Browsing by Author "Mohammed, N.I."

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Epstein-Barr virus but not cytomegalovirus is associated with reduced vaccine antibody responses in Gambian infants
(PLoS One, 2010) Holder, B.; Miles, D.J.; Kaye, S.; Crozier, S.; Mohammed, N.I.; Duah, N.O.; Roberts, E.; Ojuola, O.; Palmero, M.S.; Touray, E.S.; Waight, P.; Cotton, M.; Rowland-Jones, S.; van der Sande, M.; Whittle, H.
Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are persistent herpesviruses that have various immunomodulatory effects on their hosts. Both viruses are usually acquired in infancy in Sub-Saharan Africa, a region where childhood vaccines are less effective than in high income settings. To establish whether there is an association between these two observations, we tested the hypothesis that infection with one or both viruses modulate antibody responses to the T-cell independent meningococcal polysaccharide vaccine and the T-cell dependent measles vaccines. Methodology/Principal Findings: Infection with EBV and CMV was diagnosed by the presence of virus-specific IgM in the peripheral blood or by the presence of IgG at higher levels than that found in umbilical cord blood. Anti-meningococcus IgG and IgM were quantified by ELISA. Anti-measles antibody responses were quantified by haemagglutinin antibody inhibition assay. Infants infected with EBV had reduced IgG and IgM antibody responses to meningococcal polysaccharides and to measles vaccine. Infection with CMV alone predicted no changes in the response to meningococcal polysaccharide. While CMV alone had no discernable effect on the antibody response to measles, the response of infants infected with both CMV and EBV was similar to that of infants infected with neither, suggesting that the effects of CMV infection countered the effects of EBV on measles antibody responses. Conclusions: The results of this exploratory study indicate that infection with EBV is associated with reduced antibody responses to polysaccharides and to measles vaccine, but suggest that the response to T-cell dependent antigens such as measles haemagglutinin may be restored by infection with CMV.
Hospital-based Surveillance for Pediatric Bacterial Meningitis in the Era of the 13-Valent Pneumococcal Conjugate Vaccine in Ghana
(Clinical Infectious Diseases, 2019-09-05) Renner, L.A.; Usuf, E.; Mohammed, N.I.; Ansong, D.; Dankwah, T.; Kusah, J.T.; Owusu, S.K.; Awunyo, M.; Arhin, B.; Addo, Y.; Asamoah, J.; Biey, J.N.; Ndow, P.S.; Worwui, A.; Senghore, M.; Ntsama, B.; Mwenda, J.M.; Diamenu, S.K.; Adams, B.K.; Antonio, M.
Background Global surveillance for vaccine preventable invasive bacterial diseases has been set up by the World Health Organization to provide disease burden data to support decisions on introducing pneumococcal conjugate vaccine (PCV). We present data from 2010 to 2016 collected at the 2 sentinel sites in Ghana. Methods Data were collected from children <5 years of age presenting at the 2 major teaching hospitals with clinical signs of meningitis. Cerebrospinal fluid specimens were collected and tested first at the sentinel site laboratory with conventional microbiology methods and subsequently with molecular analysis, at the World Health Organization Regional Reference Laboratory housed at the Medical Research Council Unit The Gambia, for identification of Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, the 3 most common bacteria causing meningitis. Results There were 4008 suspected cases of meningitis during the surveillance period, of which 31 (0.8%) were laboratory confirmed. Suspected meningitis cases decreased from 923 in 2010 to 219 in 2016. Of 3817 patients with available outcome data, 226 (5.9%) died. S. pneumoniae was the most common bacterial pathogen, accounting for 68.5% of confirmed cases (50 of 73). H. influenzae and N. meningitidis accounted for 6.8% (5 of 73) and 21.9% (16 of 73), respectively. The proportion of pneumococcal vaccine serotypes causing meningitis decreased from 81.3% (13 of 16) before the introduction of 13-valent PCV (2010–2012) to 40.0% (8 of 20) after its introduction (2013–2016). Conclusions Cases of suspected meningitis decreased among children <5 years of age between 2010 and 2016, with declines in the proportion of vaccine-type pneumococcal meningitis after the introduction of 13-valent PCV in Ghana.