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The proportion of infant pertussis cases due to transmission from casual contact in the community has not been estimated since before the introduction of pertussis vaccines in the 1950s. This study aimed to estimate the proportion of pertussis transmission due to casual contact using demographic and clinical data from a study of 95 infant pertussis cases and their close contacts enrolled at 14 hospitals in France, Germany, Canada, and the U.S. between February 2003 and September 2004. A complete case analysis was conducted as well as multiple imputation (MI) to account for missing data for participants and close contacts who did not participate. By considering all possible close contacts, the MI analysis estimated 66% of source cases were close contacts, implying the minimum attributable proportion of infant cases due to transmission from casual contact with community members was 34% (95% CI = 24%, 44%). Estimates from the complete case analysis were comparable but less precise. Results were sensitive to changes in the operational definition of a source case, which broadened the range of MI point estimates of transmission from casual community contact to 20%-47%. We conclude that casual contact appears to be responsible for a substantial proportion of pertussis transmission to young infants. [ABSTRACT FROM AUTHOR]

Background: Screening substantially reduces cervical cancer incidence and mortality. More than half of invasive cervical cancers are attributable to infrequent screening or not screening at all. The current study, My Body My Test (MBMT), evaluates the impact of mailed kits for self-collection of samples for human papillomavirus (HPV) testing on completion of cervical cancer screening in low-income, North Carolina women overdue for cervical cancer screening.Methods/design: The study will enroll at least 510 US women aged 25-64 years who report no Pap test in the last 4 years and no HPV test in the last 6 years. We will randomize participants to an intervention or control arm. The intervention arm will receive kits to self-collect a sample at home and mail it for HPV testing. In both the intervention and control arms, participants will receive assistance in scheduling an appointment for screening in clinic. Study staff will deliver HPV self-collection results by phone and assist in scheduling participants for screening in clinic. The primary outcome is completion of cervical cancer screening. Specifically, completion of screening will be defined as screening in clinic or receipt of negative HPV self-collection results. Women with HPV-negative self-collection results will be considered screening-complete. All other participants will be considered screening-complete if they obtain co-testing or Pap test screening at a study-affiliated institution or other clinic. We will assess whether the self-collection intervention influences participants' perceived risk of cervical cancer and whether perceived risk mediates the relationship between HPV self-collection results and subsequent screening in clinic. We also will estimate the incremental cost per woman screened of offering at-home HPV self-collection kits with scheduling assistance as compared to offering scheduling assistance alone.Discussion: If mailed self-collection of samples for HPV testing is an effective strategy for increasing cervical cancer screening among women overdue for screening, this method has the potential to reduce cervical cancer incidence and mortality in medically underserved women at higher risk of developing cervical cancer.Trial Registration: ClinicalTrials.gov NCT02651883, Registered on 11 January 2016. [ABSTRACT FROM AUTHOR]

Background: Modelling risk of malaria in longitudinal studies is common, because individuals are at risk for repeated infections over time. Malaria infections result in acquired immunity to clinical malaria disease. Prospective cohorts are an ideal design to relate the historical exposure to infection and development of clinical malaria over time, and analysis methods should consider the longitudinal nature of the data. Models must take into account the acquisition of immunity to disease that increases with each infection and the heterogeneous exposure to bites from infected Anopheles mosquitoes. Methods that fail to capture these important factors in malaria risk will not accurately model risk of malaria infection or disease. Methods: Statistical methods applied to prospective cohort studies of clinical malaria or Plasmodium falciparum infection and disease were reviewed to assess trends in usage of the appropriate statistical methods. The study was designed to test the hypothesis that studies often fail to use appropriate statistical methods but that this would improve with the recent increase in accessibility to and expertise in longitudinal data analysis. Results: Of 197 articles reviewed, the most commonly reported methods included contingency tables which comprised Pearson Chi-square, Fisher exact and McNemar's tests (n = 102, 51.8%), Student's t-tests (n = 82, 41.6%), followed by Cox models (n = 62, 31.5%) and Kaplan–Meier estimators (n = 59, 30.0%). The longitudinal analysis methods generalized estimating equations and mixed-effects models were reported in 41 (20.8%) and 24 (12.2%) articles, respectively, and increased in use over time. A positive trend in choice of more appropriate analytical methods was identified over time. Conclusions: Despite similar study designs across the reports, the statistical methods varied substantially and often represented overly simplistic models of risk. The results underscore the need for more effort to be channelled towards adopting standardized longitudinal methods to analyse prospective cohort studies of malaria infection and disease. [ABSTRACT FROM AUTHOR]