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

Abstract

Background. Scarce information exists about immunity to hand, foot, and mouth disease (HFMD) among household contacts of index cases in Vietnam and what that means for reducing ongoing HFMD transmission in the community. Methods. We analyzed neutralizing antibodies (NT) and the incidence of enterovirus (EVs) infection among household contacts of index cases in a province where HFMD remains endemic. Throat swab and 2 mL blood samples from household contacts were collected at enrollment, during and after 2 weeks follow-up. Results. The incidence of EV-A71 infection among household contacts was 40/84 (47.6%, 95% Cl: 36.9-58.3%), compared with 106/336 (31.5%, 95% Cl: 26.6-36.5%) for CV-A6 and 36/107 (33.6%, 95% Cl: 24.7-42.6%) for CV-A16. The incidence of CV-A6 infection was fairly constant across ages; in contrast, CV-A71 and CV-A16 had some variation across ages. At baseline, higher geometric mean titer (GMT) of EV-A71, CV-A6, and CV-A16 antibody titers was found for 25-34-year groups (range 216.3 to 305.0) compared to the other age groups. There was a statistically significant difference in GMT values of CV-A6 and CV-A16 between those who had an infection or did not have infection among households with an index case of these serotypes. Conclusions. Our results indicated that adults were becoming infected with HFMD and could be contributing to the transmission. There is, therefore, a need for considering the household setting as an additional target for intervention programs for HFMD.

The secular trend of enterovirus A71 after the implementation of preventive measures in Taiwan

“…Hoang et al found that the incidence of EV A71 infection among household contacts was 47.6% [ 11 ]. Another study showed that the overall EV A71 transmission rate due to household contact was 52%, and viral transmission occurred most often among siblings and cousins [ 26 ].…”

“…Severe complications, including brainstem encephalitis, cardiopulmonary failure, and acute flaccid paralysis, may occur within two to 7 days after symptom onset [ 9 , 10 ]. Moreover, several hundreds to thousands of people with a severe case of the disease die every year in some countries [ 11 , 12 ]. Apart from a high mortality rate, EV A71 could cause long-term neurological sequelae and cognitive impairment [ 10 ].…”

“…After that, EV A71 circulated and caused outbreaks in a cyclical pattern every two to 3 years, mainly in the Asia-Pacific region [ 13 , 14 ]. Several epidemic situations leading to child death have been reported in many Asian countries such as Malaysia [ 5 ], Taiwan [ 6 ], Vietnam [ 11 ], China [ 12 ], and Cambodia [ 14 , 15 ]. On the other hand, one retrospective surveillance study conducted in 24 European and European Economic Area countries also found that EV A71 accounted for 6% of the isolated enteroviruses from 19 countries, mostly Spain and Germany, during 2015–2017 [ 16 ].…”

Epidemiological and etiological aspects of enterovirus infection in Russia and Vietnam

“…A number of publications [23,24,25,31] provide the results of some long-term studies of patients who suffered from HFMD and their contact persons who lived in the southern provinces of Vietnam. The authors proved the role of EV-A71 virus as the main etiological factor of HFMD, which was the emerging infection with the highest incidence in Vietnam over many years (2013)(2014)(2015)(2016)(2017)(2018).…”

“…At the same time, in Russia a trend towards an increase in the proportion of enterovirus infection with exanthema [2,3,4,6,15,16] has been fixed in recent years. The etiological factors of enterovirus infection with exanthema are most often enteroviruses, which belong to species A: EV-A71, Coxsackieviruses A6, A10 and A16 [2,3,4,6,15,16,19,23].…”