The World Health Organization road map for neglected tropical diseases 2021-2030: implications for onchocerciasis elimination programs

Control, elimination, and eradication efforts for neglected tropical diseases in the World Health Organization African region over the last 30 years: A scoping review

OBJECTIVES

NTDs historically receive less attention than other diseases in the same regions. Recent gap analyses revealed notable shortcomings despite NTD elimination progress. This systematic scoping review was conducted to understand NTD control, elimination, and eradication efforts in the WHO African region over the last 30 years.

METHODS

Peer-reviewed publications from PubMed, Web of Science, and Cochrane databases related to NTD control, elimination, and eradication in the WHO African Region from 1990 to 2022 were reviewed. Included articles were categorized based on NTD; study location, type, and period; and topic areas. Technical and guidance documents from WHO, UN, partner, and academic/research institutions were reviewed. Country-specific multi-year NTD master plans were documented.

RESULTS

Four hundred eighty peer-reviewed articles, six Cochrane reviews, and 134 technical reports were included. MDA and non-interventional/survey-related studies were common topics. Lymphatic filariasis, trachoma, schistosomiasis, and onchocerciasis were the most frequently studied NTDs. Tanzania, Ethiopia, and Nigeria were the most represented countries; multi-country studies were limited.

CONCLUSION

The review highlights progress made in NTD control, elimination, and eradication efforts in the WHO African Region and can inform national/regional strategies. Disease and geographical disparities were evident, warranting focus and research in certain countries. A standardized approach to NTD control programs is needed for sustained progress.

FUNDING

There was no funding source for this study.

Impact of preventive chemotherapy on Strongyloides stercoralis: A systematic review and meta-analysis

BACKGROUND

Strongyloides stercoralis is a neglected soil-transmitted helminth (STH) that leads to significant morbidity in endemic populations. Infection with this helminth has recently been recognised by the World Health Organization (WHO) as a major global health problem to be addressed with ivermectin preventive chemotherapy, and therefore, there is now, the need to develop guidelines for strongyloidiasis control that can be implemented by endemic countries. This study aimed to evaluate the impact of ivermectin preventive chemotherapy (PC) on S. stercoralis prevalence in endemic areas to generate evidence that can inform global health policy.

METHODOLOGY/PRINCIPAL FINDINGS

This study was a systematic review and meta-analysis. We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and LILACS for literature published between 1990 and 2022 and reporting prevalence of S. stercoralis before and after PC with ivermectin, administered either at school or at community level. The search strategy identified 933 records, eight of which were included in the meta-analysis. Data extraction and quality assessment were carried out by two authors. Meta-analysis of studies based on fecal testing demonstrated a significant reduction of S. stercoralis prevalence after PC: prevalence Risk Ratio (RR) 0.18 (95% CI 0.14-0.23), I2 = 0. A similar trend was observed in studies that used serology for diagnosis: RR 0.35 (95% CI 0.26-0.48), I2 = 4.25%. A sensitivity analysis was carried out for fecal tests where low quality studies were removed, confirming a post-intervention reduction in prevalence. The impact of PC could not be evaluated at different time points or comparing annual vs biannual administration due to insufficient data.

CONCLUSIONS/SIGNIFICANCE

Our findings demonstrate a significant decrease of S. stercoralis prevalence in areas where ivermectin PC has taken place, supporting the use of ivermectin PC in endemic areas.

Potential of Onchocerca ochengi inosine-5'-monophosphate dehydrogenase (IMPDH) and guanosine-5'-monophosphate oxidoreductase (GMPR) as druggable and vaccine candidates: immunoinformatics screening

Onchocerciasis is a vector-borne disease caused by the filarial nematode Onchocerca volvulus, which is responsible for most of the visual impairments recorded in Africa, Asia and the Americas. It is known that O. volvulus has similar molecular and biological characteristics as Onchocerca ochengi in cattle. This study was designed to screen for immunogenic epitopes and binding pockets of O. ochengi IMPDH and GMPR ligands using immunoinformatic approaches. In this study, a total of 23 B cell epitopes for IMPDH and 7 B cell epitopes for GMPR were predicted using ABCpred tool, Bepipred 2.0 and Kolaskar and Tongaonkar methods. The CD4+ Th computational results showed 16 antigenic epitopes from IMPDH with strong binding affinity for DRB1_0301, DRB3_0101, DRB1_0103 and DRB1_1501 MHC II alleles while 8 antigenic epitopes from GMPR were predicted to bind DRB1_0101 and DRB1_0401 MHC II alleles, respectively. For the CD8+ CTLs analysis, 8 antigenic epitopes from IMPDH showed strong binding affinity to human leukocyte antigen HLA-A*26:01, HLA-A*03:01, HLA-A*24:02 and HLA-A*01:01 MHC I alleles while 2 antigenic epitopes from GMPR showed strong binding affinity to HLA-A*01:01 allele, respectively. The immunogenic B cell and T cell epitopes were further evaluated for antigenicity, non-alllergernicity, toxicity, IFN-gamma, IL4 and IL10. The docking score revealed favorable binding free energy with IMP and MYD scoring the highest binding affinity at -6.6 kcal/mol with IMPDH and -8.3 kcal/mol with GMPR. This study provides valuable insight on IMPDH and GMPR as potential drug targets and for the development of multiple epitope vaccine candidates.Communicated by Ramaswamy H. Sarma.

Macrophage migration inhibitory factor in Nodding syndrome

Nodding syndrome (NS) is a catastrophic and enigmatic childhood epilepsy, accompanied by multiple neurological impairments and neuroinflammation. Of all the infectious, environmental and psychological factors associated with NS, the major culprit is Onchocerca Volvulus (Ov)-a parasitic worm transmitted to human by blackflies. NS seems to be an 'Autoimmune Epilepsy' in light of the recent findings of deleterious autoimmune antibodies to Glutamate receptors and to Leiomodin-I in NS patients. Moreover, we recently found immunogenetic fingerprints in HLA peptide-binding grooves associate with protection or susceptibility to NS. Macrophage migration inhibitory factor (MIF) is an immune-regulatory cytokine playing a central role in modulating innate and adaptive immunity. MIF is also involved in various pathologies: infectious, autoimmune and neurodegenerative diseases, epilepsy and others. Herein, two functional polymorphisms in the MIF gene, a -794 CATT5-8 microsatellite repeat and a -173 G/C single-nucleotide polymorphism, were assessed in 49 NS patients and 51 healthy controls from South Sudan. We also measured MIF plasma levels in established NS patients and healthy controls. We discovered that the frequency of the high-expression MIF -173C containing genotype was significantly lower in NS patients compared to healthy controls. Interestingly however, MIF plasma levels were significantly elevated in NS patients than in healthy controls. We further demonstrated that the HLA protective and susceptibility associations are dominant over the MIF association with NS. Our findings suggest that MIF might have a dual role in NS. Genetically controlled high-expression MIF genotype is associated with disease protection. However, elevated MIF in the plasma may contribute to the detrimental autoimmunity, neuroinflammation and epilepsy.