Correction: A Seroepidemiological Study of Serogroup A Meningococcal Infection in the African Meningitis Belt.

[This corrects the article DOI: 10.1371/journal.pone.0147928.]

Household transmission of Neisseria meningitidis in the African meningitis belt: a longitudinal cohort study

International audienceBackgroundInformation on transmission of meningococcal infection in the African meningitis belt is scarce. We aimed to describe transmission patterns of Neisseria meningitidis (meningococcus) in households in the African meningitis belt.MethodsCross-sectional carriage surveys were done in seven African meningitis belt countries (Chad, Ethiopia, Ghana, Mali, Niger, Nigeria, and Senegal) between Aug 1, 2010, and Oct 15, 2012. Meningococcal carriers identified in these surveys and all available people in their households were recruited into this longitudinal cohort study. We took pharyngeal swabs at first visit and took further swabs twice a month for 2 months and then monthly for a further 4 months. We used conventional bacteriological and molecular techniques to identify and characterise meningococci. We estimated the rates of carriage acquisition and recovery using a multi-state Markov model.FindingsMeningococci were isolated from 241 (25%) of 980 members of 133 households in which a carrier had been identified in the cross-sectional survey or at the first household visit. Carriage was detected subsequently in another household member who was not an index carrier in 75 households. Transmission within a household, suggested by detection of a further carrier with the same strain as the index carrier, was found in 52 of these 75 households. Children younger than 5 years were the group that most frequently acquired carriage from other household members. The overall individual acquisition rate was 2·4% (95% CI 1·6–4·0) per month, varying by age and household carriage status. The mean duration of carriage was 3·4 months (95% CI 2·7–4·4).InterpretationIn the African meningitis belt, transmission of meningococci within households is important, particularly for young children, and periods of carriage are usually of short duration

Development and Evaluation of Epitope-Blocking ELISA for Detection of Antibodies against Contagious Caprine Pleuropneumonia in Goat Sera

Enzyme linked immunosorbent assays (ELISAs) have been developed for the detection of antibodies against contagious caprine pleuropneumonia (CCPP), the causative agent of which is Mycoplasma capricolum subsp. Capripneumoniae (Mccp). The currently available commercial CCPP competitive ELISA (CCPP cELISA) kit produced and supplied by IDEXX Company (Westbrook, Maine, United States) is relatively expensive for most African laboratories. To address this issue and provide a variety of choices, a sensitive and specific blocking-ELISA (b-ELISA) test to detect antibodies against CCPP was developed. We describe the newly developed CCPP blocking-ELISA based on the blocking of an epitope of a monoclonal antibody (Mccp-25) by a positive serum sample against the Mccp protein coated on a plate. The Percentage Inhibition (PI) cut-off value for the CCPP b-ELISA was set at 50 using 466 CCPP negative and 84 CCPP positive small ruminant sera. Of the negative sera, 307 were obtained from the Botswana National Veterinary Laboratory (BNVL) and 159 from the Friedrich-Loeffler-Institute (FLI) Germany. The 84 positive sera samples came from experimentally vaccinated goats at the AU-PANVAC facility in Debre-Zeit, Ethiopia. The relative diagnostic sensitivity and specificity of the CCPP b-ELISA was 93% and 88%, respectively. This test result indicated good correlation with that of the commercial CCPP cELISA by IDEXX Company (Westbrook, Maine, United States) with a Cohen’s κ agreement of κ agreement of 0.85. The newly developed CCPP b-ELISA will be useful in the detection of antibodies for the diagnosis CCPP and for sero-surveillance during vaccination campaigns

Investigation of correlates of protection against pharyngeal carriage of <i>Neisseria meningitidis</i> genogroups W and Y in the African meningitis belt

<div><p>Background</p><p>Serum bactericidal antibody titres that correlate with protection against invasive meningococcal disease have been characterised. However, titres that are associated with protection against acquisition of pharyngeal carriage of <i>Neisseria meningitidis</i> are not known.</p><p>Methods</p><p>Sera were obtained from the members of a household in seven countries of the African meningitis belt in which a pharyngeal carrier of <i>N</i>. <i>meningitidis</i> had been identified during a cross-sectional survey. Serum bactericidal antibody titres at baseline were compared between individuals in the household of the carrier who became a carrier of a meningococcus of the same genogroup during six months of subsequent follow-up and household members who did not become a carrier of a meningococcus of this genogroup during this period.</p><p>Results</p><p>Serum bacterial antibody titres were significantly higher in carriers of a serogroup W or Y meningococcus at the time of recruitment than in those who were not a carrier of <i>N</i>. <i>meningitidis</i> of the same genogroup. Serum bactericidal antibody titres to a strain of <i>N</i>. <i>meningitis</i> of the same genogroup as the index cases were no different in individuals who acquired carriage with a meningococcus of the same genogroup as the index case than in those who did not become a carrier during six months of follow-up.</p><p>Conclusion</p><p>Serum bacterial antibody titres to <i>N</i>. <i>meningitidis</i> of genogroup W or Y in the range of those acquired by natural exposure to meningococci of these genogroups, or with cross-reactive bacteria, are not associated with protection against acquisition of carriage with meningococci of either of these genogroups.</p></div

Index and subsequent carriers by genogroup.

<p>Index and subsequent carriers by genogroup.</p

Factors influencing odds of carriage acquisition.

<p>Factors influencing odds of carriage acquisition.</p

Antibody titres by exposure and outcome.

<p>Antibody titres by exposure and outcome.</p

Reciprocal titre by exposure and outcome.

<p>Reciprocal plots of SBA titre found in individuals exposed to a carrier of <i>N</i>. <i>meningitidis</i> who became a carrier of a meningococcus belonging to the same genogroup as the index carrier during six months of follow-up and those who did not. Sera tested against a genogroup W reference strain, genogroup W local strain, genogroup Y reference strain.</p

Geometric mean by exposure and outcome.

<p>Geometric mean SBA titres and 95% CI found in current carriers of <i>N</i>. <i>meningitidis</i> genogroup W or Y and in household members exposed to a carrier who became a carrier of <i>N</i>. <i>meningitidis</i> of the same genogroup as the index case and among those who did not.</p