Analysis of anti-DENV IgG antibody by region.

<p>Analysis of anti-DENV IgG antibody by region.</p

Map of Thailand shows four provinces from which seroprevalence data were derived.

<p>Bangkok is indicated as reference. Population was based on the 2014 census data from the Official Statistics Registration System (<a href="http://stat.dopa.go.th/stat/statnew/upstat_age.php" target="_blank">http://stat.dopa.go.th/stat/statnew/upstat_age.php</a>).</p

Analysis of anti-CHIKV IgG antibody by region.

<p>Analysis of anti-CHIKV IgG antibody by region.</p

Seroprevalence of antibodies to dengue and chikungunya viruses in Thailand

<div><p>The abundance of <i>Aedes</i> mosquito species enabled widespread transmission of mosquito-borne chikungunya virus (CHIKV) and dengue virus (DENV) in Southeast Asia. Periodic seroprevalence surveys are therefore necessary to assess the viral burden in the population and the effectiveness of public health interventions. Since the current seroprevalence for CHIKV and DENV in Thailand are unknown, we evaluated evidence of past infection among Thais. Eight-hundred and thirty-five serum samples obtained from individuals living in central and southern Thailand were assessed for anti-CHIKV and anti-DENV IgG antibodies using commercial enzyme-linked immunosorbent assays. Overall, 26.8% (224/835) of individuals were seropositive for CHIKV, the majority of whom were also DENV-seropositive (91.1%, 204/224). Approximately half of all adults in their fifth decade of life had attained CHIKV seropositivity. Children under 15 years of age in southern Thailand were significantly more likely to be CHIKV-seropositive compared to those residing in central Thailand. In contrast, 79.2% (661/835) of Thais were DENV-seropositive, 30.9% (204/661) of whom also had antibodies to CHIKV. CHIKV/DENV dual seropositivity among Thais was 24.4% (204/835). The age-standardized seroprevalence for DENV was three times that of CHIKV (80.5% vs. 27.2%). Relatively high CHIKV seroprevalence among adults living in central Thailand revealed an under-recognized CHIKV burden in the region, while the low-to-moderate transmission intensity of DENV (seroprevalence <50% at 9 years) is expected to reduce the impact of DENV vaccination in Thailand. This most recent seroprevalence data provide serological baselines for two of the most common mosquito-borne viruses in this region.</p></div

Age group-specific anti-DENV IgG seroprevalence in Thailand by region.

<p>The line graphs represent regional DENV seroprevalence (y-axis) relative to age groups (x-axis). Seropositivity rates for each age group are indicated on the graphs.</p

Seroprevalence of anti-CHIKV IgG antibody.

<p>Seroprevalence of anti-CHIKV IgG antibody.</p

Seroprevalence of anti-DENV IgG antibody.

<p>Seroprevalence of anti-DENV IgG antibody.</p

Age group-specific CHIKV seroprevalence in Thailand by region.

<p>The line graphs represent regional CHIKV seroprevalence (y-axis) relative to age groups (x-axis). Seropositivity rates for each age group are indicated on the graphs.</p

Seroprevalence of Antibodies to Pertussis Toxin among Different Age Groups in Thailand after 37 Years of Universal Whole-Cell Pertussis Vaccination

<div><p>Despite the high coverage of prophylactic vaccine against <i>Bordetella pertussis</i> infection in many countries for more than three decades, pertussis remains a common vaccine-preventable disease. Infections have been detected more commonly in countries using acellular pertussis vaccine in their Expanded Program of Immunization. Thailand implemented a routine infant immunization program with whole-cell pertussis vaccine in 1977, and since 1992, the national vaccine policy has offered a five-dose whole-cell pertussis vaccine for children given at the ages of 2, 4, 6, 18, and 48 months. This study aimed to investigate the seroprevalence of antibodies to pertussis toxin among healthy people across all ages to determine the level of whole-cell vaccine-induced immunity in the population, and to identify which age group should be targeted for a booster dose. The lowest seronegative rate and highest geometric mean concentrations were found in the 0–10 years age group, corresponding to their recent pertussis vaccination. The proportion of people with undetectable IgG level was prominent, starting after 11 years of age onwards. Now that a reduced-dose pertussis vaccine with fewer adverse effects is available, a booster dose during adolescence should be considered in order to reduce the incidence of pertussis disease. Further studies exploring how long the reduced-dose pertussis vaccine can provide protective immunity against pertussis disease when administered to adults and adolescents should also be performed.</p></div

Anti-pertussis toxin IgG level in the Thai population.

<p>Anti-pertussis toxin IgG level in the Thai population.</p