Pertussis in Lao PDR: Seroprevalence and disease.

OBJECTIVES: Pertussis is a debilitating vaccine-preventable infection. The aim of this study was to determine susceptibility and exposure to pertussis in Lao PDR in different age groups and subpopulations. METHODS: A total 3072 serum samples were obtained from different cohorts: children with documented vaccination, pre-schoolers, schoolchildren, blood donors, healthcare workers (HCWs), and pregnant women and paired cord blood. Samples were tested for anti-pertussis toxin IgG antibodies. A history of Bordetella pertussis exposure was defined according to antibody titres. Four hundred and seventy-five 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%. The 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 years). B. pertussis was detected in 1.05% (5/475) of children with respiratory symptoms in Vientiane Capital. CONCLUSIONS: It is suggested that routine childhood vaccination, in particular outreach, as well as vaccination of HCWs 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 in at least one central facility.

Red cell alloantibodies in Lao blood donors.

Data of the prevalence of red cell alloantibodies in blood donors will assist in improving safe blood supply for patients needing transfusion. The purpose of this study was to determine prevalence of red cell alloantibodies in Lao blood donors. Antibody screening and identification by multiple phase indirect antiglobulin standard tube assay were performed in serum samples from 1,181 blood donor individuals following routine work at the Lao Red Cross National Blood Transfusion Center. The overall prevalence of alloantibodies was 3.90%. All of the antibodies found were naturally occurring antibodies. Anti-P1 was the most common with a frequency of 1.95% followed by anti-Le(a), anti-Le(b), anti-Le(a+b), anti-M, anti-P1 plus anti-Le(a), anti-P1 plus anti-Le(a+b) with the prevalence of 0.59%, 0.42%, 0.42%, 0.17%, and 0.08%, respectively. This is the first report about prevalence of red cell alloantibodies among Lao blood donors. The information obtained from this study will be useful for safe blood transfusion and preparation of in house antisera.