Lymphatic filariasis elimination in the Dominican Republic: History,progress, and remaining steps

Lymphatic filariasis (LF) is a mosquito-transmitted parasitic disease that is a leading cause of disability globally. The island of Hispaniola, which the Dominican Republic shares with Haiti, accounts for approximately 90% of LF cases in the Americas region. In 1998, the Dominican Ministry of Public Health created the Program to Eliminate Lymphatic Filariasis (PELF) with the goal of eliminating LF transmission by 2020. Baseline mapping revealed 19 (12% of total) endemic municipalities clustered into three geographic foci (Southwest, La Ciénaga and East), with a total at-risk population of 262,395 people. Beginning in 2002, PELF sequentially implemented mass drug administration (MDA) in these foci using albendazole and diethylcarbamazine (DEC). In total, 1,174,050 treatments were given over three to five annual rounds of house-to-house MDA per focus with a median coverage of 81.7% (range 67.4%–92.2%). By 2018, LF antigen prevalence was less than 2% in all foci, thus meeting criteria to stop MDA and begin post-treatment surveillance (PTS). This success has been achieved against a shifting landscape of limited domestic funding, competing domestic public health priorities, and sporadic external donor support. Remaining steps include the need to scale-up morbidity management and disability prevention services for LF and to continue PTS until LF transmission is interrupted across Hispaniola.     

A multicenter,community-based,mixed methods assessment of the acceptability of a triple drug regimen for elimination of lymphatic filariasis

BackgroundMany countries will not reach elimination targets for lymphatic filariasis in 2020 using the two-drug treatment regimen (diethylcarbamazine citrate [DEC] and albendazole [DA]). A cluster-randomized, community-based safety study performed in Fiji, Haiti, India, Indonesia and Papua New Guinea tested the safety and efficacy of a new regimen of ivermectin, DEC and albendazole (IDA).Methodology/Principal findingsTo assess acceptability of IDA and DA, a mixed methods study was embedded within this community-based safety study. The study objective was to assess the acceptability of IDA versus DA. Community surveys were performed in each country with randomly selected participants (>14 years) from the safety study participant list in both DA and IDA arms. In depth interviews (IDI) and focus group discussions (FGD) assessed acceptability-related themes. In 1919 individuals, distribution of sex, microfilariae (Mf) presence and circulating filarial antigenemia (CFA), adverse events (AE) and age were similar across arms. A composite acceptability score summed the values from nine indicators (range 9–36). The median (22.5) score indicated threshold of acceptability. There was no difference in scores for IDA and DA regimens. Mean acceptability scores across both treatment arms were: Fiji 33.7 (95% CI: 33.1–34.3); Papua New Guinea 32.9 (95% CI: 31.9–33.8); Indonesia 30.6 (95% CI: 29.8–31.3); Haiti 28.6 (95% CI: 27.8–29.4); India 26.8 (95% CI: 25.6–28) (P<0.001). AE, Mf or CFA were not associated with acceptability. Qualitative research (27 FGD; 42 IDI) highlighted professionalism and appreciation for AE support. No major concerns were detected about number of tablets. Increased uptake of LF treatment by individuals who had never complied with MDA was observed.Conclusions/SignificanceIDA and DA regimens for LF elimination were highly and equally acceptable in individuals participating in the community-based safety study in Fiji, Haiti, India, Indonesia, and Papua New Guinea. Country variation in acceptability was significant. Acceptability of the professionalism of the treatment delivery was highlighted.     

Influence of anti-filarial chemotherapy strategies on the genetic structure of Wuchereria bancrofti populations

Lymphatic filarial (LF) parasites have been under anti-filarial drug pressure for more than half a century. Currently, annual mass drug administration (MDA) of diethylcarbamazine (DEC) or ivermectin in combination with albendazole (ALB) have been used globally to eliminate LF. Long-term chemotherapies exert significant pressure on the genetic structure of parasitic populations. We investigated the genetic variation among 210 Wuchereria bancrofti populations that were under three different chemotherapy strategies, namely MDA with DEC alone (group I, n = 74), MDA with DEC and ALB (group II, n = 60) and selective therapy (ST) with DEC (group III, n = 34) to understand the impact of these three drug regimens on the parasite genetic structure. Randomly amplified polymorphic DNA profiles were generated for the three groups of parasite populations; the gene diversity, gene flow and genetic distance values were determined and phylogenetic trees were constructed. Analysis of these parameters indicated that parasite populations under ST with a standard dose of DEC (group III) were genetically more diverse (0.2660) than parasite populations under MDA with DEC alone (group I, H = 0.2197) or with DEC + ALB (group II, H = 0.2317). These results indicate that the MDA may reduce the genetic diversity of W. bancrofti populations when compared to the genetic diversity of parasite populations under ST.     

On-line monitoring of lipase production in fermentation processes

Summary The results obtained in on-line monitoring of lipase production byCandida rugosa in a batch fermentation process are presented. For this purpose an automatic lipase concentration analyzer has been developed and tested. Its good reproducibility and its capability to perform the analysis in less time than the classical titrimetric method make it very suitable for on-line determination lipase concentration in fermentation processes.     

Monitoring denitrification by pH-Stat titration

An improved pH-stat titrimetric procedure was developed, validated, and extensively applied to monitor biological heterotrophic denitrification in a lab-scale sequencing batch reactor (SBR). So far, titrimetric procedures were not successful in monitoring denitrification processes in full-scale wastewater (WW) treatment plants, mainly because the stoichiometric ratio between proton production and nitrate reduction is highly variable due to variability of both biomass and influent WW characteristics. In this article, a new titration procedure is proposed where a simple calibration step is performed before each experimental test. This procedure allows for the assessment of (i) nitrate content in a sample of mixed liquor; (ii) the maximum denitrification rate of sludge when fed on acetate; and (iii) the denitrification potential (DNP) of different substrates. As for (i), validation by comparison with spectrophotometric measures indicated an average discrepancy of less than 3% on more than 40 samples; as for (ii) and (iii) collected values compared well with literature data. The titrimetric method proposed here is also capable of assessing the biomass anoxic yield in a very simple way, since it does not require any analytical nitrate determination. According to the results of this experimentation, titrimetry appeared to be a simple, inexpensive, and powerful tool for monitoring and operating denitrification processes in WW treatment plants.     

On-line monitoring of PHB production by mixed microbial cultures using respirometry,titrimetry and chemometric modelling

This work describes a method for on-line monitoring of biomass production, acetate consumption and intracellular polyhydroxybutyrate (PHB) storage by mixed microbial cultures (MMC). The method is based on reliable and easily available on-line measurements, namely pH, dissolved oxygen, dissolved carbon dioxide, on-line respirometry and on-line titrimetric analysis. Biomass production refers to active biomass growth and also to the synthesis of extracellular polymeric substances (EPS). The composition and kinetics of EPS synthesis has high variability depending on the culture enrichment protocol. Since the metabolism for EPS production is rather difficult to define, it was not possible to develop a reliable estimation model based on metabolic principles only. Instead, projection of latent structures (PLS) linear regression constrained by steady state carbon balance was employed. PHB concentration and biomass production rate were directly estimated by the PLS model, whereas acetate concentration was indirectly estimated through the carbon balance. The method was validated experimentally with data of four experiments carried out in a SBR. Accurate on-line estimations were obtained with regression coefficients (r²) of 0.986 and 0.980 for biomass concentration, 0.976 and 0.999 for PHB and 0.992 and 0.999 for acetate concentration in calibration and validation, respectively. These results confirm the ability of the proposed methodology for on-line monitoring of the state variables in PHB production process by MMC.     

The anti-Parkinsonian drug selegiline delays the nucleation phase of α-synuclein aggregation leading to the formation of nontoxic species

Parkinson's disease (PD) is a movement disorder characterized by the loss of dopaminergic neurons in the substantia nigra and the formation of intraneuronal inclusions called Lewy bodies, which are composed mainly of α-synuclein (α-syn). Selegiline (Sel) is a noncompetitive monoamino oxidase B inhibitor that has neuroprotective effects and has been administered to PD patients as monotherapy or in combination with l-dopa. Besides its known effect of increasing the level of dopamine (DA) by monoamino oxidase B inhibition, Sel induces other effects that contribute to its action against PD. We evaluated the effects of Sel on the in vitro aggregation of A30P and wild-type α-syn. Sel delays fibril formation by extending the lag phase of aggregation. In the presence of Sel, electron microscopy reveals amorphous heterogeneous aggregates, including large annular species, which are innocuous to a primary culture enriched in dopaminergic neurons, while their age-matched counterparts are toxic. The inhibitory effect displayed by Sel is abolished when seeds (small fibril pieces) are added to the aggregation reaction, reinforcing the hypothesis that Sel interferes with early nuclei formation and, to a lesser extent, with fibril elongation. NMR experiments indicate that Sel does not interact with monomeric α-syn. Interestingly, when added in combination with DA (which favors the formation of toxic protofibrils), Sel overrides the inhibitory effect of DA and favors fibrillation. Additionally, Sel blocks the formation of smaller toxic aggregates by perturbing DA-dependent fibril disaggregation. These effects might be beneficial for PD patients, since the sequestration of protofibrils into fibrils or the inhibition of fibril dissociation could alleviate the toxic effects of protofibrils on dopaminergic neurons. In nondopaminergic neurons, Sel might slow the fibrillation, giving rise to the formation of large nontoxic aggregates.     

Functional analysis of the interplay between translation termination, selenocysteine codon context, and selenocysteine insertion sequence-binding protein 2

A selenocysteine insertion sequence (SECIS) element in the 3'-untranslated region and an in-frame UGA codon are the requisite cis-acting elements for the incorporation of selenocysteine into selenoproteins. Equally important are the trans-acting factors SBP2, Sec-tRNA[Ser]Sec, and eEFSec. Multiple in-frame UGAs and two SECIS elements make the mRNA encoding selenoprotein P (Sel P) unique. To study the role of codon context in determining the efficiency of UGA readthrough at each of the 10 rat Sel P Sec codons, we individually cloned 27-nucleotide-long fragments representing each UGA codon context into a luciferase reporter construct harboring both Sel P SECIS elements. Significant differences, spanning an 8-fold range of UGA readthrough efficiency, were observed, but these differences were dramatically reduced in the presence of excess SBP2. Mutational analysis of the "fourth base" of contexts 1 and 5 revealed that only the latter followed the established rules for hierarchy of translation termination. In addition, mutations in either or both of the Sel P SECIS elements resulted in differential effects on UGA readthrough. Interestingly, even when both SECIS elements harbored a mutation of the core region required for Sec incorporation, context 5 retained a significantly higher level of readthrough than context 1. We also show that SBP2-dependent Sec incorporation is able to repress G418-induced UGA readthrough as well as eRF1-induced stimulation of termination. We conclude that a large codon context forms a cis-element that works together with Sec incorporation factors to determine readthrough efficiency.     

A Community-Based Study of Factors Associated with Continuing Transmission of Lymphatic Filariasis in Leogane,Haiti

Seven rounds of mass drug administration (MDA) have been administered in Leogane, Haiti, an area hyperendemic for lymphatic filariasis (LF). Sentinel site surveys showed that the prevalence of microfilaremia was reduced to <1% from levels as high as 15.5%, suggesting that transmission had been reduced. A separate 30-cluster survey of 2- to 4-year-old children was conducted to determine if MDA interrupted transmission. Antigen and antifilarial antibody prevalence were 14.3% and 19.7%, respectively. Follow-up surveys were done in 6 villages, including those selected for the cluster survey, to assess risk factors related to continued LF transmission and to pinpoint hotspots of transmission. One hundred houses were mapped in each village using GPS-enabled PDAs, and then 30 houses and 10 alternates were chosen for testing. All individuals in selected houses were asked to participate in a short survey about participation in MDA, history of residence in Leogane and general knowledge of LF. Survey teams returned to the houses at night to collect blood for antigen testing, microfilaremia and Bm14 antibody testing and collected mosquitoes from these communities in parallel. Antigen prevalence was highly variable among the 6 villages, with the highest being 38.2% (Dampus) and the lowest being 2.9% (Corail Lemaire); overall antigen prevalence was 18.5%. Initial cluster surveys of 2- to 4-year-old children were not related to community antigen prevalence. Nearest neighbor analysis found evidence of clustering of infection suggesting that LF infection was focal in distribution. Antigen prevalence among individuals who were systematically noncompliant with the MDAs, i.e. they had never participated, was significantly higher than among compliant individuals (p<0.05). A logistic regression model found that of the factors examined for association with infection, only noncompliance was significantly associated with infection. Thus, continuing transmission of LF seems to be linked to rates of systematic noncompliance.     

Specific gas chromatographic analysis of diethylcarbamazine in human plasma using solid-phase extraction

Diethylcarbamazine (DEC, 1-diethylcarbamyl-4-methylpiperazine) is an antiparasitic piperazine derivative used in the treatment of lymphatic filariasis. DEC-N-oxide is a major metabolite in humans which has antifilarial activity. Gas chromatographic analysis of DEC in plasma can be complicated by the presence of the metabolite, since the thermally unstable DEC-N-oxide is converted to a material which coelutes with DEC under the conditions of the analysis. We now report a method to separate DEC-N-oxide from DEC in plasma using solid-phase extraction with subsequent gas chromatographic analysis using a nitrogen specific detector. 1-Diethylcarbamyl-4-ethylpiperazine (E-DEC) was the internal standard. The standard curve of DEC is linear in the range of 10 to 200 ng/ml. The limit of detection is 4 ng/ml. Reproducibility at 10, 100 and 200 ng/ml concentration points of the standard curve gives coefficients of variation of 6.1%, 7.8% and 1.6%, respectively. Recovery following solid-phase extraction is 99.3% for DEC and 94.8% for the internal standard. This sensitive and specific analytical method is suitable for pharmacokinetic studies of DEC.     

Titration biosensors for the estimation of the biochemical nitrate demand of municipal and industrial wastes

An anoxic titrimetric test was investigated for measuring denitrification potential of different wastewaters, both municipal and industrial, and to quantify the denitrifying activity in an activated sludge system. The method measures the amount of acid that is required to maintain the pH set-point value in a batch denitrification experiment, and it was performed using a DENICON (denitrification controller) biosensor. The amount of acid is proportional to the nitrate used to oxidise the biodegradable chemical oxygen demand present in the wastewater, while the acid consumption rate is used to derive the denitrifying activity. The wastewaters tested were a municipal wastewater (MW), an industrial-municipal wastewater (MIW; 70% and 30%, respectively), and four industrial wastewaters drawn from an ice-cream factory (IW1), a beet-sugar factory (IW2), a brewery (IW3), and a tuna cannery industry (IW4). Good correlation between titration data and analyses was found.     

Increasing Compliance with Mass Drug Administration Programs for Lymphatic Filariasis in India through Education and Lymphedema Management Programs

Background

Nearly 45% of people living at risk for lymphatic filariasis (LF) worldwide live in India. India has faced challenges obtaining the needed levels of compliance with its mass drug administration (MDA) program to interrupt LF transmission, which utilizes diethylcarbamazine (DEC) or DEC plus albendazole. Previously identified predictors of and barriers to compliance with the MDA program were used to refine a pre-MDA educational campaign. The objectives of this study were to assess the impact of these refinements and of a lymphedema morbidity management program on MDA compliance.

Methods/Principal Findings

A randomized, 30-cluster survey was performed in each of 3 areas: the community-based pre-MDA education plus community-based lymphedema management education (Com-MDA+LM) area, the community-based pre-MDA education (Com-MDA) area, and the Indian standard pre-MDA education (MDA-only) area. Compliance with the MDA program was 90.2% in Com-MDA+LM, 75.0% in Com-MDA, and 52.9% in the MDA-only areas (p<0.0001). Identified barriers to adherence included: 1) fear of side effects and 2) lack of recognition of one''s personal benefit from adherence. Multivariable predictors of adherence amenable to educational intervention were: 1) knowing about the MDA in advance of its occurrence, 2) knowing everyone is at risk for LF, 3) knowing that the MDA was for LF, and 4) knowing at least one component of the lymphedema management techniques taught in the lymphedema management program.

Conclusions/Significance

This study confirmed previously identified predictors of and barriers to compliance with India''s MDA program for LF. More importantly, it showed that targeting these predictors and barriers in a timely and clear pre-MDA educational campaign can increase compliance with MDA programs, and it demonstrated, for the first time, that lymphedema management programs may also increase compliance with MDA programs.     

Did medicated salt hasten the spread of chloroquine resistance in Plasmodium falciparum?

With acknowledged difficulties in achieving satisfactory compliance rates for the large-scale delivery of many antiporositic drugs, the use of medicated salt has often been seen as a useful way to improve the level o f treatment in target populations. Iodinated salt is said to have contributed to a decline in endemic goitre, and salt medicated with chloroquine and/or other antimalorials, or with diethylcarbomazine, has been widely used in public health programmes against malaria and filariosis respectively. In this article, however, David Payne suggests that chloroquinized salt programmes may have been a major factor in promoting chloroquine resistance in Plasmodium falciparum.     

Willingness to pay for prevention and treatment of lymphatic filariasis in Leogane, Haiti

BACKGROUND: Lymphatic filariasis (LF) affects more than 120 million people worldwide. Efforts to eliminate this disease require sustained community participation. This study explores community valuation of LF elimination efforts by estimating household and community willingness to pay (WTP) for the prevention of transmission and treatment of filarial lymphedema in the community of Leogane, Haiti. METHODS: A contingent valuation survey was used to assess individual WTP for specific prevention and treatment interventions. A 2-dimensional Monte Carlo simulation was developed to estimate confidence limits in mean WTP and to generate a distribution of WTP for the community, accounting for uncertainty in regression coefficients and variability within the population. RESULTS: Mean WTP was estimated to be $5.57/month/household (95% CL: $4.76, $6.72) to prevent disease transmission, and $491/yr (95% CL: $377, $662) for treatment of lymphedema for one person. Based on the estimated distributions, 7% and 39% of households were not willing to pay for prevention and treatment, respectively. CONCLUSIONS: These results suggest that the majority of the community places a positive value on both prevention and treatment of LF. Mean WTP provides a useful monetary estimate of overall societal benefit of LF prevention and treatment programs. However, for interventions which require broad and sustained community participation, the lower end of the distribution of WTP has additional implications. Cost recovery policies may result in inadequate participation and longer program duration.     

Preventive effect of Ligularia fischeri on inhibition of nitric oxide in lipopolysaccharide-stimulated RAW 264.7 macrophages depending on cooking method

Background

Ligularia fischeri (common name Gomchwi) is known for its pharmaceutical properties and used in the treatment of jaundice, scarlet-fever, rheumatoidal arthritis, and hepatic diseases; however, little is known about its anti-inflammatory effect. In this study the influence of blanching and pan-frying on the anti-inflammatory activity of Ligularia fischeri (LF) was evaluated.

Results

Fresh LF and cooked LF showed no significant effect on the viability of macrophages after 24 h incubation. Fresh LF was found to be the most potent inhibitor of nitric oxide (NO) production at 100 μg/ml, while pan-fried LF showed little inhibitory effect on lipoloysaccharide (LPS) stimulated murine machrophage RAW264.7 cells. In contrast with its effect on NO production, pan-fried LF showed significant attenuation of the expression of inducible nitiric oxide synthase (iNOS) compared with fresh LF. In the cooking method of LF, PGE₂ production was not affected in the LPS-induced RAW 264.7 cells. In LPS-induced RAW 264.7 cells, pretreatment by fresh and cooked LF increased COX2 mRNA expression. The 3-O-caffeoylquinic acid content of blanching and pan-frying LF increased by 4.92 and 9.7 fold with blanching and pan-frying respectively in comparison with uncooked LF.

Conclusions

Regardless of the cooking method, Ligularia fischeri exhibited potent inhibition of NO production through expression of iNOS in LPS-induced RAW264.7 cells.