An analysis of the safety of the single dose, two drug regimens used in programmes to eliminate lymphatic filariasis

Efficacy and safety of ivermectin-albendazole combination versus ivermectin or albendazole monotherapy in soil-transmitted helminthiasis: A systematic review and meta-analysis

BACKGROUND

Soil-transmitted helminthiasis remains a daunting challenge to global health, exerting its greatest toll on resource-limited regions of the world. A dual drug approach using the co-administration of ivermectin and albendazole has shown promising results in comparison to the traditional monotherapy strategy. In light of this, a systematic review and meta-analysis of randomized controlled trials was conducted.

METHODS

Several electronic databases including PubMed, Cochrane Central, Google Scholar, and Embase were explored to search for relevant studies from inception to September 2023. The Cochrane Risk of Bias Tool for Randomized Controlled Studies was utilized to evaluate the quality of studies.

RESULTS

A total of 8 randomized controlled trials, reporting 10 patient populations, were included. The treatment of trichuriasis significantly favored the dual therapy regimen of ivermectin-albendazole over albendazole-only monotherapy (risk ratio [RR]: 2.86; 95% confidence interval [CI]: 1.66-4.93; P = .0002), with no significant differences observed for ascariasis and hookworm. The treatment of trichuriasis and hookworm significantly favored the dual therapy regimen of ivermectin-albendazole over ivermectin-only monotherapy (RR: 1.86; 95% CI: 1.56-2.21; P < .00001 and RR: 2.31; 95% CI: 1.23-4.31; P = .009, respectively). There were no statistically significant differences between dual therapy and monotherapy in terms of adverse effects.

CONCLUSION

These findings highlight the nuanced effectiveness of combined therapy specific to certain helminth types, in addition to their comparable safety profiles, thereby providing pivotal insights that contribute to the evolving landscape of soil-transmitted helminth treatment strategies.

Three decades of research in lymphatic filariasis-lessons learned

Lymphatic filariasis (LF), one of the 21 Neglected Tropical Diseases (NTD) which is the second leading cause for disability globally. Wuchereria Bancrofti, Brugia malayi and Brugia timori are the parasites causing this infection. World Health Assembly in 1997 declared LF to be eliminated and the Global Program to eliminate LF (GPELF) was launched by WHO in 2000 with the two strategies viz, 1) stop transmission of infection through Mass Drug Administration (MDA) and 2) to alleviate the suffering of the people affected with the disease through Morbidity Management and Disability Prevention (MMDP. The 'Filariasis research unit' recommended by WHO TDR and ICMR was established in Alappuzha, Kerala in 1989 for research studies related to LF. Over the last three decades 23 studies have been completed, which included different trials to find out the dose, effectiveness and safety of the various drugs used in preventive chemotherapy as single drug or combinations, for treatment of microfilaraemia,, various studies related to morbidity management in filarial disease, socio-economic aspects of filarial disability, Pharmacokinetic study of antifilarial drugs, Study on lymphatic filariasis in children, Studies on dignostics of LF, efficacy of drugs in management of lymphedema etc. In this article an attempt is made to explain the lessons learned from these studies and its importance in development of policy decision making for GPELF.

The pipeline for drugs for control and elimination of neglected tropical diseases: 2. Oral anti-infective drugs and drug combinations for off-label use

In its 'Road map for neglected tropical diseases 2021-2030', the World Health Organization outlined its targets for control and elimination of neglected tropical diseases (NTDs) and research needed to achieve them. For many NTDs, this includes research for new treatment options for case management and/or preventive chemotherapy. Our review of small-molecule anti-infective drugs recently approved by a stringent regulatory authority (SRA) or in at least Phase 2 clinical development for regulatory approval showed that this pipeline cannot deliver all new treatments needed. WHO guidelines and country policies show that drugs may be recommended for control and elimination for NTDs for which they are not SRA approved (i.e. for 'off-label' use) if efficacy and safety data for the relevant NTD are considered sufficient by WHO and country authorities. Here, we are providing an overview of clinical research in the past 10 years evaluating the anti-infective efficacy of oral small-molecule drugs for NTD(s) for which they are neither SRA approved, nor included in current WHO strategies nor, considering the research sponsors, likely to be registered with a SRA for that NTD, if found to be effective and safe. No such research has been done for yaws, guinea worm, Trypanosoma brucei gambiense human African trypanosomiasis (HAT), rabies, trachoma, visceral leishmaniasis, mycetoma, T. b. rhodesiense HAT, echinococcosis, taeniasis/cysticercosis or scabies. Oral drugs evaluated include sparfloxacin and acedapsone for leprosy; rifampicin, rifapentin and moxifloxacin for onchocerciasis; imatinib and levamisole for loiasis; itraconazole, fluconazole, ketoconazole, posaconazole, ravuconazole and disulfiram for Chagas disease, doxycycline and rifampicin for lymphatic filariasis; arterolane, piperaquine, artesunate, artemether, lumefantrine and mefloquine for schistosomiasis; ivermectin, tribendimidine, pyrantel, oxantel and nitazoxanide for soil-transmitted helminths including strongyloidiasis; chloroquine, ivermectin, balapiravir, ribavirin, celgosivir, UV-4B, ivermectin and doxycycline for dengue; streptomycin, amoxicillin, clavulanate for Buruli ulcer; fluconazole and isavuconazonium for mycoses; clarithromycin and dapsone for cutaneous leishmaniasis; and tribendimidine, albendazole, mebendazole and nitazoxanide for foodborne trematodiasis. Additional paths to identification of new treatment options are needed. One promising path is exploitation of the worldwide experience with 'off-label' treatment of diseases with insufficient treatment options as pursued by the 'CURE ID' initiative.

Safety and tolerability of moxidectin and ivermectin combination treatments for lymphatic filariasis in Côte d'Ivoire: A randomized controlled superiority study

BACKGROUND

Moxidectin is a macrocyclic lactone registered for the treatment of human onchocerciasis. The drug has a good safety profile, large volume of distribution and a long elimination half-life. This paper reports tolerability data from the first use of moxidectin in persons with Wuchereria bancrofti infection.

METHODS

In this randomized, open-label, masked-observer superiority trial, adults with Wuchereria bancrofti microfilaremia in Côte d'Ivoire were randomized to 1 of 4 treatment arms: ivermectin + albendazole (IA), moxidectin + albendazole (MoxA), ivermectin + diethylcarbamazine (DEC) + albendazole (IDA), or moxidectin + DEC + albendazole (MoxDA). As part of a larger efficacy trial, all participants were closely monitored for 7 days after treatment.

RESULTS

One hundred sixty-four individuals were treated, and monitored for treatment emergent adverse events (TEAE). Eighty-seven participants (53%) experienced one or more mild (grade 1) or moderate (grade 2) TEAE. Four participants had transient Grade 3 hematuria after treatment (3 after IDA and 1 after IA). There were no serious adverse events. There were no significant differences in frequency or types of TEAE between treatment groups (IA = 22/41 (53%), MoxA = 24/40 (60%), IDA = 18/41 (44%), MoxDA = 15/42 (36%), p = 0.530). Fifty-nine participants (36%) had multiple TEAE, and 8.5% had a one or more grade 2 (moderate) TEAE. Grade 2 TEAE were more frequent after triple drug treatments (IDA, 14.6%; MoxDA, 9.5%) than after two-drug treatments (IA, 7.3%; MoxA, 2.5%). There was no difference in TEAEs based on baseline Mf counts (OR 0.69 (0.33, 1.43), p-value 0.319).

CONCLUSION

All treatment regimens were well tolerated. We observed no difference in safety parameters between regimens that contained ivermectin or moxidectin.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT04410406.

Broadening the range of use cases for ivermectin - a review of the evidence

Ivermectin is a broad-spectrum antiparasitic agent that interferes with glutamate-gated chloride channels found in invertebrates but not in vertebrate species. Mass drug administration (MDA) with ivermectin-based regimes has been a mainstay of elimination efforts targeting onchocerciasis and lymphatic filariasis for more than 3 decades. More recently, interest in the use of ivermectin to control other neglected tropical diseases (NTDs) such as soil-transmitted helminths and scabies has grown. Interest has been further stimulated by the fact that ivermectin displays endectocidal efficacy against various Anopheles species capable of transmitting malaria. Therefore there is growing interest in using ivermectin MDA as a tool that might aid in the control of both malaria and several NTDs. In this review we outline the evidence base to date on these emerging indications for ivermectin MDA with reference to clinical and public health data and discuss the rationale for evaluating the range of impacts of a malaria ivermectin MDA on other NTDs.

Setting the stage for a Global Programme to Eliminate Lymphatic Filariasis: the first 125 years (1875-2000)

The development of the World Health Organization's Global Programme to Eliminate Lymphatic Filariasis (GPELF) can be interpreted through many different lenses-e.g. one focusing on the health or economic plight of affected individuals and populations, another tracking the individuals and organizations responsible for building the programme or, as in this review, one identifying each of the critical requirements and specific hurdles that need to be addressed in order to successfully construct the programme. For almost 75 y after the life cycle of LF was first described, the principal tool for countering it was vector control. Discovery that diethylcarbamazine (and later ivermectin and albendazole) could effectively treat affected and at-risk populations, along with the availability of a simple, field-based diagnostic test to monitor programme progress, provided the essential tools for LF elimination. Recognition of this potential by the global health community (including the World Health Assembly) led two pharmaceutical companies (GlaxoSmithKline and Merck) to make enormous, unprecedented donations of albendazole and ivermectin to achieve this goal. Additional resource support from the public and private sectors and from health ministries in the 80 LF-endemic countries led to the creation of a Global Alliance to Eliminate LF, which launched the GPELF in 2000, just 125 y after the LF life cycle was first described.

Efficacy of Anthelminthic Drugs and Drug Combinations Against Soil-transmitted Helminths: A Systematic Review and Network Meta-analysis

Background

Periodic mass distribution of benzimidazole anthelminthic drugs is the key strategy to control soil-transmitted helminths (STHs) globally. However, benzimidazoles have low efficacy against Trichuris trichiura, and there are concerns about benzimidazole resistance potentially emerging in humans. Therefore, identifying alternative drug regimens is a pressing priority. We present a systematic review and network meta-analysis comparing the efficacy of 21 different anthelminthic drug regimens, including standard, novel, and combination treatments.

Methods

We searched PubMed, Medline, Embase, Web of Science, and Cochrane databases and identified studies comparing anthelminthic treatments to each other or placebo. The outcomes calculated were relative risk (RR) of cure and difference in egg reduction rates (dERR). We used an automated generalized pairwise modeling framework to generate mixed treatment effects against a common comparator, the current standard treatment (single-dose albendazole).

Results

Our search identified 4876 studies, of which 114 were included in the meta-analysis. Results identified several drug combinations with higher efficacy than single-dose albendazole for T. trichiura, including albendazole-ivermectin (RR of cure, 3.22 [95% confidence interval {CI}, 1.84-5.63]; dERR, 0.97 [95% CI, .21-1.74]), albendazole-oxantel pamoate (RR, 5.07 [95% CI, 1.65-15.59]; dERR, 0.51 [95% CI, .50-.52]), mebendazole-ivermectin (RR, 3.37 [95% CI, 2.20-5.16]), and tribendimidine-oxantel pamoate (RR, 4.06 [95% CI, 1.30-12.64]).

Conclusions

There are several promising drug combinations that may enhance the impact of STH control programs on T. trichiura, without compromising efficacy against Ascaris lumbricoides and hookworm. We suggest further, large-scale trials of these drug combinations and consideration of their use in STH control programs where T. trichiura is present.

International Prospective Register of Systematic Reviews Registration

CRD42016050739.

An integrated health delivery platform, targeting soil-transmitted helminths (STH) and canine mediated human rabies, results in cost savings and increased breadth of treatment for STH in remote communities in Tanzania

BACKGROUND

Achieving the Sustainable Development Goal of a 90% reduction in neglected tropical diseases (NTDs) by 2030 requires innovative control strategies. This proof-of-concept study examined the effectiveness of integrating control programs for two NTDs: mass drug administration (MDA) for soil-transmitted helminths in humans and mass dog rabies vaccination (MDRV).

METHODS

The study was carried out in 24 Tanzanian villages. The primary goal was to demonstrate the feasibility of integrating community-wide MDA for STH and MDRV for rabies. The objectives were to investigate the popularity, participation and cost and time savings of integrated delivery, and to investigate the reach of the MDA with respect to primary school-aged children and other community members. To implement, we randomly allocated villages for delivery of MDA and MDRV (Arm A), MDA only (Arm B) or MDRV only (Arm C).

RESULTS

Community support for the integrated delivery was strong (e.g. 85% of focus group discussions concluded that it would result in people getting "two for one" health treatments). A high proportion of households participated in the integrated Arm A events (81.7% MDA, 80.4% MDRV), and these proportions were similar to those in Arms B and C. These findings suggest that coverage might not be reduced when interventions are integrated. Moreover, in addition to time savings, integrated delivery resulted in a 33% lower cost per deworming dose and a 16% lower cost per rabies vaccination. The median percentage of enrolled primary school children treated by this study was 76%. However, because 37% of the primary school aged children that received deworming treatment were not enrolled in school, we hypothesize that the employed strategy could reach more school-aged children than would be reached through a solely school-based delivery strategy.

CONCLUSIONS

Integrated delivery platforms for health interventions can be feasible, popular, cost and time saving. The insights gained could be applicable in areas of sub-Saharan Africa that are remote or underserved by health services. These results indicate the utility of integrated One Health delivery platforms and suggest an important role in the global campaign to reduce the burden of NTDs, especially in hard-to-reach communities.

TRIAL REGISTRATION

clinicaltrials.gov NCT03667079 , retrospectively registered 11th September 2018.

Systems analysis-based assessment of post-treatment adverse events in lymphatic filariasis

Background

Lymphatic filariasis (LF) is a neglected tropical disease, and the Global Program to Eliminate LF delivers mass drug administration (MDA) to 500 million people every year. Adverse events (AEs) are common after LF treatment.

Methodology/Principal findings

To better understand the pathogenesis of AEs, we studied LF-patients from a treatment trial. Plasma levels of many filarial antigens increased post-treatment in individuals with AEs, and this is consistent with parasite death. Circulating immune complexes were not elevated in these participants, and the classical complement cascade was not activated. Multiple cytokines increased after treatment in persons with AEs. A transcriptomic analysis was performed for nine individuals with moderate systemic AEs and nine matched controls. Differential gene expression analysis identified a significant transcriptional signature associated with post-treatment AEs; 744 genes were upregulated. The transcriptional signature was enriched for TLR and NF-κB signaling. Increased expression of seven out of the top eight genes upregulated in persons with AEs were validated by qRT-PCR, including TLR2.

Conclusions/Significance

This is the first global study of changes in gene expression associated with AEs after treatment of lymphatic filariasis. Changes in cytokines were consistent with prior studies and with the RNAseq data. These results suggest that Wolbachia lipoprotein is involved in AE development, because it activates TLR2-TLR6 and downstream NF-κB. Additionally, LPS Binding Protein (LBP, which shuttles lipoproteins to TLR2) increased post-treatment in individuals with AEs. Improved understanding of the pathogenesis of AEs may lead to improved management, increased MDA compliance, and accelerated LF elimination.

Lymphatic filariasis (LF) is a disabling parasitic disease that affects millions of people in the developing world. The Global Programme to Eliminate Lymphatic Filariasis (coordinated by the World Health Organization) uses mass administration of antifilarial medications to cure infections, prevent disease, and reduce transmission. Some individuals develop adverse events (AEs) after treatment, and this can reduce willingness of persons in endemic areas to accept treatment. The purpose of this study was to improve understanding of the cause of AEs following treatment. We hypothesized that parasite antigens released into the blood following treatment trigger inflammatory responses that lead to AEs. To test this hypothesis we collected blood from LF-infected individuals before and after treatment and clinically assessed them for AEs. We measured parasite antigens, cytokines and other components of the immune system in blood samples and compared post-treatment changes in persons with and without AEs. We also assessed changes in transcription profiles in peripheral blood leukocytes that were associated with post-treatment AEs. Post-treatment changes in transcription profiles and in immune proteins and parasite components in plasma suggest that systemic AEs are triggered by death of the parasites following treatment with release of parasite antigens and Wolbachia bacteria into the circulation. Improved understanding of the pathogenesis of post-treatment AEs may help to improve messaging related to mass drug administration programs and lead to improved AE management.

A Trial of a Triple-Drug Treatment for Lymphatic Filariasis

BACKGROUND

The World Health Organization has targeted lymphatic filariasis for global elimination by 2020 with a strategy of mass drug administration. This trial tested whether a single dose of a three-drug regimen of ivermectin plus diethylcarbamazine plus albendazole results in a greater sustained clearance of microfilariae than a single dose of a two-drug regimen of diethylcarbamazine plus albendazole and is noninferior to the two-drug regimen administered once a year for 3 years.

METHODS

In a randomized, controlled trial involving adults from Papua New Guinea with Wuchereria bancrofti microfilaremia, we assigned 182 participants to receive a single dose of the three-drug regimen (60 participants), a single dose of the two-drug regimen (61 participants), or the two-drug regimen once a year for 3 years (61 participants). Clearance of microfilariae from the blood was measured at 12, 24, and 36 months after trial initiation.

RESULTS

The three-drug regimen cleared microfilaremia in 55 of 57 participants (96%) at 12 months, in 52 of 54 participants (96%) at 24 months, and in 55 of 57 participants (96%) at 36 months. A single dose of the two-drug regimen cleared microfilaremia in 18 of 56 participants (32%) at 12 months, in 31 of 55 participants (56%) at 24 months, and in 43 of 52 participants (83%) at 36 months (P=0.02 for the three-drug regimen vs. a single dose of the two-drug regimen at 36 months). The two-drug regimen administered once a year for 3 years cleared microfilaremia in 20 of 59 participants (34%) at 12 months, in 42 of 56 participants (75%) at 24 months, and in 51 of 52 participants (98%) at 36 months (P=0.004 for noninferiority of the three-drug regimen vs. the two-drug regimen administered once a year for 3 years at 36 months). Moderate adverse events were more common in the group that received the three-drug regimen than in the combined two-drug-regimen groups (27% vs. 5%, P<0.001). There were no serious adverse events.

CONCLUSIONS

The three-drug regimen induced clearance of microfilariae from the blood for 3 years in almost all participants who received the treatment and was superior to the two-drug regimen administered once and noninferior to the two-drug regimen administered once a year for 3 years. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT01975441 .).

Adverse events following single dose treatment of lymphatic filariasis: Observations from a review of the literature

Background

WHO’s Global Programme to Eliminate Lymphatic Filariasis (LF) uses mass drug administration (MDA) of anthelmintic medications to interrupt LF transmission in endemic areas. Recently, a single dose combination of ivermectin (IVM), diethylcarbamazine (DEC), and albendazole (ALB) was shown to be markedly more effective than the standard two-drug regimens (DEC or IVM, plus ALB) for achieving long-term clearance of microfilaremia.

Objective and methods

To provide context for the results of a large-scale, international safety trial of MDA using triple drug therapy, we searched Ovid Medline for studies published from 1985–2017 that reported adverse events (AEs) following treatment of LF with IVM, DEC, ALB, or any combination of these medications. Studies that reported AE rates by treatment group were included.

Findings

We reviewed 162 published manuscripts, 55 of which met inclusion criteria. Among these, 34 were clinic or hospital-based clinical trials, and 21 were community-based studies. Reported AE rates varied widely. The median AE rate following DEC or IVM treatment was greater than 60% among microfilaremic participants and less than 10% in persons without microfilaremia. The most common AEs reported were fever, headache, myalgia or arthralgia, fatigue, and malaise.

Interpretation

Mild to moderate systemic AEs related to death of microfilariae are common following LF treatment. Post-treatment AEs are transient and rarely severe or serious. Comparison of AE rates from different community studies is difficult due to inconsistent AE reporting, varied infection rates, and varied intensity of follow-up. A more uniform approach for assessing and reporting AEs in LF community treatment studies would be helpful.

WHO’s Global Programme to Eliminate Lymphatic Filariais (LF) supports annual mass drug administration to over 400 million people in LF-endemic areas each year. Two drug combinations (either DEC or ivermectin, given with albendazole) have been recommended in most endemic areas. With the exception of well-described serious adverse events (AEs) occurring in patients with high level loiasis, severe AEs due to these medications are extremely rare. Mild to moderate AEs, however, are common, particularly in patients with active filarial infection. In this manuscript we synthesize published data on AEs following single-dose treatment of LF with ivermectin, DEC, or albendazole. This provides a background against which to compare the safety of triple drug therapy (ivermectin, DEC, and albendazole) recently endorsed by WHO, and provides a useful context for evaluating safety of new treatments for LF. The compiled data illustrate that transient, mild to moderate AEs following single-dose LF treatment are common in microfilaremic patients and are much less common in amicrofilaremic patients. They also show that passive surveillance for post-treatment AEs underestimates AE incidence and suggest that adherence to common reporting standards would improve the usefulness of AE reporting in filariasis studies.

Efficacy and safety of co-administered ivermectin plus albendazole for treating soil-transmitted helminths: A systematic review, meta-analysis and individual patient data analysis

BACKGROUND

The soil-transmitted helminths (STH), Ascaris lumbricoides, Trichuris trichiura and hookworms, infect 1.5 billion people worldwide and cause an estimated burden of 3.3 million disability-adjusted life years (DALYs). Current control strategies focus on morbidity reduction through preventive chemotherapy (PC) but the most commonly used recommended drugs (albendazole and mebendazole) are particularly inefficacious against T. trichiura. This, together with the threat of emerging drug resistance, calls for new control strategies, including co-administration with other anthelminthics. Ivermectin plus albendazole is widely used against lymphatic filariasis, but its efficacy and safety against STH infections has not yet been fully understood.

METHODS AND FINDINGS

We conducted a systematic literature review and meta-analysis on the efficacy and safety of ivermectin-albendazole co-administration in five different databases (i.e. PubMed, ISI Web of Science, ScienceDirect, CENTRAL and clinicaltrials.gov) from 1960 to January 2018. Four studies reporting efficacy of ivermectin-albendazole against STH infections and five studies on its safety met the selection criteria and were included for quantitative analysis. Ivermectin-albendazole was significantly associated with lower risk (risk ratio (RR) = 0.44, 95% confidence interval (CI) = 0.31-0.62) for T. trichiura infection after treatment compared to albendazole alone. The co-administration revealed no or only a marginal benefit on cure and egg reduction rates over albendazole alone for A. lumbricoides and hookworm infections. Adverse events (AEs) occurring after ivermectin-albendazole co-administration were mostly mild and transient. Overall, the number of individuals reporting any AE was not different (RR = 1.09, 95% CI = 0.87-1.36) in co-treated and albendazole-treated patients. However, although not statistically significant, sub-group analysis showed a tendency for slightly more AEs in patients with filariasis treated with ivermectin-albendazole compared to those treated with albendazole alone (RR = 1.29, 95% CI = 0.81-2.05).

CONCLUSIONS

Our findings suggest a good tolerability and higher efficacy of ivermectin-albendazole against T. trichiura compared to the current standard single-dose albendazole treatment, which supports the use of this co-administration in PC programs. Large-scale definitive randomized controlled trials are required to confirm our results.

Elimination of lymphatic filariasis: current perspectives on mass drug administration

Following the London declaration on neglected tropical diseases (NTDs) in 2012 and inspired by the WHO 2020 roadmap to control or eliminate NTDs, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) intensified preventive chemotherapy and management of morbidity as the two main strategies to enhance progress towards the elimination of lymphatic filariasis (LF). This paper focuses on current perspectives of mass drug administration (MDA) towards the elimination of LF. The goal of MDA is to reduce the density of parasites circulating in the blood of infected persons and the intensity of infection in communities to levels where transmission is no longer sustainable by the mosquito vector. Three drugs, diethylcarbamazine, albendazole, and ivermectin are currently available for LF treatment, and their effectiveness and relative safety have opened the possibility of treating the entire population at risk. Currently, almost all LF endemic countries rely on the single-dose two-drug regimen recommended by the GPELF to achieve elimination. The 4th WHO report on NTDs has indicated that considerable progress has been made towards elimination of LF in some countries while acknowledging some challenges. In this review, we conclude that the 2020 elimination goal can be achieved if issues pertaining to the drug distribution, health system and implementation challenges are addressed.

Translating Research into Reality: Elimination of Lymphatic Filariasis from Haiti

Research provides the essential foundation of disease elimination programs, including the global program to eliminate lymphatic filariasis (GPELF). The development and validation of new diagnostic tools and intervention strategies, critical steps in the evolution of GPELF, required a global effort. Lymphatic filariasis research in Haiti involved many partners and was directly linked to the development of the national elimination program and to the success achieved to date. Ongoing research efforts involving many partners will continue to be important in resolving the challenges faced by the program today in its final efforts to achieve elimination.

Discovery of Specific Antigens That Can Predict Microfilarial Intensity in Loa loa Infection

Antigen-based immunoassays are currently needed for point-of-care quantification of Loa loa microfilariae (mf). Coupling transcriptomic approaches with bioinformatic analysis, we have identified 11 specific putative proteins (coding mRNAs) with potential utility as biomarkers of patent (mf ⁺ ) L. loa infection. We successfully developed antigen capture immunoassays to quantify 2 (LOAG_14221 and LOAG_15846) of these proteins in individual plasma/serum samples. Of the 2 quantifiable circulating biomarkers, LOAG_14221 showed the highest degree of specificity, particularly with a monoclonal antibody-based immunoassay. Moreover, the levels of LOAG_14221 in L. loa mf ⁺ patients were positively correlated to the mf densities in the corresponding blood samples (r = 0.53 and P = 0.008 for polyclonal assay; r = 0.54 and P = 0.004 for monoclonal assay). Thus, LOAG_14221 is a very promising biomarker that will be exploited in a quantitative point-of-care immunoassay for determination of L. loa mf densities.

New developments in chyluria after global programs to eliminate lymphatic filariasis

Chyluria, commonly seen in south Asian countries, is mainly a manifestation of lymphatic filariasis as a result of infestation with Wuchereria bancrofti, although many other causes can contribute. Many patients can be effectively treated with dietary modifications and drug therapy. The most widely used drug is diethyl carbamazine. The recurrences are common after such treatment. Such patients would benefit from sclerotherapy to obliterate the lympatico-renal fistulae located mainly in the renal pelvicalyceal system. The commonly used sclerosing agent is a combination of 5% povidone-iodine and 50% dextrose instilled through a ureteric catheter. A small percentage of patients who recur after sclerotherapy and those with systemic complications, such as hypoproteinemia and edema, might require surgery in the form of renal hilar lymphatic disconnection. Although it is a major operation, the success rates are >90%. Laparoscopic and robotic techniques have minimized the morbidity related to such surgery. With the advent of the global program for eradication of filariasis initiated by the World Health Organization, the incidence of the disease is decreasing. Mass chemotherapy with diethyl carbamazine is the mainstay of this global program. Many years after eliminating filariasis, chyluria continue to occur in such populations, though in dwindling numbers. Future research should aim at finding more efficacious sclerosing agents with minimal recurrences.

Functional genomics in Brugia malayi reveal diverse muscle nAChRs and differences between cholinergic anthelmintics

Many techniques for studying functional genomics of important target sites of anthelmintics have been restricted to Caenorhabditis elegans because they have failed when applied to animal parasites. To overcome these limitations, we have focused our research on the human nematode parasite Brugia malayi, which causes elephantiasis. Here, we combine single-cell PCR, whole muscle cell patch clamp, motility phenotyping (Worminator), and dsRNA for RNAi for functional genomic studies that have revealed, in vivo, four different muscle nAChRs (M-, L-, P-, and N-). The cholinergic anthelmintics had different selectivities for these receptors. We show that motility and patch-clamp responses to levamisole and pyrantel, but not morantel or nicotine, require the unc-38 and/or unc-29 genes. Derquantel behaved as a competitive antagonist and distinguished M-nAChRs activated by morantel (Kb 13.9 nM), P-nAChRs activated by pyrantel (Kb 126 nM), and L-nAChRs activated by levamisole (Kb 0.96 µM) and bephenium. Derquantel was a noncompetitive antagonist of nicotine, revealing N-type nAChRs. The presence of four diverse nAChRs on muscle is perhaps surprising and not predicted from the C. elegans model. The diverse nAChRs represent distinguishable drug targets with different functions: Knockdown of unc-38+unc-29 (L- and/or P-receptors) inhibited motility but knockdown of acr-16+acr-26 (M- and/or N-receptors) did not.

Monitoring rare serious adverse events from a new treatment and testing for a difference from historical controls

Background We detail the design of a study to monitor the safety of including albendazole to an existing treatment regimen to eliminate lymphatic filariasis. We wish to show that this new regimen does not increase the rate of a rare serious adverse event (SAE) compared to the old regimen. Controlled but small clinical trials have not detected any increase in the SAE using albendazole, and it is known to have added benefits; therefore, it is unethical to randomize patients to the old regimen.

Purpose A sample size for the new regimen is needed to test that the new rate of SAE is noninferior to the historic rate. If the new regimen does have an inferior rate of SAE then we wish to stop the study early. This setup is different from traditional early stopping for efficacy and futility. In that traditional case, the two stopping decisions are relative to the same null hypothesis of equality, while in our setup, we have two different null hypotheses: the noninferiority null and the equality null. When testing the former, we need not stop early if the new regimen appears better because no subjects are receiving the old regimen anymore anyway. When testing the equality of SAE rates, however, we want to stop early if the new regimen has a significantly higher rate of SAE.

Methods We create a design that uses an exact difference in proportions test for testing noninferiority, but calculates maximal sample size based on conditional power which treats the historical rates as true rates. The design allows for early stopping if the new treatment appears inferior with respect to SAE rate but makes no corrections for multiple testing. We explore the properties of this naive design without assuming the historical rates are known.

Results For our example, we show that our naive design strategy bounds the type I error of the noninferiority hypothesis in all cases and bounds it for the equality hypothesis at 0.05, as long as the true SAE rate is <0.00015. The same design has unconditional power for the noninferiority hypothesis greater than the nominal 80% as long as the true SAE rate for both regimens are <0.00025.

Limitations The type I and power results above hold only for our historical sample size of 17 877. We expect similar type I and power properties to hold with studies with SAE rates similar or less (i.e., < 0.00015) and historical sample sizes similar or smaller.

Conclusions Our design for comparing very rare historical SAE rates to SAE rates of a new treatment has large power to conclude noninferiority of the new treatment SAE rate when both rates are equal, but allows early stopping if the new SAE rates are worse. Clinical Trials 2007; 4: 598—610. http://ctj.sagepub.com

Research for new drugs for elimination of onchocerciasis in Africa

Onchocerciasis is a parasitic, vector borne disease caused by the filarial nematode Onchocerca volvulus. More than 99% of the population at risk of infection live in Africa. Onchocerciasis control was initiated in West Africa in 1974 with vector control, later complemented by ivermectin mass drug administration and in the other African endemic countries in 1995 with annual community directed treatment with ivermectin (CDTI.) This has significantly reduced infection prevalence. Together with proof-of-concept for onchocerciasis elimination with annual CDTI from foci in Senegal and Mali, this has resulted in targeting onchocerciasis elimination in selected African countries by 2020 and in 80% of African countries by 2025. The challenges for meeting these targets include the number of endemic countries where conflict has delayed or interrupted control programmes, cross-border foci, potential emergence of parasite strains with low susceptibility to ivermectin and co-endemicity of loiasis, another parasitic vector borne disease, which slows down or prohibits CDTI implementation. Some of these challenges could be addressed with new drugs or drug combinations with a higher effect on Onchocerca volvulus than ivermectin. This paper reviews the path from discovery of new compounds to their qualification for large scale use and the support regulatory authorities provide for development of drugs for neglected tropical diseases. The status of research for new drugs or treatment regimens for onchocerciasis along the path to regulatory approval and qualification for large scale use is reviewed. This research includes new regimens and combinations of ivermectin and albendazole, antibiotics targeting the O. volvulus endosymbiont Wolbachia, flubendazole, moxidectin and emodepside and discovery of new compounds.

Impact on prevalence of intestinal helminth infection in school children administered with seven annual rounds of diethyl carbamazine (DEC) with albendazole

BACKGROUND & OBJECTIVES

One third of the world's population is infected with one or more of the most common soil-transmitted helminths (STH). Albendazole (ALB) is being administered with diethyl carbamazine (DEC) in filariasis endemic areas to eliminate lymphatic filariasis (LF) and helminth infections. In this study, the cumulative impact of seven annual rounds of mass drug administrations (MDA) of DEC and ALB on STH infection in school children in selected villages in southern India was determined.

METHODS

During 2001-2010, seven MDAs were implemented by the Tamil Nadu s0 tate h0 ealth d0 epartment, India. LF and STH infections were monitored in school children from 18 villages of the two treatment arms (viz, DEC alone and DEC+ALB). Kato-Katz cellophane quantitative thick smear technique was employed to estimate STH infections at three weeks, six months and one year post MDA.

RESULTS

Prior to treatment, an overall STH prevalence was 60 per cent. After each MDA, infection markedly reduced at three weeks post-treatment in both the arms. The prevalence increased at six months period, which was maintained up to one year. After seven rounds of MDA, the infection reduced from 60.44 to 12.48 per cent in DEC+ALB arm; while the reduction was negligible in DEC alone arm (58.77 to 52.70%).

INTERPRETATION & CONCLUSIONS

Seven rounds of MDA with DEC+ALB reduced the infection load significantly, and further sustained low level of infection for 10 years. However, complete parasite elimination could not be achieved. To curtail STH infection in the community, MDA should be regularized and environmental sanitation measures need to be improved by effective community-based campaigns.

A randomized controlled trial of increased dose and frequency of albendazole with standard dose DEC for treatment of Wuchereria bancrofti microfilaremics in Odisha, India

Although current programmes to eliminate lymphatic filariasis have made significant progress it may be necessary to use different approaches to achieve the global goal, especially where compliance has been poor and ‘hot spots’ of continued infection exist. In the absence of alternative drugs, the use of higher or more frequent dosing with the existing drugs needs to be explored. We examined the effect of higher and/or more frequent dosing with albendazole with a fixed 300mg dose of diethylcarbamazine in a Wuchereria bancrofti endemic area in Odisha, India. Following screening, 104 consenting adults were randomly assigned to treatment with the standard regimen annually for 24 months (S1), or annually with increased dose (800mg albendazole)(H1) or with increased frequency (6 monthly) with either standard (S2) or increased (H2) dose. Pre-treatment microfilaria counts (GM) ranged from 348 to 459 mf/ml. Subjects were followed using microfilaria counts, OG4C3 antigen levels and ultrasound scanning for adult worm nests. Microfilarial counts tended to decrease more rapidly with higher or more frequent dosing at all time points. At 12 months, Mf clearance was marginally greater with the high dose regimens, while by 24 months, there was a trend to higher Mf clearance in the arm with increased frequency and 800mg of albendazole (76.9%) compared to other arms, (S1:64%, S2:69.2% & H1:73.1%). Although higher and/or more frequent dosing showed a trend towards a greater decline in antigenemia and clearance of “nests”, all regimens demonstrated the potential macrofilaricidal effect of the combination. The higher doses of albendazole did not result in a greater number or more severe side effects. The alternative regimens could be useful in the later stages of existing elimination programmes or achieving elimination more rapidly in areas where programmes have yet to start.

In order to achieve global elimination of lymphatic filariasis, it may be necessary to consider alternative approaches to mass treatment using higher or more frequent dosing with the existing drugs used in the programmes. Outside Africa, the drugs used are albendazole and diethylcarbamazine given annually. The current study is the first to examine the use of higher or more frequent dosing in a bancroftian filariasis endemic area outside Africa. Four groups of infected subjects were followed for two years using standard techniques for monitoring drug efficacy in Odisha, India. We showed that higher doses of albendazole, or 6-monthly treatment, were more effective than the standard regimen in producing clearance of microfilaria and reductions in antigenemia. Additionally we found that these regimens were more effective in killing the adult filarial worms in the lymphatics. Importantly, the higher doses used did not increase the risk of side effects. These alternative approaches could accelerate lymphatic filariasis elimination either at the end of existing programmes or to permit new programmes to achieve their goals faster.

A comprehensive assessment of lymphatic filariasis in Sri Lanka six years after cessation of mass drug administration

Background

The Sri Lankan Anti-Filariasis Campaign conducted 5 rounds of mass drug administration (MDA) with diethycarbamazine plus albendazole between 2002 and 2006. We now report results of a comprehensive surveillance program that assessed the lymphatic filariasis (LF) situation in Sri Lanka 6 years after cessation of MDA.

Methodology and Principal Findings

Transmission assessment surveys (TAS) were performed per WHO guidelines in primary school children in 11 evaluation units (EUs) in all 8 formerly endemic districts. All EUs easily satisfied WHO criteria for stopping MDA. Comprehensive surveillance was performed in 19 Public Health Inspector (PHI) areas (subdistrict health administrative units). The surveillance package included cross-sectional community surveys for microfilaremia (Mf) and circulating filarial antigenemia (CFA), school surveys for CFA and anti-filarial antibodies, and collection of Culex mosquitoes with gravid traps for detection of filarial DNA (molecular xenomonitoring, MX). Provisional target rates for interruption of LF transmission were community CFA <2%, antibody in school children <2%, and filarial DNA in mosquitoes <0.25%. Community Mf and CFA prevalence rates ranged from 0–0.9% and 0–3.4%, respectively. Infection rates were significantly higher in males and lower in people who denied prior treatment. Antibody rates in school children exceeded 2% in 10 study sites; the area that had the highest community and school CFA rates also had the highest school antibody rate (6.9%). Filarial DNA rates in mosquitoes exceeded 0.25% in 10 PHI areas.

Conclusions

Comprehensive surveillance is feasible for some national filariasis elimination programs. Low-level persistence of LF was present in all study sites; several sites failed to meet provisional endpoint criteria for LF elimination, and follow-up testing will be needed in these areas. TAS was not sensitive for detecting low-level persistence of filariasis in Sri Lanka. We recommend use of antibody and MX testing as tools to complement TAS for post-MDA surveillance.

Lymphatic Filariasis (LF, also known as “elephantiasis”) is a disabling and deforming disease that is caused by parasitic worms that are transmitted by mosquitoes. The Sri Lankan Anti-Filariasis Campaign provided five annual rounds of mass drug administration (MDA) with diethylcarbamazine and albendazole between 2002 and 2006 in all endemic areas (districts or implementation units), and this reduced infection rates to very low levels in all sentinel and spot check sites. Transmission Assessment Surveys (TAS, surveys for filarial antigenemia in primary school children) performed in 2012–2013 (about 6 years after the last round of MDA) showed that all 11 evaluation units in formerly endemic areas easily satisfied a key World Health Organization target for LF elimination programs. More comprehensive surveillance was performed with other tests to assess LF parameters in 19 study sites in the same eight districts. We detected evidence of persistent LF in all districts and evidence of ongoing transmission in several areas. Exposure monitoring (screening for anti-filarial antibodies in primary school children) and molecular xenomonitoring (detecting filarial DNA in mosquito vectors) were much more sensitive than TAS for detecting low level persistence of filariasis in Sri Lanka. These methods are complementary to TAS, and they are feasible for use by some national filariasis elimination programs. Results from this study suggest that TAS alone may not be sufficient for assessing the success of filariasis elimination programs.

Adverse reactions following mass drug administration with diethylcarbamazine in lymphatic filariasis endemic areas in the Northeast of Brazil

INTRODUCTION

The Global Programme to Eliminate Lymphatic Filariasis was launched with the goal of eliminating this disease via the annual mass drug administration (MDA) of a single dose of antifilarial drugs. Adverse drug reactions following MDA are a major factor of poor treatment adherence in several countries. This study assessed the occurrence of adverse drug reactions (ADRs) following the first round of mass treatment in two communities treated with different dosages of diethylcarbamazine (DEC) in the City of Recife, Brazil.

METHODS

Population-based cross-sectional surveys were conducted in a random sample of the population living in both communities (Areas I and II). The dose of DEC recommended by the WHO (6mg/kg) was calculated based on the individual's weight-for-age. In Area II, weight differences between the genders were also considered when determining dosage. Data were obtained through interviews conducted in the first 12 to 48h and on the 5th day after MDA during household visits.

RESULTS

A total of 487 and 365 individuals were interviewed in Areas I and II, respectively. The prevalence of ADRs in Area I (23.6; 95%CI: 19.1-29.5) was higher than in Area II (16.2; 95%CI:11.9-21.5)(p=0.0078). The prevalence of ADRs among females was higher than in males in Area I (p=0.0021). In Area II, no significant difference between the genders was observed (p=0.1840). Age was not associated with ADRs in either area.

CONCLUSIONS

Adjusting MDA dosage schedules according to weight-for-age and sex may be may contribute to reduce the occurrence of adverse drug reactions in the population.

A cluster randomized study of the safety of integrated treatment of trachoma and lymphatic filariasis in children and adults in Sikasso, Mali

BACKGROUND

Neglected tropical diseases are co-endemic in many areas of the world, including sub Saharan Africa. Currently lymphatic filariasis (albendazole/ivermectin) and trachoma (azithromycin) are treated separately. Consequently, financial and logistical benefit can be gained from integration of preventive chemotherapy programs in such areas.

METHODOLOGY/FINDINGS

4 villages in two co-endemic districts (Kolondièba and Bougouni) of Sikasso, Mali, were randomly assigned to coadministered treatment (ivermectin/albendazole/azithromycin) or standard therapy (ivermectin/albendazole with azithromycin 1 week later). These villages had previously undergone 4 annual MDA campaigns with ivermectin/albendazole and 2 with azithromycin. One village was randomly assigned to each treatment arm in each district. There were 7515 eligible individuals in the 4 villages, 3011(40.1%) of whom participated in the study. No serious adverse events occurred, and the majority of adverse events were mild in intensity (mainly headache, abdominal pain, diarrhoea and "other signs/symptoms"). The median time to the onset of the first event, of any type, was later (8 days) in the two standard treatment villages than in the co-administration villages. Overall the number of subjects reporting any event was similar in the co-administration group compared to the standard treatment group [18.7% (281/1501) vs. 15.8% (239/1510)]. However, the event frequency was higher in the coadministration group (30.4%) than in the standard treatment group (11.0%) in Kolondièba, while the opposite was observed in Bougouni (7.1% and 20.9% respectively). Additionally, the overall frequency of adverse events in the co-administration group (18.7%) was comparable to or lower than published frequencies for ivermectin+albendazole alone.

CONCLUSIONS

These data suggest that co-administration of ivermectin+albendazole and azithromycin is safe; however the small number of villages studied and the large differences between them resulted in an inability to calculate a meaningful overall estimate of the difference in adverse event rates between the regimens. Further work is therefore needed before co-administration can be definitively recommended.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT01586169.

Safety of a New Chewable Formulation of Mebendazole for Preventive Chemotherapy Interventions to Treat Young Children in Countries with Moderate-to-High Prevalence of Soil Transmitted Helminth Infections

The primary objective was to evaluate the safety and tolerability of the new chewable formulation of mebendazole to treat soil-transmitted helminth (STH) infections in children ≤10 years old with the goal of using this formulation in preventive chemotherapy programs and expand treatment to young children who are unable to swallow solid tablets. In this open-label, single-arm, phase 3 study conducted at Pemba Island, Zanzibar, Tanzania, children aged 2 to 10 years (median age: 4 years) were administered a single dose of the mebendazole 500 mg chewable tablet. Safety was assessed 30 minutes after dose and 3 days later. Of the 390 (98%) children who completed the study, 195 (55%) had ≥1 STH infection and 157 (45%) had no infection at baseline. The most common STH infections were Trichuris trichiura (51%), hookworm (16%), and Ascaris lumbricoides (7%). Treatment-emergent adverse events (TEAEs) were experienced by 11% of children. There was no difference in the percentage of children experiencing TEAEs between the age strata of 2–5 years and 6–10 years. Diarrhea was reported only in children aged 2–5 years. No correlation was observed between the type or percentage of AEs and presence or severity of infection. A single dose of mebendazole 500 mg chewable tablet was safe and well tolerated in children aged 2 to 10 years.

Control of soil-transmitted helminths in sub-Saharan Africa: diagnosis, drug efficacy concerns and challenges

Soil-transmitted helminthiasis (STH) occur throughout the developing world and remain a major public health problem in the poorest communities with enormous consequences on health and development of school-aged and preschool children. The extent of the problem has long been neglected because these diseases rarely kill at a young age, due to their insidious and chronic nature. Today there exists a momentum and an unprecedented opportunity for a cost-effective control of these neglected tropical diseases. The control of these diseases has become a priority on the agenda of many governments, donors and international agencies, which provides important funding opportunities for STH control through integration and co-implementation of control interventions. In the era of preventive chemotherapy, the intensification of mass administration of anthelminthic drugs will result in epidemiological changes of STH transmission levels, with a rapid increase of light infections as far as control programmes are successful. As consequence, the current diagnostic tools may not be always appropriate and may therefore require adaptation or development of alternative assays adapted to the stage of control. This paper reviews aspects relevant to diagnosis and appropriate tools for accurate surveillance and monitoring of STH control programmes and drug efficacy. Prospects, opportunities and challenges for the control are discussed.

Reduction in acute filariasis morbidity during a mass drug administration trial to eliminate lymphatic filariasis in Papua New Guinea

BACKGROUND

Acute painful swelling of the extremities and scrotum are debilitating clinical manifestations of Wuchereria bancrofti infection. The ongoing global program to eliminate filariasis using mass drug administration is expected to decrease this and other forms of filarial morbidity in the future by preventing establishment of new infections as a consequence of eliminating transmission by the mosquito vector. We examined whether mass treatment with anti-filarial drugs has a more immediate health benefit by monitoring acute filariasis morbidity in Papua New Guinean communities that participated in a 5-year mass drug administration trial.

METHODOLOGY/PRINCIPAL FINDINGS

Weekly active surveillance for acute filariasis morbidity defined by painful swelling of the extremities, scrotum and breast was performed 1 year before and each year after 4 annual mass administrations of anti-filarial drugs (16,480 person-years of observation). Acute morbidity events lasted <3 weeks in 92% of affected individuals and primarily involved the leg (74-79% of all annual events). The incidence for all communities considered together decreased from 0.39 per person-year in the pre-treatment year to 0.31, 0.15, 0.19 and 0.20 after each of 4 annual treatments (p<0.0001). Residents of communities with high pre-treatment transmission intensities (224-742 infective bites/person/year) experienced a greater reduction in acute morbidity (0.62 episodes per person-year pre-treatment vs. 0.30 in the 4(th) post-treatment year) than residents of communities with moderate pre-treatment transmission intensities (24-167 infective bites/person/year; 0.28 episodes per person-year pre-treatment vs. 0.16 in the 4(th) post-treatment year).

CONCLUSIONS

Mass administration of anti-filarial drugs results in immediate health benefit by decreasing the incidence of acute attacks of leg and arm swelling in people with pre-existing infection. Reduction in acute filariasis morbidity parallels decreased transmission intensity, suggesting that continuing exposure to infective mosquitoes is involved in the pathogenesis of acute filariasis morbidity.

A randomised controlled clinical trial on the safety of co-administration of albendazole, ivermectin and praziquantel in infected schoolchildren in Uganda

Integrated chemotherapy of neglected tropical diseases (NTD) through mass drug administration given as a single dose would increase treatment coverage and cost-effectiveness. This study reports on the safety of a combination of albendazole, ivermectin and praziquantel in the treatment of lymphatic filariasis (LF), schistosomiasis and soil-transmitted helminthiasis (STH) in infected children. In this randomised, controlled, single-blinded clinical trial conducted in 235 primary school children aged 5-18 years in Yumbe District in Northern Uganda, the triple combination therapy was compared with the current NTD programme regimen. Liver function testing was performed for all children who received combined therapy. The study included 48 children with LF alone, 60 children with schistosomiasis (Schistosoma mansoni), 41 children with STH, 49 children with schistosomiasis + LF and 37 children with all three types of infection. Children were closely monitored by a paediatrician for any adverse reactions for 7 days. No serious adverse events were experienced. However, 4 of 18 children in the test group and 2 of 3 children in the control group who did not report any ill conditions before treatment developed adverse drug reactions. The combined and conventional therapies were found to be equally safe. The efficacies of both therapies were comparable and satisfactory. [ClinicalTrials.gov identifier: NCT01050517].

A low-tech analytical method for diethylcarbamazine citrate in medicated salt

The World Health Organization has called for an effort to eliminate Lymphatic Filariasis (LF) around the world. In regions where the disease is endemic, local production and distribution of medicated salt dosed with diethylcarbamazine (DEC) has been an effective method for eradicating LF. A partner of the Notre Dame Haiti program, Group SPES in Port-au-Prince, Haiti, produces a medicated salt called Bon Sel. Coarse salt is pre-washed and sprayed with a solution of DEC citrate and potassium iodate. Iodine levels are routinely monitored on site by a titrimetric method. However, the factory had no method for monitoring DEC. Critical analytical issues include 1) determining whether the amount of DEC in each lot of Bon Sel is within safe and therapeutically useful limits, 2) monitoring variability within and between production runs, and 3) determining the effect of a common local practice (washing salt before use) on the availability of DEC. This paper describes a novel titrimetric method for analysis of DEC citrate in medicated salt. The analysis needs no electrical power and requires only a balance, volumetric glassware, and burets that most salt production programs have on hand for monitoring iodine levels. The staff of the factory used this analysis method on site to detect underloading of DEC on the salt by their sprayer and to test a process change that fixed the problem.

As researchers develop more sophisticated technologies, parts of the world are left behind. The front lines of fighting many diseases lie in regions where expensive technology is not feasible. As part of the effort to eradicate lymphatic filariasis in Haiti, our group's goal was to design an assay that would allow a chemist, with basic equipment, to quantify the levels of diethylcarbamazine citrate on medicated salt. With access to university research facilities, we were able to devise and test a back-titration procedure that can measure the medication levels with sufficient accuracy and precision. Our method capitalized on the fact that the medication is acidic. This characteristic allows us to combine an unknown, medicated salt sample with a known quantity of base and then back-titrate with acid to determine diethylcarbamazine citrate concentration based on the neutralization point. Developing this protocol has put the power of quality control into the hands of the Haitian factory producing the medicated salt. With the ability to better monitor dosing levels, we have increased the effectiveness of this program in Haiti. Using modern research facilities to produce effective, low-tech methods could be a useful approach for tackling many worldwide medical and environmental issues.

Use of high-dose, twice-yearly albendazole and ivermectin to suppress Wuchereria bancrofti microfilarial levels

BACKGROUND

Annual mass treatment with albendazole and ivermectin is the mainstay of current strategies to interrupt transmission of Wuchereria bancrofti in Africa. More-effective microfilarial suppression could potentially reduce the time necessary to interrupt transmission, easing the economic burden of mass treatment programs in countries with limited resources.

METHODS

To determine the effect of increased dose and frequency of albendazole-ivermectin treatment on microfilarial clearance, 51 W. bancrofti microfilaremic residents of an area of W. bancrofti endemicity in Mali were randomized to receive 2 doses of annual, standard-dose albendazole-ivermectin therapy (400 mg and 150 μg/kg; n = 26) or 4 doses of twice-yearly, increased-dose albendazole-ivermectin therapy (800 mg and 400 μg/kg; n = 25).

RESULTS

Although microfilarial levels decreased significantly after therapy in both groups, levels were significantly lower in the high-dose, twice-yearly group at 12, 18, and 24 months. Furthermore, there was complete clearance of detectable microfilariae at 12 months in the 19 patients in the twice-yearly therapy group with data available at 12 months, compared with 9 of 21 patients in the annual therapy group (P < .001, by Fisher's exact test). This difference between the 2 groups was sustained at 18 and 24 months, with no detectable microfilariae in the patients receiving twice-yearly treatment. Worm nests detectable by ultrasonography and W. bancrofti circulating antigen levels, as measured by enzyme-linked immunosorbent assay, were decreased to the same degree in both groups at 24 months, compared with baseline.

CONCLUSIONS

These findings suggest that increasing the dosage and frequency of albendazole-ivermectin treatment enhances suppression of microfilariae but that this effect may not be attributable to improved adulticidal activity.

Lymphatic filariasis control in Tanzania: effect of repeated mass drug administration with ivermectin and albendazole on infection and transmission

Background

In most countries of sub-Saharan Africa the control of lymphatic filariasis (LF) is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole, in order to interrupt transmission. Here we present the first detailed study on the effect of 3 repeated MDAs with this drug combination, as implemented by the Tanzanian National Lymphatic Filariasis Elimination Programme (NLFEP).

Methodology/Principal Findings

Infection and transmission was monitored during a five-year period (one pre-intervention and four post-intervention years) in a highly endemic community (Kirare village) in north-eastern Tanzania. The vectors were Anopheles gambiae, An. funestus and Cx. quinquefasciatus. After start of intervention, human microfilaraemia initially decreased rapidly and statistically significant (prevalence by 21.2% and 40.4%, and mean intensity by 48.4% and 73.7%, compared to pre-treatment values after the first and second MDA, respectively), but thereafter the effect levelled off. The initial decrease in microfilaraemia led to significant decreases in vector infection and vector infectivity rates and thus to a considerable reduction in transmission (by 74.3% and 91.3% compared to pre-treatment level after first and second MDA, respectively). However, the decrease in infection and infectivity rates subsequently also levelled off, and low-level transmission was still noted after the third MDA. The MDAs had limited effect on circulating filarial antigens and antibody response to Bm14.

Conclusion/Significance

Critical issues that may potentially explain the observed waning effect of the MDAs in the later study period include the long intervals between MDAs and a lower than optimal treatment coverage. The findings highlight the importance of ongoing surveillance for monitoring the progress of LF control programmes, and it calls for more research into the long-term effect of repeated ivermectin/albendazole MDAs (including the significance of treatment intervals and compliance), in order to optimize efforts to control LF in sub-Saharan Africa.

Lymphatic filariasis (LF) is a disabling mosquito borne parasitic disease and one of the major neglected tropical diseases. In most countries of Sub-Saharan Africa the control of LF is based on yearly mass drug administration (MDA) with a combination of ivermectin and albendazole, in order to interrupt transmission. We monitored the effect of 3 repeated MDAs with this drug combination, as implemented by the Tanzanian National Lymphatic Filariasis Elimination Programme, on human infection and mosquito transmission during a five-year period (one pre-intervention and four post-intervention years) in a highly endemic community in north-eastern Tanzania. After start of intervention, human infection with the blood-stage larva of the parasite (microfilaria) initially decreased rapidly, leading to considerable reduction in transmission. The effects thereafter levelled off and transmission still occurred at low level after the third MDA. The MDAs had limited effect on molecular markers of adult worm burden (circulating filarial antigens) and transmission exposure (antibodies to Bm14 antigen) in the human population. The study highlights the importance of monitoring and regular evaluation in order to make evidence based programme adjustments, and it points to a need for further assessment of the long-term effect of repeated ivermectin/albendazole MDAs (including the importance of application intervals and treatment coverage), in order to optimize efforts to control LF in sub-Saharan Africa.

The development of albendazole for lymphatic filariasis

The history of the development of ivermectin and diethylcarbamazine for the treatment of human filarial infections is relatively well known and documented. The story of how albendazole became involved in the global elimination programmes is, however, less well known. This review examines the thinking and the processes behind the development of albendazole, from the first ideas in the mid 1980s to the establishment of the Global Programme to Eliminate Lymphatic Filariasis. Throughout, the approaches were essentially different from those of traditional drug development and, in the end, there was a recommendation for a particular public-health use that was not formally approved by the regulatory authorities. While there is no doubt about the efficacy of albendazole for the treatment of many helminth diseases, as a single agent it could never be recommended for filariasis.

Imported bancroftian filariasis: diethylcarbamazine response and benzimidazole susceptibility of Wuchereria bancrofti in dynamic cross-border migrant population targeted by the National Program to Eliminate Lymphatic Filariasis in South Thailand

The implementation on the Thailand-Myanmar border of annual mass drug administration (MDA) of a single 6 mg/kg dose of diethylcarbamazine (DEC) plus 400mg albendazole, part of the National Program to Eliminate Lymphatic Filariasis (PELF), has been challenging. In particular, chain migration of cross-border Myanmar workers at risk for nocturnally periodic Wuchereria bancrofti infection can lead to imported bancroftian filariasis (IBF) in Thailand. IBF is targeted for multiple-dose MDA with 300 mg DEC, in addition to what is recommended by the World Health Organization (WHO). The dynamic Myanmar migrants in Phang-nga, southern Thailand were sampled to test whether the responsible W. bancrofti has a genetic predisposition of benzimidazole exposure, and IBF exhibits DEC susceptibility. The long-term migrants had more access to DEC. IBF in W. bancrofti antigenemic (microfilaremic vs. amicrofilaremic) short-term migrants exhibited susceptibility to a 300-mg single-dose DEC treatment. During the course of a 3-month follow-up, antigenemia was significantly reduced, but microfilaremia was fluctuated. Surprisingly, a newly recognized Mansonella infection co-existing among W. bancrofti-affected Myanmar migrants elicited microfilaremia clearance within a month after treatment. As a result of the presence of genetically stable W. bancrofti beta-tubulin (Wbtubb) gene responsible for benzimidazole susceptibility, IBF did not possess a genetic predisposition for benzimidazole exposure. Point mutations at positions Phe167Tyr and Phe200Tyr were not detected by Wbtubb locus-specific nested PCR and sequencing. This study has the potential to help guide not only the Thai/Myanmar PELF surveillance and monitoring of mass treatment impacts on W. bancrofti, but also the other endemic countries allied with the Global Program to Eliminate Lymphatic Filariasis (GPELF).

Brugia malayi: Effects of nitazoxanide and tizoxanide on adult worms and microfilariae of filarial nematodes

There is an urgent need for safe and effective antifilarials. Prior studies have shown that the nitazoxanide (NTZ) exhibits broad activity against anaerobic bacteria, protozoa, and certain intestinal helminths. We examined the effects of NTZ and tizoxanide (TZ) on Brugia malayi nematodes in vitro and in vivo. In vitro, NTZ and TZ reduced worm motility and viability in a dose-dependent manner. Worm viability was reduced by 50% with both compounds at 2.5 and 20 microg/ml killed adult worms. NTZ or TZ (5 microg/ml) significantly reduced microfilaria release. These compounds blocked worm's embryogenesis, and decreased microfilarial motility and viability. Treated worms had damaged cuticles and abnormal mitochondria. Wolbachia were not cleared by NTZ or TZ treatment. Neither NTZ nor TZ cleared adult worms or microfilariae in infected gerbils. These results show that NTZ and TZ have potent effects on B. malayi nematodes in vitro. However, they were not effective in vivo.

A review and meta-analysis of the impact of intestinal worms on child growth and nutrition

More than a half of the world's population are infected with one or more species of intestinal worms of which the nematodes Ascaris lumbricoides, Trichuris trichiura and the hookworms are the most common and important in terms of child health. This paper: (1) introduces the main species of intestinal worms with particular attention to intestinal nematodes; (2) examines how such worms may affect child growth and nutrition; (3) reviews the biological and epidemiological factors that influence the effects that worms can have on the growth and nutrition of children; (4) considers the many factors that can affect the impact of treatment with anthelmintic drugs; (5) presents the results of a meta-analysis of studies of the effect of treating worm infections on child growth and nutrition; (6) discusses the results in terms of what is reasonable to expect that deworming alone can achieve; (7) describes some important characteristics of an ideal study of the effects of deworming; and (8) comments on the implications for programmes of recommendations concerning mass deworming.

Triple co-administration of ivermectin, albendazole and praziquantel in zanzibar: a safety study

BACKGROUND

Public health interventions based on distribution of anthelminthic drugs against lymphatic filariasis (LF), onchocerciasis, soil-transmitted helminthiasis (STH) and schistosomiasis have been implemented separately to date. A better use of available resources might be facilitated by a more coordinated approach to control such infections, including the possibility of co-administering the three recommended anthelminthic drugs through a single, large-scale intervention.

METHODOLOGY/PRINCIPAL FINDINGS

Ivermectin, albendazole and praziquantel were co-administered to 5,055 children and adults living in areas endemic for LF, STH and schistosomiasis in Zanzibar, United Republic of Tanzania, during a pilot intervention aimed at elucidating and quantifying possible side-effects. Subsequently, these drugs were co-administered to about 700,000 individuals during a countrywide intervention targeting a large part of the total population of Zanzibar. Passive and active surveillance measures carried out during both interventions showed that side-effects attributable to the three drugs given at the same time were mild and self-limiting events.

CONCLUSIONS/SIGNIFICANCE

Our data suggest that co-administration of ivermectin, albendazole and praziquantel is safe in areas where lymphatic filariasis, soil-transmitted helminthiasis and schistosomiasis are co-endemic and where several rounds of treatment with one or two drugs have been implemented in the past. Passive surveillance measures, however, should be continued and detection, management and reporting of possible side-effects should be considered a key component of any health intervention administering drugs.

Efficacy and safety of drug combinations in the treatment of schistosomiasis, soil-transmitted helminthiasis, lymphatic filariasis and onchocerciasis

This review concerns the efficacy and safety of combinations of various drugs, including albendazole (ALB), diethylcarbamazine (DEC), ivermectin (IVM), mebendazole and praziquantel (PZQ). There were no significant pharmacokinetic interactions when ALB-PZQ, ALB-DEC, ALB-IVM or ALB-IVM-PZQ were co-administered. ALB did not add to the cure rate of PZQ in the treatment of Schistosoma japonicum, S. mansoni and S. haematobium. ALB and DEC in combination and alone were ineffective against S. haematobium infections. No combinations (ALB-PZQ, ALB-IVM and ALB-DEC) were superior to ALB against Ascaris lumbricoides and hookworm infections, whilst IVM, but not PZQ or DEC, added to the effect of ALB in the treatment of Trichuris trichiura. Results with ALB added to single-drug therapy with IVM or DEC against lymphatic filariasis were inconclusive, but DEC and IVM in combination appeared to be superior to DEC or IVM alone. None of the drug combinations against lymphatic filariasis showed more adverse reactions than single-drug therapy. In onchocerciasis patients, ALB and IVM were safe in those also infected with lymphatic filariasis, but were not superior to IVM alone. Existing policies are based on limited knowledge. Well conducted, comparative, randomised controlled studies would greatly aid in the future use of these drug combinations.

Projected benefits from integrating NTD programs in sub-Saharan Africa

The integration of preventive chemotherapy programs (PCPs) targeting multiple neglected tropical diseases (NTDs) with similar strategic approaches offers opportunities for enhanced cost-effectiveness. To estimate the potential cost savings and health outcomes of integrated programs, the data available for five NTDs (lymphatic filariasis, onchocerciasis, intestinal helminthiasis, schistosomiasis and trachoma) can be used to define eligible target populations, the probable overlap of at-risk populations, and the cost per person treated in stand-alone and integrated programs. If all targets for 2006 in sub-Saharan Africa are met, then savings of 26-47% can be projected from such integration (a cost of US dollar 58-81 million versus dollar 110 million for stand-alone PCPs). These first estimates can be refined as empirical data become available from integrated PCPs in the future.

A blueprint for success: integration of neglected tropical disease control programmes

The rapid expansion of chemotherapy-based control programmes for neglected tropical diseases has been catalysed by funding from the Bill and Melinda Gates Foundation, donations of several drugs from pharmaceutical manufacturers, and the reduced price of the drug praziquantel. Focussing on lymphatic filariasis, schistosomiasis and soil-transmitted helminthiasis, we review here the progress made to date with the implementation and integration of large-scale control programmes. Unresolved issues include a means for rapid identification of communities at highest risk of co-morbidity, cost-effective approaches for integrating the technical interventions into setting-specific packages, and determination of the most appropriate and sustainable delivery systems.

Discovering New Classes of Brugia malayi Asparaginyl-tRNA Synthetase Inhibitors and Relating Specificity to Conformational Change

SLIDE software, which models the flexibility of protein and ligand side chains while docking, was used to screen several large databases to identify inhibitors of Brugia malayi asparaginyl-tRNA synthetase (AsnRS), a target for anti-parasitic drug design. Seven classes of compounds identified by SLIDE were confirmed as micromolar inhibitors of the enzyme. Analogs of one of these classes of inhibitors, the long side-chain variolins, cannot bind to the adenosyl pocket of the closed conformation of AsnRS due to steric clashes, though the short side-chain variolins identified by SLIDE apparently bind isosterically with adenosine. We hypothesized that an open conformation of the motif 2 loop also permits the long side-chain variolins to bind in the adenosine pocket and that their selectivity for Brugia relative to human AsnRS can be explained by differences in the sequence and conformation of this loop. Loop flexibility sampling using Rigidity Optimized Conformational Kinetics (ROCK) confirms this possibility, while scoring of the relative affinities of the different ligands by SLIDE correlates well with the compounds' ranks in inhibition assays. Combining ROCK and SLIDE provides a promising approach for exploiting conformational flexibility in structure-based screening and design of species selective inhibitors.

Lymphatic Filariasis: Treatment, Control and Elimination

Lymphatic filariasis (LF) is a disease not just treatable or controllable; it is a disease that can be eliminated. Indeed, LF is currently the target of a major global initiative to do just that; a few visionaries of the past 50 years did hypothesize that LF elimination was feasible. However, for most of the scientific and global health communities, the elimination of such a broadly disseminated, mosquito-borne disease has seemed highly unlikely. During the past decade, however, both the treatment strategies and the control strategies for LF have undergone profound paradigm shifts-all because of a rapid increase in knowledge and understanding of LF that derived directly from a series of remarkable achievements by the scientific and medical research communities. As a result, a public health dimension with a focus on affected populations, now supplements the earlier, predominantly patient-oriented clinical approach to LF. The early uncertainties, then the essential steps leading to this change in outlook are outlined below, followed by descriptions of the new strategy for LF elimination, the Global Programme created to attain this goal and the successes achieved to date.

Mass chemotherapy options to control lymphatic filariasis: a systematic review

Understanding the efficacy of microfilaricidal drugs is important in guiding the global programme for the elimination of lymphatic filariasis as a public-health problem. We did a systematic review of the available literature to determine which currently available drug intervention most effectively decreases circulating Wuchereria bancrofti microfilaria in individuals and populations. 57 randomised studies of drug efficacy were identified. Data were combined and compared using weighted mean effect estimates taking into account the longitudinal nature of the data. Combined treatment with diethylcarbamazine plus ivermectin, diethylcarbamazine plus albendazole, and ivermectin plus albendazole resulted in average microfilarial intensity decreases that were 0.7%, 4.6%, and 12.7% of the pre-treatment values, respectively. Drug combinations containing diethylcarbamazine were the most effective against microfilarial prevalence and intensity relative to single drugs or other combinations. The relative efficacies of drug combinations have not been well documented from existing studies and therefore limit the application of evidenced-based recommendations for chemotherapy-based interventions to control lymphatic filariasis. These results provide valuable estimates of drug effect using existing data, but highlight the need for more comprehensive comparative drug studies.

Impact of two rounds of mass drug administration using diethylcarbamazine combined with albendazole on the prevalence of Brugia timori and of intestinal helminths on Alor Island, Indonesia

Background

Annual mass drug administration (MDA) using diethylcarbamizine (DEC, 6 mg/kg) combined with albendazole (alb, 400 mg) is recommended by the Global Programme to Eliminate Lymphatic Filariasis (GPELF). This strategy has been shown to be efficient in the of control bancroftian filariasis, but data on brugian filariasis as well as on the positive side effects on intestinal helminths are lacking.

Methods

The effect of one selective treatment and two rounds of MDA using DEC and alb on the prevalence and intensity of Brugia timori infection were studied on Alor island using a cross-sectional and a cohort approach. Before the campaign and ten months after each treatment cycle microfilariae (mf) were assessed by filtration of night blood. Before and ten months after MDA, stool samples were collected and the prevalence of intestinal helminths were determined.

Results

In all, the mf-rate dropped from 26.8% before any treatment to 3.8% following the second MDA. Almost all mf-positive, treated individuals showed very low mf densities. The crude prevalence of hookworm dropped from 25.3% to 5.9%. The reduction of prevalence of Ascaris lumbricoides (32.3% to 27.6%) and Trichuris trichiura (9.4% to 8.9%) was less pronounced. Within a cohort of 226 individuals, which was examined annually, the prevalence of A. lumbricoides dropped from 43.8% to 26.5% and of T. trichiura from 12.8% to 6.6%. The results indicate that this MDA approach reduces not only the mf prevalence of B. timori but also the prevalence of hookworm and to a lesser extent also of A. lumbricoides and T. trichiura.

Conclusion

The MDA using DEC and alb as recommended by GPELF is extremely effective for areas with brugian filariasis. The beneficial effect of MDA on intestinal helminths may strengthen the national programme to eliminate lymphatic filariasis in Indonesia and may set resources free which are otherwise used for deworming campaigns of schoolchildren.

Significant decrease in the prevalence of Wuchereria bancrofti infection in anopheline mosquitoes following the addition of albendazole to annual, ivermectin-based, mass treatments in Nigeria

A prospective entomological survey was conducted in four sentinel villages in central Nigeria from 1999-2002, to assess the impact of annual, single-dose, mass drug administrations (MDA), with a combination of ivermectin and albendazole, on the transmission of Wuchereria bancrofti. As they were also endemic for human onchocerciasis, the four villages had received annual MDA based on ivermectin alone for 7 years prior to the addition of albendazole. Resting Anophelines gambiae s. l., An. funestus and Culex species were collected from 92 sequentially sampled households and dissected. Mosquitoes harbouring any larval stage of W. bancrofti were classified as 'infected', and those containing the third-stage larvae of the parasite were classified as 'infective'. Over the 41-month observation period, 4407 mosquitoes were captured and dissected, of which 64% were An. gambiae s. l., 34% An. funestus, and 1% Culex species. The baseline data, from dissections performed before the addition of albendazole to the MDA, showed high prevalences of mosquito infection (8.9%) and infectivity (2.9%), despite apparently good treatment coverages during the years of annual ivermectin monotherapy. Only the anopheline mosquitoes were found to harbour W. bancrofti larvae. After the third round of MDA with the ivermectin-albendazole combination, statistically significant decreases in the prevalences of mosquito infection (down to 0.6%) and infectivity (down to 0.4%) were observed (P<0.0001 for each). The combination of albendazole and ivermectin appears to be superior to ivermectin alone for reducing the frequency of W. bancrofti infection in mosquitoes.