Changing Pattern of Dengue Virus Serotypes in Thailand between 2004 and 2010.

Dengue virus infection is a major concern in several countries, and more than 50 million people are infected worldwide each year. Thailand is one of the countries where people are susceptible to infection due to favourable geographical and environmental conditions. In this retrospective study, we reported the changing pattern of dengue virus serotypes during the period between 2004 and 2010. The following percentage prevalence showed different serotypes of dengue virus (DENV) predominant in respective years: DENV1 in 2004 (56.41%), DENV4 in 2007 (50%), DENV1 in 2008 (57.41%), and DENV3 in 2010 (38.7%). Moreover, the major serotypes were not stable as they showed a shift from one serotype to another. We also found co-infection with two different serotypes and reported the clinical manifestations, which were not different from infection with a single serotype. Co-infection with various serotypes may not necessarily cause more severe disease.

Seroprevalence of Hepatitis A among Thai Population Residing Near Myanmar Border.

When compared with Thailand, the seroprevalence of hepatitis A virus (HAV) is extremely high among its neighbouring countries. To investigate the seroprevalence of HAV among the Thai people residing in the border area between Thailand and Myanmar, 308 residents in Umphang, Maesod district, Tak, were recruited. Sera were tested for HAV IgG antibodies by enzyme-linked immunosorbent assay. The overall seroprevalence among the Thai people residing in the border area of Thailand was significantly higher than that among the general Thai population (71% vs 27% respectively, p<0.05). As asymptomatic or mild HAV infection typically occurs in children, the Thai people residing in the border area may receive little benefit from universal HAV vaccination. Lower protective antibodies against HAV, along with the exclusion of HAV vaccine from the Expanded Programme on Immunization, potentially increase the susceptibility to HAV among the general Thai population and may lead to more future outbreaks if HAV is introduced from the border areas. The findings suggest that HAV vaccines should be recommended to travellers before their journey to the border between Thailand and Myanmar where HAV is endemic.

Serological Analysis of Human Pandemic Influenza (H1N1) in Thailand.

The study was aimed at determining the prevalence of pandemic influenza (H1N1) 2009 among patients with respiratory tract diseases during July-December 2009 using real-time reverse transcription polymerase chain reaction. Haemagglutination inhibition (HI) assay was performed to detect antibody titres against pandemic influenza in 255 medical personnel, 307 members of the general population during the second week of December 2009 in Khon Kaen province, Thailand, and in 100 stored sera collected from people of different age-groups during 2008. The results showed that the pandemic (H1N1) 2009 had occurred during July-December 2009. The results of the HI test after the wave of this outbreak showed that 123 (48%) of the 255 sera collected from the medical personnel, 109 (36%) of the 307 sera obtained from the general population, and only two of the 100 stored sera from 2008 contained antibodies (HI titres ≥40) against pandemic influenza. Antibody against the pandemic (H1N1) 2009 was found in at least one-third of the population. In conclusion, the prevalence of virus and serological data obtained from the study can be used as the serological background level of the Thai population after the July-December pandemic. Finally, the serological data might be useful for outbreak-prevention and control strategies and for the management of vaccination for the pandemic (H1N1) 2009 in Thailand.

Prevalence of respiratory viruses isolated from dogs in Thailand during 2008-2009.

Background: A highly contagious respiratory disease in canines is infectious tracheobronchitis or kennel cough characterized by inflammation of the upper respiratory tract. The cause of kennel cough has been associated with multiple or complex agents such as canine adeno virus (CAV), canine influenza virus (CIV), canine distemper virus (CDV), and canine para influenzavirus (CPIV). Objective: Study the prevalence of canine respiratory viruses detected from in Thailand during 2008-2009. Methods: Nasal swab samples collected from 102 healthy dogs and 109 dogs with respiratory diseases. Then CAV, CIV, CDV, and CPIV were detected by in-house nested PCR and further confirmed by nucleotide sequencing. Results: Nested PCR showed that primers designed and used in this study yielded high specificity without any non-specific amplification. The prevalence of CAV, CIV, CDV and CPIV in healthy dogs was 0%, 2.94%, 2.94%, and 0.98%, whereas that found in dogs with respiratory diseases was 9.17%, 1.83%, 2.75%, and 11.93%, respectively. In healthy dogs, co-infection with CPIV + CDV was detected in only 0.98%. On the other hand, dogs with respiratory symptoms showed multiple infections with CAV + CIV in 1.83%, CIV + CPIV in 0.92%, CAV + CPIV in 1.83%, and CAV + CDV + CPIV in 0.92%. Conclusion: The prevalence data obtained from this study may be useful for outbreak preventions and to raise awareness of potential transmission of the newly emerged canine influenza virus to humans.

Determination of antibody response to the human pandemic influenza H1N1 2009 among patients with influenza-like illness and high risk groups.

The global population has been exposed to the novel pandemic H1N1 influenza virus since mid March 2009, causing the expansion of respiratory illness around the world, including Thailand. To evaluate the an-tibody titers against human pandemic influenza (H1N1) in Thai people with influenza-like illness (ILI), 45 paired se-rum samples (acute and convalescent) were subjected to hemagglutination inhibition (HI) test and real-time RT-PCR. Most serum samples of ILI patients positive by real-time RT-PCR displayed an at least four-fold antibody in-crease of HI titers against pandemic influenza (H1N1). In addition, to determine cross-reactivity with human sea-sonal H1N1 influenza, viral antigen from the seasonal H1N1 was used to detect antibody against seasonal H1N1 influenza and all sera showed negative results. We also studied the single sera samples from the high risk medical personals collected before and after the pandemic influenza (H1N1) outbreaks for antibodies against seasonal H3 influenza virus infection. The results showed lack of cross-reactivity to the human pandemic H1N1 influenza virus. HI antibody testing to pandemic influenza (H1N1) can be used for the diagnosis, preventive and control measures of potential outbreaks.

Relationship between hybrid capture II ratios and DNA amplification of E1, E6 and L1 genes used for the detection of human papillomavirus in samples with different cytological findings.

The hybrid capture II (HCII) assay is widely used in the detection of human papillomavirus virus (HPV). However, due to the limited number of HPV genotypes, it does not permit a comprehensive typing of viruses and “grey zone” (borderline negative or positive results) are often difficult to interpret. As such, polymerase chain reaction (PCR) should be used in parallel with HCII assays, and consensus PCR detection is capable of covering a wider detection range than with the HCII method. We examined the relationship between HCII relative light unit/cut-off (RLU/CO) ratios and PCR amplification results. This was done using previously described primer sets (MY/GP) as well as with our primers for HPV E1, L1 and E6 gene amplification, and performed on samples exhibiting differ-ent cytological findings. Together, 243 samples were divided into three groups having RLU/CO ratios of < 0.4 (n = 21), 0.4-4 (n = 64) and ≥ 4 (n = 158), respectively. All samples were subjected to PCR amplification using MY/GP and the newly designed E1, L1 and E6 primers. Results were verified by direct sequencing. PCR amplification sen-sitivities were higher when using the E1 primers than for the MY/GP, E6 or L1 primers. The E1 assay can be used for HPV detection with a sensitivity of 102 copies μl-1. Samples with RLU/CO ratios exceeding 4, and grey zone samples of 0.4-4, were amplified using E1 primers in 79.74% and 26.56% of the total cases, respectively. Cytologi-cal data of grey zone samples were primarily found to be normal (77%) whereas those with RLU/CO ratios > 4 were found in any of the cytological data categories. We concluded that HPV screening by HCII for grey zone sam-ples should be analyzed together with cytological data, as well as with a PCR screening tool that incorporates the E1 primers.

High prevalence of hepatitis c virus genotype 6 in Vietnam.

This study aimed to update the prevalence of the various Hepatitis C virus genotypes in Vietnamese blood donors. One hundred and three HCV antibody-positive plasma samples were collected from blood donors at the National Institute of Hematology and Blood Transfusion, Hanoi, Vietnam. All specimens were subjected to RT-PCR of the 5’ untranslated region (UTR) to confirm the presence of HCV RNA. The core and NS5B regions of the positive samples were subsequently amplified by RT-PCR followed by direct sequencing and phylogenetic analy-sis. Seventy out of 103 samples (68.0%) were RNA positive. Core and NS5B were successfully amplified and se-quences were obtained for 70 and 65 samples, respectively. Phylogenetic analysis revealed that genotype 6a was the most predominant among Vietnamese blood donors with a prevalence of 37.1% (26/70), followed by genotype 1a at 30.0% (21/70) and genotype 1b at 17.1% (12/70). The prevalence of two other genotype 6 variants, 6e and 6l was 8.6% and 1.4%, respectively. Further analysis of recent studies showed that the geographic distribution of genotype 6 covered mainly southern China and the mainland of Southeast Asia including Vietnam, Laos, Thailand, and Myanmar. The GenBank accession numbers for the sequences reported in this study are FJ768772- FJ768906.

Seroprevalence of antibodies to measles, mumps, and rubella among Thai population: evaluation of measles/MMR immunization programme.

Stored serum specimens, from four regions of Thailand, of healthy children attending well baby clinics and of healthy people with acute illnesses visiting outpatient clinics were randomly sampled and tested for IgG antibody to measles, mumps, and rubella (MMR). The immunity patterns of rubella and mumps fitted well with the history of rubella and MMR vaccination, seroprotective rates being over 85% among those aged over seven years. A high proportion of younger children acquired the infection before the age of vaccination. MMR vaccination should preferably be given to children at an earlier age. For measles, 73% seroprotective rates among children, aged 8-14 years, who should have received two doses of measles/MMR vaccine, were lower than expected. This finding was consistent with the age-group reported in outbreaks of measles in Thailand. The apparent ineffectiveness (in relation to measles) of MMR immunization of 1st grade students warrants further studies.

Liver function test results and outcomes in children with acute liver failure due to dengue infection.

This retrospective study compared the liver function test results and outcomes between children with acute liver failure (ALF) due to dengue hemorrhagic fever (DHF) and due to other causes. We retrospectively reviewed patients less than 15 years old with a diagnosis of ALF admitted to 13 participating centers from different parts of Thailand for the years 2000 and 2001, and those admitted to King Chulalongkorn Memorial Hospital for the year 1997 to 2004. The diagnosis of ALF was based on prothrombin time (PT) prolongation to greater than 2 times the normal control value and the presence of encephalopathy without pre-existing liver disease. The patients were divided into 2 groups: group I (n=16) had DHF with ALF and group II (n=37) had ALF due to other causes. DHF patients had AST levels significantly higher than ALT levels. The mortality rate in group I (50%) was lower than in group II (72.9%), although the difference was not statistically significant. The non-DHF patients who died had a significantly longer duration of jaundice before the onset of encephalopathy and a significantly higher PT ratio compared to survivors. There were no significant differences in the duration of jaundice before the onset of encephalopathy and liver function between dengue patients who died and those who survived.

Insulin-like growth factor-1 (IGF-1) in children with postoperative biliary atresia: a cross-sectional study.

Biliary atresia is the leading cause of chronic infantile cholestasis which eventually leads to cirrhosis. Re-establishment of biliary drainage by Kasai portoenterostomy and liver transplantation for end-stage liver disease has favorably altered the clinical outcome. However, growth failure, one of the major complications of chronic liver disease, remains a major problem. The aim of the study is to evaluate growth, nutritional status and serum growth factor IGF-1 in children with biliary atresia after Kasai operation and at comparing these data between the groups with successful and unsuccessful operation. Fifty-four children with postoperative biliary atresia were evaluated for their clinical outcome, height, blood biochemistry related nutritional status and serum IGF-1. Height and serum IGF-1 were expressed as standard deviation score (SDS) to minimize the influence of age. With 44.4% of the enrolled patients the operation had been unsuccessful and jaundice persisted. The mean age of children with jaundice in comparison with the jaundice free groups was not significantly different (42.0 and 49.9 months, p = 0.458). In jaundice-free patients, hematocrit, serum albumin, calcium and phosphorus were normal and significantly higher. In the successful Kasai group, the height SDS and serum IGF-1 SDS were within the normal range and significantly higher (height SDS 0.2 +/-1.0 vs. -0.9 +/- 1.2, p < 0.01 and IGF-1 SDS 0.5 +/- 2.2 vs. -1.3 +/- 1.0, p < 0.01). The mean IGF-1 SDS in the failed Kasai group was less than -1. Children with good outcome of postoperative biliary atresia showed better growth, better nutritional status and higher serum IGF-1 levels when compared to those with unsuccessful operation.

The prevalence and persistence of human parvovirus B19 infection in thalassemic patients.

Human parvovirus B19 infection was studied in 60 thalassemic patients in Thailand. Seroprevalence, persistence of parvovirus B19 and their genotypes were identified in blood samples. Prevalence of anti-parvovirus B19 IgG and DNA found in thalassemic patients were 38% and 13%, respectively. Anti-parvovirus B19 IgM could be detected in 4% of these positive anti-parvovirus B19 IgG patients. The seroprevalence and parvovirus B19 DNA in patients with a history of blood transfusion were not significantly higher than those without such a history (44% vs. 34% and 20% vs. 9%, respectively). Phylogenetic analysis of NS1 nucleotide sequences of three parvovirus B19 samples revealed that they were parvovirus B19 genotype 1. They showed low genetic diversity from prototype (Au) strain. We concluded that acute and chronic persistent parvovirus B19 infection were found in the thalassemic Thai patients. Chronic persistence of parvovirus B19 infection might play important clinical role in thalassemic patients because of the high prevalence of parvovirus B19 DNA. Blood transfusion had no significant influence to increase the prevalence of parvovirus B19 infection in thalassemic patients.

Dynamics of HBV DNA levels, HBV mutations and biochemical parameters during antiviral therapy in a patient with HBeAg-negative chronic hepatitis B.

Chronic hepatitis B virus (HBV) infection leads to long-term sequelae such as cirrhosis and hepatocellular carcinoma. Antiviral therapy aims at controlling the viral replication and thus, decreasing the likelihood of such complications. In this study, we evaluated the dynamics of biochemical and virological parameters over 10 years of antiviral therapy in a Thai patient with chronic HBeAg-negative HBV infection, who had relapsed after two courses of interferon alfa treatment. Lamivudine administration initially led to a significant reduction in alanine aminotransferase (ALT) and HBV DNA levels, but a subsequent emergence of YIDD mutants caused an ALT flare and a virus breakthrough. A 4-log HBV DNA decrease and normalization of the ALT level were achieved within 3 months of adefovir monotherapy without any relapse during follow-up exceeding 20 months. Thus, careful monitoring during treatment and knowledge of cross-resistance to antiviral salvage therapy are crucial for the management of patients with chronic hepatitis B.

Seroepidemiology and genotypes of hepatitis C virus in Thailand.

HCV can be classified into 6 major genotypes based on the phylogenetic analysis of the genomic sequences. The 3 major genotypes found in Thailand are 3, 1 and 6, respectively. In 2004, an epidemiological survey was carried out to evaluate the seroprevalence of HCV infections among populations aged 2-60 years in four provinces of Thailand, representing the North, Northeast, Center and South of the country, respectively. One hundred and twenty five out of 5,825 serum samples (2.15%) were positive for anti-HCV by ELISA. Fifty eight out of 100 anti-HCV positive samples (58.0%) were positive by RT-PCR of the 5'UTR. The core region of 45 representative samples was sequenced allowing classification into genotype variants 1a (6.7%), 1b (26.7%), 2a (2.2%), 2c (2.2%), 3a (51.1%), 3b (2.2%) and 6 (8.9%). This information might be crucial for public health surveillance and prevention of HCV infection.

Seroprevalence of tetanus antibody in the Thai population: a national survey.

Tetanus is a disease with high mortality and the most important measure for effective prevention is vaccination. Tetanus immunization has been introduced to Thailand's national immunization program for 30 years. Yet, the coverage and seroprevalence of tetanus antibody in vast parts of the population has not been assessed. This study has been performed on 1,277 subjects aged between 6 months and 60 years or above from four geographically distinct provinces of Thailand. Tetanus antibody levels were measured using a commercially available ELISA kit. Most of the Thai population had immunity against tetanus. The level of antibodies to tetanus, as demonstrated by the geometric mean titer of antibody (GMT) (and 95% confidence interval) was 2.62 (2.34-2.91) IU/ml. The highest and lowest GMT was found in subjects aged between 5 and 9 years, and above 60 years of age with GMT (and 95% confidence intervals) of 3.64 (3.34-3.96) and 1.24 (0.67-2.29) IU/ml respectively. The minimum protective level of antitoxin (>0.01 IU/ml) was detected in 99.7 % of subjects. More than 90% of subjects displayed durable antibody protection levels (DAPL) (> or = 1.0 IU/ml), except for subjects above the age of 60 years (82%). According to this study, the majority of the population expresses tetanus antibody levels that can confer long term protection. Yet, considering the lowest GMT and the highest incidence of tetanus cases found in subjects aged above 60 years, re-immunization should be targeted at this age group especially if they had sustained any tetanus-prone injury.

Myristica fragrans Houtt. methanolic extract induces apoptosis in a human leukemia cell line through SIRT1 mRNA downregulation.

BACKGROUND: Myristica fragrans Houtt. (nutmeg) contains antibacterial, antiviral and anti-cancer activities. However the mechanisms underlying those activities have not been clearly explained. OBJECTIVE: To study the effect of Myristica fragrans Houtt. methanolic extract on Jurkat human leukemia T cell line. MATERIAL AND METHOD: Methanol extract of Myristica fragrans Houtt. (Myristicaceae) was used to study the effect on Jurkat cell metabolic activity using an MTT assay and on apoptosis using annexin V staining. Expression of SIRT1 gene was determined by RT-PCR. RESULTS: At the concentrations 50 and 100 ig/mL, the methanol extract of Myristica fragrans Houtt significantly inhibited Jurkat cell proliferation and induced apoptosis as detected by annexin V staining. Downregulation of SIRT1 mRNA expression in Jurkat cells was observed even when the amount of methanol extract was 10 microg/mL. CONCLUSION: Methanol extract of Myristica fragrans Houtt induced apoptosis of Jurkat leukemia T cell line in a mechanisms involving SIRTI mRNA downregulation.

Comparison of a slide agglutination test, LeptoTek Dri-Dot, and IgM-ELISA with microscopic agglutination test for Leptospira antibody detection.

A slide agglutination test (SAT), LeptoTek Dri-Dot and IgM-ELISA were compared with a microscopic agglutination test (MAT) for the detection of Leptospira antibodies. Paired sera from 10 patients whose leptospirosis was clinically suspected and diagnosed by MAT, were evaluated in this study. Our data, especially from acute samples, demonstrate the SAT and Dri-Dot were more sensitive as initial screening tests than MAT. IgM-ELISA has an advantage over MAT, SAT, and Dri-Dot since the results can be interpreted from a single serum testing if the results of the test are positive. Eight of the ten cases could be diagnosed by IgM-ELISA. Our data suggest that IgM-ELISA may be used for the diagnosis of leptospirosis. However, the agglutination test is useful for screening and for secondary infection cases for which IgM antibodies may be undetectable. MAT can be performed as a reference test and when information regarding the causative serovar is required.

Binding of Leptospira to extracellular matrix proteins.

BACKGROUND: Leptospirosis is a zoonotic disease of global importance. Pathogenesis caused by this infectious disease remains unclear. Attachment of pathogenic leptospires to host tissues is a crucial initial step to establish the infection. OBJECTIVE: Study the binding of the spirochete to three types of extracellular matrix (ECM), collagen type IV, fibronectin, and laminin, which are major components of target organs. MATERIAL AND METHOD: ELISA-based experiments were performed to determine binding of pathogenic (serovar icterohaemorrhagie) and non-pathogenic (serovar Patoc) serovars, to purified ECM. RESULTS: Both pathogenic and non-pathogenic serovars bound to all three types of ECM in the dose-dependent manner and the binding to fibronectin is higher than to collagen and laminin (p < 0.005). CONCLUSION: Pathogenic leptospires can bind to various types of ECM and the binding of leptospires to fibronectin was higher than to collagen and laminin. However, this capability may not be the only mechanism that makes leptospires virulent since non-pathogenic leptospire can bind the ECM as well.

Plasma levels of nitric oxide in children with congenital heart disease and increased pulmonary blood flow.

BACKGROUND: Development of pulmonary hypertension commonly accompanies congenital heart disease; nitric oxide (NO) is evidently an important mediator of pulmonary vascular reactivity. OBJECTIVE: Investigate the effect of pulmonary hypertension (PH) associated with congenital heart disease on NO production. MATERIAL AND METHOD: The authors measured plasma levels of nitric oxide-related compounds in 28 patients, aged 3 months to 12 years with congenital heart disease (CHD) and increased pulmonary blood flow. Blood samples were obtained during their cardiac catheterization. The subjects were subsequently divided into two groups, namely: group 1 CHD were those with left-to-right shunt; and group 2, CHD with right-to-left shunt. RESULTS: Four patients had severe pulmonary hypertension (mean pulmonary arterial pressure > 60 mmHg). The total levels of NO-related compounds between the two groups were not statistically different as well as the levels in pre- and post-pulmonary artery. In patients with left-to-right shunt with mild to moderate pulmonary hypertension, the levels of total NO-related compounds were directly correlated with the level of pulmonary arterial pressure and pulmonary vascular resistance (r = 0.67; p-value < 0.05, and r = 0.75; p-value < 0.05). Additionally, in patients with severe pulmonary hypertension, the levels of total NO-related compounds decreased when compared to the levels in patients with mild to moderate pulmonary hypertension. CONCLUSION: The present results suggested that the hemodynamic status of the pulmonary circulation in congenital heart defect is at least partly correlated with the blood levels of nitric oxide.

Efficacy of pulsed dyed laser (585 nm) in the treatment of molluscum contagiosum subtype 1.

Molluscum contagiosum is a common cutaneous disease that may be difficult to treat when there are multiple lesions; especially in children. This study was conducted to determine the efficacy of pulsed dye laser (585 nm) in the treatment of molluscum contagiosum in 20 children. In the treated group, 70.5% of lesions healed after the first treatment; the remaining 10.6% after the second treatment (2 weeks later). The overall cure rate was significantly different from the control group (p< 0.01). The therapy was also well tolerated. Only mild transient hypopigmentation and erythema were observed. None encountered infectious events. In conclusion, pulsed dye laser is a good alternative treatment for molluscum contagiosum due to high efficacy and mild transient side effects.

Seroprevalence and risk factors of hepatitis B virus infection among health care workers at the Institute of Neurology.

OBJECTIVES: To define the seroepidemiology of Hepatitis B virus (HBV) infection among health care workers (HCWs) in the Institute of Neurology, and to evaluate the risk factors of HBV markers. MATERIAL AND METHOD: Blood samples were taken from 548 HCWs for HBV profiling (HBsAg, anti-HBs and anti-HBc) by Microparticle Enzyme Immunoassay (MEIA) methods. Questionnaires of demographics, type, and duration of work, history of blood exposure, HBV vaccination, and non-occupational risks of HBV infection were interviewed. RESULTS: Twenty-nine (5.3%) HCWs were HBsAg positive, 135 (24.6%) had anti-HBc with anti-HBs suggesting immunity acquired from a previous HBV infection, 232 (42.3%) had totally negative profiles, 40 (7.3%) had anti-HBc only, 105 (19.2%) had protective levels of anti-HBs, 7 (1.3%) had low anti-HBs levels. The significant risk factors included not having received the hepatitis B vaccine, male gender, past history of jaundice, viral hepatitis, family history of hepatoma, spouse with hepatitis B, and duration of employment in a clinical environment exceeding 5 years. No significant differences were found among HCWs regarding frequency of exposure to blood products. CONCLUSION: Base on the significant risk factors of hepatitis B virus infection among HCWs, these findings will help implement effective measures aimed at preventing HBV infection.