Biomedical subjects

F S Gilbert

Publications and source records attributed to F S Gilbert.

18 recordsLinked to original sources

PubMed2004

Factors affecting the component community structure of haemoparasites in common voles ( Microtus arvalis) from the Mazury Lake District region of Poland.

The prevalence and abundance of infections with haemoparasites were studied over a 4-year period in Microtus arvalis (common vole, n =321) sampled from fallow grassland sites in north-eastern Poland. Total species richness was five (prevalence= Haemobartonella sp. 63.9%, Bartonella spp. 27.7%, Babesia microti 9.0%, Trypanosoma sp. 8.4% and and Hepatozoon lavieri 3.1%) with 76.9% of the voles carrying at least one species and a mean infracommunity species richness of 1.1. Variation in species richness was determined primarily by season and year, the interaction of these factors, and that of year with host age. The observed frequency distribution of infracommunity species richness did not differ from that predicted by a null model, suggesting that there were no marked associations between the species. Analyses of prevalence and abundance of infection with each species in turn, revealed that overall the principal causes of variation were temporal and seasonal, their interaction, and interactions with intrinsic factors (age and sex), the latter playing only a minor role in their own right. However, the relative importance of these combinations varied and was distinct for each of the species in the study. Prevalence data revealed eight sets of two- and three-way associations between species, mostly dependent to some extent on one of the intrinsic and extrinsic factors in the model. Analysis of quantitative associations suggested two sets of positive two-way interactions, none of which remained after controlling for the effect of extrinsic and intrinsic factors on the abundance of each species. These data are discussed in the context of the changing ecological profiles in this region of Eastern Europe and, in a wider context, in relation to current understanding of the factors that shape component community structures of haemoparasites in wild rodents.

Animals↗

PubMed2004

Variation in the helminth community structure in spiny mice (Acomys dimidiatus) from four montane wadis in the St Katherine region of the Sinai Peninsula in Egypt.

We compared helminth communities in spiny mice (Acomys dimidiatus) from 4 wadis in the arid montane region of the southern Sinai in Egypt, in a 4-week period in late summer. Total helminth species richness was 14 (8 nematodes, 5 cestodes and 1 acanthocephalan) with 94% of mice carrying at least 1 species and an overall mean species richness of 1.85. The most prevalent parasites were Protospirura muricola (47.8 %) and Dentostomella kuntzi (46.3%). One larval cestode, Joyeuxiella rossicum, represents a new host record. The helminth community was dominated by intestinal nematodes (88.7%) of which 58.2% were arthropod-transmitted heteroxenic species. At the component community level, 70% of the worms were recovered from mice in just two wadis (Gharaba and Tlah) and 48.6 % of intestinal nematodes were from Wadi Gharaba. Although only 7 species of helminths were recorded from Wadi Gharaba, this site gave the highest Berger-Parker dominance index because of P. muricola. P. muricola was also dominant in Wadi El Arbaein whilst Syphacia minuta was the dominant species in Wadis Gebal and Tlah. At the infracommunity level, mean species richness and Brillouin's index of diversity were highest in Wadi Tlah and lowest in Wadi Gebal, and the former was age dependent. Whilst mice from different wadis differed in the nematodes that were most common, those from Wadi Gharaba carried the highest mean number of worms/mouse. The abundance of P. muricola in particular varied markedly between sites: Wadi Gharaba was distinct as the site showing the highest mean worm burden whereas mice from Wadi Gebal were uninfected. None of the directly transmitted oxyuroid nematodes showed significant variation in abundance between wadis, or host sex or age classes. Overall, the single extrinsic factor in the study, site of capture, was more important than the intrinsic factors in explaining variation in helminth communities in the region. We conclude that in the high mountains of southern Sinai, each wadi is distinct in terms of its rodent parasites, and hence we expect spatially different coevolutionary pressures on their hosts, with resultant variation in life-histories.

Age Factors↗

PubMed2003

Polyparasitism with Schistosoma haematobium and soil-transmitted helminth infections among school children in Loum, Cameroon.

Prevalence and abundance of Schistosoma haematobium and soil-transmitted helminths (STH) were assessed among a total of 1600 pupils (urine, n = 1190; faecal samples, n = 1454) attending five schools in Loum, Littoral Province, Cameroon, with the specific aim of assessing the extent of polyparasitism and the extent to which infections were focused in particular subsets of the study group. Prevalence of S. haematobium was 62.8% with an abundance (arithmetic mean of egg counts) of 54 eggs/10 ml urine. For the STH these were 47.7% and 619 eggs per gram of faeces (EPG) for Trichuris trichiura, 65.5% and 3636 EPG for Ascaris lumbricoides, and 1.4% and <0.1 EPG for hookworms. Most children (90.3%) were infected with at least one of these four species, the largest proportion (34.3%) carrying two species; 27.4% carried three and 1.1% carried concurrently all four species of parasites. The average number of species harboured increased with age, as did the prevalences of S. haematobium and T. trichiura but not that of A. lumbricoides. All STH showed marked differences in prevalence between the five schools but only T. trichiura varied significantly between sexes. Mean abundance of infection varied significantly between age classes, among schools and between the sexes, with females showing heavier mean EPGs for A. lumbricoides and T. trichiura and males higher mean eggs/10 ml urine for S. haematobium infections. A highly significant association was detected between A. lumbricoides and T. trichiura, that was not context-dependent. This was confirmed in quantitative analyses after controlling for differences in abundance between schools, sexes and age classes. A weaker context-dependent association (prevalence data) was detected between S. haematobium and A. lumbricoides (sex- and age-dependent) but quantitative associations between these two species, as well as between S. haematobium and T. trichiura, were not convincing.

Adolescent↗

PubMed2002

Prevalence and abundance of Cryptosporidium parvum and giardia spp. in wild rural rodents from the Mazury Lake District region of Poland.

Prevalence and abundance of Cryptosporodium parvum and Giardia spp. were studied in 3 species of rodents from forests and abandoned agricultural fields in N.E. Poland (Clethrionomys glareolus n = 459; Microtus arvalis n = 274; Apodemus flavicollis n = 209). Overall prevalence was consistently higher in the voles compared with A. flavicollis (70.6, 73.0 and 27.8% respectively for C. parvum and 93.9, 96.3 and 48.3% respectively for Giardia spp.). Prevalence and abundance of infection also varied markedly across 3 years with 1998 being a year of higher prevalence and abundance with both species. Fewer older animals (especially C. glareolus and M. arvalis) carried infection with C. parvum and infections in these animals were relatively milder. Although seasonal differences were significant, no consistent pattern of changes was apparent. Host sex did not influence prevalence or abundance of infection with C. parvum, but made a small contribution to a 4-way interaction (in 5-way ANOVA) with other factors in the case of Giardia spp. The 2 species co-occurred significantly and in animals carrying both parasites there was a highly significant positive correlation between abundance of infection with each, even with between-year, seasonal, host age, sex and species differences taken into account. Quantitative associations were confined to the 2 vole species in the study. These results are discussed in relation to the importance of wild rodents as reservoir hosts and sources of infection for local human communities.

Age Factors↗

PubMed2001

Factors affecting the component community structure of haemoparasites in bank voles (Clethrionomys glareolus) from the Mazury Lake District region of Poland.

The prevalence and abundance of infections with haemoparasites were studied over a 3 year period in Clethrionomys glareolus (bank vole, n = 420) sampled from forests in the NE of Poland. Total species richness was 5 (Prevalence = Haemobartonella sp. 63.1%, Bartonella grahamii 27.4%, Hepatozoon erhardovae 31.4%, Trypanosoma evotomys 15% and Babesia microti 1.0%) with 81.9% of the voles carrying at least 1 species and a mean infracommunity species richness of 1.4. Variation in species richness was determined primarily by season and year, and the interaction of these factors. The observed frequency distribution of infracommunity species richness did not differ from that predicted by a null model, suggesting that there were no marked associations between the species. Analyses of prevalence and abundance of infection with each species in turn, revealed that overall the principal causes of variation were temporal and seasonal and their interaction, intrinsic factors such as age and sex playing only a minor role. However, the relative importance of specific extrinsic, and rarely intrinsic, factors varied and was distinct for each of the species in the study. Prevalence data revealed 4 sets of 2-way associations between species, mostly varyingly dependent on combinations of intrinsic and extrinsic factors. Analysis of quantitative associations suggested 4 sets of positive 2-way interactions, 3 of which remained after controlling for the effect of extrinsic and intrinsic factors on the abundance of each species, but only one could be unequivocally accepted (Haemobartonella sp. +B. grahamii) after correction for multiple comparisons. These data are discussed in the context of the changing ecological profiles in this region of Eastern Europe and, in a wider context, in relation to current understanding of the factors which shape component community structures of haemoparasites in wild rodents.

Age Factors↗

PubMed2000

The epidemiology of human hookworm infections in the southern region of Mali.

Two surveys of hookworm (Necator americanus) infections, conducted three years apart (December 1994 and January 1998) in a village in the Sikasso region of Mali, revealed that overall prevalence of infection was 68.7% and 53%, respectively. In both years there was a highly significant difference between the sexes in the prevalence and abundance of infection, with male subjects carrying heavier infections than females. Both prevalence and abundance of infection increased with age, although in 1998 there was a strong interaction between sex and age, arising from the declining egg counts among 16-20-year-old females and the continuing increase among males, reinforced by the subsequent reduction among the older males (> or = 61 years) and concomitant increase among females. After controlling for the effects of age, sex and their interaction, a highly significant positive relationship was detected between faecal egg counts of individuals who were examined in both 1994 and 1998 (n = 134), indicating predisposition to infection. This relationship remained significant in each of 4 age classes spanning 7-79 years. The members of some family compounds were shown to carry heavier infections than expected whilst others were less infected, suggesting compound-related clustering of hookworm infections. The use of footwear increased with age but there was no significant relationship between the extent of use of footwear and the abundance of hookworm infection. Eyesight deteriorated with age and impaired vision was particularly prominent among the older sectors of the community, a legacy from the time when onchocerciasis was widely prevalent in the region. Although men with partially damaged eyes carried lower infections than expected for their age, no overall significant relationship was found between quality of vision and hookworm infections. These results are discussed in relation to hookworm epidemiology in general and in Mali in particular.

Adolescent↗

PubMed2000

Seasonal and site specific variation in the component community structure of intestinal helminths in Apodemus sylvaticus from three contrasting habitats in south-east England.

Seasonal fluctuations in the prevalence and abundance of infection with intestinal helminths were studied in Apodemus sylvaticus (wood mouse, n = 399), from three contrasting habitats in southern England, to test the hypothesis that both intrinsic (host sex, age) and extrinsic (season, site) factors influence parasite species richness and abundance. Five species of helminths were recovered but only one of these (Capillaria murissylvatici) was site-specific (Dungeness). Total species richness was therefore 5 at Dungeness and 4 at the other two sites. Mean species richness was 1.4, but in adult mice there was a pronounced difference between the sites, and an independent highly significant effect of season. Syphacia stroma and Corrigia vitta both showed marked differences between sites in respect of prevalence and abundance of infection. Capillaria murissylvatici was encountered at Dungeness mostly in the spring whereas seasonal changes in abundance of S. stroma were consistent across all three sites. Seasonal fluctuations in the abundance of Catenotaenia pusilla were compounded by differences between sites. Host sex was not a significant factor in any species, although a posteriori analysis of S. stroma worm burdens for the Isle of Wight site revealed a moderate local sex effect. Overall the principal determinants of variation in helminth burdens were the extrinsic factors, site and season.

Animals↗

PubMed2000

Intestinal helminths of spiny mice (Acomys cahirinus dimidiatus) from St Katherine's Protectorate in the Sinai, Egypt.

Spiny mice, Acomys cahirinus dimidiatus, inhabiting the wadis close to St Katherine in the mountains of the Sinai peninsula, were trapped and their helminth parasites were studied. Sixty one mice provided faeces for analysis and 27 were killed and autopsied. Six species of helminths were recorded (the spirurid nematodes, Protospirura muricola (74.1%) and Mastophorus muris (11.1%), the oxyuroid nematodes, Dentostomella kuntzi (59.3%), Aspiculuris africana (3.7%), and Syphacia minuta (3.7%) and the hymenolepidid cestode Rodentolepis negevi (18.5%)). The spirurids were the dominant species present, accounting for up to 0.87% of total host body weight. Analysis of worm weights and lengths suggested that transmission had been taking place in the months preceding our study. No sex difference in the prevalence or abundance of spirurids was detected. Significant differences were identified in the abundance of total nematode burdens and the mean helminth species richness between the three wadis which provided multiple captures of mice. There was also a marked effect of host age on both parameters. A highly significant positive correlation between spirurid egg counts and total worm biomass indicated that non-invasive techniques based on egg counts could be used to quantify worm burdens and when this technique was applied to a larger sample size (n = 61), a significant difference between sites but no host sex or age effects were detected for spirurid faecal egg counts. The data suggest that there are differences between helminth component communities infecting spiny mice in different neighbouring wadis, a hypothesis which will be explored further through our continuing studies in the Sinai.

Age Factors↗

PubMed1999

The response of Nigerian West African Dwarf goats to experimental infections with Haemonchus contortus.

One option for controlling haemonchosis in warm pastoral regions is improvement of resistance by selective breeding. Variation in acquired immunity to H. contortus and immunological correlates of infection were studied in West African Dwarf (WAD) goats. Following exposure to 5000 L3, 63 per cent of the inoculum established but 77 per cent of established worms were expelled by week 5. All infected animals were anaemic (day 14). When exposed to 2000L3, 36 per cent of the inoculum was still present (day 35) with no loss by day 49. Persisting primary infection worms survived a superimposed challenge (day 35), but their growth was slowed and resistance to challenge was significant. Most goats showed eosinophilia and parasite-specific IgG responses to primary infection, but only eosinophilia increased after challenge. No consistent associations were found between parasite burden and any immunological measures of infection, but parasite egg counts showed considerable variation. Overall, our results suggest that resistant genotypes exist among the WAD goat population.

Animals↗

PubMed1999

Helminth infections in Apodemus sylvaticus in southern England: interactive effects of host age, sex and year on the prevalence and abundance of infections.

Helminth parasites were studied in the wood mouse, Apodemus sylvaticus, in southern England in September of each of four successive years (1994-1997). Nine species of helminths were recorded: five nematodes (Heligmosomoides polygyrus, Syphacia stroma, Pelodera strongyloides, Trichuris muris, Capillaria murissylvatici), two cestodes (Microsomacanthus crenata, Taenia taeniaeformis) and two trematodes (Corrigia vitta, Brachylaemus recurvum). In total, 134 mice were examined and 91.8% carried at least one species of helminth. The majority of mice carried two to three species (60.5%) and the highest combination was six of the nine species recorded in the study. The patterns of between-year variations in the prevalence and abundance of infection were different for each of the six species for which sufficient quantitative data were available to enable statistical analysis. For H. polygyrus, the most important source of variation arose from between-year differences, host age and the interaction of these factors: abundance increased with host age but in 1995 the age pattern was markedly different from that in the remaining years. The abundance of C. vitta also varied significantly between years but additionally there was a strong independent age effect. For M. crenata, the year x age interaction was significant, indicating that abundance among different age cohorts varied from year to year but there was also a weak significant main effect of age arising from the youngest age cohort carrying no parasites and the oldest age cohort the heaviest infections. For P. strongyloides the only significant factor was between-year variation with 1995 being a year of exceptionally low prevalence and abundance of infection. No significant between-year variation was detected for S. stroma but there was a strong sex effect (males carrying heavier infections) and an age effect (older mice of both sexes carrying heavier infections). The abundance of Trichuris muris varied only in relation to host age, worm burdens growing in intensity with increasing age, but there was also a significant interaction between year and host sex with respect to prevalence. For the remaining three species, the prevalence of infections was too low (< 8.2%) to enable any meaningful interpretation. This analysis emphasizes the need for carefully controlled statistical procedures in aiding the interpretation and the prioritization of the factors affecting worm burdens in wild rodents.

Age Factors↗

PubMed1996

Analysis of the prevalence of infection and associations between human gastrointestinal nematodes among different age classes living in the urban and suburban communities of Port Harcourt, Nigeria.

Fresh stool samples from 300 subjects presenting at out-patient clinics in two major hospitals in Port Harcourt were analysed for the prevalence and intensity of gastrointestinal (GI) nematode infections and 85.3% were found to carry at least one of the four species of GI nematodes recognized during the study. The most common species was Ascaris lumbricoides (54%), followed by Trichuris trichiura (43.7%) and Necator americanus (42.7%) and lastly Strongyloides stercoralis (33%). Peak prevalence for A. lumbricoides was among the < or = 9 years age cohorts, whilst those for the remaining species all coincided among the 15-19 years age cohort. The frequencies of single, double and triple-species infection categories, across the species and within most of the specific combinations were lower than the expected frequencies calculated from overall prevalence data for each species. Observed cases of non-infected individuals and those carrying all four species were higher than expected, suggesting that a greater than expected subset of the population was free from infection, particularly among subjects > or = 30 years old and another subset more prone to infection by all four species, predominantly among the age cohorts < or = 29 years. N. americanus and T. trichiura were more commonly encountered among multiple species infection combinations than expected, but the intensity of the former declined as the number of other concurrently infecting species increased. In contrast, the intensity of infection with S. stercoralis increased as the number of other species increased. Positive associations between A. lumbricoides and T. trichiura, N. americanus and S. stercoralis, and T. trichiura and N. americanus were identified in respect of greater than expected co-occurrence of these combinations and significant positive correlations between their respective intensities of infection. These were related to specific age cohorts which were identified as particularly prone to multiple infections.

Adolescent↗

PubMed1994

Effect of ivermectin on infection with gastro-intestinal nematodes in Sierra Leone.

Levels of intestinal nematode infections were assessed six months after a two year trial of ivermectin for efficacy against onchocerciasis had ended. In the trial the inhabitants of six villages in Sierra Leone were offered treatment with ivermectin or placebo at six monthly intervals for four rounds in total. Quantitative faecal egg counts were carried out on stool samples provided by 202 subjects, all of whom had received all four rounds of treatment, in two of the villages (Dodo and Mogibisi). These data were analysed by a novel procedure in which a 3-way ANOVA with negative binomial errors enabled village and host gender influences on the outcome of treatment to be identified. Necator americanus was the most common species showing an overall prevalence of 90% but a higher intensity in Mogibisi relative to Dodo, particularly among male subjects. Neither prevalence nor intensity of infection were altered in ivermectin-treated compared with placebo-treated subjects. Trichuris trichiura was the least common species with a prevalence of 15%. It was concluded that there was no significant protection from infection with this species among the ivermectin relative to the placebo-treated subjects. Ascaris lumbricoides, with an overall prevalence of 39%, was more common among female (50%) compared with male (27%) villagers. Prevalence was not significantly affected by ivermectin but the intensity of infection declined by 91.3% in Dodo whilst in Mogibisi intensity was only reduced by 14.6%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Development of a "Steps Questionnaire".

Thousands of men and women have begun their recovery from alcoholism through the support of Alcoholics Anonymous (AA) and its well-known "12-Step" program. The purpose of the present study was to develop a scale to measure alcoholics' levels of agreement with the first three of AA's 12 Steps and to test the relationship between sobriety and belief in these three steps. Using both factor analysis and Rasch analysis, two versions of a "Steps Questionnaire" were developed. A 96-member subset of the original subject pool was assessed quarterly for 1 year following inpatient treatment to determine the predictive validity of the questionnaire. The results of this study suggested that agreement with AA's first three steps can be measured and that agreement with AA's first step correlates with number of sober days posttreatment. The dichotomization of Steps Questionnaire scores into total agreement versus partial agreement with Step 1, and from this the reduction of uncertainty in the prediction of abstention over a lengthy follow-up period, provides support for AA's contention that total surrender to one's powerlessness over alcohol is part of the process of achieving abstention.

Alcohol Drinking↗

PubMed1989

Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): dose-dependent expulsion of adult worms.

The survival of Heligmosomoides polygyrus was monitored during primary infections in female C57Bl10, NIH and BALB/c mice at low and high intensities of infection. Survivorship curves were fitted for each data set and analysed. C57Bl10 mice, given either low or high intensities of infection, harboured parasites for 28-37 weeks, heavier infections surviving marginally but significantly longer. Essentially the survivorship curves of H. polygyrus in C57Bl10 mice could be accounted for by senility, the increased probability of worms with a longer life-span occurring at high infection intensities and, possibly, by a contribution from host-protective immune mechanisms in the terminal stages of infection. The pattern of survivorship was different in NIH and BALB/c mice. NIH mice showed weak but significant density-dependent suppression of parasite loss and infections in this strain did not exceed 27.5 weeks in duration. Primary infections in BALB/c mice were briefer still and showed marked dependence on parasite density. Thus low-level infections lasted 10-15 weeks whereas heavier infections survived for 21-34 weeks. The data suggested that both strains developed host-protective responses to adult H. polygyrus and that parasite survival was curtailed earlier than would be expected if senility alone was involved. The hybrid strains (C57Bl10 x NIH)F1 and (B10G x NIH)F1 both expelled H. polygyrus in a dose-dependent manner, worm loss commencing within 10 weeks of infection. In some experiments worm loss was clearly evident by weeks 4 and 6. These hybrid strains showed gene complementation in that adult worms were cleared considerably earlier than in parental strains.

Animals↗

PubMed1989

Communication skills training with alcoholics for improving performance of two of the alcoholics anonymous recovery steps.

Thousands of men and women have begun their recovery from alcoholism through the support of Alcoholics Anonymous (AA). AA recognizes its social support role in defining itself as a "fellowship," but it also sees itself as offering a program of recovery. This program is comprised of the well-known "12-Step" method, which has been adapted by a variety of self-help groups. The purpose of the present study was to determine whether performance of two of these steps, Steps 4 and 5, could be facilitated by teaching communication skills specifically designed to improve their performance. Hospitalized alcoholics were assigned to communication-skills training, discussion and assessment-only groups, and their pre- and posttreatment performance on videotaped role-plays of Steps 4 and 5 was assessed. Subjects in the communication-skills training group were found to improve significantly on internal versus external focus, personal responsibility taking, congruent affect and composite skill variables compared to the discussion and assessment-only groups. These results suggest that, among treatment programs that utilize AA's recovery program, the behavioral skills inherent in completing Steps 4 and 5 need to be taught. Merely discussing or alluding to the steps, as is often-times done in group therapy of "step-study" sessions, is unlikely to have any effect on alcoholics' abilities to "work the steps."

Adult↗

PubMed1988

The effect of type of aftercare follow-up on treatment outcome among alcoholics.

Past research on methods for actively engaging alcoholics in aftercare has been mixed with respect to the effects of such efforts on treatment outcome. The present study examined whether active follow-up methods do aid in engaging the alcoholic in treatment, whether such procedures improve treatment outcome and how much responsibility the therapist must be willing to assume in order to maintain the patient in treatment. Appointment keeping was significantly improved by a home-visit follow-up method in the first 6 months postdischarge (p less than .01). However, there was no one-to-one correspondence between improved therapy attendance and improved treatment outcome. When subjects were classified into treatment dropout and treatment completion groups, however, a treatment effect was achieved. The most intensive follow-up condition increased the probability of treatment completion, supporting to some degree the utility of aggressive follow-up. However, it was concluded that the cost of such procedures probably will limit their use since a significant economic variable (number of days hospitalized during the follow-up year) was not affected by type of aftercare.

Adult↗

PubMed1987

Predicting attendance at follow-up evaluations in alcoholism treatment outcome research.

The potential utility of an early-warning system involving the use of attendance at scheduled clinical appointments to predict attrition of research subjects from follow-up evaluations was investigated. Subjects (N = 92) discharged from an inpatient alcoholism treatment program into a treatment outcome study were monitored on their aftercare attendance for 1 year postdischarge. Attendance at clinical aftercare sessions during the follow-up year was correlated significantly with attendance at the research project's quarterly follow-up evaluations (p less than .001) and with total number of research evaluations completed (p less than .001). Number of weeks spent in aftercare before dropping out also improved prediction of attendance or nonattendance at quarterly follow-up evaluations during the first 6 months postdischarge (p less than .01). The findings suggest that monitoring attendance at clinical services may be a useful step in minimizing attrition of research subjects from follow-up evaluations.

Aftercare↗

PubMedDate not supplied

Comparison of the efficacy of mebendazole, albendazole and pyrantel in treatment of human hookworm infections in the southern region of Mali, West Africa.

A randomized, placebo-controlled trial of the efficacy of pyrantel (single dose 12.5 mg/kg bodyweight), mebendazole (single 500 mg dose) and albendazole (single 400 mg dose) in the treatment of hookworm infections (Necator americanus) was carried out in January 1998 in the Southern Region of Mali, West Africa, during the period of Ramadan (Islamic fast). Statistical analysis of the pre-intervention faecal egg counts showed that there was a significant pre-treatment chance bias, despite randomization of subjects into treatment groups, arising from the main effect of sex (heavier infections among males) and a sex x treatment interaction (the sex bias was not evident in the pyrantel-treatment group). The participants were re-examined 10 days after treatment, and after controlling for the drift in faecal egg counts in the placebo-treated subset, age, sex, fasting and intensity of infection, albendazole was clearly the most effective drug showing consistently efficacies in the range 92.1 to 99.7%, depending on the method of evaluation and the particular subset of the treatment group. Neither mebendazole nor pyrantel was as effective, with efficacies ranging from 60.9 to 89.8% and 4.8 to 89.7%, respectively. Fasting made no difference to drug efficacy. On the basis of our results the single 400 mg dose of albendazole is the treatment of choice for hookworm infections in this region of Mali. We emphasize the need for standardization of the methods used for trial designs, for calculation of summary data relating to drug efficacies and the accompanying statistical tests.

Adolescent↗