DEC-medicated Salt Research Articles

Economic performance and cost-effectiveness of using a DEC-salt social enterprise for eliminating the major neglected tropical disease, lymphatic filariasis

BackgroundSalt fortified with the drug, diethylcarbamazine (DEC), and introduced into a competitive market has the potential to overcome the obstacles associated with tablet-based Lymphatic Filariasis (LF) elimination programs. Questions remain, however, regarding the economic viability, production capacity, and effectiveness of this strategy as a sustainable means to bring about LF elimination in resource poor settings.Methodology and principal findingsWe evaluated the performance and effectiveness of a novel social enterprise-based approach developed and tested in Léogâne, Haiti, as a strategy to sustainably and cost-efficiently distribute DEC-medicated salt into a competitive market at quantities sufficient to bring about the elimination of LF. We undertook a cost-revenue analysis to evaluate the production capability and financial feasibility of the developed DEC salt social enterprise, and a modeling study centered on applying a dynamic mathematical model localized to reflect local LF transmission dynamics to evaluate the cost-effectiveness of using this intervention versus standard annual Mass Drug Administration (MDA) for eliminating LF in Léogâne. We show that the salt enterprise because of its mixed product business strategy may have already reached the production capacity for delivering sufficient quantities of edible DEC-medicated salt to bring about LF transmission in the Léogâne study setting. Due to increasing revenues obtained from the sale of DEC salt over time, expansion of its delivery in the population, and greater cumulative impact on the survival of worms leading to shorter timelines to extinction, this strategy could also represent a significantly more cost-effective option than annual DEC tablet-based MDA for accomplishing LF elimination.SignificanceA social enterprise approach can offer an innovative market-based strategy by which edible salt fortified with DEC could be distributed to communities both on a financially sustainable basis and at sufficient quantity to eliminate LF. Deployment of similarly fashioned intervention strategies would improve current efforts to successfully accomplish the goal of LF elimination, particularly in difficult-to-control settings.

Assessing endgame strategies for the elimination of lymphatic filariasis: A model-based evaluation of the impact of DEC-medicated salt

Concern is growing regarding the prospects of achieving the global elimination of lymphatic filariasis (LF) by 2020. Apart from operational difficulties, evidence is emerging which points to unique challenges that could confound achieving LF elimination as extinction targets draw near. Diethylcarbamazine (DEC)-medicated salt may overcome these complex challenges posed by the endgame phase of parasite elimination. We calibrated LF transmission models using Bayesian data-model assimilation techniques to baseline and follow-up infection data from 11 communities that underwent DEC salt medication. The fitted models were used to assess the utility of DEC salt treatment for achieving LF elimination, in comparison with other current and proposed drug regimens, during the endgame phase. DEC-medicated salt consistently reduced microfilaria (mf) prevalence from 1% mf to site-specific elimination thresholds more quickly than the other investigated treatments. The application of DEC salt generally required less than one year to achieve site-specific LF elimination, while annual and biannual MDA options required significantly longer durations to achieve the same task. The use of DEC-medicated salt also lowered between-site variance in extinction timelines, especially when combined with vector control. These results indicate that the implementation of DEC-medicated salt, where feasible, can overcome endgame challenges facing LF elimination programs.

Diethylcarbamazine (DEC)-medicated salt for community-based control of lymphatic filariasis

Mass treatment with diethylcarbamazine (DEC)-medicated salt has been used in a number of places as a control measure for lymphatic filariasis. We sought reliable evidence about its effect on lymphatic filariasis transmission. To evaluate the effects of DEC-medicated salt on infection with lymphatic nematodes in studies of individuals and communities. In August 2006, we searched the Cochrane Infectious Disease Group Specialized Register, CENTRAL (The Cochrane Library 2006, Issue 3), MEDLINE, EMBASE, and LILACS. We also checked reference lists. Studies of DEC-medicated salt in endemic populations or microfilaraemic individuals that reported on some measure of human infection before and after the intervention. Two authors assessed study eligibility and methodological quality. We calculated the percentage change in microfilariae prevalence and density, adult worm prevalence, disease rates, and vector infection and infectivity. We carried out meta-regression to explore the variability in percentage reduction in microfilariae prevalence between studies. Twenty-one studies were included; two compared DEC-medicated salt with other forms of DEC, five had some control group, and 14 were before-and-after studies. Five were efficacy and safety studies of individuals who were all microfilaraemic at baseline; the rest studied endemic communities. Percentage reductions in microfilariae prevalence were large (43% to 100%) and consistent in most studies with high levels of coverage. Large reductions in microfilariae density were also observed, though most studies reported changes in microfilariae density only for people with microfilaraemia at baseline. Vector infection and infectivity also declined, but the samples were usually small. Changes in disease prevalence were inconclusive as most studies were not powered for this outcome. Adverse events seemed mild. Only two studies compared DEC-medicated salt with other forms of DEC (such as annual or standard 12-day dose), but in both performance of DEC-medicated salt was better.A few studies included longer term follow up (two to 19 years). Reductions in microfilariae prevalence, density, and vector infectivity were maintained over time. The DEC concentration in the salt and the duration of intervention were significant factors influencing the percentage reduction in microfilariae prevalence in these studies. DEC-medicated salt is an effective intervention when maintained with levels of coverage of at least 90% for at least six months. Further studies are required to assess the effects of continuous low-dose, DEC-medicated salt on adult worms, disease prevalence, and development of drug resistance.

Medical treatment of filariasis and chyluria

The medical treatment of filariasis and chyluria is based on dietary modification, i.e. a diet excluding fat, supplemented by medium chain triglycerides (MCT) and high protein content. Drug therapy include administration of antifilarial drugs like diethylcarbamizine (DEC), ivermectin and albendazole. Annual mass drug administration of DEC combined with albendazole is recommended by the Global Programme to Eliminate Lymphatic Filariasis (GPELF) in endemic areas. DEC-medicated salt has been effectively used in various filarial endemic countries and as well as in certain parts of India. Vector control is a useful means in addition to chemotherapy in control of lymphatic filariasis.

A high performance liquid chromatographic method for the estimation of diethylcarbamazine content in medicated salt samples

A simple and reproducible method for the estimation of diethylcarbamazine citrate (DEC) by high performance liquid chromatography (HPLC) in DEC-medicated salt was developed. HPLC analysis was conducted with a mobile phase containing acetonitrile/phosphate buffer (20 mM KH 2PO 4, adjusted to pH 3.2 with 10% ortho-phosphoric acid) in the ratio of 1:9 and at a flow rate of 1.5 ml/min. A Phenomenex C8 column (15 cm×4.6 mm) of 5 μm particle size was used for the analysis. Analysis was done at UV 210 nm, 0.02 a.u.f. and 40 °C. The coefficient of variation was <10% in the range of 1–25 μg/ml and the minimum detectable level was 0.5 μg/ml. The quality of DEC-medicated salt prepared by two methods was analyzed by using the HPLC method. In spray drying method, 29 and 71% of the samples and in rotating drum method, 9 and 12% of samples were found to contain DEC at 0.15–0.25% and >0.25%, respectively. Thus, this quick and simple HPLC method for the estimation of DEC could play a vital role in checking the quality of the DEC medicated salt used for the control of filariasis.

Tolerance to diethylcarbamazine-medicated salt in individuals infected with Onchocerca volvulus

The tolerance of Onchocerca volvulus-infected individuals to diethylcarbamazine (DEC)-medicated salt (0·33% w/w) was assessed in 1996 in Tanzania in a double-blind placebo-controlled hospital-based trial involving 4 groups, each of 10 adult males. Groups I and II had O. volvulus microfilariae (mf) only, group III had both O. volvulus and Wuchereria bancrofti mf, and group IV had W. bancrofti mf only. Groups I, III and IV received DEC-medicated salt, whereas group II was a control to group I and received normal cooking salt. Medication was given for 10 days. The most pronounced adverse reactions in groups I and III were mild-to-moderate itching and rash, beginning after 3–4 days and lasting for the remaining medication period. The reactions did not interfere with normal daily activities. By 20 days after the end of medication, adverse reactions had disappeared in all individuals. The low daily dose of DEC had no significant effect on the O. volvulus pre-medication mf geometric mean intensities (GMIs). In contrast, the medication significantly reduced the pre-medication W. bancrofti mf GMIs. The prospects for using DEC-medicated salt for control of bancroftian filariasis in areas where incidental infections with O. volvulus occur are discussed.

Long-term effect of mass diethylcarbamazine chemotherapy on bancroftian filariasis: results at four years after start of treatment

The long-term effect of 4 strategies for control of bancroftian filariasis using mass diethylcarbamazine (DEC) chemotherapy was assessed and compared in 4 endemic communities in Tanzania over a period of 4 years. The strategies were the standard 12 d treatment (strategy I), semi-annual single dose treatment (strategy II), monthly low dose treatment (strategy III), and DEC-medicated salt treatment (strategy IV). Treatment was given only during the first year. All strategies resulted in considerable reductions in microfilaraemia, with maximum effects occurring 1–2 years after start of treatment. At 2 years, the greatest reductions were seen for strategies III and IV, followed by strategy II and finally strategy I. The overall performance of the 4 strategies evaluated over the 4 years period followed the same sequence. Between the 2 years and 4 years follow-up surveys, a significant increase in microfilarial (mf) burden occurred in all 4 communities, but the mf geometric mean intensities (GMI) remained low. Thus, in individuals who were microfilaraemic before treatment, the rates of microfilaraemia were 66%, 44%, 34% and 43%, and the mf GMIs were 6·8%, 3·3%, 0·5% and 0·7%, of pre-treatment level, 4 years after start of treatment with strategies I, II, III and IV, respectively. Most individuals who developed microfilaraemia between the 2 years and 4 years follow-up surveys had been microfilaraemic before the start of treatment. Hence, the rate of development of microfilaraemia was much higher (18 times on average in the 4 communities) among those who were microfilaraemic before treatment than among those who were amicrofilaraemic. The long-lasting effect of treatment adds a promising potential to the use of mass DEC chemotherapy for the control of bancroftian filariasis.

Mass administration of DEC-medicated salt for filariasis control in South India : An assessment

Mass administration of DEC-medicated salt for filariasis control in South India : An assessment

Mass diethylcarbamazine chemotherapy for control of bancroftian filariasis through community participation: comparative efficacy of a low monthly dose and medicated salt

The efficacy of 2 strategies for the control of bancroftian filariasis using diethylcarbamazine (DEC) mass chemotherapy delivered through community participation was evaluated and compared in 2 endemic communities in Tanzania with pre-treatment microfilarial (mf) prevalences of 34·7% and 31·0%, and mf geometric mean intensities (GMI) of 1122 mf/mL and 933 mf/mL, respectively. In the first community, all individuals aged ⩾1 year were offered treatment for one year with a low monthly dose (50 mg DEC to children aged < 15 years and 100 mg DEC to adults aged ⩾15 years; given independently of body weight), and in the second community all households were offered 0·33% w w DEC-medicated cooking salt for one year. Both treatment strategies resulted in dramatic reductions in the mf loads. Among those microfilaraemic before treatment, the low monthly dose and the DEC-medicated salt gave mf clearance rates of 55·3% and 92·1%, respectively, and the pre-treatment mf GMIs were reduced by 99·4% and 99·9%, respectively, one year after starting treatment. At community level, the mf prevalences were reduced to 15·8% and 2·4% (reductions of 54·5% and 92·3%) and the mf GMIs were reduced to 100 mf/mL and 32 mf/mL (reductions of 91·1% and 96·6%), one year after starting treatment with the low monthly dose and DEC-medicated salt respectively. Males with hydrocele before treatment improved remarkably one year after the start of treatment. Since both strategies were simple to administer and well accepted by the communities, they appear highly feasible for integration into large scale control programmes based on community participation.

Diethylcarbamazine salt in the control of lymphatic filariasis.

Where lymphatic filariasis has diminished since about the 1950s, it has most frequently, though not always, been a direct result of chemotherapeutic intervention against the parasite. Diethylcarbamazine (DEC), a well-established drug, has been the single agent of chemotherapeutic control and has been successful in a wide variety of regimens. This paper reviews the experience with one strategy: long-term, low-dose treatment through DEC-medicated common salt. Diethylcarbamazine-medicated salt played a major role in the Chinese filariasis control program and has been successful in more limited trials in India, Brazil, and Tanzania. It is not being used today in any endemic area, but the evidence suggests that it is safe, effective, and relatively inexpensive. Enough is already known about the beneficial effects of DEC-medicated salt from community-wide studies to develop specific guidelines for its use in community programs.

Social and economic factors and the control of lymphatic filariasis: A review

Formal control programmes do not exist for lymphatic filariasis in much of the endemic world. The literature on the social, economic and clinical impacts of the disease is so sparse as to provide virtually no guidance on whether the disease should be accorded more importance in national or local public health programmes. This type of research is a major priority. Putting together what little is known about the socioeconomic determinants of filariasis with the fairly extensive experience in control leads to a finding that control programmes must be undertaken at the community level to be effective. Diethylcarbamazine (DEC) is a readily available and apparently safe drug that can be deployed successfully for community control. While research currently is exploring the potential for individuals to protect themselves with DEC or a newer drug, ivermectin, community-wide control is unlikely to be achieved in that way. Under some special circumstances, controlling the mosquito vectors may be sufficient to control the disease, and in other cases, it may complement chemotherapy, but in general, it cannot be relied upon as a primary measure. DEC may be used in a variety of regimens which vary in their cost, duration, incidence of side effects and degree of community participation. Some, including DEC-medicated salt, are particularly attractive alternatives for many filariasis-endemic areas. The search for less expensive, yet effective, control options must continue, and this requires research not only into the costs of the various options, but also into the determinants of community acceptance, compliance and participation.

Eradication of bancroftian filariasis by diethylcarbamazine-medicated common salt on Little Kinmen (Liehyu District), Kinmen (Quemoy) Islands, Republic of China

Since bancroftian filariasis constituted a major public health problem on Little Kinmen (Liehyu District), Kinmen (Quemoy) Islands, a control programme was conducted on this island from 1970 to 1982. A pre-control survey recorded a microfilarial rate (mfr) of 9.6%, a night blood microfilarial density (mfd) of 14.4/20 microliters blood, and a clinical rate of 26.2%. Culex quinquefasciatus was found to be the only vector of the parasitosis on the island, with an infection rate (Ir) with all filarial larval stages of 9.1% and a larval density (Ld) of 6.2. Diethylcarbamazine (DEC)-medicated salt (0.33% w/w) was administered to the whole population on Little Kinmen. Each person was estimated to take 12.7 g salt with 42 mg DEC daily for six months (July-December 1974). All accepted the programme, and no adverse side-effect was noted. During the control, the mfr and mfd were reduced to 0.3% and 1.9/20 microliters blood. The Ir and Ld were reduced to 0.8% and 1.3. Eight post-control surveys (1975-1982) revealed only two of 459 pre-control carriers positive and the remaining population of 7125 inhabitants negative. The two carriers were cured with a course of 5 g DEC. All family members of these carriers and their neighbours' families were given DEC-medicated salt for four months to clear the only remaining source of filarial transmission. In addition to a reduction in the prevalence of filariasis in humans and in mosquitoes to zero, the clinical manifestations disappeared in 52.4% of the pre-control carriers and improved in 19.0%. There was no change in 19.8 and 8.7% had new manifestations.

Effects of various concentrations of diethylcarbamazine citrate applied as eye drops in ocular onchocerciasis, and the possibilities of improved therapy from continuous non-pulsed delivery.

Diethylcarbamazine was given as eye drops in varying concentrations in a half-log dilution series from 1.0 to 0.0001% to patients with ocular onchocerciasis. Migration of microfilariae into the cornea, followed by their straightening and disintegration, was observed with delivery rates as low as 0.1 microgram/hour. Dose-related adverse inflammatory reactions, including the development of globular limbal infiltrates with itching and redness, were seen with delivery rates as low as 0.6 microgram/hour, but substantial inflammatory reactions, including severe vasculitis, were seen only with delivery rates of or above 1.0 microgram/hour. This suggests that it should be possible to achieve beneficial clearing of the microfilarial load, without adverse reactions, by continuous non-pulsed delivery of the drug. Technology exists for such delivery, either directly into the eye or systemically by a transdermal system that could give 3 to 7 days' treatment from each application. The observations reported suggest that after preliminary clearing of the microfilarial load by carefully controlled delivery of DEC it may be possible to maintain therapy by less strictly controlled delivery in DEC-medicated salt, or to use treatment with suramin, without incurring substantial adverse reactions, such as a deterioration in vision in cases in which the optic nerve is already compromised. Continuous non-pulsed DEC delivery systems could have a place in the management of onchocercal sclerosing keratitis. The unique opportunities for using the ocular model to define the requirements for beneficial non-damaging therapy with DEC should be explored in further field trials.