanding global problem. The disease is caused by four closely related dengue serotypes; it ranges from asymptomatic infection to undifferentiated fever, dengue fever (DF) and dengue hemorrhagic fever (DHF). DHF is characterized by fever, bleeding diathesis and a tendency to develop apotentially fatal shock syndrome. Dengue infection with organ impairment mainly involves the central nervous system and liver. Consistent hematological findings include vasculopathy, coagulopathy and thrombocytopenia. Laboratory diagnoses include virus isolation, serology, and detection ofdengue ribonucleic acid. Successful treatment, which is mainly supportive, depends on early recognition of the disease and careful monitoring for shock. A severity-based revised dengue classification for medical interventions has been developed and validated in many countries. So far however, there has not been any specific dengue treatment; prevention is currently limited to vector control measures. The world's first, large-scale dengue vaccine, efficacy study demonstrated its efficacy and a reduction of dengue's severity in a study of more than 10,000 volunteers in Asia. Initial safety data are consistent with a good safety profile.

Proceedings of the 6th Asia Dengue Summit, June 2023.

The 6th Asia Dengue Summit (ADS) themed "Road Map to Zero Dengue Death" was held in Thailand from 15th-16th June 2023. The summit was hosted by Tropical Medicine Cluster, Chulalongkorn University, Bangkok, Thailand in conjunction with Queen Saovabha Memorial Institute, The Thai Red Cross Society; Faculty of Tropical Medicine, Mahidol University; and the Ministry of Public Health. The 6th ADS was convened by Asia Dengue Voice and Action (ADVA); Global Dengue and Aedes Transmitted Diseases Consortium (GDAC); Southeast Asian Ministers of Education Tropical Medicine and Public Health Network (SEAMEO TROPMED); Fondation Mérieux (FMx) and the International Society for Neglected Tropical Diseases (ISNTD). Dengue experts from academia and research, and representatives from the Ministries of Health, Regional and Global World Health Organization (WHO) and International Vaccine Institute (IVI) participated in the three-day summit. With more than 51 speakers and 451 delegates from over 24 countries, 10 symposiums, and 2 full days, the 6th ADS highlighted the growing threat of dengue and its antigenic evolution, flagged the urgent need to overcome vaccine hesitancy and misinformation crisis, and focused on dengue control policies, newer diagnostics, therapeutics and vaccines, travel-associated dengue, and strategies to improve community involvement.

Dengue amid COVID-19 pandemic.

The increasing in dengue cases nowadays is a global threat concern. Fifty per cent of the world's population is vulnerable to dengue infection with Asia contributing over two-thirds of the global burden. The double trouble of Coronavirus disease 2019 (COVID-19) arising from novel severe respiratory syndrome coronavirus (SARS-CoV-2) and dengue virus is a major challenge, particularly in developing countries due to overburdened public health systems and economic constraints including the ability to diagnose. The objective of this study was to analyze the prevalence of dengue in Thailand during the outbreak of COVID-19. We studied data on dengue cases reported at epidemiological information centers, the Bureau of Epidemiology, and the Ministry of Public Health, Thailand during 2019 to 2021. Patients can be observed across all age groups, particularly adolescents and adults. Dengue was seen year-round, with highest incidence in the rainy seasons between June and September. Total number of cases was markedly declined by nearly 93 percentage from 2019 to 2011. Taken together, Thailand is still at risk of spreading of dengue in the midst of COVID-19 pandemic. Continuous status updates on dengue patients in Thailand should be incorporated into global health advisory on preventive measures before travelling.

The Surveillance of Acute Encephalitis Syndrome in Thailand, 2003-2019: A Perspective for Prevention and Control.

Background: Acute encephalitis syndrome (AES) is an infection of the central nervous system with high case-fatality rates. Japanese encephalitis virus (JEV) is the most common vaccine preventable cause of AES in Asia and part of the Western Pacific. In 2003, the JE vaccine was introduced into Thailand's National Immunization Program and expanded to all provinces. This study reviews data from the national surveillance system on the incidence of AES, including Japanese encephalitis in Thailand to guide surveillance, control, and prevention strategies. Materials and Methods: We collected data on all patients diagnosed with AES and reported to the Bureau of Epidemiology, Ministry of Public Health, Thailand, from 2003 to 2019. Results: A total of 9566 AES patients and 266 death cases were reported during these 17 years. Six hundred and forty-two (6.7%) patients were JE with 16 deaths. The incidence of AES increased from 0.47-0.51-1.36 cases per 100,000 population with a preponderance of cases in adults. CFR reduced from 6.25% - 6.94% in 2003-2005 to 0.78% in 2019. AES cases occurred all year round in all the age groups with a male predilection JE vaccination coverage had reached 83% by 2019. The patients were mainly from the north-eastern region of Thailand. Conclusion: Integrated surveillance regular monitoring, strengthening, and making immunization sustainable is required to improve and maintain progress toward JE control and prevention.

Seroprevalence of leptospirosis among blood donors in an endemic area.

Thailand is known to be endemic for leptospirosis. This bacterium may pose a potential risk to transfusion safety. This study was a cross-sectional study examining the seroprevalence of leptospirosis among Thai blood donors. A total of 1053 serum specimens collected from blood donors residing in 5 regions of Thailand during March to September 2020 were included in this study. All samples were tested for the presence of antibodies to 22 leptospiral serovars using the microscopic agglutination test (MAT) and anti-Leptospira IgG antibodies using commercially available enzyme immunoassay. We found no evidence of recent exposure to Leptospira spp. in sera of healthy Thai blood donors by MAT, including those in higher-risk areas. However, in this same group, we did find small numbers of past exposure (1.7%) to Leptospira spp. by IgG ELISA. According to the findings of this study, there is currently no evidence for implementing new blood banking procedures to identify possible carriers in Thailand, however these should be continually monitored and revised according to the infectious disease burden in each country. It should be noted that there was a difference in the occupation rate between the general population reported in Thailand and blood donors in this study; it may not reflect the actual situation in the country.

Serum Cortisol as a Biomarker of Severe Dengue.

Dengue infection presents a wide range of clinical symptoms. Serum cortisol is known as a severity predictor of serious infection but is not yet clearly understood in dengue infection. We aimed to investigate the pattern of cortisol response after dengue infection and evaluate the possibility of using serum cortisol as the biomarker to predict the severity of dengue infection. This prospective study was conducted in Thailand during 2018. Serum cortisol and other laboratory tests were collected at four time points: day 1 at hospital admission, day 3, day of defervescence (DFV) (4-7 days post-fever onset), and day of discharge (DC). The study recruited 265 patients (median age (IQR) 17 (13, 27.5)). Approximately 10% presented severe dengue infection. Serum cortisol levels were highest on the day of admission and day 3. The best cut-off value of serum cortisol level for predicting severe dengue was 18.2 mcg/dL with an AUC of 0.62 (95% CI, 0.51, 0.74). The sensitivity, specificity, PPV and NPV were 65.4, 62.3, 16 and 94%, respectively. When we combined serum cortisol with persistent vomiting and day of fever, the AUC increased to 0.76. In summary, serum cortisol at day of admission was likely to be associated with dengue severity. Further studies may focus on the possibility of using serum cortisol as one of the biomarkers for dengue severity.