Transmission and serotype features of hand foot mouth disease in household contacts in Dong Thap, Vietnam

Abstract

BackgroundHand, foot and mouth disease (HFMD) has emerged as a major public health issue in Vietnam since 2003. We aimed to investigate the household transmission of HFMD and its causative viruses from 150 households in a high incidence province in Vietnam.MethodsA longitudinal study was conducted in patients presenting to the provincial hospital with a HFMD-like syndrome, along with their household members between April and August 2014 in Dong Thap Province. Each participant was followed up for 2 weeks. We enrolled 150 patients aged under 15 who were clinically diagnosed with HFMD in Dong Thap Hospital, 600 household members, and 581/600 household members completed the study. All participants were interviewed using a standard questionnaire. Throat swabs and blood samples were taken for molecular detection of viruses and assessment of neutralizing antibodies, respectively. Index cases were defined using a clinical case definition, household contact cases were defined using a similar definition applied to the 2 weeks before admission and 2 weeks after discharge of the index case. Characteristics of index cases, household contacts, the attack rate, serotype features and related factors of HFMD were reported.ResultAmong 150 index cases, 113 were laboratory confirmed: 90/150 were RT-PCR-positive, 101/142 had a ≥ 4-fold increase of neutralizing antibody against Enterovirus A71 (EV-A71), Coxsackievirus (CV) A6 or CV-A16 across the two samples collected. 80/150 (53%) were males, and 45/150 (30%) were under the age of 1. The predominant serotype was CV-A6, identified in 57/87 (65.5%) of the specimens. No deaths were reported. Among 581 household contacts, 148 were laboratory confirmed: 12/581 were RT-PCR-positive, 142/545 had a ≥ 4-fold increase of neutralizing antibodies against EV-A71, CV-A6 or CV-A16; 4 cases experienced HFMD in the past 4 weeks. Attack rate among household contacts was 148/581 (25.5%). In 7/12 (58%) instances, the index and secondary cases were infected with the same serotype. Having a relationship to index case was significantly associated with EV infection.ConclusionThe attack rate among household contacts was relatively high (25.5%) in this study and it seems justified to also consider the household setting as an additional target for intervention programs.

Incidence of Infection of Enterovirus 71 and Coxsackieviruses A6 and A16 among Household Contacts of Index Cases in Dong Thap Province, Southern Vietnam

“…Demographic, medical, environmental, socioeconomic, behavioral, and epidemiological characteristics have been published elsewhere [ 7 ]. In brief, for the 150 index cases who were clinically diagnosed with HFMD, the median age was 1.5 years (interquartile range (IQR) 0.2-5.2).…”

“…The design and population of this longitudinal study have been published and described in detail previously [ 7 ]. Briefly, we recruited 150 patients aged under 15 who were clinically diagnosed with HFMD in Dong Thap Hospital and 581/600 household contacts who had close contact with the patient for 2 weeks before enrollment.…”

“…In the current study, seropositivity was defined as a NTtiter ≥ 1 : 8. An infection among household contacts was defined as those who had an RT-PCR positive swab or a 4-fold change or from negative to positive in a single EV-A71, CV-A6, and CV-A16 (or more) serotype neutralizing antibody titers between sample 1 and sample 2 [ 7 , 18 ]. The incidence of HFMD infection was calculated by dividing the total number of new household contact infections for each serotype observed during a period of 2 weeks by the total members of households with an index case of that serotype for during the same time period [ 18 ].…”

Tunable expression rate control of a growth-decoupled T7 expression system by l-arabinose only

“…Creation of pET30a(GFPmut3.1)cer is described elsewhere [ 18 ]. MP-GFP fusion proteins (YhdY-GFP [ 70 , 71 , 75 ], Psta-GFP [ 68 , 76 – 78 ], YliF-GFP [ 66 , 79 – 82 ], Ydik-GFP [ 83 ], YhhJ-GFP [ 66 , 70 , 71 ] and YfbF-GFP [ 17 , 66 , 84 ]) were established in pET28a vector backbone. MP-GFP fusion proteins have been designed according to Daley et al and dsDNA was synthesized [ 66 ].…”

Association of environmental factors and high HFMD occurrence in northern Thailand

“…In 2018, more than 1.6 million cases were reported in the western Pacific regions (China, Japan, Korea, Singapore and Vietnam) [1]. HFMD has become a major public health threat, especially among people living in tropical zones [2]. Several health resources have been used for treatment, care, prevention and control.…”