Epidemiology and diagnosis of gout in sub-saharan Africa: a scoping review.

BACKGROUND: The episodic nature of gout and diagnostic uncertainty in the absence of microcrystal evidence make it particularly difficult to estimate the frequency of gout. Our aim was to review the literature on the epidemiological and diagnostic aspects of gout in sub-Saharan Africa. METHODS: This literature review was conducted using the MEDLINE database (via PUBMED), Google Scholar, and conference abstracts. The selection process was based on reading the titles first, then the abstracts, and then the full texts once the articles had been selected. Studies were included in this review if they presented original findings on the epidemiological and/or diagnostic aspects of gout in sub-Saharan Africa. Two groups of two investigators independently reviewed the studies. The results were analysed descriptively. RESULTS: The literature search identified 131 articles and 22 conference abstracts. Nineteen articles were included in our review. Twelve studies were retrospective, five were cross-sectional, one was prospective, and one was both retrospective and cross-sectional. The duration of the studies ranged from 1 to 15 years, and the sample size ranged from 15 to 511 patients, for a total of 2557 patients. Gout was quite common, with a maximum frequency of 11.87%. Fourteen articles diagnosed gout via criteria, including 9 studies totaling 1174 patients via the 1977 ACR criteria. Gout tophi were reported in 15 articles involving 464 patients. Of these studies, seven looked for monosodium urate crystals in 317 (43.85%) of 723 patients. Among the 317 patients, monosodium urate crystals were detected in 263 (82.97%) patients. Eleven studies reported mean uricemia values ranging from 452.09 µmol/L to 642.44 µmol/L, with a mean of 510.63 µmol/L. CONCLUSIONS: This review revealed that all the studies conducted in sub-Saharan Africa were intrahospital studies, and the majority were retrospective. Consequently, there is a clear need for population-based studies.

Population-Level Persistence of Immunity 2 Years After the PsA-TT Mass-Vaccination Campaign in Mali.

BACKGROUND: In 2010, Africa's first preventive meningococcal mass vaccination campaign was launched using a newly developed Neisseria meningitidis group A (NmA) polysaccharide-tetanus toxoid conjugate vaccine, PsA-TT (MenAfriVac), designed specifically for the meningitis belt. Given PsA-TT's recent introduction, the duration of protection against meningococcal group A is unknown. METHODS: We conducted a household-based, age-stratified seroprevalence survey in Bamako, Mali, in 2012, 2 years after the vaccination campaign targeted all 1- to 29-year-olds. Randomly selected participants who had been eligible for PsA-TT provided a blood sample and responded to a questionnaire. Sera were analyzed to assess NmA-specific serum bactericidal antibody titers using rabbit complement (rSBA) and NmA-specific immunoglobulin G (IgG) by enzyme-linked immunosorbent assay. The proportion of participants putatively protected and the age group- and sex-specific rSBA geometric mean titers (GMTs) and IgG geometric mean concentrations (GMCs) were determined. RESULTS: Two years postvaccination, nearly all of the 800 participants (99.0%; 95% confidence interval [CI], 98.3%-99.7%) maintained NmA-specific rSBA titers ≥8, the accepted threshold for protection; 98.6% (95% CI, 97.8%-99.4%) had titers ≥128, and 89.5% (95% CI, 87.4%-91.6%) had titers ≥1024. The rSBA GMTs were significantly higher in females than in males aged <18 years at vaccination (P < .0001). NmA-specific IgG levels ≥2 µg/mL were found in 88.5% (95% CI, 86.3%-90.7%) of participants. CONCLUSIONS: Two years after PsA-TT introduction, a very high proportion of the population targeted for vaccination maintains high antibody titers against NmA. Assessing the duration of protection provided by PsA-TT is a priority for implementing evidence-based vaccination strategies. Representative, population-based seroprevalence studies complement clinical trials and provide this key evidence.

Higher Tetanus Toxoid Immunity 2 Years After PsA-TT Introduction in Mali.

BACKGROUND: In 2010, mass vaccination with a then-new meningococcal A polysaccharide-tetanus toxoid protein conjugate vaccine (PsA-TT, or MenAfriVac) was undertaken in 1- to 29-year-olds in Bamako, Mali. Whether vaccination with PsA-TT effectively boosts tetanus immunity in a population with heterogeneous baseline tetanus immunity is not known. We assessed the impact of PsA-TT on tetanus toxoid (TT) immunity by quantifying age- and sex-specific immunity prior to and 2 years after introduction. METHODS: Using a household-based, age-stratified design, we randomly selected participants for a prevaccination serological survey in 2010 and a postvaccination survey in 2012. TT immunoglobulin G (IgG) antibodies were quantified and geometric mean concentrations (GMCs) pre- and postvaccination among all age groups targeted for vaccination were compared. The probability of TT IgG levels ≥0.1 IU/mL (indicating short-term protection) and ≥1.0 IU/mL (indicating long-term protection) by age and sex was determined using logistic regression models. RESULTS: Analysis of 793 prevaccination and 800 postvaccination sera indicated that while GMCs were low pre-PsA-TT, significantly higher GMCs in all age-sex strata were observed 2 years after PsA-TT introduction. The percentage with short-term immunity increased from 57.1% to 88.4% (31.3-point increase; 95% confidence interval [CI], 26.6-36.0;, P < .0001) and with long-term immunity increased from 20.0% to 58.5% (38.5-point increase; 95% CI, 33.7-43.3; P < .0001) pre- and postvaccination. CONCLUSIONS: Significantly higher TT immunity was observed among vaccine-targeted age groups up to 2 years after Mali's PsA-TT mass vaccination campaign. Our results, combined with evidence from clinical trials, strongly suggest that conjugate vaccines containing TT such as PsA-TT should be considered bivalent vaccines because of their ability to boost tetanus immunity.