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.

Since isolates of Hymenolepis nana infecting humans and rodents are morphologically indistinguishable, the only way they can be reliably identified is by comparing the parasite in each host using molecular tools. In the current study, isolates of H. nana from rodent and human hosts from a broad geographical range were sequenced at the ribosomal first internal transcribed spacer (ITS1), the mitochondrial cytochrome c oxidase subunit 1 (C01) gene and the nuclear paramyosin gene loci.# Twenty-three isolates of H. nana were sequenced at the ITS1 locus and this confirmed the existence of spacers which, although similar in length (approximately 646 bp), differed in their primary sequences which led to the separation of the isolates into 2 clusters when analysed phylogenetically. This sequence variation was not, however, related to the host of origin of the isolate, thus was not a marker of genetic distinction between H. nana from rodents and humans. Sequencing of a 444 bp fragment of the mitochondrial cytochrome c oxidase 1 gene (C01) in 9 isolates of H. nana from rodents and 6 from humans identified a phylogenetically supported genetic divergence of approximately 5 % between some mouse and human isolates. This suggests that H. nana is a species complex, or ' cryptic ' species (=morphologically identical yet genetically distinct). A small segment of the nuclear gene, paramyosin, (625 bp or 840 bp) was sequenced in 4 mouse and 3 human isolates of H. nana. However, this gene did not provide the level of heterogeneity required to distinguish between isolates from rodent and human hosts. From the results obtained from faster evolving genes, and the epidemiological evidence, we believe that the life-cycle of H. nana that exists in the north-west of Western Australia is likely to involve mainly ' human to human ' transmission.

We analysed 3 independently collected datasets of fully censused helminth burdens in wood mice, Apodemus sylvaticus, testing the a priori hypothesis of Behnke et al. (2005) that the presence of the intestinal nematode Heligmosomoides polygyrus predisposes wood mice to carrying other species of helminths. In Portugal, mice carrying H. polygyrus showed a higher prevalence of other helminths but the magnitude of the effect was seasonal. In Egham, mice with H. polygyrus showed a higher prevalence of other helminth species, not confounded by other factors. In Malham Tarn, mice carrying H. polygyrus were more likely to be infected with other species, but only among older mice. Allowing for other factors, heavy residual H. polygyrus infections carried more species of other helminths in both the Portugal and Egham data ; species richness in Malham was too low to conduct a similar analysis, but as H. polygyrus worm burdens increased, so the prevalence of other helminths also increased. Our results support those of Behnke et al. (2005), providing firm evidence that at the level of species richness a highly predictable element of co-infections in wood mice has now been defined : infection with H. polygyrus has detectable consequences for the susceptibility of wood mice to other intestinal helminth species.

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.

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractPopulations of Egyptian spiny mice (Acomys cahirinus dimidiatus) in a fragmented montane wadi system in the Sinai showed significant differences in the abundance of gut helminths. Differences in parasite load between populations were positively associated with measures of androgen activity but showed no significant relationship with glucocorticoid activity. Social discrimination tests with adult males from different wadis showed that those from sites with greater helminth abundance were less likely to investigate odours from other males and were less aggressive when subsequently interacting with the odour donors. Subjects showed markedly more investigation towards the odours of males from distant wadis compared with those from their own or immediately neighbouring wadi, but were less aggressive when confronted with odour donors from distant wadis. Despite this, there was a positive relationship between the amount of investigation towards distant male odour and subsequent aggression towards the male. While aggressiveness was positively associated with measures of androgen and glucocorticoid activity, no significant relationship emerged with individual helminth infection. Thus aggressiveness appeared to relate to overall local population levels of infection rather than individual challenge.