Albendazole, a new anthelmintic drug was evaluated in Malaysia in 91 patients, with single or mixed infections of Ascaris, Trichuris, and hookworm. Albendazole was administered as a single dose of 400 mg, 600 mg, or 800 mg. The cure rate for Ascaris at all three doses was 100% at days 14 and 21 post-treatment; for hookworm it was 98.8%, 100% and 98%, respectively, at day 14 and 68.8%, 100% and 84%, respectively, at day 21; for Trichuris it was 31.2%, 57.1% and 42.3%, respectively, at day 14 and 27.3%, 60.9% and 48.0%, respectively, at day 21. The egg reduction rate at day 21 was 100% at all three doses for Ascaris, 94.5%, 100% and 96.1%, respectively, for hookworm; and 39.2%, 85.1% and 72.8%, respectively, for Trichuris. There were no side effects, and biochemical examination of blood and urine did not indicate any unfavourable changes. Based on this trial, the recommended dosage for Ascaris and hookworm is a 400 mg single dose, and for Trichuris is a 600 mg single dose. Albendazole appears to be more effective than other available anthelmintic drugs.
Once-yearly, mass deworming with broad spectrum anthelmintics over a period of five years among four types of communities in Malaysia resulted in an overall education in the prevalence of soil-transmitted helminthiases by one-third to two-thirds. The reduction in prevalence of infection was highest among inhabitants in semi-urban settlements (65.5%), followed by those in the rural estates (53.0%) and high-rise flats (43.9%). Soil-transmitted helminthiases were only reduced by 35.5% in the urban slums. Reduction in infection with Trichuris trichiura was better than that with Ascaris lumbricoides whereas hook-infection was completely eliminated in some of the communities surveyed. The reduction in prevalence ofsoil-transmitted helminthiases by long-term, once-yearly deworming alone, without other supplementary interventions, reinforces the potential and feasibility of regular mass-deworming as an immediate and effective measure for the control ofsoil-transmitted helminthiases. This is of great public health significance especially in highly endemic communities where some form of intervention is urgently needed and facilities for other control measures such as the improvement of environmental sanitation and nutritional status and health education are neither feasible nor possible nor immediately available.
Serum IgG levels and complement C3 levels were assayed on Day 0, 1, 3-4, 7 and 56-70 post-treatment with diethylcarbamizine citrate (DEC) in a series to 26 patients with Brugia malayi infection and 6 volunteers without infection. On treatment, the microfilariae were cleared from the blood within 24 hours. The eosinophils decreased dramatically on Day 1 post-treatment but increased rapidly by Day 4 to 7 and then dropped to normal levels in 45 days. The serum IgG mean levels decreased briefly following treatment with DEC but then returned to original levels. However, the complement C3 levels gradually increased over the 2 months period of study reaching statistical significance levels (p less than 0.01) in patients with initial high blood microfilariae. The observation suggests that Brugia malayi infection probably induces a high rate of synthesis of complement C3 and this process continued in the post-treatment phase. Since, DEC treatment did not cause a decrease in complement C3 with the elimination of blood microfilariae, it would appear that the complement C3 is consumed following antibody attachment to the microfilariae as they enter the blood circulation.
CGP 20376, a 5-methoxyl-6-dithiocarbamic-S- (2-carboxy-ethyl) ester derivative of benzothiazole was evaluated for its antifilarial properties and shown to be extremely effective against subperiodic Brugia malayi in the leaf-monkey, Presbytis cristata at oral doses of 20-100 mg/kg. The compound and/or its metabolites had complete micro- and microfilaricidal activities even when given at a single dose of 20 mg/kg. Lower doses had incomplete filaricidal action.
Albendazole, oxfendazole, fenbendazole, levamisole, closantel, ivermectin and febantel were administered to sheep on four farms and their efficacy assessed by faecal egg count reduction test. High level of resistance of Haemonchus contortus was found to benzimidazoles (albendazole, oxfendazole, fenbendazole) on all farms and to febantel on the one farm where it was tested. No resistance to closantel and levamisole was observed. Resistance to ivermectin was absent on the three farms examined under this study, but has been reported on the fourth farm in earlier work. It is concluded that anthelmintic resistance to benzimidazoles and the probenzimidazole, febantel, is a serious and widespread problem in H. contortus in sheep in Malaysia.
The therapeutic and prophylactic effects of closantel on natural infections with Haemonchus contortus were studied in goats in Peninsular Malaysia. Closantel was highly effective against H. contortus, either at a subcutaneous (s.c.) injection of 5.0 mg kg-1 body weight (100%), or in an oral drench mixture with mebendazole at a dose of 10.0 mg kg-1 (99.2%), as indicated by faecal egg counts. H. contortus larvae were absent from faecal cultures for 5, 6 and 7 weeks following treatment with s.c. injections of closantel at doses of 2.5 mg kg-1, 5.0 mg kg-1 and 10.0 mg kg-1 respectively, and for 6 weeks after treatment with closantel at 10.0 mg kg-1, given orally. Through its sustained activity, closantel not only prevented reinfection with H. contortus but also caused a dramatic reduction in pasture contamination. The potential utility of closantel in the strategic control of haemonchosis in goats, and as an alternative treatment for benzimidazoles and levamisole resistant H. contortus strains, is discussed.
The anthelmintic efficacy of benzimidazoles, levamisole, closantel, ivermectin and moxidectin was evaluated on an institutional farm in Malaysia using faecal egg count reduction tests, controlled slaughter trials and an in vitro egg hatch assay. The results of this study indicated simultaneous resistance of Haemonchus contortus against benzimidazoles and ivermectin and of Trichostrongylus colubriformis against benzimidazoles and levaminsole on the same farm. Moxidectin was effective against the ivermectin resistant H. contortus.
A previous study had suggested that local strains of goat trichostrongyles, comprising largely Haemonchus contortus, might have developed resistance to benzimidazole anthelmintics. A trial involving 18 goats was conducted to confirm this. There was a significant (P < 0.01) reduction in worm burdens in goats given levamisole, but this was not so for those animals given albendazole, fenbendazole, oxfendazole and mebendazole (P > 0.05).
Intestinal permeability of 246 early primary schoolchildren at 2 schools (106 of whom were infected with intestinal helminths) was assessed by using the lactulose/mannitol differential absorption test. The ratio of the urinary recoveries of lactulose and mannitol was determined after oral administration of a standard solution of the 2 sugars. Assessment of intestinal permeability was repeated on 100 infected children after treatment and on a cohort of 68 uninfected children. Infected and uninfected groups were compared with respect to baseline lactulose/mannitol ratio (L/M1) and change in lactulose/mannitol ratio between assessments (delta L/M). The correlations between baseline intensity of infection and L/M1, and between fall in intensity and delta L/M, were evaluated. Based on a crude index of socioeconomic status, each child was assigned to one of 3 socioeconomic groups; all but 3 children belonged to either groups 2 or 3. Trichuris trichiura and Ascaris lumbricoides were the 2 predominant infections; the hookworm infection rate was relatively low. The results suggested that helminthiasis exerted only a marginal effect on intestinal permeability, the impact of which in children from lower socioeconomic backgrounds was negligible in comparison with the cumulative effects of other factors.
Trials using albendazole and mebendazole, as single 400 mg dose treatments, against soil-transmitted helminths, were carried out in 7-9 and 10-12 years-old schoolchildren living in urban and rural environments in Penang, Malaysia. Both drugs were equally effective in treating trichuriasis and ascariasis in both age groups and environments. However, mebendazole is not so effective in the treatment for hookworms when compared to albendazole. It is suggested that albendazole should be considered the drug of choice for mass chemotherapy for Penang.
Stool examination of 249 early primary schoolchildren at 2 schools in north-eastern peninsular Malaysia revealed that 73 were infected with Ascaris lumbricoides, 103 with Trichuris trichiura, and 18 with hookworms. Infected children were treated with a single dose of 400 mg of albendazole. The school attendance records during a 60 d period before treatment and 2 consecutive 60 d periods after treatment were examined. The absenteeism rate did not improve more among infected children after treatment than it did among the uninfected control children. The correlation between worm intensity and the number of lost school-days was poor. There was no evidence that intestinal helminthiasis caused school absenteeism among this group of children.