Viral, Bacterial, Metabolic, and Autoimmune Causes of Severe Acute Encephalopathy in Sub-Saharan Africa: A Multicenter Cohort Study

OBJECTIVES

To assess whether viral, bacterial, metabolic, and autoimmune diseases are missed by conventional diagnostics among children with severe acute encephalopathy in sub-Saharan Africa.

STUDY DESIGN

One hundred thirty-four children (6 months to 18 years) presenting with nontraumatic coma or convulsive status epilepticus to 1 of 4 medical referral centers in Uganda, Malawi, and Rwanda were enrolled between 2015 and 2016. Locally available diagnostic tests could be supplemented in 117 patients by viral, bacterial, and 16s quantitative polymerase chain reaction testing, metagenomics, untargeted metabolomics, and autoimmune immunohistochemistry screening.

RESULTS

Fourteen (12%) cases of viral encephalopathies, 8 (7%) cases of bacterial central nervous system (CNS) infections, and 4 (4%) cases of inherited metabolic disorders (IMDs) were newly identified by additional diagnostic testing as the most likely cause of encephalopathy. No confirmed cases of autoimmune encephalitis were found. Patients for whom additional diagnostic testing aided causal evaluation (aOR 3.59, 90% CI 1.57-8.36), patients with a viral CNS infection (aOR 7.91, 90% CI 2.49-30.07), and patients with an IMD (aOR 9.10, 90% CI 1.37-110.45) were at increased risk for poor outcome of disease.

CONCLUSIONS

Viral and bacterial CNS infections and IMDs are prevalent causes of severe acute encephalopathy in children in Uganda, Malawi, and Rwanda that are missed by conventional diagnostics and are associated with poor outcome of disease. Improved diagnostic capacity may increase diagnostic yield and might improve outcome of disease.

Rotavirus infections and their genotype distribution in Rwanda before and after the introduction of rotavirus vaccination

Rotavirus vaccination has reduced mortality and hospital admissions due to rotavirus diarrhoea, but its effect on rotavirus infections and the impact of rotavirus genotypes are still unclear. Real-time PCR was used to detect rotavirus and other pathogens in faeces samples from children below five years of age with acute diarrhoea, collected before (n = 827) and after (n = 807, 92% vaccinated) the introduction of vaccination in Rwanda in 2012. Rotavirus was genotyped by targeting VP7 to identify G1, G2, G3, G4, G9 and G12 and VP4 to identify P[4], P[6] and P[8]. In vaccinated children, rotavirus infections were rarer (34% vs. 47%) below 12 months of age, severe dehydration was less frequent, and rotavirus was more often found as a co-infecting agent. (79% vs 67%, p = 0.004). Norovirus genogroup II, astrovirus, and sapovirus were significantly more often detected in vaccinated children. The predominant rotavirus genotypes were G2P[4] and G12P[6] in 2009-2010 (50% and 12%), G9P[8] and G1P[8] in 2011-2012 (51% and 22%), and G12P[8] in 2014-2015 (63%). Rotavirus vaccination in Rwanda has reduced the severity of rotavirus gastroenteritis and rotavirus infection frequency during the first year of life. Rotavirus infections were frequent in vaccinated children with diarrhoea, often as co-pathogen. Rotavirus genotype changes might be unrelated to vaccination because shifts were observed also before its introduction.

IFNL4 Genotypes Predict Clearance of RNA Viruses in Rwandan Children With Upper Respiratory Tract Infections

Polymorphisms in the interferon lambda gene locus (IFNL) such as the IFNL4 genetic variants rs12979860 and rs368234815 are predictive of resolution of hepatitis C virus infection, but information about the impact of these variants in other infections is scarce. This study aimed at determining the potential impact of IFNL4 variation for the clearance of respiratory tract pathogens in Rwandan children (≤5 years old, n = 480) seeking medical care for acute respiratory infections. Nasopharyngeal swabs were retrieved from all children at the first hospital referral and from 161 children at follow-up visits 2 weeks later. The swabs were analyzed for pathogens by real-time PCR and for host cell IFNL4 genotype at rs12979860 and rs368234815. Approximately 1/3 of the children were homozygous for the rs12979860 T allele and the rs368234815 ΔG allele, which are overrepresented in subjects of African descent. These IFNL4 variants were significantly associated with reduced clearance of RNA viruses. Our results suggest that IFNL4 genotypes that are common among subjects of African descent may determine inefficacious clearance of RNA viruses from the respiratory tract.

Coinfection with Enteric Pathogens in East African Children with Acute Gastroenteritis-Associations and Interpretations

Enteric coinfections among children in low-income countries are very common, but it is not well known if specific pathogen combinations are associated or have clinical importance. In this analysis, feces samples from children in Rwanda and Zanzibar less than 5 years of age, with (N = 994) or without (N = 324) acute diarrhea, were analyzed by real-time polymerase chain reaction targeting a wide range of pathogens. Associations were investigated by comparing co-detection and mono-detection frequencies for all pairwise pathogen combinations. More than one pathogen was detected in 840 samples (65%). A negative association (coinfections being less common than expected from probability) was observed for rotavirus in combination with Shigella, Campylobacter, or norovirus genogroup II, but only in patients, which is statistically expected for agents that independently cause diarrhea. A positive correlation was observed, in both patients and controls, between Ct (threshold cycle) values for certain virulence factor genes in enteropathogenic Escherichia coli (EPEC) (eae and bfpA) and toxin genes in enterotoxigenic E. coli (eltB and estA), allowing estimation of how often these genes were present in the same bacteria. A significant positive association in patients only was observed for Shigella and EPEC-eae, suggesting that this coinfection might interact in a manner that enhances symptoms. Although interaction between pathogens that affect symptoms is rare, this work emphasizes the importance and difference in interpretation of coinfections depending on whether they are positively or negatively associated.

Comparison of rectal swabs and faeces for real-time PCR detection of enteric agents in Rwandan children with gastroenteritis

Background

Molecular diagnostics have emerged as an efficient and feasible alternative for broad detection of pathogens in faeces. However, collection of stool samples is often impractical in both clinical work and in epidemiology studies. The aim of this study was to investigate the diagnostic performance of rectal swabs as compared with traditional faeces samples for detection of enteric agents by PCR.

Method

Three hundred twenty-six pairs of rectal swab and stool samples, obtained from Rwandan children aged 0.5-4.99 years, with or without diarrhoea, were analysed by multiple real-time PCR amplifying 3 viral, 6 bacterial and one protozoan target.

Results

For all agents there was a significant correlation (R² 0.31-0.85) between Ct values in faeces and rectal swabs. For most agents the Ct values, a marker for target concentration, were significantly lower (by 1–3 cycles) in faeces, indicating pathogen content up to ten times higher than in rectal swabs. Despite this, there was no significant difference in detection rate between faeces and rectal swabs for any agent, reflecting that pathogen concentration was far above the limit of detection in the majority of cases.

Conclusion

The similar detection rates and the Ct value correlations as compared with traditional faeces samples indicate that rectal swabs are accurate for real-time PCR-based identification of enteric agents and may be used also for quantitative estimation of pathogen load.