The impact of single-dose diethylcarbamazine treatment of bancroftian filariasis in a low-endemicity setting in Egypt

This study was designed to evaluate the effect of a single dose of diethylcarbamazine (DEC, 6 mg/kg) on Wuchereria bancrofti infections in a low-endemicity setting in Egypt (microfilaremia, or MF, 3.7%, median MF 34/mL). Subjects with MF or filarial antigenemia were treated and restudied 1 year later. Treatment with DEC dramatically reduced blood MF counts, with clearance in 69% of subjects. Treatment also reduced filarial antigen levels, but low clearance rates suggest that some adult worms survived treatment in most patients. Mass treatment was administered in one village; 27 months later, MF prevalence had decreased 84% (from 4.9% to 0.8%). These results show that single-dose DEC treatment can have a major effect on MF prevalence rates and levels in low-endemicity settings. Although the World Health Organization advocates repeated multidrug regimens for filariasis elimination, mass treatment with DEC alone may be sufficient to interrupt transmission in areas with low infection intensities and prevalence rates.     

Effects of combined diethylcarbamazine and albendazole treatment of bancroftian filariasis on parasite uptake and development in Culex pipiens L

We studied effects of combined diethylcarbamazine (DEC) and albendazole (ALB) treatment on Wuchereria bancrofti microfilaria (MF) uptake and development of infective larvae (L3) in Culex pipiens. Consenting Egyptian adults with microfilaremia (MF > 300/mL) were treated with one or seven daily doses of DEC/ALB. Laboratory-reared mosquitoes were fed on subjects before and after treatment. MF uptake and infectivity (assessed by mosquito dissection) were reduced by 89.6% and 82.9%, respectively, 12 months after single-dose treatment and by 96.2% and 99.7%, respectively, after multi-dose treatment. The L3:mosquito ratio decreased by 88% to 0.082 after single-dose treatment and by 99.8% to 0.001 after multi-dose treatment. If high coverage rates can be achieved for several annual cycles, mass drug administration (MDA) with DEC/ALB has the potential to decrease transmission to unsustainable levels and eliminate filariasis in populations. Multi-dose MDA (especially in the first year) might interrupt transmission with fewer cycles than single-dose treatment.     

Effects of ivermectin and diethylcarbamazine on microfilariae and overall microfilaria production in bancroftian filariasis

Ivermectin and diethylcarbamazine (DEC) are used in mass treatment programs for the elimination of lymphatic filariasis because of their strong effects on microfilaremia. However, the effects of treatment on adult worms and the degree of individual variation in efficacy are unclear. We analyzed series of microfilaria (Mf) counts from individuals treated with a single dose of 400 microg/kg ivermectin or 6 mg/kg DEC (N = 23 in each group; 1 year follow-up). For each individual, we estimated the microfilaricidal effect and the reduction in overall Mf production (e.g., caused by death or sterilization of worms, or inhibited Mf release from the female worm uterus). Ivermectin on average killed 96% of Mf and reduced Mf production by 82%. DEC killed 57% of Mf and reduced Mf production by 67%, with some individuals responding very poorly. The strong reduction in overall Mf production is good news for control of lymphatic filariasis, but the prospects of elimination will be diminished if part of the population systematically responds poorly to treatment.     

Comparison of high dose ivermectin and diethylcarbamazine for activity against bancroftian filariasis in Haiti

This three-phase study was designed to compare high dose ivermectin with a standard diethylcarbamazine (DEC) regimen for patient tolerability, potential to kill adult filaria, and duration of microfilarial suppression in 30 Haitian subjects with Wuchereria bancrofti microfilaremia. All were first given a 1-mg oral dose of ivermectin (phase 1) to reduce microfilaria densities. Participants were randomized into three groups: Group 1 received DEC (6mg/kg per day for 12 days), Group 2 received 200 mcg/kg of ivermectin, and Group 3 received 400 mcg/kg of ivermectin (200 mcg/kg per day for 2 days). All drug regimens were well tolerated with few adverse reactions. Most reactions occurred during phase I and consisted primarily of headache, fever, and myalgia. At the end of phase 1, 27 of 30 (90%) patients were microfilaria negative. During phase 2, four of the six men receiving DEC developed scrotal reactions suggesting killing adult worms; no such reactions were noted in 10 men receiving ivermectin (p less than 0.05). At one-year follow up (phase 3), all treatment groups had less than 10% return to pretreatment microfilaria levels. The mean percent of baseline microfilaria counts were for Group 1, 0.9% (range 0-5%); Group 2, 8.2% (range 0-31%); and Group 3, 3.8% (range 0-25%). Seven individuals in Group 1 were microfilaria-negative, while only one and three individuals were microfilaria-negative in Groups 2 and 3, respectively. These results suggest that DEC causes more damage to the adult worms and greater reduction in microfilaria densities than ivermectin, but that high doses of ivermectin may suppress microfilaremia in lymphatic filariasis for periods much longer than previously reported.     

Relationships between Wuchereria bancrofti microfilaria counts in human blood and parasite uptake and maturation in Culex pipiens,with observations on the effects of diethylcarbamazine treatment on these parameters

This study examined relationships between blood microfilaria (MF) counts and parasite uptake and maturation in Culex pipiens fed on Egyptian volunteers with bancroftian filariasis. Uptake of MF and production of infective larvae (L3) were more closely correlated with MF counts in finger prick blood than in venous blood. Only a minority of ingested MF developed into L3. Few MF were ingested, and very few L3 were produced by mosquitoes that fed on infected subjects who were amicrofilaremic by 50 microL thick blood smear; the contribution of such carriers to filariasis transmission in Egypt is probably negligible. These results suggest that filariasis elimination programs should aim to achieve MF smear rates of zero. Single-dose diethylcarbamazine therapy reduced MF counts by 87.9% 6-7 months after treatment; similar reductions were observed for MF uptake, MF/mosquito, infectivity, and L3/mosquito. Thus, single-dose diethylcarbamazine had a major impact on MF ingestion and L3 production by mosquitoes.     

Efficacy of ivermectin for control of microfilaremia recurring after treatment with diethylcarbamazine. I. Clinical and parasitologic observations

We compared the efficacy of a single dose of ivermectin with that of a standard course of diethylcarbamazine (DEC) for the control of microfilaremia in 60 patients with bancroftian filariasis who had developed recurrent microfilaremia after each of three or more prior treatments with DEC. The study was done as a randomized, double-blind trial. Complete, but in some cases, transient clearance of microfilaremia was observed in both treatment groups. At one year, recurrent microfilaremia was present in seven patients treated with ivermectin and in five treated with DEC. Pretreatment levels of microfilaremia were significantly higher in patients who relapsed within one year after treatment than in those who remained amicrofilaremic. Side effects with both treatments were common, but mild. Febrile reactions were more frequent in the ivermectin group; localized reactions consistent with a flare-up of acute filarial disease occurred mostly in the DEC group. We conclude that ivermectin is an effective and practical alternative to DEC for treatment of recurrent microfilaremia due to bancroftian filariasis.     

伊维菌素对海群生治疗后微丝蚴血症复现者的疗效 Ⅰ.临床和寄生虫学观察

本文对60例经过3—4个疗程海群生(DEC)治疗后微丝蚴血症复现者用单剂量伊维菌素和标准疗程DEC的疗效比较。用随机抽样,双盲法进行实验。两种治疗组病人均出现完全而短暂的清除微丝蚴血症的作用。一年后,采用伊维菌素治疗组中7例复现微丝蚴血症,DEC组为5例,疗前微丝蚴密度高的患者,疗后一年微丝蚴血症复现也多。两治疗组的副作用均轻微,伊维菌素组常出现发热反应,DEC组则常出现淋巴丝虫病的局部反应。 我们认为伊维菌素是一种有效而实用、可替代DEC治疗班氏丝虫病微丝蚴血症复现者的药物。     

A single diethylcarbamazine dose for treatment of Wuchereria bancrofti carriers in French Polynesia: efficacy and side effects

In the fall of 1988, 14 Tahitian Wuchereria bancrofti carriers were treated by a single diethylcarbamazine (DEC) 3 mg/kg dose. Determination of blood microfilarial (mf) density was carried out on days 0, 7, 14, 30, 90 and 180 using the membrane filtration technique. Clinical signs and side effects were noted during the 3 days following treatment. Complete clearance of microfilaremia was observed in two carriers (negativation rate 14%). A decrease of mf density was noted in all of the 14 carriers, ranging from 35.2 to 99.2% (median 78.75%). The percentage decrease in mf density, determined for the whole group from the geometric mean of the 14 mf counts, was 86% by day 7 and reached 95% by day 180. Side effects were observed in 10 patients (71%) of whom 3 only were unable to perform usual activities for less than 24 hours. Though it induced an incomplete initial mf clearance, a single DEC 3 mg/kg dose was effective in reducing about 90% of the microfilaremia and in sustaining this reduction over a period of six months. Such long-term reduction (comparable to that observed in W. bancrofti carriers treated with a daily DEC 6 mg/kg dose during 12 days) is likely responsible for the consistent decrease of total mf counts observed in the Tahitian population which has been treated for years with single DEC doses given every six months.     

湖南省丝虫病防治后期监测及流行病学动态分析

湖南省基本消灭丝虫病后１９８７～１９９１年横向监测４６个县（市）的４０８个村，血检２８７８６４人，查出微丝蚴血症者４人，平均微丝蚴率为０．００１％，各年微丝蚴率依次为０．００４％、０．００３％、０、０．００２％和０．００１％。解剖致倦库蚊２６８５２只，仅１９８８年发现阳性蚊１３只；解剖中华按蚊５７７１只，未发现幼丝虫。血清学监测流行区人群平均抗体阳性率为３．７６％，与非流行区抗体水平相近。４个纵向监测点的观察结果表明，低密度微丝蚴血症者能自然转阴。６个县（市）的晚期丝虫病患病率调查结果显示，基本消灭丝虫病后不再出现新的象皮肿病人，鞘膜积液的新发病例显著减少，但仍继续出现新的乳糜尿病人。     

Efficacy of bi-annual administration of DEC in the control of bancroftian filariasis.

The efficacy of bi-annual administration of DEC at the dose of 6 mg/kg body weight was evaluated on the microfilaraemia prevalence, density and vector filarial infection rates. Administration of four doses (4 x 6 mg/kg) of DEC significantly (P < 0.05) reduced the microfilaria rate of the community from 6.02 per cent to 2.31 per cent, microfilaria density from 0.66 to 0.17 and infectivity rate of the vector population from 0.8 per cent to 0.39 per cent.     

Efficacy of ivermectin for control of microfilaremia recurring after treatment with diethylcarbamazine. II. Immunologic changes following treatment

We compared the effect of a single dose of ivermectin with that of a standard course of diethylcarbamazine (DEC) on several parameters of the host's antifilarial immune response in 60 patients with bancroftian filariasis enrolled in a double-blind drug trial. All participants had measurable serum levels of antifilarial antibodies and parasite antigens at the onset of the study. Drug-induced clearance of microfilaremia was associated with a temporary increase in HC 11 antigenemia and a decrease in serum levels of antibodies to soluble filarial antigens. Antigenemia progressively declined in patients who remained amicrofilaremic after treatment, but declined and then increased in persons with recurrent microfilaremia. Treatment triggered a sustained increase in serum levels of interleukin-1, tumor necrosis factor, and interleukin-6 in all patients studied. Although ivermectin and DEC are believed to exert their antiparasite activity via different mechanisms, the same pattern of serologic changes was observed in patients treated with either drug.     

Duplex Doppler sonographic assessment of the effects of diethylcarbamazine and albendazole therapy on adult filarial worms and adjacent host tissues in Bancroftian filariasis

We used duplex Doppler sonography to assess effects of diethylcarbamazine and albendazole therapy (DEC/ALB) on adult Wuchereria bancrofti in vivo. The study was performed in clinically normal Egyptian adults with blood microfilaria counts > 80/mL. Motile adult worms were observed before treatment in dilated scrotal lymphatic vessels in 28 of 36 men (78%) and over the proximal extremities in 5 of 22 women (23%). Most worm nests were inactivated in the months following treatment (90% at 12 months). Circulating filarial antigen levels (a marker for living adult worms) also fell dramatically following treatment. Some men had intrascrotal calcifications and/or non-palpable hydroceles detectable by ultrasound before they were treated. New hydroceles and intrascrotal calcifications appeared after treatment in many cases. However, most of these were transient and of no clinical significance. Prevelance rates for hydrocele and intrascrotal calcifications 24 months after treatment were essentially the same as those prior to treatment. These results show that DEC/ALB is highly active against adult W. bancrofti. They also suggest that host responses to dying adult worms are important in the pathogenesis of filarial hydroceles.     

The Global Programme to Eliminate Lymphatic Filariasis: History and achievements with special reference to annual single-dose treatment with diethylcarbamazine in Samoa and Fiji

Diethylcarbamazine (DEC), first introduced in 1947, was shown to have strong efficacy and safety for treatment of human lymphatic filariasis, which is caused mostly by a species Wuchereria bancrofti. Many studies to optimize the dosage and treatment schedule of DEC followed, and, based on the results, control programs with various regimens were implemented in different endemic areas/countries. By the mid 1970s, with endorsement by the WHO Expert Committee on Filariasis (3rd report, 1974), the standard DEC regimen for W. bancrofti infection in mass treatment had been established in principle: a total dose of 72 mg/kg of body weight given in 12 divided doses, once weekly or monthly, at 6 mg/kg each. Not long after the committee report, the efficacy of annual single-dose treatment at 6 mg/kg, which is only one twelfth of the WHO-recommended dose in a year, was reported effective in French Polynesia (study period: 1973-78), and later in Samoa (study period: 1979-81). These results were published between 1978 and 1985 in the Bulletin of WHO but received little attention. In the mid 1980s, the efficacy of ivermectin, the first-choice drug for onchocerciasis, against lymphatic filariae came to light. Since the effect at a single dose was remarkable, and often better than DEC, it was predicted that the newly introduced drug would replace DEC. Treatment experiments with ivermectin increased quickly in number. Meanwhile, annual single-dose mass drug administration (MDA) with DEC at 6 mg/kg was under scrutiny in Samoa and Fiji. In the early 1990s, the Samoan study, which covered the entire population of 160,000 with 3 annual MDAs, reported a significant reduction in microfilaria (mf) prevalence and mean mf density, while in Fiji, the efficacy of 5 rounds of annual MDA (total dose, 30 mg/kg) was shown to be as effective as 28 multi-dose MDA spread over 2 years (6 weekly plus 22 monthly treatments at 5 mg/kg; total dose, 140 mg/kg). Several additional studies carried out in Samoa in relation to the annual single-dose MDAs revealed that low density mf carriers, who have a very low mf count of 1-20/ml of venous blood, could not play a significant role in filariasis transmission.From around 1990, studies on spaced low-dose DEC treatments and various types of combination chemotherapy with DEC and ivermectin increased. Albendazole, a well-known anti-intestinal helminths agent, was later added to the combination. The main findings of these studies with W. bancrofti are: (i) a single dose of DEC at 6 mg/kg reduced mean mf density by ca. 90% 1 year after treatment; (ii) the same dose could damage/kill adult worms; (iii) a single dose of ivermectin at ca. 400 μg/kg was more effective than DEC in reducing mf density during the first year and was similarly or less effective in the second year; (iv) ivermectin probably could not kill adult worms; (v) a single combined dose of albendazole (400 mg) and DEC (6 mg/kg) was effective to reduce mf density by 85 to nearly 100% 12-24 months after treatment; and (vi) ivermectin or albendazole included in the combination chemotherapy produced "beyond-filariasis" benefits: clearance/reduction of intestinal helminths, and, additionally, in the case of ivermectin, skin-dwelling ectoparasites.The Global Programme to Eliminate Lymphatic Filariasis (GPELF) started its worldwide activities in 2000, with the target of elimination by 2020. The basic strategy is to conduct annual single-dose MDAs for 4-6 years. In 2000-2007, a minimum of 570 million individuals were treated in 48 of 83 endemic countries. The drugs used are DEC 6 mg/kg plus albendazole 400 mg in most countries, or ivermectin 200-400 μg/kg plus albendazole 400 mg particularly in onchocerciasis endemic countries in Africa. (MDAs with DEC alone had been used in India.)The GPELF achieved impressive results in terms of parasitological cure/improvement, clinical benefits, social and economic impacts, etc. However, the most impressive result of all was the programme's success in mobilizing hundreds of millions of local people, who not only took drugs but many of them actively supported MDAs as drug distributors and volunteers. Beyond filariasis, the role people can play in supplementing rural health services is now a topic of discussion and a source of hope for a new sustainable system.     

A community-based trial for the control of lymphatic filariasis and iodine deficiency using salt fortified with diethylcarbamazine and iodine.

To evaluate the effectiveness of salt fortified with diethylcarbamazine (DEC) and iodine for elimination of Bancroftian filariasis and iodine deficiency, all consenting residents of Miton, Haiti (n = 1,932) were given salt fortified with 0.25% diethylcarbamazine and 25 ppm of iodine for one year. Wuchereria bancrofti microfilaria prevalence and intensity, antigenemia, and urinary iodine were measured before and one year after salt distribution began. To measure the effect of DEC-fortified salt on adult worm motility, 15 microfilaria-positive men were examined by ultrasound of the scrotal area. Entomologic surveys were conducted to determine the proportion of W. bancrofti-infected Culex quinquefasciatus. After one year of treatment, the prevalence and intensity of microfilaremia were both reduced by more than 95%, while antigenemia levels were reduced by 60%. The motility of adult worms, as detected by ultrasound, was decreased, but not significantly, by DEC-fortified salt. The proportion of vector mosquitoes carrying infective stage larvae decreased significantly from 2.3% in the nine months before the intervention to 0.2% in the last three-month follow-up period. Iodine deficiency, which had been moderate to severe, was eliminated after one year of iodized salt consumption. The DEC-fortified salt was well accepted by the community and reduced microfilaremia and transmission to low levels in the absence of reported side effects. Based on these results, salt cofortified with DEC and iodine should be considered as a concurrent intervention for lymphatic filariasis and iodine deficiency elimination programs.     

Efficacy of single-dose diethylcarbamazine compared with diethylcarbamazine combined with albendazole against Wuchereria bancrofti infection in Papua New Guinea

The efficacy of diethylcarbamazine alone was compared with diethylcarbamazine plus albendazole in residents of an island in Papua New Guinea endemic for Wuchereria bancrofti. There was no statistically significant difference between the two drug regimens in decreasing the microfilaria positive rate at 12 and 24 months after a single-dose treatment with either regimen, e.g., 50.0% clearance of microfilaria at 24 months for diethylcarbamazine alone versus 65.7% clearance of microfilaria for diethylcarbamazine plus albendazole (P > 0.05). In contrast, diethylcarbamazine plus albendazole resulted in a significant decrease in Og4C3 antigen prevalence (17%; P = 0.003) at 24 months whereas diethylcarbamazine did not (10%; P = 0.564). These data showed no statistically significant difference in the efficacy of the two drug regimens in lowering the microfilaria reservoir, but they support the use of diethylcarbamazine combined with albendazole in mass treatment programs on the basis of greater activity against adult worms.     

Short-term effects of treatment with 300 mg oral-dose diethylcarbamazine on nocturnally periodic Wuchereria bancrofti microfilaremia and antigenemia

Seven microfilaremic Myanmar patients were treated with a single 300 mg dose of diethylcarbamazine (DEC) orally, as part of a case-finding survey in Ranong Province, Southern Thailand. This was conducted in order to evaluate the short-term effects of single-dose DEC on Wuchereria bancrofti microfilaremia and antigenemia during a 12-week course of treatment. Analysis of microfilarial periodicity on initial treatment revealed the microfilarial peak density (k) was at 52 minutes after midnight (0052). The periodicity index was then 103.26%. Single-dose DEC treatment did not affect the k values. A linear model of W. bancrofti microfilarial density reduction predicts a sharp decrease in the mean microfilarial density 2 weeks after DEC intake (Z = -2.197, p = 0.028). Over a longer period, a non-linear model predicts an increase in the mean microfilarial density to pre-treatment levels, having little or no macrofilaricidal effects. We reconfirmed the existence of nocturnally periodic W. bancrofti infection in Myanmar migrants in Ranong Province, and the short-term microfilaricidal activity of 300 mg single-dose DEC treatment used for biannual mass treatment and the DEC provocative test. Without an adequate DEC treatment dose, recrudescence can occur. A rational approach to the management of introduced nocturnally periodic W. bancrofti in Myanmar migrants, who came for short periods of stay in transmission-prone areas, is needed.     

The impact of six rounds of single-dose mass administration of diethylcarbamazine or ivermectin on the transmission of Wuchereria bancrofti by Culex quinquefasciatus and its implications for lymphatic filariasis elimination programmes

Lymphatic filariasis (LF) is targeted for global elimination. Transmission interruption through repeated annual single-dose mass administration of anti-filarial drugs is the mainstay of the LF elimination strategy. This study examined the ability of six rounds of mass administration of diethylcarbamazine (DEC) or ivermectin (IVM) to interrupt transmission of Wuchereria bancrofti by Culex quinquefasciatus, the predominant parasite and vector species, respectively. After six rounds of mass drug administration (MDA), received by 54-75% of the eligible population (> or =15 kg body weight), the resting vector infection and infectivity rates fell by 83% and 79% in the DEC arm, 85% and 84% in the IVM arm and 31% and 45% in the placebo arm, respectively. The landing vector infection and infectivity rates fell by 83% and 94% in the DEC arm, 63% and 75% in the IVM arm and 1% each in the placebo arm, respectively. The filarial larval load per resting mosquito declined by 92% and 93% and per landing mosquito by 83% and 69% in the DEC and IVM arms, respectively. The annual infective biting rate (AIBR) fell from 735 to 93 (87%) in the DEC arm, 422 to 102 (76%) in the IVM arm and 472 to 398 (16%) in the placebo arm. The annual transmission potential (ATP) declined from 2514 to 125 (95%), 1212 to 241 (80%) and 1547 to 1402 (9%) in the DEC, IVM and placebo arms, respectively. However, mosquitoes with infection [microfilaria/larva 1/larva 2 (Mf/L1/L2)] were found in all study villages. Three of five villages in the IVM arm and two of five in the DEC arm recorded no resting mosquitoes with infective-stage (L3) larva. Although the ATP, after six rounds of MDA, fell substantially and remained at 125 and 241 in the DEC and IVM arms, respectively, the cumulative exposure to infective stage larvae (ATP) during the treatment period of 6 years was as high as 2995 in the DEC arm and 1522 in the IVM arm, because of considerable level of transmission during the initial (1-3) rounds of MDA. We conclude that (i) six rounds of MDA, even with 54-75% treatment coverage, can reduce LF transmission very appreciably; (ii) better treatment coverage and a few more rounds of MDA may achieve total interruption of transmission; (iii) high vector densities may partly nullify the reductions achieved in vector infection and infectivity rates by MDA and (iv) achievement of 'true zero' Mf prevalence in communities and 0% infection rate (mosquitoes with Mf/L1/L2) in mosquitoes may be necessary to totally interrupt Culex-transmitted LF.     

湖南省消除丝虫病后的监测

目的　探讨达到消除丝虫病地区继续监测的措施及效果。　方法　选择湖南省边远、贫困地区、防治监测中可能存在薄弱环节的地区和外来流动人口聚集区搜索残存传染源 ,对原微丝蚴血症者追踪观察并进行蚊媒监测。采用常规厚血膜双片法检查微丝蚴 ;个体解剖方法检查蚊媒感染幼丝虫情况。　结果　复查经治疗转阴 2 0～ 2 6年后的原微丝蚴血症者 611例和防治监测工作中存在薄弱环节地区血检 13 171人以及流动人口 3 63 1人 ,均未检出微丝蚴血症者 ;解剖致倦库蚊 3 0 5 0只 ,未检出幼丝虫感染蚊。　结论　湖南省消除丝虫病后的成果巩固 ,但全国和全球尚未消灭丝虫病 ,监测措施仍不能终止 ,其方法需要改进。     

Two-year follow-up of the microfilaraemia of asymptomatic brugian filariasis, after treatment with two, annual, single doses of ivermectin, diethylcarbamazine and albendazole, in various combinations

Repeated, single, oral doses of combinations of ivermectin, diethylcarbamazine (DEC) or albendazole are recognized as important tools for parasite control in lymphatic filariasis. In order to assess the effects of re-treatment using these combinations in Brugia malayi infections, 40 asymptomatic microfilaraemics were re-treated at the end of the first year, with an additional, single, dose of the combination they had previously received. They were then followed-up for another year. The subjects, of both sexes and aged 14-70 years, each received a two-drug combination: ivermectin (200 micrograms/kg) with DEC (6 mg/kg); ivermectin (200 micrograms/kg) with albendazole (400 mg); or DEC (6 mg/kg) with albendazole (400 mg). The kinetics of microfilarial clearance were similar to that seen during the first treatment, the members of the two groups given DEC having less intense microfilaraemias, 1 year after the re-treatment, than those given ivermectin with albendazole (P < 0.001 for each comparison). At this time, the two DEC groups also had a higher proportion of amicrofilaraemic individuals (22 of 26) than the ivermectin + albendazole group (three of nine). There were fewer adverse reactions in all the groups after re-treatment than seen after the first treatment. In countries such as India, where there is no co-endemicity of onchocerciasis or loiasis, the options for control programmes in areas where brugian filariasis is endemic are DEC alone or DEC in combination with ivermectin or albendazole. Where there is no access to ivermectin, transmission control must be based on DEC alone or in combination with albendazole.     

Changes in circulating parasite antigen levels after treatment of bancroftian filariasis with diethylcarbamazine and ivermectin

This study assessed changes in circulating parasite antigen levels after diethylcarbamazine (DEC) and ivermectin treatment of bancroftian filariasis to determine effects of these drugs on adult Wuchereria bancrofti in vivo. Thirty adult Haitians with microfilaremia were treated with 1 mg of ivermectin to reduce counts of microfilariae. Later, subjects were treated with either one or two 200 micrograms/kg doses of ivermectin or with 12 daily 6 mg/kg doses of DEC. Macrofilaricidal activity of these drugs was indirectly monitored by measuring circulating W. bancrofti antigen by EIA. Antigen levels fell by 75% after DEC and by 34% after ivermectin. These results suggest that low-dose ivermectin treatment followed by a standard course of DEC is a more effective macrofilaricidal regimen for W. bancrofti than either of the multidose ivermectin regimens used in this study.