Rapid identification of influenza A virus (H5N1) is very important for endemic control and prevention. RT-PCR method proved good rapidity. The sensitivity and the specificity is needed to be improved with complete design of primer pairs.
Influenza A Virus, H5N1 Subtype ; Diagnosis

A major epidemic of DF/DHF occurred at Ha Noi in 1998, and 3348 cases of have been reported. Serological surveillance confirmed that the epidemic of dengue fever was caused by dengue 3 and dengue 1 virus types 32/37 positive samples were dengue 3 (86.48%). Dengue virus type 3 was isolated in 6 districts of Ha Noi
Dengue Virus ; Dengue ; epidemiology

Introduction: Antiviral resistance has been reported in seasonal influenza A viruses and avian influenza A(H5N1) viruses in Viet Nam, raising concerns about the efficacy of treatment. Methods: We analysed specimens from two sources during the period 2009–2012: influenza-positive samples from influenza-like illness patients at sentinel clinics in northern Viet Nam and isolates from patients with confirmed A(H5N1) infections. Pyrosequencing was used to detect mutations: H275Y [for A(H1N1) and A(H5N1)], E119V [for A(H3N2)] and I117V [for A(H5N1)]. A neuraminidase inhibition assay was used to determine the Inhibitory Concentration 50 (IC50) values for all influenza A and B isolates. Results: There were 341 influenza A positive samples identified; influenza A(H1N1)pdm09 was identified most frequently (n = 215). In 2009, oseltamivir resistance was observed in 100% (19 of 19) of seasonal A(H1N1) isolates and 1.4% (3/215) of A(H1N1)pdm09 isolates. This H275Y mutation was not found in influenza subtypes A(H5N1) or A(H3N2) isolates. Discussion: In Viet Nam, seasonal and A(H5N1) influenza vaccines are not currently available; thus, effective treatment is required. The presence of oseltamivir-resistant viruses is therefore a concern. Active surveillance for oseltamivir resistance among influenza viruses circulating in Viet Nam should be continued.

Objective:Highly pathogenic avian influenza A(H5N1) is endemic in poultry in Viet Nam. The country has experienced the third highest number of human infections with influenza A(H5N1) in the world. A study in Hanoi in 2001, before the epizootic that was identified in 2003, found influenza A(H5N1) specific antibodies in 4% of poultry market workers (PMWs). We conducted a seroprevalence survey to determine the seroprevalence of antibodies to influenza A(H5N1) among PMWs in Hanoi, Thaibinh and Thanhhoa provinces.Methods:We selected PMWs from five markets, interviewed them and collected blood samples. These were then tested using a horse haemagglutination inhibition assay and a microneutralization assay with all three clades of influenza A(H5N1) viruses that have circulated in Viet Nam since 2004.Results:The overall seroprevalence was 6.1% (95% confidence interval: 4.6–8.3). The highest proportion (7.2%) was found in PMWs in Hanoi, and the majority of seropositive subjects (70.3%) were slaughterers or sellers of poultry.Discussion:The continued circulation and evolution of influenza A(H5N1) requires comprehensive surveillance of both human and animal sites throughout the country with follow-up studies on PMWs to estimate the risk of avian–human transmission of influenza A(H5N1) in Viet Nam.

BACKGROUND: The diagnosis of influenza based on clinical grounds alone may be inaccurate, because the presenting symptoms of influenza are similar to those caused by other infectious agents. We evaluate two influenza rapid tests, SD BIOLINE Influenza Ag (Standard Diagnostic inc., Yongin, Korea) and QuickVueTM Influenza Test (Quidel corporation, San Diego, USA) with influenza virus culture and RT-PCR. METHODS: The two commercially available rapid test kits, SD BIOLINE Influenza Ag and QuickVueTM Influenza Test, for influenza virus detection were evaluated with 189 respiratory specimens collected during Dec. 2004 to Nov. 2005 in Vietnam and compared with viral culture and RT-PCR. RESULTS: Overall, the SD BIOLINE Influenza Ag and QuickVueTM Influenza Test showed high sensitivities (88.4% and 82.6%, respectively) and high specificities (99.0% and 99.0%, respectively), high positive predictive value (PPV) (98.7% and 98.6%, respectively) and high negative predictive value (NPV) (91.1% and 87.2%, respectively). CONCLUSION: Both SD BIOLINE Influenza Ag and QuickVueTM Influenza Test were easy to perform and showed high sensitivity and can be used as an additional tool for rapid diagnosis of influenza virus.
Diagnosis ; Gyeonggi-do ; Immunoassay* ; Influenza, Human* ; Membranes* ; Orthomyxoviridae* ; Sensitivity and Specificity ; Vietnam

Objective: To determine the concentration and rate of decay of maternal IgG antibodies against measles prevalence in infants of vaccinated or naturally infected mothers and study initial measles immunization occurs in nine-month-old children. Methods: In total, 401 pregnant women and the same number of their subsequent newborns were recruited in the Bavi district of Hanoi in 2016-2017; they were divided into two groups: Older women (born before 1985, n=201) and younger women (born after 1990, n=200). Samples were collected at five time-points; week 36 of pregnancy, birth (cord), and 3, 6, and 9 months after birth. Measles-specific IgG antibody levels were recorded. Results: In total, 77.06% of the 401 pregnant women were seropositive for measles-specific IgG antibodies. A significantly greater proportion of mothers aged 30 and older (88.06%) and their newborn (93.53%) were seropositive compared to the mothers aged 25 and younger (66.00%), and their newborn (72.00%) (P<0.001). The infants of older mothers had significantly higher geometric mean titres (GMT) of measles IgG antibodies than the infants of younger mothers (P<0.001) at all time-points of the study period. The proportion of measles IgG antibodies together with GMT decreased from 82.97% (506.96) at the age of three months to 23.19% (45.22) at the age of nine months. Conclusions: This study provides a profile of maternal antibodies against measles in Vietnamese infants and investigates the early susceptibility to measles in both the infants of vaccinated mothers and mothers with naturally acquired immunity. These data suggest that determining the appropriate age for measles vaccination is paramount for the elimination of measles in Vietnam.

Objective To characterize viral co-infections among representative hospitalized measles cases during the 2014 Hanoi outbreak. Methods Throat swabs were collected from 54 pediatric patients with confirmed measles, and molecular diagnostics performed for 10 additional viral respiratory pathogens (Influenza A/H1N1pdm09; A/H3N2 and influenza B; Parainfluenza 1, 2, 3; Respiratory Synctial Virus, RSV; human Metapneumovirus, hMPV; Adenovirus and Picornavirus). Results Twenty-one cases (38.9%) showed evidence of infection with other respiratory viruses: 15 samples contained measles plus one additional virus, and 6 samples contained measles plus 2 additional viruses. Adenovirus was detected as a predominant cause of co-infections (13 cases; 24.1%), followed by RSV (6 cases; 11.1%), A/H1N1pdm09 (3 cases; 5.6%), PIV3 (3 cases; 3.7%), Rhinovirus (3 cases; 3.7%) and hMPV (1 case; 1.96%). Conclusions Viral co-infections identified from pediatric measles cases may have contributed to increased disease severity and high rate of fatal outcomes. Optimal treatment of measles cases may require control of multiple viral respiratory pathogens.

Background: The VEGFA gene encodes vascular endothelial growth factor A (VEGF-A), which plays a key role in vasculogenesis and angiogenesis. The VEGFA rs3025039 (+936C>T) polymorphism is associated with many diseases. This study aimed to: (1) Apply PCR-RFLP technique to identify the VEGFA rs3025039 (+936C>T) polymorphism; (2) Primarily evaluate the distribution of genotypes and allele frequencies of the rs3025039 polymorphism in volunteers. Materials and methods: DNA extraction was isolated from peripheral blood of 60 volunteers. Determining the VEGFA rs3025039 (+936C>T) polymorphism by PCR-RFLP technique. Confirming the results of the genotypes randomly by Sanger sequencing. Results: All PCR-RFLP results of validated samples were in concordance with sequencing results. The distribution of CC, CT and TT genotypes by rs3025039 polymorphism accounted for 80%, 16.7% and 3.3%, respectively. The frequencies of C and T alleles were 88.3% and 11.7%, respectively. Conclusion: Successfully applying PCR-RFLP technique to determine the VEGFA rs3025039 (+936C>T) polymorphism, which establishes the groundwork for further research into the association between this polymorphism and various disorders.