A controlled trial of ivermectin and diethylcarbamazine in lymphatic filariasis

Parasitic infections of the central nervous system in children. Part II: Disseminated infections

In the second segment of this three-part review of parasitic infections of the central nervous system in children, we consider parasitic infections which typically involve various tissues and organs in addition to the brain and spinal cord. Parasites capable of dissemination in immunocompetent hosts are discussed first, and, as in Part I, organisms are grouped according to their predominant geographic location. This is followed by a discussion of the unique aspects of toxoplasmosis, strongyloidiasis and infection with microsporidia in immunocompromised patients, with an emphasis on the central nervous system.

Treatment of bancroftian filariasis in Recife, Brazil: a two-year comparative study of the efficacy of single treatments with ivermectin or diethylcarbamazine

The effectiveness of single oral doses of ivermectin (200 or 400 micrograms/kg) and diethylcarbamazine (DEC, 6 mg/kg), preceded 4 d earlier by either placebo or very small doses of these drugs, was compared, over a 2-year period, in a double-blind trial in 67 microfilaraemic Brazilian men with bancroftian filariasis. Regimens containing ivermectin alone decreased the number of microfilariae significantly faster and more effectively for the first month after treatment than regimens containing DEC alone, but the latter were significantly more effective throughout the second year after treatment (1.7-8.2% of pretreatment levels with DEC vs. 12.6-30.8% with ivermectin during that period); the higher ivermectin dose showed a tendency towards more effectiveness than the lower dose. Most effective was the combination of ivermectin (20 micrograms/kg) followed 4 d later by DEC (6 mg/kg), with reduction of microfilaraemia to 2.4% of pretreatment levels at 2 years. Adverse reactions were well tolerated with all regimens, the reactions being significantly more generalized (i.e., fever) following ivermectin and localized (i.e., scrotal inflammatory nodules around dying adult worms) following DEC. Further trials of single-dose combination therapy vs. single high doses of ivermectin or DEC should determine the ideal regimen for treatment and control of bancroftian filariasis.

Advantages of ivermectin at a single dose of 400 micrograms/kg compared with 100 micrograms/kg for community treatment of lymphatic filariasis in Polynesia

In April and October in 1991-1993, 5 supervised single doses of ivermectin were given to inhabitants aged > or = 3 years in a Polynesian district: the first 3 treatments were with 100 micrograms/kg and the 2 latter with 400 micrograms/kg. At each treatment, about 97% of the eligible population (899) were treated and blood samples were collected just before treatment from 96% of the 613 inhabitants aged > or = 15 years. Following the 5 successive treatments, adverse reactions were observed in, respectively, 23.8, 13, 6.2, 13.6 and 7.9% of the microfilariae (mf) carriers, and in less than 1% of amicrofilaraemic subjects. Neither the frequency nor the intensity of adverse reactions was significantly different between single doses of 100 micrograms/kg and 400 micrograms/kg. Although the geometric mean microfilaraemia (GMM) was reduced, the mf carrier prevalence remained unchanged before and after 3 mass treatments with 100 micrograms/kg (21.4 and 20.7% respectively), and the mf recurrence rate 6 months after each dose of 100 micrograms/kg was roughly stable (respectively, 34.3%, 21.6% and 31.2% of the initial GMM). In contrast, after one dose round of 400 micrograms/kg, the mf carrier prevalence decreased significantly to 14.9% (P < 10(-6)), and the mf recurrence rate dropped to 9.9% (P < 10(-3)) of the initial GMM. These results confirm the safety and the effectiveness of 400 micrograms/kg of ivermectin for lymphatic filariasis control.

Tolerance of diethylcarbamazine by microfilaraemic and amicrofilaraemic individuals in an endemic area of Bancroftian filariasis, Recife, Brazil

To determine the tolerance to diethylcarbamazine (DEC) treatment of patients with Bancroftian filariasis, 193 individuals (138 asymptomatic microfilaraemic, 30 amicrofilaraemic diseased patients and 25 asymptomatic amicrofilaraemic endemic residents) were enrolled in a prospective trial with different dose schedules, in a hospital and outpatient clinic setting in Brazil. Systemic adverse reactions, localized adverse reactions, and side effects, related to microfilariae, adult worms and the drug itself, were evaluated. Systemic reactions occurred irrespective of the DEC dose and schedule in about 40% of the microfilariae carriers, but not in amicrofilaraemic diseased patients or residents; they usually consisted of microscopic haematuria, followed by fever and malaise. Localized reactions were manifested by the appearance of inflammatory reactions, mainly in the scrotal area. Nodules containing degenerating adult worms developed mainly in the scrotal lymphatics of microfilaraemic patients, diseased amicrofilaraemic patients, and residents. Drowsiness, which increased with higher doses of DEC, was the most common side effect in both microfilaraemic and amicrofilaraemic individuals, followed by nausea and gastric upset. The results indicate that the occurrence of systemic and local adverse reactions was unrelated to either the dose of DEC or the pretreatment microfilarial density. The severity of systemic reactions was proportional to the microfilarial density. Side effects were dependent on the drug dosage irrespective of infection status.

Side reactions following ivermectin therapy in high density bancroftian microfilaraemics

Side reactions following ivermectin treatment were evaluated in sixty males with high density bancroftian microfilaremia (GM 1388/ml). Following a single oral dose of ivermectin of different strengths (20, 50, 100 or 200 micrograms/kg), microfilariae clearance and side reactions were monitored in a double blind fashion. Microfilaria levels fell rapidly after ivermectin administration in all dosage groups and 98% of pretreatment microfilariae was cleared after 12 h of treatment. The rate of microfilaria (mf) clearance was slower with 20 micrograms/kg than with the highest dose (200 micrograms/kg) administered. Forty-six patients (77%) became amicrofilaraemic within 2 weeks of treatment. Side reactions were noted in 97% of cases. The most common reactions were fever, headache, weakness, myalgia and cough which appeared by 12 h and subsided by 72 h following treatment. The frequency and intensity of side reactions were related to pretreatment mf densities and were independent of the dose administered. Unusual side reactions were noted in a few patients with high density microfilaraemia. These included intense cough, shortness of breath, blood tinged mucoid expectoration associated with patchy pneumonitis of the lung. Itchy rashes, lymphatic nodules and raised alkaline phosphatase level were also observed in some patients. These side reactions were transient, self limiting and were not serious enough to warrant any treatment. These exaggerated unusual reactions were possibly due to allergic response of the susceptible host to rapid killing of large number of microfilariae.

A comparative study of the efficacy and tolerability of single and split doses of ivermectin and diethylcarbamazine in periodic brugian filariasis

The use of ivermectin in lymphatic filariasis (both bancroftian and brugian) has been recently explored in several studies. We report in this paper, for the first time, a direct comparison of the efficacy and tolerability of single doses of ivermectin and diethylcarbamazine (DEC) in brugian filariasis. We also present our findings on the use of split doses of ivermectin and DEC on microfilaraemia levels and the occurrence of adverse reactions. Fifty male, asymptomatic microfilaremics drawn from the Alleppey District, Kerala, India, were allocated one of the following five treatment regimens in a double blind randomized study: (1) single oral 6 mg/kg dose of DEC; (2) single oral 6 mg/kg dose of DEC preceded by 1 mg/kg DEC primer; (3) single oral 220 micrograms/kg dose of ivermectin; (4) single oral 200 micrograms/kg dose of ivermectin preceded by a 20 micrograms/kg ivermectin primer; or (5) a single oral 400 micrograms/kg dose of ivermectin preceded by a 20 micrograms/kg ivermectin primer. The kinetics of microfilaria clearance differed in the two (DEC/ivermectin) groups in the first month post-treatment. At the end of 1 year there were no differences in the microfilaria levels in the two DEC-tested groups and the 420 micrograms/kg ivermectin group. The safety of the 400 micrograms/kg dose of ivermectin was established in this study which has also shown that, currently, this dose would be the best choice for brugian filariasis. Patients in the ivermectin groups had significantly lower adverse reaction scores than patients who had received DEC. There was no advantage in splitting the dose of either DEC or ivermectin, either in terms of efficacy or tolerability.(ABSTRACT TRUNCATED AT 250 WORDS)

Mass chemoprophylaxis of lymphatic filariasis with a single dose of ivermectin in a Polynesian community with a high Wuchereria bancrofti infection rate

In April 1991 supervised mass prophylaxis of lymphatic filariasis with a single dose of ivermectin, 100 micrograms/kg, was carried out in a Polynesian village with a high infection rate of Wuchereria bancrofti in humans and active transmission by the vector mosquito, Aedes polynesiensis. Of 876 inhabitants aged 3 years or more (pregnant women excluded), 864 (98.6%) were treated. Simultaneously, venous blood samples were collected from 577 (97.5%) of the 595 inhabitants aged 15 years or more, of whom 122 (21.4%) were found to be microfilaria (mf) carriers (86 males and 36 females). The geometric mean microfilariae (GMM) count was 358.7 mf/ml for the whole group, 387 mf/ml for males (range 1-8160 mf/ml) and 280 mf/ml for females (range 1-7769 mf/ml). Following treatment, 33 (3.8%) of the 864 persons treated experienced some adverse reactions (21 with grade 1 and 12 with grade 2). Of the 33 with reactions, 29 were among the 122 (23.8%) mf carriers and 4 among the 831 (0.5%) non-microfilaraemic persons. Six months later, 123 (21.1%) of 584 inhabitants sampled were microfilaraemic: the GMM count for the whole group was 106 mf/ml (1-8177), with 29 mf/ml (1-3740) in 35 female and 177 mf/ml (1-8177) in 88 male carriers. Of these 123, 15 (whose GMM count was 4.5 mf/ml; range 1-204) were amicrofilaraemic 6 months before, and 19 had a microfilaraemia level higher than that 6 months earlier, before treatment. 117 of the 122 carriers identified in April were resampled: comparison of their GMM counts before and 6 months after mass treatment indicated that treatment with a single dose of 100 micrograms/kg ivermectin resulted in a reduction of microfilaraemia by 69%.

Ivermectin for the treatment of periodic malayan filariasis: a study of efficacy and side effects following a single oral dose and retreatment at six months

Ivermectin, a new antifilarial drug and currently the drug of choice for the treatment of onchocerciasis, has been shown to be effective in bancroftian filariasis. We report here, for the first time, the efficacy and safety of the drug in the treatment of filariasis caused by periodic Brugia malayi. Sixty male, asymptomatic microfilaraemics of Alleppey district, Kerala, South India, received single oral doses of ivermectin in a double blind study. Four dosages were used: 20, 50, 100 and 200 micrograms kg-1 body weight. Clearance of microfilariae, which was not complete, began as early as 12 hours post-treatment and was maximal at the end of one month. Microfilaria levels began to rise thereafter and reached 20-50% of pretreatment levels at six months. The two higher doses (100 and 200 micrograms kg-1) were more effective in suppressing microfilaraemia at six months (P < 0.05). After six months, 32 patients were retreated using the same dose of ivermectin that they had received initially. The pattern of clearance was essentially similar to that seen during the first treatment phase and microfilaria levels were 10-35% of pretreatment levels at the end of the next six months. Twenty-eight individuals who were not retreated at six months continued to have increasing levels of microfilariae, reaching 60% of pretreatment levels at the end of the next six months. Side effects (such as fever, headache, myalgia), which were mild to moderate, were seen in most patients and were unrelated to the dose (P > 0.05) or pretreatment levels of microfilariae.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute lymphatic filariasis in an American traveler

Acute lymphatic filariasis developed in an American traveling recreationally to Asia. The illness was characterized by fatigue, eosinophilia, and lymphedema of the arm and chest wall, but no lymphangitis, lymphadenitis, or pain. Complete resolution occurred over 1-2 years. We discuss this syndrome and describe the use of new diagnostic tests in its diagnosis and management.

Brugia malayi and Acanthocheilonema viteae: antifilarial activity of transglutaminase inhibitors in vitro

The possible involvement of transglutaminase-catalyzed reactions in survival of adult worms, microfilariae (mf), and infective larvae of the filarial parasite Brugia malayi was studied in vitro by using the specific pseudosubstrate monodansylcadaverine (MDC) and the active-site inhibitors cystamine or iodoacetamide. These inhibitors significantly inhibited parasite mobility in a dose-dependent manner. This inhibition was associated with irreversible biochemical lesions followed by filarial death. A structurally related, inactive analog of MDC, dimethyldansylcadaverine, did not affect the mobility or survival of the parasites. Adult worms failed to release mf when they were incubated in the presence of MDC or cystamine, and this inhibitory effect on mf release was concentration dependent. Similar embryostatic and macrofilaricidal effects of MDC were observed in Acanthocheilonema viteae adult worms. These studies suggest that transglutaminase-catalyzed reactions may play an important role in the growth, development, and survival of filarial parasites.