Pertussis in Lao PDR: Seroprevalence and disease.

OBJECTIVES: Pertussis is a debilitating vaccine-preventable infection. We aimed to determine susceptibility and exposure to pertussis in Lao PDR in different age groups and subpopulations. METHODS: 3072 serum samples were obtained from different cohorts: children with documented vaccination, pre-schoolers, school-children, blood donors, healthcare workers (HCW) and pregnant women and paired cord blood. Samples were tested for anti-pertussis-toxin IgG antibodies. History of B. pertussis exposure was defined according to antibody titres. 475 throat swabs and nasopharyngeal aspirates were analysed by PCR for the presence of B. pertussis in symptomatic children at the Children's Hospital in Vientiane. RESULTS: Overall pertussis seroprevalence was 57.5%. Prevalence of titres indicating acute infection or recent vaccination or infection/vaccination within the last 12 months ranged from 7.4% (100/1356) in adults to 21.4% (25/117) in pre-schoolers (age 1-5). B. pertussis was detected in 1.05% (5/475) of children with respiratory symptoms in Vientiane Capital. CONCLUSIONS: We suggest that routine childhood vaccination, in particular outreach, as well as vaccination of HCW should be strengthened. A childhood booster and vaccination of pregnant mothers should be considered. There is also a need to improve reporting and to introduce pertussis testing at least in one central facility.