The establishment of Neisseria meningitidis serogroup W135 of the clonal complex ET-37/ST-11 as an epidemic clone and the persistence of serogroup A isolates in Burkina Faso.

We analyzed 48 invasive isolates of Neisseria meningitidis that were isolated from meningitis cases in Burkina Faso (April 2002 to April 2003). Thirty-nine of these isolates had the phenotype (serogroup:serotype:serosubtype) W135:2a:P1.5,2, eight isolates were A:4:P1.9 and one isolate was nongroupable:nonserotypable:nonserosubtypable. Genotyping of meningococcal isolates showed that W135 isolates belonged to the sequence type (ST)-11. The nongroupable isolate was of genogroup W135 and belonged to ST-192. Isolates of serogroup A belonged to ST-2859 (a member of the subgroup III/ST-5 clonal complex). W135 (ST-11) isolates involved in meningitis outbreaks in Burkina Faso differed from those involved in the Hajj-2000 associated outbreak by their pulsed-field gel electrophoresis profile. These data confirm the changing epidemiology of meningococcal infection in Burkina Faso with the establishment and expansion of serogroup W135 N. meningitidis strains of the ET-37/ST-11 clonal complex, as well as the emergence of a new clone within the subgroup III/ST-5 clonal complex.

Interlaboratory comparison of PCR-based identification and genogrouping of Neisseria meningitidis.

Twenty clinical samples (18 cerebrospinal fluid samples and 2 articular fluid samples) were sent to 11 meningococcus reference centers located in 11 different countries. Ten of these laboratories are participating in the EU-MenNet program (a European Union-funded program) and are members of the European Monitoring Group on Meningococci. The remaining laboratory was located in Burkina Faso. Neisseria meningitidis was sought by detecting several meningococcus-specific genes (crgA, ctrA, 16S rRNA, and porA). The PCR-based nonculture method for the detection of N. meningitidis gave similar results between participants with a mean sensitivity and specificity of 89.7 and 92.7%, respectively. Most of the laboratories also performed genogrouping assays (siaD and mynB/sacC). The performance of genogrouping was more variable between laboratories, with a mean sensitivity of 72.7%. Genogroup B gave the best correlation between participants, as all laboratories routinely perform this PCR. The results for genogroups A and W135 were less similar between the eight participating laboratories that performed these PCRs.

HIV-1 superinfections in a cohort of commercial sex workers in Burkina Faso as assessed by an autologous heteroduplex mobility procedure.

OBJECTIVE: To describe and evaluate a simple procedure to identify HIV-1 co- or super-infections based on a heteroduplex mobility assay (HMA). METHODS: To identify heteroduplexes corresponding to divergent viral populations in a the same individual, HMA was applied to single DNA samples from each subject in a prospective cohort of commercial sex workers (CSW) in Bobo-Dioulasso, Burkina Faso. After denaturation and renaturation of env DNA amplicons, hybridized DNA was separated by electrophoresis through polyacrylamide gel. HIV-1 co-infections were suspected by slow migration of heteroduplex, at a level comparable to that of mixed reference strains. Following electrophoresis, DNA in bands representing heteroduplex was extracted and cloned in a plasmid vector; identification of phylogenetically distinct clones was confirmed by sequencing divergent clones identified through a second HMA step of a pair of two mixed clones. RESULTS: Among 147 HIV-1 infected CSW, four had an autologous HMA profile comparable to low mobility of hybridized DNA from mixed reference strains representing most frequent HIV-1 clades and circulating recombinant forms (CRF) prevalent in Burkina Faso. In two of them, two phylogenetically distinct HIV-1 populations were coexisting. The first woman presented with a CRF02-AG and CRF06-cpx co-infection, and the second with a CRF02-AG and a divergent virus co-infection not significantly related to any other known subtypes. In both women, retrospective analyses of stored samples by the same HMA procedure showed acquisition of a second virus concomitent with an increasing plasma HIV RNA. CONCLUSIONS: Autologous HMA procedure followed by acrylamide extraction of heteroduplexes allowed identifying HIV-1 co- and super-infections in a large cohort study. HIV-1 super-infection is not an uncommon phenomenon.

Limited diversity of measles field isolates after a national immunization day in Burkina Faso: progress from endemic to epidemic transmission?

Despite recent National Immunization Days in Burkina Faso, the rural province of Houët reported >400 measles cases in 2001 (82% not vaccinated). Phylogenetic analysis of 58 measles virus field isolates plus the first sequences from the Democratic Republic of the Congo and the Republic of Congo are reported. All viruses were genotype B3, which is common in the region. In Houët, there were two geographically confined genetic variants, suggesting two independent importation events. Strain diversity in Houët (1.5%) and the Congos was limited in comparison with Ibadan, Nigeria (4.6%), where measles is endemic. Strain variability, assessed by heteroduplex mobility assay, confirmed these findings. Despite large local pools of susceptible persons even after several rounds of vaccination, the limited strain diversity suggests that parts of rural Burkina Faso may be moving from an endemic to an epidemic transmission pattern of measles virus.