Global programme to eliminate lymphatic filariasis: the processes underlying programme success

Lessons from integrating mental health as part of lymphatic filariasis morbidity management and disability prevention services in Jigawa State, Nigeria

Lymphatic filariasis (LF) is a neglected tropical disease affecting >120 million people worldwide. LF has debilitating effects on humans and leads to morbidity and sometimes irreversible disability. A significant proportion of persons affected by LF morbidity also suffer from ill health, such as depression, anxiety, pain, stigma and social isolation due to disfigurement, as well as loss of mobility, livelihood and income. Mental health is often overlooked as a component of morbidity management and disability prevention (MMDP) services, despite the high prevalence of depression and anxiety among people affected by LF. To address this gap, Christian Blind Mission (CBM) piloted a comprehensive approach providing morbidity management and disability prevention by integrating mental health as part of the MMDP care package. The participatory evaluation of the project reviewed the project documents and a review meeting, small group discussions and in-depth interviews with project stakeholders. Findings suggest that project training and service delivery targets were exceeded in most cases. In addition, the disability and gender disaggregated data highlights the interplay of gender and disability in accessing care and the existence of unmet mental health needs. The financial cost of transportation to utilise referrals or access other MMDP services, such as replenishing treatment supplies, was a major constraint in accessing services for LF morbidity patients and low levels of awareness, fear of hydrocoele surgery and social stigmatisation were reported. The project outcomes demonstrate the feasibility and effectiveness of integrating mental health as part of a comprehensive MMDP package of care. Integration strategies should target training of MMDP providers in basic mental health skills, screening for mental health issues and the provision of mental health services and other MMDP services within the same facilities. Integration is an important step towards comprehensive care for people affected by LF and other NTD morbidities and disabilities.

The national distribution of lymphatic filariasis cases in Malawi using patient mapping and geostatistical modelling

BACKGROUND

In 2020 the World Health Organization (WHO) declared that Malawi had successfully eliminated lymphatic filariasis (LF) as a public health problem. Understanding clinical case distributions at a national and sub-national level is important, so essential care packages can be provided to individuals living with LF symptoms. This study aimed to develop a national database and map of LF clinical cases across Malawi using geostatistical modelling approaches, programme-identified clinical cases, antigenaemia prevalence and climate information.

METHODOLOGY

LF clinical cases identified through programme house-to-house surveys across 90 sub-district administrative boundaries (Traditional Authority (TA)) and antigenaemia prevalence from 57 sampled villages in Malawi were used in a two-step geostatistical modelling process to predict LF clinical cases across all TAs of the country. First, we modelled antigenaemia prevalence in relation to climate covariates to predict nationwide antigenaemia prevalence. Second, we modelled clinical cases for unmapped TAs based on our antigenaemia prevalence spatial estimates.

PRINCIPLE FINDINGS

The models estimated 20,938 (95% CrI 18,091 to 24,071) clinical cases in unmapped TAs (70.3%) in addition to the 8,856 (29.7%), programme-identified cases in mapped TAs. In total, the overall national number of LF clinical cases was estimated to be 29,794 (95% CrI 26,957 to 32,927). The antigenaemia prevalence and clinical case mapping and modelling found the highest burden of disease in Chikwawa and Nsanje districts in the Southern Region and Karonga district in the Northern Region of the country.

CONCLUSIONS

The models presented in this study have facilitated the development of the first national LF clinical case database and map in Malawi, the first endemic country in sub-Saharan Africa. It highlights the value of using existing LF antigenaemia prevalence and clinical case data together with modelling approaches to produce estimates that may be used for the WHO dossier requirements, to help target limited resources and implement long-term health strategies.

Identification and prioritisation of potential vaccine candidates using subtractive proteomics and designing of a multi-epitope vaccine against Wuchereria bancrofti

This study employed subtractive proteomics and immunoinformatics to analyze the Wuchereria bancrofti proteome and identify potential therapeutic targets, with a focus on designing a vaccine against the parasite species. A comprehensive bioinformatics analysis of the parasite's proteome identified 51 probable therapeutic targets, among which "Kunitz/bovine pancreatic trypsin inhibitor domain-containing protein" was identified as the most promising vaccine candidate. The candidate protein was used to design a multi-epitope vaccine, incorporating B-cell and T-cell epitopes identified through various tools. The vaccine construct underwent extensive analysis of its antigenic, physical, and chemical features, including the determination of secondary and tertiary structures. Docking and molecular dynamics simulations were performed with HLA alleles, Toll-like receptor 4 (TLR4), and TLR3 to assess its potential to elicit the human immune response. Immune simulation analysis confirmed the predicted vaccine's strong binding affinity with immunoglobulins, indicating its potential efficacy in generating an immune response. However, experimental validation and testing of this multi-epitope vaccine construct would be needed to assess its potential against W. bancrofti and even for a broader range of lymphatic filarial infections given the similarities between W. bancrofti and Brugia.

Molecular detection of Dirofilaria immitis and its Wolbachia endosymbionts in dogs from Myanmar

Heartworm disease in dogs and cats caused by Dirofilaria immitis continues to be a major clinical issue globally. This study focused on dogs suspicious of having tick-borne diseases (TBD) brought to a clinic and a veterinary teaching hospital in Myanmar. Blood samples were collected and initially screened using SNAP® 4Dx® Plus test kit. All dog blood samples were subjected to conventional PCR to detect both Dirofilaria spp. (cox1 gene) and Wolbachia spp. (16S rDNA) infections. Infection with D. immitis was detected in 14 (28.0%) of 50 examined samples, while the detection rate of TBD causative agents, including Anaplasma phagocytophilum and Ehrlichia canis, was 26.0% (13/50) and 26.0% (13/50), respectively, as determined by ELISA rapid test. In this study, D. immitis infection was moderately but significantly correlated with TBD infections (Pearson's r = 0.397, P = 0.008). Comparative sequence and phylogenetic analyses provided molecular identification of D. immitis in Myanmar and confirmed the identity of its Wolbachia endosymbiont with Wolbachia endosymbionts isolated from D. immitis, Rhipicephalus sanguineus and Aedes aegypti. The present study contributes to our understanding of the coexistence of D. immitis and Wolbachia endosymbiosis in dogs, and the findings may benefit the future prevention and control of dirofilariasis in dogs.

Programmed cell death pathways as targets for developing antifilarial drugs: Lessons from the recent findings

More than half a century has passed since the introduction of the National Filariasis Control Program; however, as of 2023, lymphatic filariasis (LF) still prevails globally, particularly in the tropical and subtropical regions, posing a substantial challenge to the objective of worldwide elimination. LF is affecting human beings and its economically important livestock leading to a crucial contributor to morbidities and disabilities. The current scenario has been blowing up alarms of attention to develop potent therapeutics and strategies having efficiency against the adult stage of filarial nematodes. In this context, the exploration of a suitable drug target that ensures lethality to macro and microfilariae is now our first goal to achieve. Apoptosis has been the potential target across all three stages of filarial nematodes viz. oocytes, microfilariae (mf) and adults resulting in filarial death after receiving the signal from the reactive oxygen species (ROS) and executed through intrinsic and extrinsic pathways. Hence, it is considered a leading target for developing antifilarial drugs. Herein, we have shown the efficacy of several natural and synthetic compounds/nanoformulations in triggering the apoptotic death of filarial parasites with little or no toxicity to the host body system.

Pharmacokinetics of Moxidectin combined with Albendazole or Albendazole plus Diethylcarbamazine for Bancroftian Filariasis

Moxidectin (MOX) is a milbemycin endectocide recently approved by the U.S. FDA for the treatment of onchocerciasis in persons at least 12 years of age. MOX has been shown to have a good safety profile in recent clinical trials. The efficacy of MOX for the treatment of lymphatic filariasis (LF) and its potential use in mass drug administration protocols for the elimination of LF is currently under evaluation. In the context of a clinical trial, we investigated the pharmacokinetics and drug interactions of a combination of MOX plus albendazole (ALB) with or without diethylcarbamazine (DEC) compared to ivermectin (IVM) plus ALB with or without DEC in the following four different treatment arms: (I) IVM (0.2mg/kg) plus DEC (6 mg/kg) and ALB (400mg); (II) IVM plus ALB; (III) MOX (8 mg) plus DEC and ALB; and (IV) MOX plus ALB. Drug concentrations were determined using validated liquid chromatography-mass spectrometric methods. Pharmacokinetic parameters were determined using standard non-compartmental analysis methods. Statistical analysis was performed using JMP software. Fifty-eight of 164 study participants (53 men and five women) were included with ages ranging from 18 to 63 yrs (mean = 37). MOX apparent oral clearance (Cl/F) ranged from 0.7 to 10.8 L/hr with Cmax values ranging from 20.8 to 314.5 ng/mL. The mean (range) area under the curve (AUC)0-∞ for MOX, 3405 ng*hr/mL (742-11376), and IVM 1906 ng*hr/mL (692-5900), varied over a ~15.3 and ~8.5-fold range, respectively. The geometric mean ratio for Cmax, AUC0-t, and AUC0-∞ were within the no-drug interaction range of 80-125% for all drugs. This indicates that the addition of MOX to ALB alone or ALB plus DEC for LF therapy did not alter the drug exposure of co-administered drugs compared to IVM combinations. Clinical Trial Registration: NCT04410406, https://clinicaltrials.gov/.

Evaluating the availability and quality of services for lymphatic filariasis morbidity in Ghana

BACKGROUND AND METHODOLOGY

In districts where lymphatic filariasis (LF) is endemic, the goal is to provide 100% geographical coverage of the essential package of care. Additionally, countries seeking elimination status must document the availability of services for lymphoedema and hydrocele in all endemic areas. To do this, the WHO recommends conducting assessments of the readiness and quality of services provided to identify service delivery and quality gaps. This study used the recommended WHO Direct Inspection Protocol (DIP), which consists of 14 core indicators related to LF case management, medicine and commodities, staff knowledge and patient tracking. The survey was administered in 156 health facilities across Ghana designated and trained to provide LF morbidity management services. Patient and health provider interviews were also conducted to assess challenges and feedback.

PRINCIPAL FINDINGS

The highest performing indicators across the 156 surveyed facilities were related to staff knowledge; 96.6% of health workers correctly identified two or more signs and symptoms. The lowest scoring indicators concerned medication availability, with the two lowest scoring indicators in the survey being availability of antifungals (26.28%) and antiseptics (31.41%). Hospitals performed best with an overall score of 79.9%, followed by health centers (73%), clinics (67.1%) and CHPS compounds (66.8%). The most commonly reported challenge from health worker interviews was lack of medications and supplies, followed by a lack of training or poor motivation.

CONCLUSIONS AND SIGNIFICANCE

The findings from this study can help the Ghana NTD Program identify areas of improvement as they seek to achieve LF elimination targets and continue to improve access to care for those with LF-related morbidity as part of overall health systems strengthening. Key recommendations include prioritizing refresher and MMDP training for health workers, ensuring reliable patient tracking systems, and integrating lymphatic filariasis morbidity management into the routine healthcare system to ensure medicine and commodity availably.

Population pharmacokinetic model of ivermectin in mass drug administration against lymphatic filariasis

BACKGROUND

Ivermectin (IVM) is a broad-spectrum anthelmintic drug used to treat diseases caused by filarial worms, such as onchocerciasis and lymphatic filariasis (LF). IVM is part of a triple-drug therapy used by the Mass Drug Administration (MDA) as a preventive strategy to eradicate LF in sub-Saharan Africa. The drug shows high variability in drug exposure in previous pharmacokinetic studies. This study aims to build a population pharmacokinetic (PopPK) model to identify and quantify the possible sources of the variability of IVM exposure after a single-oral dose in LF-infected subjects and healthy individuals.

METHODOLOGY / PRINCIPAL FINDINGS

In this analysis, 724 samples were collected from treatment-naïve Wuchereria bancrofti-infected (n = 32) and uninfected (n = 24) adults living in Côte d'Ivoire who had received one dose of IVM as a part of triple-drug therapy. PopPK analysis was conducted using Phoenix NLME 8.3 software. The Monte Carlo simulation based on the final model was performed to simulate drug exposure among different dosing groups (200 μg/kg, 18 mg, and 36 mg). A two-compartment model with zero-order dose input into the absorption compartment with a lag time function followed by first-order absorption and linear elimination best described the IVM's pharmacokinetic (PK) parameters. The final model identifies that the PK parameters of IVM are not affected by LF infection. Sex was a significant covariate on the peripheral volume of distribution (Vp/F, 53% lower in men than in women). IVM drug exposure shows linear pharmacokinetic behavior among the simulated dosing groups with similar drug exposure based on sex.

CONCLUSION/SIGNIFICANCE

We have developed a PopPk model to describe and identify possible sources of the variability of IVM exposure. To our knowledge, this is the first PopPK study of IVM in patients with LF.

TRIAL REGISTRATION

NCT02845713; NCT03664063.

Coverage and compliance of mass drug administration in lymphatic filariasis amidst the COVID-19 pandemic: A community based epidemiological study

Background

Despite the target of elimination of lymphatic filariasis by 2015, a few districts of West Bengal including Bankura district failed to achieve it. Under-coverage and unsupervised consumption of medicines during mass drug administration (MDA) campaign were implicated for the failure. Thereby, directly observed therapy (DOT) and mop up by repeated home visits for MDA were adopted.

Objective

The objective of this study is to assess the coverage of anti-filarial medicines distribution and rate of consumption as well as to find out the causes of nonconsumption.

Materials and Methods

A cross-sectional survey was conducted in three sub-centers each of three blocks and three wards of Bankura municipality of Bankura district, WB, India, selected through the stratified random sampling method. Information was collected interviewing inhabitants of the house hold selected through the systematic random sampling technique.

Results

Overall, appropriate medicine distribution was 82.9% with 95.3% of correct consumption of both medicines under supervision. 91.87% of the respondents were aware about Lymphatic filariasis (LF) of which 89.95% reported swelling of leg/foot/hand, 9.57% as pain, 6.22% fever, and 1.44% reported swelling of testis as symptoms of LF. Altogether 10.6% individual, who consumed any medicine (527), reported AEs, out of that 66.1%, 19.6%, and 14.3% complained of dizziness/headache, nausea/vomiting, and drowsiness, respectively, and 28.6% of them sought consultation with health workers.

Conclusion

Substantial supervised consumption in the form DOT in this round too leads to the fact that the effective coverage of MDA has reached the target. It seemed that some segment of the beneficiary is remaining as persistent noncomplaints. Mass mobilization for motivating this persistent defaulter section is the need of the hour.

Status of Lymphatic Filariasis Transmission after Two Additional Rounds of Filariasis Mass Drug Administration: A Case Study in Pekalongan City, Central Java, Indonesia

BACKGROUND: Lymphatic filariasis (LF) is a neglected tropical disease caused by mosquito-containing filarial worms Wuchereria bancrofti, Brugia malayi, and Brugia timori. World Health Organization (WHO) had set up the global program to interrupt transmission with mass drug administration and manage morbidity and prevent disability. AIM: This study aimed to determine the status of LF transmission in Pekalongan City after two additional rounds of mass drug administration. A cross-sectional study was conducted in Pekalongan City, Indonesia. METHOD: Three villages had been selected purposively as study sites: free, non-endemic, and endemic of LF as more than 600 finger blood samples were taken from study participants in the night between 21:00 and 01:00. Laboratory testing for microfilaria examination was conducted in Bendan and Bedono Public Health Center Pekalongan, Indonesia. Mosquitoes were collected in three areas of the study site from the middle of the night until the morning. Identification and biomolecular examination of caught mosquitoes used a polymerase chain reaction. Statistical analysis was made using IBM SPSS Statistics 26 software. RESULT: This research found two microfilaria positive samples from 600 finger blood samples examined (microfilariae rate: 0.33%). There were four positive reactions to filaria. The identified mosquito species consisted of Culex quinquefasciatus, Culex vashnui, and Aedes aegypti. Aedes aegypti was only confirmed filaria positive. CONCLUSION: A non-endemic village was only found one blood sample positive, but blood and mosquito sample positive were found in endemic villages. It seemed that LF transmission was still in running di endemic village in Pekalongan City.  

Crude protein fraction with high thioredoxin reductase (TrxR) enzyme activity from filarial parasite Setaria cervi counters lipopolysaccharide (LPS)-induced inflammation in macrophages

Host-parasite interaction has always been an area of interest to the parasite biologists. The complex immune interactions between the parasite and/or the parasite-derived products with the host immune cells determine the fate of the disease biology. Parasitic organisms are widely equipped with a vast array of protective machineries including antioxidant enzymes to withstand the hostile condition inside the host body. The reactive oxygen species (ROS) generated inside the host as a result of parasitic intervention can be endured by the parasite by their own tools to ensure their survival. One such antioxidant enzyme in the filarial parasite that plays a significant role in redox homeostasis, survivability and disease progression is the thioredoxin reductase (TrxR). Herein, we have projected a crude lysate of the bovine filarial parasite Setaria cervi enriched with high TrxR enzyme activity has the capacity to downregulate lipopolysaccharide (LPS)-induced inflammatory macrophages. TrxR-mediated inhibition of the TLR4-NF-κB axis resulting into downregulation of the pro-inflammatory cytokines with concomitant upregulation of the anti-inflammatory cytokines supports the filarial parasite to produce an anti-inflammatory milieu which ultimately promotes worm survivability inside the host and pathogenesis.

Lymphatic filariasis vaccine development: neglected for how long?

INTRODUCTION

Lymphatic filariasis (LF), also known as elephantiasis, has been recognized by the world health organization and the centers for disease control and prevention as one of the neglected tropical diseases. The huge prevalence and risk of manifestation to date reflect the poor management of this disease. The disease poses vast public health and socio-economic burdens and generates a dire need for the development of a prophylactic solution for mass administration.

AREAS COVERED

Vaccination has been a sought-out strategy for dealing with ever-evolving infectious diseases and can be duly tuned to become a cost effective means of disease control and eventual eradication. In this review, we highlight the epidemiology of LF with the current diagnosis and treatment modules. The need for the development of a potential vaccine candidates, and challenges are discussed. The evidence presented in this review aims to enlighten the readers regarding the essential factors governing LF and its management using prophylactic measures.

EXPERT OPINION

The complex nature of filarial parasites is evident from the absence of a single vaccine for LF. The development and selection of an appropriate preclinical model and its translation into clinical practice is deemed to be a major task needing in-depth evaluation to formulate an effective vaccine. Explorations of the existing vaccine platforms would serve to be an apt strategy in this direction.

Highlighting the Relevance of CD8+ T Cells in Filarial Infections

The T cell immune responses in filarial infections are primarily mediated by CD4+ T cells and type 2-associated cytokines. Emerging evidence indicates that CD8+ T cell responses are important for anti-filarial immunity, however, could be suppressed in co-infections. This review summarizes what we know so far about the activities of CD8+ T cell responses in filarial infections, co-infections, and the associations with the development of filarial pathologies.

Evolution of the monitoring and evaluation strategies to support the World Health Organization's Global Programme to Eliminate Lymphatic Filariasis

The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was established with the ambitious goal of eliminating LF as a public health problem. The remarkable success of the GPELF over the past 2 decades in carrying out its principal strategy of scaling up and scaling down mass drug administration has relied first on the development of a rigorous monitoring and evaluation (M&E) framework and then the willingness of the World Health Organization and its community of partners to modify this framework in response to the practical experiences of national programmes. This flexibility was facilitated by the strong partnership that developed among researchers, LF programme managers and donors willing to support the necessary research agenda. This brief review summarizes the historical evolution of the GPELF M&E strategies and highlights current research needed to achieve the elimination goal.

Progress in the elimination of lymphatic filariasis in the Western Pacific Region: successes and challenges

The Western Pacific Region is the largest and most diverse region in the world, made up of 37 countries and territories in the Pacific, Oceania and parts of Asia, with a population of more than 1.9 billion people stretching over an area from China and Mongolia in the north to New Zealand in the south. In 1999, 22 countries and territories in the Pacific joined together and launched the Pacific Programme to Eliminate Lymphatic Filariasis. Shortly after, the Global Programme to Eliminate Lymphatic Filariasis was launched in 2000. In 2004, 12 countries in the Asia subregion of the Western Pacific Region and Southeast Asian Region joined and developed the Mekong-Plus Strategic Plan for Elimination of Lymphatic Filariasis. Since then, significant efforts have been made by all endemic countries, with annual mass drug administration (MDA) as a principal strategy, through strong partnership with the WHO and other donors and partners. As a result, by the end of 2019, 10 of 22 endemic countries in the region, including 8 of 16 countries in the Pacific and 2 countries in the Asia subregion, achieved WHO validation for elimination of lymphatic filariasis (LF) as a public health problem. All the other countries are either progressing with post-MDA surveillance or accelerating efforts by adoption of the new triple drug therapy strategy and enhancement of MDA campaigns to tackle persistent transmission. Some 85% of the originally endemic implementation units have stopped MDA and the number of people requiring MDA for LF in the Western Pacific Region was reduced by 72% from 2000 to 2018. This paper reviews the progress, key success factors and remaining challenges and indicates the way forward to achieve LF elimination in the Western Pacific Region.

Assessing the Filariasis Causing Parasites in Adult Mosquitoes and the Vector Mosquito Larval Breeding in Selected Medical Officer of Health Areas in Gampaha District, Sri Lanka

The present study was conducted to determine the prevalence of filariasis causing parasites in adult mosquitoes and vector mosquito larval breeding in four Medical Officer of Health (MOH) areas in Gampaha district, Sri Lanka. Adult female mosquitoes at their resting places were collected using a prokopack aspirator operated twice a day from 7.00 am to 8.00 am and 8.00 pm to 9 pm in predetermined dates. Microfilarial worms in dissected mosquitoes were morphologically identified. Nine species of mosquitoes, namely, Culex quinquefasciatus, Cx. pipiens, Cx. fuscocephala, Cx. gelidus, Armigeres subalbatus, Mansonia uniformis, Ma. annulifera, Aedes aegypti, and Ae. Albopictus, were captured. A total of 1194 mosquito larvae were collected that belonged into three genera, namely, Culex (62.73%), Armigeres (25.62%), and Mansonia (11.64%), from blocked drains, polluted drains, blocked canals, large polluted water bodies, stagnant water bodies, marsh lands, rice field mudflats, and concrete pits. Large polluted water bodies (Shannon-Wiener diversity index/H' = 1.5591) were the most diversed habitat type. In breeding water, average pH mainly lied in between 6 and 8 and average dissolved oxygen ranged from 3 to 7 mg/L. Cx. quinquefasciatus and Armigeres subalbatus adult female mosquitoes captured from Kelaniya MOH area were positive for microfilariae and were identified as Wuchereria bancrofti and Dirofilaria repens, respectively. This study concludes possible lymphatic filariasis situation is in extremely very low level persistent (0.06%) where transmission cannot be sustained and is restricted only to isolated pockets in the study area. The zoonotic strains of filariasis causing subcutaneous dirofilariasis in humans by Dirofilaria repens is continuing to survive due to the presence of stray dogs that serve as reservoir hosts.

Safety and Tolerability of Mass Diethylcarbamazine and Albendazole Administration for the Elimination of Lymphatic Filariasis in Kenya: An Active Surveillance Study

Preventive chemotherapy with diethylcarbamazine citrate (DEC) and albendazole (ALB) is the core intervention strategy to eliminate lymphatic filariasis (LF). We conducted a large-scale prospective active safety surveillance study to identify the incidence, type, severity, and risk factors for adverse events (AEs) following mass drug administration (MDA) of single-dose DEC and ALB in 10,010 participants from Kilifi County, Kenya. AEs were actively monitored and graded at 24 h, 48 h, and on day 7 Post-MDA. Out of 10,010 enrolled study participants, 1621 participants reported a total of 3102 AEs during a seven-day follow-up. The cumulative incidence of AEs was 16.2% (95% CI, 15.5–16.9%). The proportion of participants who experienced one, two, or ≥three types of AEs was 9.2%, 4.6%, 2.4%, respectively. AEs were mild (87.3%), moderate (12.4%), and severe (0.3%) and resolved within 72 h. The five most common AEs were dizziness (5.9%), headache (5.6%), loss of appetite (3.3%), fever (2.9%), and drowsiness (2.6%). Older age, taking concurrent medications, ≥three tablets of DEC, and type of meal taken before MDA were significant predictors of AEs. One in six participants experienced systemic mild-to-moderate severity grading and transient AEs. DEC and ALB co-administration for the elimination of LF is generally safe and well-tolerated.

Community-directed distributors-The "foot soldiers" in the fight to control and eliminate neglected tropical diseases

The neglected tropical diseases (NTDs) affect hundreds of millions of people, predominantly in rural, often difficult-to-access areas, poorly served by national health services. Here, we review the contributions of 4.8 million community-directed distributors (CDDs) of medicines over 2 decades in 146,000 communities in 27 sub-Saharan African countries to control or eliminate onchocerciasis and lymphatic filariasis (LF). We examine their role in the control of other NTDs, malaria, HIV/AIDS interventions, immunisation campaigns, and support to overstretched health service personnel. We are of the opinion that CDDs as community selected, trained, and experienced “foot soldiers,” some of whom were involved in the Ebola outbreak responses at the community level in Liberia, if retrained, can assist community leaders and support health workers (HWs) in the ongoing Coronavirus Disease 2019 (COVID-19) crisis. The review highlights the improved treatment coverage where there are women CDDs, the benefits and lessons from the work of CDDs, their long-term engagement, and the challenges they face in healthcare delivery. It underscores the value of utilising the CDD model for strong community engagement and recommends the model, with some review, to hasten the achievement of the NTD 2030 goal and assist the health system cope with evolving epidemics and other challenges. We propose that, based on the unprecedented progress made in the control of NTDs directly linked to community engagement and contributions of CDDs “foot soldiers,” they deserve regional and global recognition. We also suggest that the World Health Organization (WHO) and other international stakeholders promote policy and guidance for countries to adapt this model for the elimination of NTDs and to strengthen national health services. This will enhance the accomplishment of some Sustainable Development Goals (SDGs) by 2030 in sub-Saharan Africa.

Community-directed distributors (CDDs), sometimes known as community health workers (CHWs), have proved to be critical in the delivery of medicines and other tools for the control of neglected tropical diseases (NTDs), prevention of malaria, and other beneficial health interventions. The distributors are the unsung heroes and heroines without whom the health of hundreds of thousands of communities in rural Africa would be worse than it is today. In this paper, we document more than 2 decades (1997–2019) of the contributions of 146,000 communities and 4.8 million CDDs of medicines for NTDs, unpaid or minimally compensated, some have provided 18 years of uninterrupted service. We report on the burden of work and their perspectives of the challenges involved in mass drug administration (MDA) across 27 countries in sub-Saharan Africa. We suggest that they have not been adequately recognised and that harnessing such community human resources could contribute to improving health system’s responses to the ongoing Coronavirus Disease 2019 (COVID-19) crisis. We recommend policy measures for a wider application of existing networks of CDDs by countries’ health systems to consolidate and accelerate the achievements made as well as for the attainment of the goals set forth in the newly developed World Health Organization (WHO) NTD Roadmap.

Drugs that target early stages of Onchocerca volvulus: A revisited means to facilitate the elimination goals for onchocerciasis

Several issues have been identified with the current programs for the elimination of onchocerciasis that target only transmission by using mass drug administration (MDA) of the drug ivermectin. Alternative and/or complementary treatment regimens as part of a more comprehensive strategy to eliminate onchocerciasis are needed. We posit that the addition of “prophylactic” drugs or therapeutic drugs that can be utilized in a prophylactic strategy to the toolbox of present microfilaricidal drugs and/or future macrofilaricidal treatment regimens will not only improve the chances of meeting the elimination goals but may hasten the time to elimination and also will support achieving a sustained elimination of onchocerciasis. These “prophylactic” drugs will target the infective third- (L3) and fourth-stage (L4) larvae of Onchocerca volvulus and consequently prevent the establishment of new infections not only in uninfected individuals but also in already infected individuals and thus reduce the overall adult worm burden and transmission. Importantly, an effective prophylactic treatment regimen can utilize drugs that are already part of the onchocerciasis elimination program (ivermectin), those being considered for MDA (moxidectin), and/or the potential macrofilaricidal drugs (oxfendazole and emodepside) currently under clinical development. Prophylaxis of onchocerciasis is not a new concept. We present new data showing that these drugs can inhibit L3 molting and/or inhibit motility of L4 at IC₅₀ and IC₉₀ that are covered by the concentration of these drugs in plasma based on the corresponding pharmacological profiles obtained in human clinical trials when these drugs were tested using various doses for the therapeutic treatments of various helminth infections.

High concentrations of membrane-fed ivermectin are required for substantial lethal and sublethal impacts on Aedes aegypti

Background

With widespread insecticide resistance in mosquito vectors, there is a pressing need to evaluate alternatives with different modes of action. Blood containing the antihelminthic drug ivermectin has been shown to have lethal and sub-lethal effects on mosquitoes. Almost all work to date has been on Anopheles spp., but impacts on other anthropophagic vectors could provide new options for their control, or additional value to anti-malarial ivermectin programmes.

Methods

Using dose-response assays, we evaluated the effects of ivermectin delivered by membrane feeding on daily mortality (up to 14 days post-blood feed) and fecundity of an Indian strain of Aedes aegypti.

Results

The 7-day lethal concentration of ivermectin required to kill 50% of adult mosquitoes was calculated to be 178.6 ng/ml (95% confidence intervals 142.3–218.4) for Ae. aegypti, which is much higher than that recorded for Anopheles spp. in any previous study. In addition, significant effects on fecundity and egg hatch rates were only recorded at high ivermectin concentrations (≥ 250 ng/ul).

Conclusion

Our results suggest that levels of ivermectin present in human blood at current dosing regimes in mass drug administration campaigns, or even those in a recent higher-dose anti-malaria trial, are unlikely to have a substantial impact on Ae. aegypti. Moreover, owing to the strong anthropophagy of Ae. aegypti, delivery of higher levels of ivermectin in livestock blood is also unlikely to be an effective option for its control. However, other potential toxic impacts of ivermectin metabolites, accumulation in tissues, sublethal effects on behaviour, or antiviral action might increase the efficacy of ivermectin against Ae. aegypti and the arboviral diseases it transmits, and require further investigation.

Assessment of the impact of morbidity management and disability prevention for lymphatic filariasis on the disease burden in villupuram district of Tamil Nadu, India

Background:

The global program to eliminate lymphatic filariasis (GPELF) was started in 2003 with two strategies: the mass drug administration (MDA) to interrupt disease transmission and the morbidity management and disability prevention (MMDP) to provide the basic hygienic care to filariasis lymphedema patients. Among the two strategies, the MDA is well advanced and got the desired results, but the MMDP is lagging due to poor execution.

Objectives:

To assess the awareness of MMDP and ongoing morbidity management practices by lymphedema patients and to estimate the impacts of the MMDP on the prevalence and severity of lymphedema.

Materials and Methods:

This study was conducted among 100 lymphedema patients in 7 filariasis endemic villages of Villupuram district, Tamil Nadu, India through interviews using a structured, pretested questionnaire. The grading and adenolymphangitis (ADL) attack determination were done by a clinician. The impact was assessed in terms of changes in the lymphedema grades, frequency of ADL attacks, and changes in the burden.

Results:

Of the 100 patients, 70% were aware of the program and among them, only 48% were practising MMDP regularly (i.e. two times per day). The majority of them (80%) were taking treatment during ADL attacks. The overall lymphedema grades reversal and progression were observed in 13% and 52% of cases, respectively.

Conclusion:

This study has revealed that the second arm of the GPELF, “MMDP” has not yielded the desired results as evidenced by the incidence of frequent ADL attacks and advancement of lymphedema grades.

The role of medicine donations in the global programme for the elimination of lymphatic filariasis

World Health Assembly Resolution 50.29, adopted in 1997, committed the World Health Organization (WHO) and its member states to eliminate lymphatic filariasis (LF) as a public health problem. In 2000, to support this ambitious goal and the health ministries in the >70 LF-endemic countries, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) was created. The resulting WHO elimination strategy consists of two main components: to stop the spread of infection by interrupting transmission and to alleviate the suffering of affected populations (by controlling morbidity). The GPELF has brought together a broad global partnership of public and private actors, including three pharmaceutical companies with headquarters in three different continents. The medicine donations programmes from GlaxoSmithKline, MSD (trade name of Merck & Co., Kenilworth, NJ, USA) and Eisai have enabled significant achievements during the first 20 y of the GPELF and are positioned to provide essential contributions to the GPELF's goals for the next decade. As we celebrate the progress towards LF elimination during the GPELF's first 20 y, this article reflects on the factors that led to the creation of the three donation programmes, the contributions these programmes have made and some lessons learned along the way. We close by emphasizing our continued commitments to LF elimination and perspectives on the next decade.

The role of non-governmental development organizations in the implementation of lymphatic filariasis programmes

The Lymphatic Filariasis (LF) Non-governmental Development Organization (NGDO) Network was established to engage in supporting both international and national LF elimination agendas covering areas such as assisting ministries of health as an on-the-ground link between communities and programmes, which additionally gives the Network members an important voice from the field at international meetings; playing key roles in programme evolution (especially helping to both scale up and scale down mass drug administration [MDA] as elimination thresholds are met); having a role in operational research and developing new programme delivery models that can be taken to scale (such as linkages with other disease programmes and approaches to morbidity management and disability prevention); developing advocacy and policy approaches with other partners; convening other important stakeholders (academic, technical, programmatic and funding); mobilizing financial and technical resources to support programmes; supporting national human resource capacity building to catalyse national ownership of LF programmes; providing leadership in LF governance structures and working in areas of conflict to ensure that everybody in LF-endemic areas enjoys treatment services. Three case studies will illustrate the roles identified for NGDOs in LF programmes covering development of operational research, policy and advocacy linkage between LF and malaria programmes; launching LF morbidity management projects and NGDO's ability to work and deliver LF services in areas of conflict. In addition, the case studies will show the role of NGDOs in mobilising financial and technical resources that support national human resources, leading to national ownership of programmes. Conclusions will be drawn on the role of NGDOs in the Global Alliance for LF elimination and the need for continued partnerships to reach programme goals.

New Molecular Data on Filaria and its Wolbachia from Red Howler Monkeys (Alouatta macconnelli) in French Guiana-A Preliminary Study

Previous studies have reported filarial parasites of the genus Dipetalonema and Mansonella from French Guiana monkeys, based on morphological taxonomy. In this study, we screened blood samples from nine howler monkeys (Alouatta macconnelli) for the presence of filaria and Wolbachia DNA. The infection rates were 88.9% for filaria and 55.6% for wolbachiae. The molecular characterization, based on the 18S gene of filariids, revealed that A. macconnelli are infected with at least three species (Mansonella sp., Brugia sp. and an unidentified Onchocercidae species.). Since the 18S and cox1 generic primers are not very effective at resolving co-infections, we developed ITS genus-specific PCRs for Mansonella and Brugia genus. The results revealed coinfections in 75% of positives. The presence of Mansonella sp. and Brugia sp. was also confirmed by the 16S phylogenetic analysis of their associated Wolbachia. Mansonella sp., which close to the species from the subgenus Tetrapetalonema encountered in New World Monkeys, while Brugia sp. was identical to the strain circulating in French Guiana dogs. We propose a novel ITS1Brugia genus-specific qPCR. We applied it to screen for Brugia infection in howler monkeys and 66.7% were found to be positive. Our finding highlights the need for further studies to clarify the species diversity of neotropics monkeys by combining molecular and morphological features. The novel Brugia genus-specific qPCR assays could be an effective tool for the surveillance and characterization of this potential zoonosis.

Coexistent malaria and filaria among the febrile patients attending for malaria diagnosis: A clinic-based study

CONTEXT

Both malaria and lymphatic filariasis (LF) are mosquito-borne diseases caused by protozoal and nematode parasites, respectively, and are serious public health problem in India. Although the vectors of the diseases are different, they can coexist in favorable conditions. Fever is the common symptom for both the diseases, but the emphasis is given for diagnosis and treatment of malaria due to its life-threatening severity, LF remained neglected. Detection and management of microfilaria are equally important. During the diagnosis of malaria, a few microfilaria were detected, which prompted us to undertake this study with following objectives.

OBJECTIVES

The objective of the study was to determine the incidence of microfilaremia among the febrile patients attending for malaria diagnosis.

SUBJECTS AND METHODS

Thick and thin peripheral blood smears from all patients attended were examined following Giemsa staining. Different malarial indexes were analyzed.

RESULTS

Out of 8681 patients examined, 1778 were positive for Plasmodium vivax and 328 for Plasmodium falciparum with a slide positivity rate 20.48%. Twenty-six patients were positive for microfilaria of Wuchereria bancroftii among which five were coinfected with P. vivax and one with P. falciparum. Most of the microfilaria-positive patients were adult and originally from northern districts of Bihar.

CONCLUSIONS

High incidence of microfilaria among febrile patients attending for malaria is alarming for urban Kolkata. Although the patients were originally from Bihar, they are staying in Kolkata for a long time, might be a source for transmission. Epidemiological study by collecting night blood samples and entomological survey is highly suggestive to explore local transmission if any.

Designing antifilarial drug trials using clinical trial simulators

Lymphatic filariasis and onchocerciasis are neglected tropical diseases (NTDs) targeted for elimination by mass (antifilarial) drug administration. These drugs are predominantly active against the microfilarial progeny of adult worms. New drugs or combinations are needed to improve patient therapy and to enhance the effectiveness of interventions in persistent hotspots of transmission. Several therapies and regimens are currently in (pre-)clinical testing. Clinical trial simulators (CTSs) project patient outcomes to inform the design of clinical trials but have not been widely applied to NTDs, where their resource-saving payoffs could be highly beneficial. We demonstrate the utility of CTSs using our individual-based onchocerciasis transmission model (EPIONCHO-IBM) that projects trial outcomes of a hypothetical macrofilaricidal drug. We identify key design decisions that influence the power of clinical trials, including participant eligibility criteria and post-treatment follow-up times for measuring infection indicators. We discuss how CTSs help to inform target product profiles.

Drugs for filariases are under development and clinical trial simulators could help to inform the design of clinical trials. Here, Walker et al. use an individual-based onchocerciasis transmission model to project trial outcomes of a hypothetical macrofilaricidal drug, resolving key design choices.

Prevalence and Correlates of Lymphatic Filariasis Infection and Its Morbidity Following Mass Ivermectin and Albendazole Administration in Mkinga District, North-Eastern Tanzania

Lymphatic filariasis (LF) is a neglected tropical disease targeted for elimination as public health problem through morbidity management and preventive annual mass drug administration (MDA). This cross-sectional community-based surveillance assessed the prevalence and correlates of LF infection in Mkinga district, Tanga-region, Tanzania. A total of 4115 individuals (49.7% males, 35.2% children) were screened for circulating filarial antigens (CFA), microfilaremia (mf) and disease manifestations in 15 villages between November 2018 and January 2019. MDA uptake in the previous year was assessed. Overall prevalence of CFA-positivity was 5.8% (239/4115; 95% CI: 5.1–6.6), with significant heterogeneity between villages (range 1.2% to 13.5%). CFA-positivity was higher in males (8.8%) than females (3.3%), and correlated with increasing age (p < 0.001). Prevalence of mf among CFA-positives was 5.2%. Only 60% of eligible inhabitants in the study area took MDA in the previous year, and CFA-positivity was 2-fold higher in those who missed MDA (p < 0.0001). Prevalence of scrotal enlargement, hydrocele, arms or legs swelling, lymphoedema and lymphadenopathy was 6.4%, 3.7%, 1.35%, 1.2% and 0.32%, respectively. Compared to baseline data, 16 years of MDA intervention significantly reduced LF transmission and morbidity, although the intended elimination target of <1% mf and <2% antigenemia to level where recrudescence is unlikely to occur by the year 2020 may not be attained. The finding of hotspots with ongoing transmission calls for intensified control measures.

Elimination of diurnally sub-periodic Wuchereria bancrofti in Andaman and Nicobar Islands, India, using mass DEC-fortified salt as a supplementary intervention to MDA

Feasibility of implementing a DEC-fortified (DEC at 0.2% w/w and iodine) salt strategy to hasten elimination of diurnally sub-periodic Wuchereria bancrofti (DspWB) from the lone foci in Nancowry islands, Nicobar district, India, was assessed. This is a two-arm community-based study: one arm (12 villages, population 2936) received double fortified salt along with annual mass drug administration (MDA) of DEC plus albendazole (DEC-salt+MDA-arm), and another (14 villages; population 4840) received MDA under the National Filaria Elimination Programme. DEC salt was distributed on camp mode supplemented by door delivery. Monthly survey was carried out in fixed and random households to assess the coverage, usage of DEC salt and DEC content. The impact on prevalence of mf at community level and antigenaemia among children was assessed. A total of 21 metric tonnes of free-flow DEC salt manufactured by Tamil Nadu Salt Corporation, India, was distributed for 1 year. In the DEC-salt+MDA-arm, > 90% of the households received and used the DEC salt. DEC was within therapeutic range (0.2-0.32% w/w) in the samples collected from kitchens. Community mf prevalence reduced from 2.27 to 0.14% in the DEC-salt-arm (< 1% in all the villages) and 1.26 to 0.74% (> 1% in 4 out of 14 villages) in the MDA-arm. Ag prevalence reduced to zero from 1.0 (DEC-salt+MDA-arm) and 6.3% (MDA-arm) in 2-3 years old, 1.2 and 3.6% from 2.9 in the DEC-salt-arm and 4.5% in the MDA-arm among 6-7 years old. It was feasible to deliver DEC-fortified salt covering > 90% of the households with compliance reaching the elimination target in the islands.

Macrofilaricidal Benzimidazole-Benzoxaborole Hybrids as an Approach to the Treatment of River Blindness: Part 2. Ketone Linked Analogs

The optimization of a series of benzimidazole–benzoxaborole hybrid molecules linked via a ketone that exhibit good activity against Onchocerca volvulus, a filarial nematode responsible for the disease onchocerciasis, also known as river blindness, is described. The lead identified in this series, 21 (AN15470), was found to have acceptable pharmacokinetic properties to enable an evaluation following oral dosing in an animal model of onchocerciasis. Compound 21was effective in killing worms implanted in Mongolian gerbils when dosed orally as a suspension at 100 mg/kg/day for 14 days but not when dosed orally at 100 mg/kg/day for 7 days.

Macrofilaricidal Benzimidazole-Benzoxaborole Hybrids as an Approach to the Treatment of River Blindness: Part 1. Amide Linked Analogs

A series of benzimidazole–benzoxaborole hybrid molecules linked via an amide linker are described that exhibit good in vitro activity against Onchocerca volvulus, a filarial nematode responsible for the disease onchocerciasis, also known as river blindness. The lead identified in this series, 8a (AN8799), was found to have acceptable pharmacokinetic properties to enable evaluation in animal models of human filariasis. Compound 8a was effective in killing Brugia malayi, B. pahangi, and Litomosoides sigmodontis worms present in Mongolian gerbils when dosed subcutaneously as a suspension at 100 mg/kg/day for 14 days but not when dosed orally at 100 mg/kg/day for 28 days. The measurement of plasma levels of 8a at the end of the dosing period and at the time of sacrifice revealed an interesting dependence of activity on the extended exposure for both 8a and the positive control, flubendazole.

Applications of Recombinant Monoclonal Antibodies against Filarial Antigen Proteins

This study investigated the applications of recombinant monoclonal antibodies (rmAbs) produced against two recombinant filarial proteins of diagnostic value. Ab5B and Ab3A were produced against recombinant BmSXP, and Ab4 and Ab4-fragment crystallizable (Fc) against recombinant BmR1. Ab5B and Ab4-Fc were found to be useful as quality control (QC) reagents for two commercial rapid test kits, such as Brugia Rapid^TM and BLF Rapid^® (Reszon Diagnostics International Sdn. Bhd., 47600 Subang Jaya, Selangor, Malaysia), respectively. The two rmAbs reacted positively with the corresponding recombinant proteins lined on the nitrocellulose strips of the cassette tests, thus may replace or reduce the need for patient serum samples as positive controls for QC of the commercial kits. They were also successfully conjugated to gold nanoparticles and reacted positively with the test lines containing the corresponding recombinant proteins when directly applied to the cassette tests. The gold-conjugated reagents can be used to confirm the antigenicity of test lines after the storage of the rapid tests for a prolonged period or under unfavorable conditions. Furthermore, Ab5B and Ab3A were shown to be able to capture the target recombinant proteins through immunoaffinity purification, enabling their use for applications that need very highly purified proteins. In conclusion, this study demonstrated several potential uses of rmAb proteins produced against recombinant filarial proteins.

Genomic Epidemiology in Filarial Nematodes: Transforming the Basis for Elimination Program Decisions

Onchocerciasis and lymphatic filariasis are targeted for elimination, primarily using mass drug administration at the country and community levels. Elimination of transmission is the onchocerciasis target and global elimination as a public health problem is the end point for lymphatic filariasis. Where program duration, treatment coverage, and compliance are sufficiently high, elimination is achievable for both parasites within defined geographic areas. However, transmission has re-emerged after apparent elimination in some areas, and in others has continued despite years of mass drug treatment. A critical question is whether this re-emergence and/or persistence of transmission is due to persistence of local parasites-i.e., the result of insufficient duration or drug coverage, poor parasite response to the drugs, or inadequate methods of assessment and/or criteria for determining when to stop treatment-or due to re-introduction of parasites via human or vector movement from another endemic area. We review recent genetics-based research exploring these questions in Onchocerca volvulus, the filarial nematode that causes onchocerciasis, and Wuchereria bancrofti, the major pathogen for lymphatic filariasis. We focus in particular on the combination of genomic epidemiology and genome-wide associations to delineate transmission zones and distinguish between local and introduced parasites as the source of resurgence or continuing transmission, and to identify genetic markers associated with parasite response to chemotherapy. Our ultimate goal is to assist elimination efforts by developing easy-to-use tools that incorporate genetic information about transmission and drug response for more effective mass drug distribution, surveillance strategies, and decisions on when to stop interventions to improve sustainability of elimination.

The importance of vector control for the control and elimination of vector-borne diseases

Vector-borne diseases (VBDs) such as malaria, dengue, and leishmaniasis exert a huge burden of morbidity and mortality worldwide, particularly affecting the poorest of the poor. The principal method by which these diseases are controlled is through vector control, which has a long and distinguished history. Vector control, to a greater extent than drugs or vaccines, has been responsible for shrinking the map of many VBDs. Here, we describe the history of vector control programmes worldwide from the late 1800s to date. Pre 1940, vector control relied on a thorough understanding of vector ecology and epidemiology, and implementation of environmental management tailored to the ecology and behaviour of local vector species. This complex understanding was replaced by a simplified dependency on a handful of insecticide-based tools, particularly for malaria control, without an adequate understanding of entomology and epidemiology and without proper monitoring and evaluation. With the rising threat from insecticide-resistant vectors, global environmental change, and the need to incorporate more vector control interventions to eliminate these diseases, we advocate for continued investment in evidence-based vector control. There is a need to return to vector control approaches based on a thorough knowledge of the determinants of pathogen transmission, which utilise a range of insecticide and non-insecticide-based approaches in a locally tailored manner for more effective and sustainable vector control.

Advances in Vaccine Development for Human Lymphatic Filariasis

According to the World Health Organization, over 880 million people are currently at risk of acquiring lymphatic filariasis (LF) in over 52 countries worldwide. Current approaches to control LF by 2020 are short of the anticipated goal. Several studies suggest the existence of protective immunity against LF in humans. Thus, it is possible to develop a prophylactic vaccine against LF in humans. Several potential vaccine candidates were identified and tested for their potential against LF. To date, preclinical studies suggest that it is possible to develop a prophylactic vaccine against LF. Much work needs to be done, but it is clear that a prophylactic vaccine, combined with targeted chemotherapy, is critically required for eliminating LF worldwide.

Assessment of transmission in areas of uncertain endemicity for lymphatic filariasis in Brazil

BACKGROUND

The objective of the Global Program to Eliminate Lymphatic Filariasis (GPELF) is to phase out this endemic disease as a public health problem by 2020. Validation of elimination is obtained from the World Health Organization through evidence of non-transmission in countries that have already been subjected to mass drug administration (MDA) and in places adjoining these endemic areas. While three municipalities in Brazil have completed MDA, the epidemiological situation remains uncertain in nine adjoining municipalities. To determine the epidemiological status, this study was to perform a review of the literature and a school-based survey to describe the past and recent endemicity of lymphatic filariasis (LF) theses nine municipalities in Brazil.

METHODOLOGY/PRINCIPLE FINDINGS

For review of the literature, both formal and informal literature sources were accessed since the first reports of filariasis in the Metropolitan Region of Recife, Brazil. We conducted a school-based survey in 2016 using immunochromatographic card tests (ICTs) among schoolchildren aged 6-10 years living in nine municipalities contiguous with the endemic areas in which MDA was conducted. Our review of the literature identified eight studies involving surveys demonstrating that microfilariae had been circulating in eight of the municipalities since 1967, with a low prevalence of microfilaremia, isolated autochthonous cases, and treatment of individual cases. The school-based survey included 17,222 children in 185 urban schools in the nine areas of Brazil with uncertain endemicity. One child affected by allochthonous transmission was antigen positive based on ICT and lived in a municipality adjacent to Recife; this child's family came from Recife, but no other case was diagnosed within the family.

CONCLUSIONS/SIGNIFICANCE

The study results suggest that there is no transmission of LF in the municipalities investigated. However, these areas have population migration and socioenvironmental conditions favorable to mosquito breeding grounds; therefore, surveillance is strongly recommended in these areas.

Transcriptomic analysis of insecticide resistance in the lymphatic filariasis vector Culex quinquefasciatus

Culex quinquefasciatus plays an important role in transmission of vector-borne diseases of public health importance, including lymphatic filariasis (LF), as well as many arboviral diseases. Currently, efforts to tackle C. quinquefasciatus vectored diseases are based on either mass drug administration (MDA) for LF, or insecticide-based interventions. Widespread and intensive insecticide usage has resulted in increased resistance in mosquito vectors, including C. quinquefasciatus. Herein, the transcriptome profile of Ugandan bendiocarb-resistant C. quinquefasciatus was explored to identify candidate genes associated with insecticide resistance. High levels of insecticide resistance were observed for five out of six insecticides tested, with the lowest mortality (0.97%) reported to permethrin, while for DDT, lambdacyhalothrin, bendiocarb and deltamethrin the mortality rate ranged from 1.63-3.29%. Resistance to bendiocarb in exposed mosquitoes was marked, with 2.04% mortality following 1 h exposure and 58.02% after 4 h. Genotyping of the G119S Ace-1 target site mutation detected a highly significant association (p < 0.0001; OR = 25) between resistance and Ace1-119S. However, synergist assays using the P450 inhibitor PBO, or the esterase inhibitor TPP resulted in markedly increased mortality (to ≈80%), suggesting a role of metabolic resistance in the resistance phenotype. Using a novel, custom 60 K whole-transcriptome microarray 16 genes significantly overexpressed in resistant mosquitoes were detected, with the P450 Cyp6z18 showing the highest differential gene expression (>8-fold increase vs unexposed controls). These results provide evidence that bendiocarb resistance in Ugandan C. quinquefasciatus is mediated by both target-site mechanisms and over-expression of detoxification enzymes.

Molecular Analysis of Canine Filaria and Its Wolbachia Endosymbionts in Domestic Dogs Collected from Two Animal University Hospitals in Bangkok Metropolitan Region, Thailand

Canine filariasis is caused by several nematode species, such as Dirofilaria immitis, Dirofilaria repens, Brugia pahangi, Brugia malayi, and Acanthocheilonema reconditum. Zoonotic filariasis is one of the world's neglected tropical diseases. Since 2000, the World Health Organization (WHO) has promoted a global filarial eradication program to eliminate filariasis by 2020. Apart from vector control strategies, the infection control of reservoir hosts is necessary for more effective filariasis control. In addition, many studies have reported that Wolbachia is necessary for the development, reproduction, and survival of the filarial nematode. Consequently, the use of antibiotics to kill Wolbachia in nematodes has now become an alternative strategy to control filariasis. Previously, a case of subconjunctival dirofilariasis caused by Dirofilaria spp. has been reported in a woman who resides in the center of Bangkok, Thailand. Therefore, our study aimed to principally demonstrate the presence of filarial nematodes and Wolbachia bacteria in blood collected from domestic dogs from the Bangkok Metropolitan Region, Thailand. A total of 57 blood samples from dogs with suspected dirofilariasis who had visited veterinary clinics in Bangkok were collected. The investigations for the presence of microfilaria were carried out by using both microscopic and molecular examinations. PCR was used as the molecular detection method for the filarial nematodes based on the COI and ITS1 regions. The demonstration of Wolbachia was performed using PCR to amplify the FtsZ gene. All positive samples by PCR were then cloned and sequenced. The results showed that the filarial nematodes were detected in 16 samples (28.07%) using microscopic examinations. The molecular detection of filarial species using COI-PCR revealed that 50 samples (87.72%) were positive; these consisted of 33 (57.89%), 13 (22.81%), and 4 (7.02%) samples for D. immitis, B. pahangi, and B. malayi, respectively. While the ITS1-PCR showed that 41 samples (71.93%) were positive-30 samples (52.63%) were identified as containing D. immitis and 11 samples (19.30%) were identified to have B. pahangi, whereas B. malayi was not detected. Forty-seven samples (82.45%) were positive for Wolbachia DNA and the phylogenetic tree of all positive Wolbachia was classified into the supergroup C clade. This study has established fundamental data on filariasis associated with Wolbachia infection in domestic dogs in the Bangkok Metropolitan Region. An extensive survey of dog blood samples would provide valuable epidemiologic data on potential zoonotic filariasis in Thailand. In addition, this information could be used for the future development of more effective prevention and control strategies for canine filariasis in Thailand.

In Vitro and In Vivo Antifilarial Activity of Standardized Extract of Calotropis procera Flowers against Brugia malayi

BACKGROUND

Lymphatic filariasis (LF) is a parasitic disease that causes permanent disability (elephantiasis). Currently used antifilarial drugs are failing to control LF and there is resurgence in some areas. Looking for new antifilarial leads, we found that Calotropis procera plant parts have been used in traditional medicine for alleviating elephantiasis but the antifilarial activity is not known.

OBJECTIVE

In the present study, the antifilarial activity of ethanolic extract (A001) and its hexane fraction (F001) of C. procera flowers was investigated using the human filarial parasite Brugia malayi.

METHODS

A001 and F001 were tested for antifilarial activity using motility and 3-(4,5-dimethylthiazol-2- yl)-2,5 diphenyltetrazolium bromide (MTT) assays (in vitro) and in the rodent models B. malayi- Meriones unguiculatus and B. malayi-Mastomys coucha. In the rodent models, A001 and F001 were administered orally for 5 consecutive days, and the adult worm burden and course of microfilaraemia were determined.

RESULTS

Both A001 and F001 showed microfilaricidal and macrofilaricidal activity in vitro. In animal models, A001 killed ~49-54% adult worms. In M. coucha model, F001 killed 12-60% adult worms in a dose (125-500 mg/kg) dependent manner; A001 and F001 suppressed microfilaraemia till days 91 and 35 post initiation of treatment, respectively. HPTLC revealed 0.61% lupeol, 0.50% β-sitosterol and 1.50% triacontanol in F001.

CONCLUSION

Flowers of C. procera have definite microfilaricidal and macrofilaricidal activities. Whether this activity is due to lupeol, β-sitosterol and triacontanol found in the hexane fraction remains to be investigated. This is the first report on the antifilarial efficacy of flowers of the plant C. procera.

Evaluation of lymphatic filariasis in endemic area of Brazil where mass drug administration is not required

Mass drug administration (MDA) is the main counter-transmission strategy of the Global Programme to Eliminate Lymphatic Filariasis. In endemic countries, there are areas where MDA is not required. However, there is no standard approach in these areas, and studies are important to evaluate the epidemiological status. This study aimed to investigate lymphatic filariasis and strategies developed for its control in an area where MDA is not required. Together with the 2018 morbidity evaluation, a survey was conducted using point-of-care immunochromatographic test-AD12 tests for diagnostic screening in an area where MDA is not required. The methodology also included desk research based on Health Department reports of the control activities for lymphatic filariasis during 2003-2016. Among the 934 cases investigated in 2018, there was a 0.64% prevalence of circulating filarial antigen positive, comprising five adults and one 2-year-old child. Six patients aged 39-63 years had filarial disease. Fourteen surveys have already been conducted as control activities, and since 2009, there have been no positive cases. This study showed that the prevalence of antigenemia decreased from 2.97% in 2003 to 0.64% in 2018. Moreover, the transmission of filariasis infection was under control in this area. Our study provides insights into the surveillance phase by identifying areas of low transmission and where MDA is not required. Although we have not identified cases of filarial infection, there is a need to provide services that will provide assist those already affected with morbidity and help reduce and prevent disability.

Systematic sampling of adults as a sensitive means of detecting persistence of lymphatic filariasis following mass drug administration in Sri Lanka

Background

Sri Lanka’s Anti-Filariasis Campaign conducted 5 annual rounds of mass drug administration (MDA) with diethylcarbamazine (DEC) plus albendazole to eliminate lymphatic filariasis (LF) in all endemic districts between 2002 and 2006. Post-MDA surveillance has consistently documented Wuchereria bancrofti microfilaremia (Mf) rates below 1% in all sentinel and spot check sites since that time, and all implementation units easily satisfied WHO’s target for school-based transmission assessment surveys (school-TAS) in 2013. However, more detailed studies have identified foci of persistent infection in the large coastal evaluation unit (EU) (population about 0.6 million) in Galle district. Therefore, the purpose of this study was to assess the sensitivity and feasibility of community-based TAS in adults (adult-TAS) and to compare results obtained by adult-TAS with prior school-TAS and molecular xenomonitoring (MX, molecular detection of filarial DNA in systematically sampled mosquitoes) results in this known problem area.

Methodology and principal findings

Two cluster surveys were performed in independent samples of 30 evaluation areas (EAs) in the coastal Galle EU in 2015. Each survey tested approximately 1,800 adults for circulating filarial antigenemia (CFA) with the Alere Filariasis Test Strip. The CFA prevalence for all persons tested (N = 3,612) was 1.8% (CI 1.4–2.2), and this was significantly higher than the CFA rate of 0.4% obtained by school-TAS in 2013. CFA prevalences in the two samples were similar [1.5% (CI 1.0–2.2), and 2.0% (CI 1.4–2.7)]. Antigenemia prevalence in sampled EUs was highly variable (range 0–11%), and it exceeded 5% in 6 EAs. The 30 EAs sampled in one of our adult-TAS surveys had recently been assessed for persistent filariasis by molecular xenomonitoring (MX). CFA prevalence in adults and filarial DNA prevalence in mosquitoes in these EAs were significantly correlated (r = 0.43; P = 0.02).

Conclusions

Community based adult-TAS provided a reproducible measure of persistent W. bancrofti infection in a large evaluation unit in Sri Lanka that has low-level persistence of LF following multiple rounds of MDA. In addition, adult-TAS and MX results illustrate the focality of persistent LF in this setting. Adult-TAS may be more sensitive than school-TAS for this purpose. Adult-TAS and MX are potential options for post-MDA and post-validation surveillance programs to identify problem areas that require mop-up activities. Adult-TAS should also be useful for remapping areas with uncertain LF endemicity for possible inclusion in national LF elimination programs.

Lymphatic filariasis (LF, also commonly known as “elephantiasis) is a leading cause of disability in the developing world. It is caused by parasitic worms that are transmitted by mosquitoes. The Sri Lankan Anti-Filariasis Campaign provided five annual rounds of MDA with diethylcarbamazine and albendazole in all infected areas between 2002 and 2006, and this reduced infection prevalence to very low levels in all sentinel and spot check sites. Sri Lanka conducted transmission assessment surveys (TAS, surveys for filarial antigenemia in primary school children) based on WHO guidelines in 2012–2013, and all evaluation units (EUs) in formerly endemic areas easily passed this test. However, other types of post-MDA surveys (antigenemia and microfilaremia assessments in communities, anti-filarial antibody assessment in primary grade school children and mosquito monitoring for filarial DNA) have shown evidence of persistent LF in Sri Lanka, with the strongest signals in a coastal EU in Galle district. Results from this study show that adult-TAS efficiently detected residual filarial infections in this EU that had passed school-TAS. Adult-TAS results were highly correlated with results from prior surveys that used molecular xenomonitoring (MX) to detect filarial parasite DNA in pools of mosquitoes collected in the same study areas. Thus adult-TAS and MX should be considered as an alternative surveillance approaches for verifying that LF has been eliminated following MDA and for identifying areas that require additional intervention.

Therapeutic efficacy of doxycycline in domestic cats naturally infected with Brugia malayi in field condition

OBJECTIVE

The aim of this study was to evaluate the efficacy of oral doxycycline treatment for Brugia malayi as measured by microfilarial and filarial DNA clearance in naturally infected domestic cats.

METHODS

This study included 8 domestic cats that lived with families that resided in Tak Bai District of Narathiwat Province, which is located in Southern Thailand. The study area is a known B. malayi endemic area. All study cats received doxycycline treatment doses by their respective owners according to a previously described protocol. Briefly, doxycycline (VibraVet^@) was given orally once a day during weeks 1-4, 10-11, and 16-17. Blood collections were performed at baseline before treatment, and then every month for 12 months after the initial dose of doxycycline to assess microfilaraemia by Giemsa stain, and filarial DNA detection by high-resolution melt (HRM) real-time polymerase chain reaction (PCR).

RESULTS

One month after the start of doxycycline treatment, five of eight cats were negative for microfilaraemia, and 4 of those were negative for filarial DNA. All cats receiving doxycycline treatment were negative for microfilaria by Giemsa stain, and for filarial DNA by HRM real-time PCR within 8 months after receiving the initial dose of doxycycline treatment.

CONCLUSION

Administration of oral doxycycline to domestic cats naturally infected with B. malayi in disease endemic areas can significantly reduce microfilaraemia at 1 month and filarial DNA was undetectable by 8 months after the initial dose of doxycycline treatment. No recurrence of microfilaraemia or filarial DNA was observed in study cats at 1 year after the start of doxycycline. Included cats appeared to tolerate doxycycline (VibraVet^@) well, with no adverse drug reactions reported by any study cat owner.

Efficacy and safety of ivermectin and albendazole co-administration in school-aged children and adults infected with Trichuris trichiura: study protocol for a multi-country randomized controlled double-blind trial

BACKGROUND

Soil-transmitted helminthiasis affects almost 2 billion people worldwide in tropical climates. Preventive chemotherapy, using the benzimidazoles (albendazole and mebendazole) is the current main recommended control strategy. Nevertheless, there is limited efficacy of these drugs against hookworm infection and, to a greater extent, against trichuriasis. We describe a protocol for a trial investigating the efficacy and safety of the co-administration of ivermectin and albendazole against trichuriasis.

METHODS

A double-blind, placebo-controlled randomized controlled trial will be conducted in three countries (Côte d'Ivoire, Tanzania and Lao PDR) with the aim to determine the efficacy, safety and extended effects of co-administered ivermectin and albendazole compared to standard albendazole monotherapy. We will enroll 600 participants aged 6-60 years in each setting. The primary outcome is cure rate (CR) against Trichuris trichiura infection as assessed by Kato-Katz 14-21 days after treatment. Secondary outcomes include CRs against concomitant soil-transmitted helminth (STH) infections (Ascaris lumbricoides, hookworm and Strongyloides stercoralis) and egg reduction rates (ERRs) against STH at 14-21 days, 180 days and 360 days. Tolerability of treatment, infection status assessed by polymerase chain reaction (PCR), and potential benefits of deworming on nutritional and morbidity indicators will be assessed. The primary analysis will include an available-case set and use logistic regression models adjusted for age, sex and weight.

DISCUSSION

This trial will provide robust results on the efficacy and safety of co-administration of ivermectin and albendazole with the aim to better inform WHO recommendations on control of STHs. Furthermore, secondary and explanatory outcomes will provide direct evidence on the extended effects of combination therapy and insight on the relationship between nutrition and morbidity parameters and infection status and intensity.

TRIAL REGISTRATION

NCT03527732 (date assigned: 17 May 2018).

Elimination of lymphatic filariasis as a public health problem in Niue under PacELF, 1999-2016

Background

Lymphatic filariasis (LF) is a mosquito-borne parasitic disease which is targeted for elimination as a public health problem worldwide. Niue is a small self-governing South Pacific island nation with approximately 1600 residents that was formerly LF endemic. Here, we review the progress made towards eliminating LF in Niue since 1999.

Methods

This study has reviewed all the available literature relating to LF in Niue to assess surveillance efforts and the elimination of transmission. Reviewed documentation included both published and unpublished works including historical reports of LF, WHO PacELF records, and Niue Country Reports of the national LF elimination program.

Findings

Niue conducted mapping of baseline LF endemicity by testing the total present and consenting population for LF antigen with immunochromatographic test (ICT) in 1999, when circulating filarial antigen prevalence was 3.1% (n = 1794). Five nationwide annual mass drug administration (MDA) rounds with albendazole (400 mg) and diethylcarbamazine citrate (DEC) were undertaken from 2000 to 2004, with coverage reported from distribution records ranging from 78 to 99% of the eligible population, which excluded pregnant women and children under 2 years of age. A further whole population survey using ICT in 2001 found 1.3% positive (n = 1630). In 2004, antigen prevalence had reduced to 0.2% (n = 1285). A similar post-MDA survey in 2009 indicated antigen prevalence to be 0.5% (n = 1378). Seven positive cases were re-tested and re-treated every six months until negative.

Conclusions

After five rounds of MDA, Niue had reduced the LF antigen population prevalence in all ages from 3.1% to below 1% and maintained this prevalence for a further  five years. Due to Niue’s small population, surveillance was done by whole population surveys. Niue’s results support the WHO recommended strategy that five to six rounds of annual MDA with effective population coverage can successfully interrupt the transmission of LF. Niue received official acknowledgement of the validation of elimination of LF as a public health problem by the WHO Director-General and WHO Western Pacific Regional Office (WPRO) Regional Director at the 67th session of the Regional Committee for the Western Pacific held in Manila in October 2016.

An assessment of mosquito collection techniques for xenomonitoring of anopheline-transmitted Lymphatic Filariasis in Ghana

Monitoring vectors is relevant to ascertain transmission of lymphatic filariasis (LF). This may require the best sampling method that can capture high numbers of specific species to give indication of transmission. Gravid anophelines are good indicators for assessing transmission due to close contact with humans through blood meals. This study compared the efficiency of an Anopheles gravid trap (AGT) with other mosquito collection methods including the box and the Centres for Disease Control and Prevention gravid, light, exit and BioGent-sentinel traps, indoor resting collection (IRC) and pyrethrum spray catches across two endemic regions of Ghana. The AGT showed high trapping efficiency by collecting the highest mean number of anophelines per night in the Western (4.6) and Northern (7.3) regions compared with the outdoor collection methods. Additionally, IRC was similarly efficient in the Northern region (8.9) where vectors exhibit a high degree of endophily. AGT also showed good trapping potential for collecting Anopheles melas which is usually difficult to catch with existing methods. Screening of mosquitoes for infection showed a 0.80-3.01% Wuchereria bancrofti and 2.15-3.27% Plasmodium spp. in Anopheles gambiae. The AGT has shown to be appropriate for surveying Anopheles populations and can be useful for xenomonitoring for both LF and malaria.

Community and Drug Distributor Perceptions and Experiences of Mass Drug Administration for the Elimination of Lymphatic Filariasis: A Rapid Review of Qualitative Research

STUDY OBJECTIVES

This article presents findings from a rapid review of qualitative research conducted to inform decision makers about community and drug distributor perceptions and experiences of mass drug administration campaigns for the elimination of lymphatic filariasis. We focused on questions related to acceptability of the mass drug administration campaigns within these groups and their thoughts around the feasibility of planning and carrying out the campaigns.

METHODS

We carried out a systematic search in five databases to identify potential studies. We included studies that focused on community members and drug distributors and used qualitative methods for data collection and analysis. We conducted a thematic framework analysis using the Supporting the Use of Research Evidence framework. Due to time constraints, one author conducted the screening, extraction and data analysis.

FINDINGS

Studies found that communities lack knowledge and information about lymphatic filariasis and the mass drug administration campaigns and that this can have an impact on how many community members choose to take medication. Health workers often had a good understanding that lymphatic filariasis was a problem in their setting, of its cause and mode of transmission and that hydrocele and elephantiasis had the same cause. However, this knowledge was not as prevalent amongst community drug distributors who often had misconceptions surrounding the topic. Furthermore, studies found that the length, timing, level of community and health system involvement, access to care for side effects, inadequate numbers of drug distributors and supervisors and motivation of drug distributors influenced participation in mass drug administration campaigns. Finally, the inadequate training of drug distributors could influence community trust in the mass drug administration program and the drug distributor themselves if there was a perception that the person was uninformed or not trained to carry out their tasks.

Development of an urban molecular xenomonitoring system for lymphatic filariasis in the Recife Metropolitan Region, Brazil

Introduction

Molecular xenomonitoring (MX)—pathogen detection in the mosquito rather than human—is a promising tool for lymphatic filariasis (LF) surveillance. In the Recife Metropolitan Region (RMR), the last LF focus in Brazil, Culex quinquefasciatus mosquitoes have been implicated in transmitting Wuchereria bancrofti parasites. This paper presents findings on the ideal mosquito collection method, mosquito dispersion, W. bancrofti infection in mosquitoes and W. bancrofti antigen in humans to aid MX development.

Methods

Experiments occurred within two densely populated urban areas of Olinda, RMR, in July and August 2015. U.S. Centers for Disease Control and Prevention (CDC) light traps were compared to battery-powered aspirators as collection methods, and mosquito dispersion was measured by mosquito mark release recapture (MMRR). Female Cx. quinquefasciatus were tested by PCR for W. bancrofti infection, and study area residents were screened by rapid tests for W. bancrofti antigen.

Results

Aspirators caught 2.6 times more total Cx. quinquefasciatus, including 38 times more blood-fed and 5 times more gravid stages, than CDC light traps. They also collected 123 times more Aedes aegypti. Of the 9,644 marked mosquitoes released, only ten (0.01%) were recaptured, nine of which were < 50m (34.8m median, 85.4m maximum) from the release point. Of 9,169 unmarked mosquitoes captured in the MMR, 38.3% were unfed, 48.8% blood-fed, 5.5% semi-gravid, and 7.3% gravid. PCR on 182 pools (1,556 mosquitoes) found no evidence of W. bancrofti infection in Cx. quinquefasciatus. Rapid tests on 110 of 111 eligible residents were all negative for W. bancrofti antigen.

Conclusions

Aspirators were more effective than CDC light traps at capturing Ae. aegypti and all but unfed stages of Cx. quinquefasciatus. Female Cx. quinquefasciatus traveled short (< 86m) distances in this urban area. Lack of evidence for W. bancrofti infection in mosquitoes and antigen in humans in these fine-scale studies does not indicate that LF transmission has ceased in the RMR. A MX surveillance system should consider vector-specific collection methods, mosquito dispersion, and spatial scale but also local context, environmental factors such as sanitation, and host factors such as infection prevalence and treatment history.

Lymphatic filariasis (LF) is a parasitic disease transmitted by mosquitoes, and can cause elephantiasis. It is the world’s leading cause of disability due to infectious diseases, affects over 120 million people globally, and is scheduled for global elimination via mass drug administration (MDA) and mosquito control. Molecular xenomonitoring (MX) is a process of screening mosquitoes—not humans—for parasites to estimate whether they are circulating in human populations. MX is especially useful during and following MDA, when new case detection becomes difficult, but is challenging to design and conduct in cities. Using two study sites in the Recife Metropolitan Region, Brazil, we investigated two crucial questions for urban MX development—“What is the best operationally feasible tool to catch adult mosquitoes?” and “How far do mosquitoes disperse in cities?”—in order to determine placement of future surveillance sites. We also screened a proportion of mosquitoes and all eligible residents from the study sites for LF infection. We determined that handheld battery powered aspirators were the best mosquito collection tool; that mosquitoes flew no more than about 85m; and—in this small sample of mosquitoes and very small sample of humans—there was no evidence of LF infection in mosquitoes or study area residents.

Innovative Surveillance Strategies to Support the Elimination of Filariasis in Africa

Lymphatic filariasis (LF) and onchocerciasis are two neglected tropical diseases (NTDs) of public health significance targeted for global elimination. The World Health Organization (WHO) African Region is a priority region, with the highest collective burden of LF and onchocerciasis globally. Coendemic loiasis further complicates elimination due to the risk of adverse events associated with ivermectin treatment. A public health framework focusing on health-related data, systematic collection of data, and analysis and interpretation of data is used to highlight the range of innovative surveillance strategies required for filariasis elimination. The most recent and significant developments include: rapid point-of-care test (POCT) diagnostics; clinical assessment tools; new WHO guidelines; open-access online data portals; mHealth platforms; large-scale prevalence maps; and the optimisation of mathematical models.