Comparison of ivermectin and thiabendazole in the treatment of uncomplicated human Strongyloides stercoralis infection

Ivermectin is the drug of choice in the treatment of onchocerciasis, and has been proven to be highly effective against Strongyloides stercoralis. This study compares ivermectin's efficacy and safety with that of thiabendazole, an established drug of choice for strongyloidiasis, in 252 confirmed cases of uncomplicated human intestinal strongyloidiasis. Subjects were administered orally with ivermectin (200 mg/kg) in a single dose or thiabendazole, 25 mg/kg, twice daily (50mg/kg/day) for 3 consecutive days. Stools were parasitologically examined 7, 21 and 30 days after treatment. Only 18 of 113 and 22 of 103 ivermectin- and thiabendazole-treated subjects, respectively, had stools positive for larvae 30 days post-treatment. This indicates parasitological cure rates of 84.07% and 78.64% for ivermectin and thiabendazole, respectively. Ivermectin was not significantly more effective than thiabendazole (P < 0.05). There was considerable reduction in parasite output in parasitologically uncured subjects with mean of 81% in ivermectin-treated and 75% in thiabendazole-treated groups, respectively. Clinical adverse reactions were mild and transient in subjects treated with ivermectin, while they varied from mild to severe in those treated with thiabendazole. Single-dose ivermectin provides efficacy comparable with standard, multiple-dose thiabendazole, with a much reduced incidence of adverse effects and consequently better patient compliance. Key words: Ivermectin, thiabendazole, Strongyloides stercoralis, strongyloidiasis. African Journal of Biotechnology Vol.2(11) 2003: 465-46

Relative prevalence of the human hookworm species, Necator americanus and Ancylostoma duodenale in an urban community in Ogun State, Nigeria

In order to estimate the proportion of hookworm infections represented by Necator americanus and Ancylostoma duodenale, the 2 major species of human hookworms in Nigeria, stool samples from 1253 hookworm-positive schoolchildren were cultured to the third-stage (L3), filariform larvae, using the Harada-Mori test-tube method. N. americanus larvae were recovered from a total of 1177 (93.9%) coprocultures while A. duodenale larvae were recovered from a total of 274 (21.9%) stool cultures. 58.2% of the hookworm infections were due solely to N. americanus, 6.1% solely to A. duodenale and 25.8% were mixed infections with both species. In all mixed infections, much higher number of N. americanus larvae were recorded compared with those of A. duodenale. Key words: Hookworm species, Necator americanus, Ancylostoma duodenale, filariform larvae. African Journal of Biotechnology Vol.2(11) 2003: 470-47

Effects of varying concentrations of the crude aqueous and ethanolic extracts of Dalbergia sissoo plant parts on Biomphalaria pfeifferi egg masses.

This study evaluated, using replicated laboratory bioassays, the toxicities of the crude aqueous and ethanolic extracts of Dalbergia sissoo Roxb. 1832 (family Leguminosae) fruits, leaves, roots and stem bark against egg masses of Biomphalaria pfeifferi (Krauss, 1848), the snail intermediate host of Schistosoma mansoni (Sambon, 1907) in Nigeria. Viable 0-24 hr-old embryonated egg masses were separately exposed to five different concentrations (7.81-2000 mg/l) of extracts for 24 hrs, washed in dechlorinated tap water and incubated at room temperature for a maximum of 4 weeks. The LC50 and LC90 values of test extracts for egg masses were calculated by probit analysis. The activities of the tested extracts were concentration-dependent. However, only the ethanolic extract of the fruits demonstrated significant activity (24 hr-LC90 value < 100 mg/l: 89.29 mg/l). Mortalities of eggs were manifested at the gastrula/exogastrula and or the prehatch snail stage of development. The percentage of dead embryos at the prehatch snail stage decreased while the deaths of embryos at the gastrula/exogastrula stage increased, with increasing concentration of extract. Lethality of the ethanolic extract of D. sissoo fruits to embryonated egg masses of B. pfeifferi is an added advantage to its potential development for use as a plant molluscicide, as the overall efficacy of a molluscicide is greatly enhanced if it also shows significant toxicity towards snail eggs.Key words: Dalbergia sissoo, Biomphalaria pfeifferi, Schistosoma mansoni, Egg masse

Randomized Clinical Trial on Ivermectin versus Thiabendazole for the Treatment of Strongyloidiasis

Strongyloidiasis is the infection caused by the worm Strongyloides stercoralis. Due to its peculiar life cycle Strongyloides may remain indefinitely in the host, if not effectively cured. Although the disease is usually mild, in case of weakening of the host's immune defenses the worm may invade virtually all organs and tissues (disseminated strongyloidiasis, almost invariably fatal). The treatment must then reach the goal of the complete elimination of the parasite. Small size clinical trials showed similar, high efficacy of the two drugs ivermectin (used as a single dose) and thiabendazole (used twice daily for two consecutive days). All trials used as the criterion for cure the absence of larvae in stool exams. The latter however may easily miss the infection, falsely suggesting that the infection has been cured. This trial, using a test detecting specific Strongyloides antibodies as an additional and more sensitive diagnostic tool, confirms previous reports: the two drugs have similar efficacy but ivermectin is better tolerated and is therefore the first choice. However the cure rate was lower than 70% for the standard, single dose. The authors then conclude that a larger, multi center trial is needed to find the optimal dose schedule of ivermectin

Mechanical transport and dissemination of soil-transmitted helminth eggs by the common housefly, Musca domestica, under laboratory conditions

In previous studies, helminth eggs were isolated from wild-caught Musca domestica L. (Diptera: Muscidae). This laboratory study investigated the potential of the fly for mechanical transport and transmission of soil-transmitted helminths. Naïve, 2-3 day old, laboratory-reared adult flies were exposed to a mixture of Ascaris lumbricoides and Trichuri strichiura infective eggs in sucrose solution (as food) for 15 to 60 minutes (experiment 1); 15 minutes followed by exposure to sterile food for 2 to 24 hours (Experiment 2) or 0.5 to 8 hours (Experiment 3). Flies and droplets therefrom (Experiment 3) were processed and examined microscopically. Eggs of A. lumbricoides and/or T. trichiura were recovered from fly body surfaces and/or gut and in fly droplets up to 24 and 8 hours post exposure, respectively. The proportion of flies transporting eggs and number of eggs transported declined gradually with time post-exposure. Significantly more eggs (p&lt;0.05) were recovered from fly guts than on body surfaces. There were no significant differences (p&gt;0.05) between the mean numbers of A. lumbricoides and T. trichiura eggs from fly body surfaces or gut. M. domestica adults can transport on body surfaces and in gut, and disseminate on surfaces subsequently visited, eggs of soil-transmitted helminths acquired from contaminated substrates.Keywords: Ascaris lumbricoides; Musca domestica; Trichuris trichiura; mechanical vector; soil-transmitted helminths; Nigeri