Search Results (99)

Background/Objectives: Although the COVID-19 pandemic has largely concluded, the varied trajectories it has followed in different regions of the world remain incompletely understood. Intensive research is needed to fully grasp its course and the implications for future global health challenges. Notably, the milder trajectory of the COVID-19 pandemic in Sub-Saharan Africa has defied initial predictions. An emerging body of evidence suggests that, in addition to the continent’s younger average age and the lower prevalence of relevant comorbidities, co-infections with helminths may have also impressively shaped the pandemic’s milder trajectory in the region. Indeed, helminths are renowned for their ability to modulate human immune responses, which, while potentially beneficial in limiting excessive inflammation, could also diminish vaccine efficacy and impede viral clearance. This study investigated different aspects of the intricate interactions between COVID-19 and Lymphatic Filariasis (LF), a helminth infection caused by parasitic worms such as Wuchereria bancrofti, Brugia malayi, and Brugia timori and endemic to various regions in Sub-Saharan Africa and the tropics. Methods: For this purpose, samples of a larger and ongoing clinical trial (ethical approval codes: CHRPE/AP/525/17 and 325/21; trial registration number ISRCTN14042737) were collected from 222 individuals from endemic areas of Ghana, along with comprehensive clinical and demographic data. The samples include LF patients (n = 222) grouped according to their Lymphoedema (LE) stages, as well as COVID-19 vaccinated (n = 81) and non-vaccinated individuals (n = 141). All vaccinated participants received the COVID-19 vaccine ChAdOx1-S (also known as Vaxzevria) developed by the University of Oxford and AstraZenca. The expressions of SARS-CoV-2 and filarial-specific antibodies (IgG, IgA) were accessed using ELISA, while Luminex-based immunoassays were employed to measure the expression of SARS-CoV-2 variant-specific neutralizing antibodies. The interplay between vaccine responses and demographic factors was analyzed using group comparisons with the Kruskal-Wallis or Mann-Whitney U tests. Results: The results indicate that a remarkable portion of unvaccinated individuals (56% IgA seropositive, 39% IgG seropositive) developed antibodies against SARS-CoV-2 despite no confirmed infection. Notably, the study identified a robust antibody response to COVID-19 vaccination, which was independent of the degree of LF pathology or parasitic status. An important observation was the reduced SARS-CoV-2 antibody response in individuals seropositive for Ascaris lumbricoides (p = 0.0264), highlighting an interaction between roundworm infection and COVID-19. Conclusions: The study concludes that the ChAdOx1-S COVID-19 vaccine (AstraZeneca) triggers a strong immune response in LF patients; however, filarial and/or soil-transmitted helminth seropositivity might influence the COVID-19 infection-induced response. These findings emphasize the complexity of infectious disease dynamics in co-infected populations and the need to decipher parasite-induced immunomodulatory mechanisms on COVID-19 vaccination. Full article

Background/Objectives: Many tropical diseases such as malaria, Chagas, human African Trypanosomiasis, and Lymphatic filariasis coexist in endemic countries, affecting more than 1 billion people worldwide, and are recognised as major global vector-borne diseases. Tackling this disease requires an accurate diagnosis that is sensitive, specific, and rapid. This study aimed to describe and validate a new highly sensitive and specific multiple-analysis system that can effectively detect numerous etiological agents in a single test. Methods: A total of 230 human blood samples were assessed retrospectively for parasite characterisation, as well as 58 stool samples from non-human primates. Primers and probes were designed in the small subunit ribosomal RNA gene, except for Plasmodium spp., for which the novel target was Cytochrome Oxidase Subunit 1. Results: The analytical specificity of the presented method was 100%, with no unspecific amplifications or cross-reactions with other blood parasitic diseases. The detection limit obtained was between 0.6 and 3.01 parasites/µL for Plasmodium species, 1.8 parasites/mL for Trypanosomatidae, and 2 microfilariae/mL in the case of Filariae. The sensitivity, specificity, predictive values, and kappa coefficient reached almost 100%, except for Filariae, whose sensitivity dropped to 93.9% and whose negative predicted value dropped to 89.5%. The operational features described a turnaround and a hands-on time shorter than the compared methods with a lower cost per essay. Conclusions: This work presents a cost-effective and highly sensitive multiplexed tool (RT-PCR-bp) capable of performing simultaneous detection for blood parasitic diseases using specific fluorescence probes, enabling the diagnosis of low parasite loads and coinfections. Full article

Lymphatic filariasis (LF), or elephantiasis, is a neglected tropical disease caused by filarial worms, primarily Wuchereria bancrofti, transmitted through mosquito bites. It often begins in childhood but may not show symptoms until later, leaving many individuals asymptomatic for long periods. LF disrupts the lymphatic system, causing severe swelling in the limbs and genitals, leading to deformities and disabilities. The World Health Organization estimates that around 51 million people are affected globally, with 36 million suffering from chronic conditions like lymphedema and hydrocele. In 2021, approximately 882.5 million people in 44 countries required preventive chemotherapy, making LF the second leading parasitic cause of disability, significantly impacting socioeconomic status. The immune response to filarial parasites is complex, involving both innate and adaptive immune cells. A key feature of LF immunology is the antigen-specific Th2 response, expansion of IL-10-producing CD4⁺ T cells, and a muted Th1 response. This T cell hypo-responsiveness is crucial for sustaining long-term infections with high parasite densities. While the correlates of protective immunity are not fully understood—due in part to a lack of suitable animal models—T cells, particularly CD4⁺ Th2 cells, and B cells, play essential roles in immune protection. Moreover, host immune responses contribute to the disease’s pathological manifestations. A failure to induce T cell hypo-responsiveness can lead to exaggerated inflammatory conditions such as lymphedema, hydrocele, and elephantiasis. Filarial infections also induce bystander effects on various immune responses, impacting responses to other infectious agents. This intricate immune interplay offers valuable insights into the regulation of immune responses to chronic infections. This review explores recent immunological research on lymphatic filarial worms, highlighting their effects on both innate and adaptive immune responses in humans and the mechanisms underlying this neglected tropical disease. Full article

Accurate rapid diagnostic tests (RDTs) are needed to diagnose lymphatic filariasis (LF) in global elimination programmes. We evaluated the performance of the new STANDARD Q Filariasis Antigen Test (QFAT) against the Bioline Filariasis Test Strip (FTS) for detecting W. bancrofti antigen (Ag) in laboratory conditions, using serum (n = 195) and plasma (n = 189) from LF-endemic areas (Samoa, American Samoa and Myanmar) and Australian negative controls (n = 46). The prior Ag status of endemic samples (54.9% Ag-positive) was determined by rapid test (ICT or FTS) or Og4C3 ELISA. The proportion of samples testing positive at 10 min was similar for QFAT (44.8%) and FTS (41.3%). Concordance between tests was 93.5% (kappa 0.87, n = 417) at 10 min, and it increased to 98.8% (kappa 0.98) at 24 h. The sensitivities of QFAT and FTS at 10 min compared to the prior results were 92% (95% CI 88.0–96.0) and 86% (95% CI 80.0–90.0), respectively, and they increased to 97% and 99% at 24 h. Specificity was 98% for QFAT and 99% for FTS at 10 min. Both tests showed evidence of cross-reaction with Dirofilaria repens and Onchocerca lupi but not with Acanthochilonema reconditum or Cercopithifilaria bainae. Under laboratory conditions, QFAT is a suitable alternative RDT to FTS. Full article

Lymphatic filariasis (LF) continues to impact 657 million individuals worldwide, resulting in lifelong and chronic impairment. The prevalent anti-filarial medications—DEC, albendazole, and ivermectin—exhibit limited adulticidal efficacy. Despite ongoing LF eradication programs, novel therapeutic strategies are essential for effective control. This study examines the mechanism of action of Ocimum sanctum on the filarial parasites Setaria cervi via a synergistic biochemical and proteomics methodology. The ethanolic extract of Ocimum sanctum (EOS) demonstrated potential anti-filarial action in the MTT reduction experiment, with an LC₅₀ value of 197.24 µg/mL. After EOS treatment, an elevation in lipid peroxidation (51.92%), protein carbonylation (48.99%), and NADPH oxidase (88.88%) activity, along with a reduction in glutathione (GSH) (−39.23%), glutathione reductase (GR) (−60.17%), and glutathione S transferase (GST) (−50.48%) activity, was observed. The 2D gel electrophoresis identified 20 decreased and 11 increased protein spots in the EOS-treated parasites relative to the control group. Additionally, in drug docking analysis, the EOS bioactive substances ursolic acid, rutin, and rosmarinic acid show a significant binding affinity with the principal differentially expressed proteins. This paper demonstrates, for the first time, that the anti-filarial efficacy of EOS is primarily facilitated by its impact on energy metabolism, antioxidant mechanisms, and stress response systems of the parasites. Full article

A deterministic model for controlling the neglected tropical filariasis disease known as elephantiasis, caused by a filarial worm, is developed. The model incorporates drug resistance in human and insecticide-resistant vector populations. An investigation into whether the model is of biological importance reveals that it is positively invariant, mathematically well posed, and tractable for epidemiological studies. The filariasis-free and filariasis-present equilibrium points were obtained. The next-generation matrix technique is used to derive the basic reproduction number $R_0$, which is then used to determine the local stability analysis of the model. It is established that the system is locally asymptotically stable when $R_0<1$. The technique by Castillo-Chavez and a Lyapunov function were employed to prove the global stability of the model’s fixed points. The results of this analysis of filariasis-free equilibrium show that the system is globally asymptotically stable when $R_0<1$ and unstable when $R_0>1$. Similarly, the filariasis-present equilibrium point is proved to be globally asymptotically stable when $R_0>1$ and unstable otherwise. This indicates that the fight against the spread of the disease is achievable. It is observed that increasing human-infected mosquito contacts or mosquito-infected human contacts raises the value of $R_0$, whereas decreasing the progression of micro-filaria into infective larva and killing more mosquitoes will decrease the $R_0$ value according to the sensitivity analysis of the model. The variable precision arithmetic technique executed in MATLAB R2014a was used to determine the elasticity indices of the parameters of $R_0$, which showed that the value of $R_0=0.94639$. Further investigations revealed that ${\omega }_2$ has a significant influence on the reproduction number, suggesting that treatment of acute infections is crucial in the control of the disease. Pontryagin’s Maximum Principle (PMP) is used for optimal control analysis. The numerical result revealed that strategy D is the most effective based on the infection averted ratio (IAR) value. Full article

The elimination of lymphatic filariasis (LF) as a public health problem remains an ongoing challenge in the Pacific region. This study reports on antigen (Ag) and microfilaria (Mf) prevalence in Samoa in 2019, 7–9 months after the completion of the first round of triple-drug mass drug administration (MDA). It evaluates the effectiveness of the intervention for reducing Ag prevalence to below a 2% threshold, and how this differs between 5–9-year-olds and ≥10-year-olds. We surveyed 30 randomly selected and five purposefully selected primary sampling units (PSUs) in Samoa in 2018 (1–3 months post-triple-drug MDA) and, again, in 2019. In each PSU, we conducted a community survey of 15–20 households and a convenience survey of 5–9-year-old children. A finger-prick blood sample was collected from all participants to test for Ag and Mf. Demographic details were also collected. There was no significant change in adjusted Ag prevalence in the 30 randomly selected PSUs between 2018 (3.9% [95% CI: 2.7–5.6%]) and 2019 (4.1% [95% CI 2.7–5.9%]). Significantly higher Ag prevalence was observed in participants aged ≥10 years (4.6%, 95% CIs 3.0–6.7%) compared to 5–9-year-olds (1.1%, 95% CIs 0.5–2.2%), supporting existing evidence that post-MDA surveillance should not be based on Ag prevalence among 6–7-year-olds. A single round of triple-drug MDA was insufficient to break LF transmission in Samoa 7–9 months post-MDA. Full article

Wuchereria bancrofti is a parasite transmitted by mosquitoes and can cause a neglected tropical disease called Lymphatic filariasis. However, the genome of W. bancrofti was not well studied, making novel drug development difficult. This study aims to identify microRNA, annotate protein function, and explore the pathogenic mechanism of W. bancrofti by genome-wide analysis. Novel miRNAs were identified by analysis of expressed sequence tags (ESTs) from this parasite. Protein homology was obtained by a bidirectional best-hit strategy using BLAST. By an EST-based method, we identified 20 novel miRNAs in the genome. The AU content of these miRNAs ranged from 39.7% to 80.0%, with a mean of 52.9%. Among them, 14 miRNA homologs were present in mammal genomes, while six miRNA homologs were present in non-mammal genomes. By conducting a detailed sequence alignment using BLAST, we have successfully annotated the functions of 75 previously unannotated proteins, enhancing our understanding of the proteome and potentially revealing new targets for therapy. Homology distribution analysis indicated that a set of critical proteins were present in parasites and mosquitoes, but not present in mammals. By searching the literature, ten proteins were found to be involved in the pathogenic infection process of W. bancrofti. In addition, the miRNA–gene network analysis indicated that two pathogenic genes (CALR and HMGB2) are regulated by newly identified miRNAs. These genes were supposed to play key roles in the infection mechanism of W. bancrofti. In conclusion, our genome-wide analysis provided new clues for the prevention and treatment of W. bancrofti infection. Full article

Lymphatic filariasis (LF) is a neglected tropical disease associated with poverty and poor environmental conditions. With the inclusion of vector control activities in LF surveillance actions, there is a need to develop simple methods to identify areas with higher mosquito density and thus a higher consequent risk of W. bancrofti transmission. An ecological study was conducted in Igarassu, which is in the metropolitan region of Recife, Pernambuco, Brazil. The mosquitoes were captured in 2060 houses distributed across 117 census tracts. The vector density index (VDI), which measures the average number of lymphatic-filariasis-transmitting mosquitoes per number of houses collected in the risk stratum, was constructed. Moreover, the social deprivation indicator (SDI) was constructed and calculated through principal component factor analysis. An average of 242 female C. quinquefasciatus were found in the high-risk stratum, while the average in the low-risk stratum was 108. The overall VDI was 6.8 mosquitoes per household. The VDI for the high-risk stratum was 13.2 mosquitoes per household, while for the low/medium-risk stratum, it was 5.2. This study offers an SDI for the density of C. quinquefasciatus mosquitoes, which can help reduce the costs associated with data collection and allows for identifying priority areas for vector control actions. Full article

Background: Neglected tropical diseases (NTDs) are a diverse group of twenty diseases that occur in tropical and subtropical regions that particularly affect vulnerable and often marginalised populations. Five of these are classified as “preventive chemotherapy” (PC) diseases such as trachoma, onchocerciasis, geo-helminthiasis, lymphatic filariasis, and schistosomiasis. This study aimed to describe the knowledge, attitudes, and practices of healthcare providers in the Forecariah health district with respect to PC-NTDs in Guinea in 2022. Methods: A descriptive cross-sectional study was conducted from 7 to 22 November 2022 among healthcare providers in the health district of Forécariah in Guinea. Data on participants’ socio-demographic characteristics and knowledge of and attitudes and practices regarding PC-NTDs were collected using an electronic (KoboToolbox) semi-structured questionnaire and analysed using descriptive statistics. Results: Among the 86 healthcare providers who participated in this study, nurses (44.2%) and young adults aged between 25 and 49 years (81.4%) were mostly represented. The majority of respondents declared having already heard about onchocerciasis (70.7%) and lymphatic filariasis (60.0%) but only the minority declared having already heard about geo-helminthiasis (30.7%), schistosomiasis (21.3%), and trachoma (9.3%). Only a few respondents knew how to prevent PC-NTDs (onchocerciasis 26.7%, lymphatic filariasis 26.7%, geo-helminthiasis 29.3%, and schistosomiasis 17.3%). Many healthcare providers reported they would refer cases of onchocerciasis (50.6%), lymphatic filariasis (58.7%), and schistosomiasis (46.7%) to a management centre. Conclusions: This study highlights the varying levels of knowledge, attitudes, and practices among healthcare providers in dealing with PC-NTDs, suggesting areas for improvement in training and resource allocation. Full article

Neglected tropical diseases (NTDs) with skin manifestations present a significant health and societal problems challenge worldwide. This study aimed to analyzed factors associated with the knowledge, attitudes and practices (KAPs) of primary healthcare workers (HCW) concerning NTDs with skin manifestations in the Dakar region of Senegal. We conducted a cross-sectional study utilizing a semi-structured questionnaire which was administered to eligible HCW (general practitioners, nurses and midwives) working at the 24 health centers located in the Dakar region. Data were collected using the ODK Collect application (version 2022.3.6). KAPs measures were constructed from questionnaire responses, and bivariate analysis was used to identify associated factors. Of the 187 HCW surveyed, 75.9% were female, with a mean age of 35.1 years (SD: 8.56). The majority of HCWs had a bachelor’s degree (40.6%), were nurses (49.2%) and had between 1- and 10-years of professional experience (52.4%). Regarding their knowledge of NTDs with skin manifestations, only 43.3% of HCW had received initial training on NTDs. The most commonly reported NTDs with skin manifestations were leprosy (53.5%), lymphatic filariasis (51.3%), scabies (49.7%), onchocerciasis (45.5%) and schistosomiasis (42.8%). Television was the main source of information about these NTDs (38.5%). In term of practices, only 47.6% of HCW reported being able to diagnose NTDs with skin. Factors associated with good knowledge regarding NTDs with skin manifestations included having received training on NTDs (p = 0.0015) and more years of professional experience (p = 0.004). In summary, there is a need to strengthen and raise awareness about NTDs with skin manifestations among HCWs and promote quality management of patients in Senegal. Full article

This study documents the experiences of health system personnel in the implementation of mass distribution campaigns for the control of lymphatic filariasis in rural Guinea. This was an exploratory qualitative study using data collected from implementing actors of mass distribution campaigns in the Boké health district. The results showed four main facilitators of mass distribution campaign rollout in the Boké health district: (i) support to the district teams in the organization of the campaigns; (ii) involvement of community-based associations in social mobilization; (iii) strong adherence of the communities to the different mass distribution campaigns, facilitated through the involvement of community relays, who are members of these communities, in the distribution of drugs; and (iv) transparency in the allocation of incentives to drug dispensers and supervisors. However, the frequent shortages of medicines, the difficulty of access to rural areas, and the lack of logistical means for the supervision of activities were the main obstacles to the success of the various mass distribution campaigns in Boké. The provision of buffer stocks for special areas such as Boké by national programme actors and partners, joint planning of campaign activities with local managers of health systems and services, and improvement of existing mechanisms for motivating health workers, including community health workers, during future campaigns should help to achieve national objectives in the fight against NTDs in Guinea. Full article

Filarial nematodes of the genus Brugia include parasites that are significant to both human and veterinary medicine. Accurate diagnosis is essential for managing infections by these parasites and supporting elimination programs. Traditional diagnostic methods, such as microscopy and serology, remain vital, especially in resource-limited settings. However, advancements in molecular diagnostics, including nucleic acid amplification tests, offer enhanced sensitivity and specificity. These techniques are becoming increasingly field-friendly, expanding their applications in diagnostics. By refining existing methods, developing novel biomarkers, and understanding the zoonotic potential of various Brugia species, it is possible to improve control measures and better support elimination efforts. Full article

Lymphatic filariasis (LF) causes disfiguring and disabling lymphoedema, which can lead to mental distress and requires life-long self-care treatment. This study applies syndemic theory to understand the biosocial relationship between LF and mental distress in Malawi. Using in-depth qualitative methods, we critically evaluate experiences of mental distress and LF through 21 life-history interviews, to narrate experiences from the perspective of persons affected by LF, and to understand how enhanced self-care (ESC) for lymphoedema management disrupts the syndemic relationship. Complementary key informant interviews with Ministry of Health LF programme staff were conducted to further understand intervention and health system delivery. All interviews were recorded, transcribed, and translated, and then subject to thematic analysis. Our findings suggest that for persons affected by LF in Malawi, before being trained in ESC, absent referral pathways, inequalities in healthcare provision or available treatment, and limited knowledge of the condition (LF) drove the syndemic of LF and mental distress. Distress was often exacerbated by stigma and social exclusion, and shaped by intersections of gender, generation, poverty, and extreme climate conditions. We argue that addressing the syndemic suffering associated with LF and mental distress through interventions which center the needs of persons affected is critical in effective and equitable LF care delivery. Full article

(1) Background and rationale: To validate the reported therapeutic coverage, a lymphatic filariasis post-mass drug administration (MDA) campaign survey was conducted in the Lukonga health zone from 10 June to 15 July 2023. (2) Materials and methods: This was a descriptive, cross-sectional study conducted at the community level in 30 villages in the Lukonga health zone from 10 June to 15 July 2023. The study population included all individuals from the visited communities. The study variables included age, sex, drug use (ivermectin + albendazole), adverse events, and adherence to MDA guidelines for supervised drug use. Questionnaires were administered on Android phones using the SurveyCTO platform. Stata version 17 was used for data analysis. (3) Results: Of the 1092 respondents, 54.8% were female and one-third were between the ages of 5 and 14. Two-thirds of the households surveyed, or 64%, had more than six people living in them, and 1031 individuals, or 94%, reported being present during the community mass drug distribution. Notably, 678 individuals, or 66%, reported taking the drugs offered, and 66.4% of those who took the drugs reported doing so in the presence of drug distributors. Thus, the survey coverage was 65.7% [95% CI: 62.9–68.7]. The results of this study show that the survey coverage was above the 65% threshold recommended by the WHO but below the 82.3% reported by the Lukonga health zone. The main reason for non-compliance was a fear of ivermectin-related side effects (47%). Supervised or directly observed treatment was not adhered to (66.4%). (4) Discussion and conclusions: Key challenges to further increase treatment coverage include assessing data quality, building capacity, motivating drug distributors, improving data reporting tools, proper recording by drug distributors, and accurate reporting on non-residents who take the drugs during the MDA. In addition, harmonization of the numerator for calculating drug coverage in the health zone is critical. It is imperative to provide the public with explicit information regarding the objective of drug distribution and the probable adverse effects. Full article