A study has been carried out to determine the morphological changes to the adult liver fluke, Fasciola hepatica after treatment in vivo with artemether. Rats were infected with the triclabendazole-resistant Sligo isolate of F. hepatica, dosed orally with artemether at a concentration of 200 mg/kg and flukes recovered at 24, 48 and 72 h post-treatment (p.t.). Surface changes were monitored by scanning electron microscopy and fine structural changes to the tegument and gut by transmission electron microscopy. Twenty-four hours p.t., the external surface showed minor disruption, in the form of mild swelling of the tegument. The tegumental syncytium and sub-tegumental tissues appeared relatively normal. Forty-eight and seventy-two hours p.t., disruption to the tegumental system increased, with isolated patches of surface blebbing and reduced production of secretory bodies by the tegumental cells being the main changes seen. The gastrodermal cells showed a relatively normal morphology 24 h p.t. By 48 h, large numbers of autophagic vacuoles and lipid droplets were present. Autophagy increased in magnitude by 72 h p.t. and substantial disruption to the granular endoplasmic reticulum was observed. Results from this study show that flukes treated in vivo with artemether display progressive and time-dependent alterations to the tegument and gut. Disruption to the gut was consistently and substantially more severe than that to the tegument, suggesting that an oral route of uptake for this compound predominates. This is the first study providing ultrastructural information on the effect of an artemisinin compound against liver fluke.

Eighty-nine samples of grey wolf (Canis lupus L.) faeces were collected between 2002 and 2004 from two areas in the western Beskidy Mts (south Poland). Helminth eggs were observed in 56.2% of faeces examined. These included: Alaria alata (2.2%), taeniid eggs (11.2%), Toxocara canis (5.6%), Toxascaris leonina (1.1%), Eucoleus aerophilus (14.6%), Ancylostoma caninum (12.3%), Uncinaria stenocephala (37%) and unidentified roundworm eggs of the family Strongyloididae (1.1%). Eucoleus aerophilus is recorded for the first time from Poland. The results are compared with the helminth fauna of other wolf populations in Europe.

The entomopathogenic nematode Steinernema yirgalemense is considered a promising agent in the biocontrol of insects. However, little is known about the bacteria living in symbiosis with the nematode. In this study, we have identified the only available bacterial strain (157-C) isolated from S. yirgalemense, as a member of the species Xenorhabdus indica. Identification was based on 16S rDNA, recA, dnaN, gltX, gyrB and infB gene sequence analyses. The relatedness of strain 157-C to the type strain of X. indica (DSM 17 382) was confirmed with DNA–DNA hybridization. The phenotypic characteristics of strain 157-C are similar to those described for the type strain of X. indica. This is the first report associating X. indica with S. yirgalemense.

1. With the aid of field growth curves, age-prevalence curves can be derived from field collections of snails, using cercarial shedding as proof of infection by schistosomes.

2. Such curves were obtained from eight collections of field snails: one sample each of Bulinus (Physopsis) nasutus productus and Biomphalaria pfeifferi, intermediate hosts respectively of Schistosoma haematobium and S. mansoni in Tanzania, and six samples of Biomphalaria glabrata, intermediate host of S. mansoni on St. Lucia, West Indies.

3. Catalytic curves were fitted to the data and in each case the two-stage curve gave the most satisfactory fit.

4. This curve is the resultant of two opposing forces: one force being the rate of infection and the other the rate of loss of infection in a snail population.

5. The rate of infection may be defined as the number of successful snail-miracidium contacts per 1,000 snails per week, while the rate of loss of infection is taken to represent the number of deaths per 1,000 infected snails per week.

6. The underlying assumptions of this form of analysis are discussed and, in view of the independent verification of some of the calculated rates, the values are considered realistic.

7. Besides providing quantitative data for inclusion in mathematical models of schistosome transmission, the technique offers an additional means of assessing the efficacy of certain methods of controlling transmission.

Schistosoma species have traditionally been arranged in groups based on egg morphology, geographical origins, and the genus or family of snail intermediate host. One of these groups is the ‘S. indicum group’ comprising species from Asia that use pulmonate snails as intermediate hosts. DNA sequences were obtained from the four members of this group (S. indicum, S. spindale, S. nasale and S. incognitum) to provide information concerning their phylogenetic relationships with other Asian and African species and species groups. The sequences came from the second internal transcribed spacer (ITS2) of the ribosomal gene repeat, part of the 28S ribosomal RNA gene (28S), and part of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene. Tree analyses using both distance and parsimony methods showed the S. indicum group not to be monophyletic. Schistosoma indicum, S. spindale and S. nasale were clustered among African schistosomes, while S. incognitum was placed as sister to the African species (using ITS2 and 28S nucleotide sequences and CO1 amino acid sequences), or as sister to all other species of Schistosoma (CO1 nucleotide sequences). Based on the present molecular data, a scenario for the evolution of the S. indicum group is discussed.

Histological examination of the small intestine of mice infected with Heligmosomoides polygyrus indicates that the final site of the larvae is in the circular muscle layer of the muscularis externa of the anterior small intestine. The larvae become embedded in the muscle between the first and third days after infection and are subsequently sequestered by a localized leucocytic response. There is no evidence of a true cyst. Histological evidence suggests that the larvae actively feed on the tissues of the host during their development.

The abundance of six species of trematodes: Aphanurus stossichi, Bacciger israelensis, Diphterostomum israelense, Plagioporus idoneus, Lepocreadium album and L. pegorchis, parasitic in the digestive tract of marine teleostei (Sparidae) collected near Jounieh (east Mediterranean), was analysed as a function of the host-size. In two parasite/host systems, infections were observed from the lowest size classes of the sample, with a clear tendency to an increase of abundance in older fish. In four others, parasites appear only above a rather high threshold class, young individuals never being infected. In the last three parasite/host systems, host invasion may occur early or late, but infection decreases above a well defined size class, old fishes rarely or never being infected. A given trematode species. when parasitizing several host species, shows similar abundance/host size relationships, e.g. P. idoneus in Diplodus vulgaris and Oblada melanura. When more than one species of trematode infects a single host species, curves can be markedly distinct; for instance, L. pegorchis was collected from Pagellus erythrinus below 15 cm. whereas D. israelense parasitized the same fish approximately above the same size. There is no evidence that such a replacement of one trematode by another in the course of host growth is a result of interspecific competition.

Monogenean richness of marine fish is highly variable among host families and species. On the basis of 160 fish species selected because their parasite fauna was considered as ‘adequately’ investigated, an attempt was made to find associations between parasite richness and various characters of the hosts. No clear correlation was found with maximal size, although the smallest species (less than 10cm) seem to never harbour monogeneans. Correlations were found with nectonic, migrating and gregarious behaviours. However, taxonomy of fish appears to be extremely important as a determinant of monogenean richness. In the absence of a satisfactory phylogeny of hosts, no attempt was made to control the analysis for phylogeny. However, removing some families characterized by a high parasite richness (sparids, sciaenids, mugilids) shows that the association with gregariousness holds, whereas the others tend to disappear.

Rainbow trout were experimentally infected with the ectoparasitic monogenean Gyrodactylus derjavini at three temperatures, 5.5°C, 11.6°C and 18.7°C. Subsequently, the infection level was monitored during the following 6 weeks. The population growth was positively correlated with temperature in the initial part of the investigation. At 18.7°C growth of the parasite population was fast reaching a peak abundance within 3 weeks, whereafter the infection level decreased significantly. Peak abundance was recorded in week 5 at 11.6°C. A very slow but steady parasite reproduction was noted at 5.5°C, but no peak abundance was reached within 6 weeks. The decline in parasite population after reaching peak levels is likely to be caused by a host response. The host response is also indicated by the parasites' active selection of particular microhabitats. This anti-monogenean response developed fastest at 18.7°C, more slowly at 11.6°C and was not recorded within 6 weeks at 5.5°C.

The susceptibility of Bulinus truncatus, B. tropicus, B. natalensis, B. coulboisi, B. globosus, B. cernicus and B. wrighti to Schistosoma haematobium from Egypt were examined. Eighteen different populations of B. truncatus were investigated.

A new method of measuring the compatibility between schistosomes and the intermediate snail hosts, the total cercarial production per 100 exposed snail, is introduced.

All B. truncatus populations became infected and could be divided in four groups according to the total cercarial production per 100 exposed snails. In the first group the cercarial production varied from 250 000 to 500 000 and in the last group between 5000 and 20 000. The first group had a high infection rate of 62 to 100% and a low mortality of approximately 10% and the last group showed a very low infection rate and a high mortality.

B. globosus (Rhodesia), B. cernicus and B. wrighti became infected, while B. globosus (Zaire), B. coulboisi, B. natalensis and B. tropicus were refractory.

The shortest prepatent period was 26 days at a room temperature of 26°C. The maximum cercariae production for one snail in one day was 600 and the longest duration of infection was 200 days.

Experimenting with different doses of miracidia, 5 to 50 per snail, resulted in a one hundred per cent infection and a low mortality of 10%. There was only a slight variation in the cercarial production.

The plant-parasitic nematodes have this in common with their relatives parasitic in animals, that they are unusually resistant to chemical control. It is not merely that substances lethal to the nematode are harmful to the animal or plant, for in both cases there are usually in the nematode’s life cycle free-living stages, and these are also highly resistant. Apparently the nematode cuticle, egg shell, and vitelline membrane are effective barriers to the penetration of many substances which might be expected to be good contact poisons. Several of the best modern insecticides have given disappointing results against plant eelworms (Ellis and Clayton, 1948). On the other hand some of the simpler halogenated hydrocarbons have been fairly effective, against both animal nematodes (CCl4, C2C14) and plant eelworms in the soil (C2H4Br2, C3H4Cl2).

Eighty three carcasses of pigs were examined at three abattoirs in Moshi, Arusha and Mbulu in northern Tanzania. Taenia solium metacestodes were found in all the three abattoirs with an overall prevalence of 13.3%. During routine meat inspection in Kiboroloni, Moshi 6.2–6.9% of the pigs were found to harbour T. solium metacestodes. The mean number of hooks on the protoscolices was 27 and the length of the small hooks varied from 105 mm to 130 μm while that of the larger hooks varied from 168 mm to 174 mm confirming that the cysts were metacestodes of T. solium. Although cystlike lesions were recovered from livers of both pigs and cattle, no booklets of sizes in the range of 5–37mm were found indicating that no Taiwan Taenia metacestodes were recovered during carcass examination.

The citrus mealybug, Planococcus citri, is a highly destructive pest of citrus, occurring only in the aerial parts of plants. Humidity will be one of the key factors to consider when using entomopathogenic nematodes (EPN) as biological control agents. Different adjuvants can be added to suspensions of EPNs, to improve control as a foliar application. An aqueous suspension containing Heterorhabditis zealandica and 0.3% Zeba® significantly increased P.citri mortality by 22% at 80% relative humidity (RH) with a temperature cycle starting at 22°C for 14 h and 11°C for 11 h. The same polymer formulation was tested for Steinernema yirgalemense and mortality of P. citri increased by 21% at 60% RH and by 27% at 80% RH. The addition of Nu-Film-P® and Zeba® to H. zealandica suspensions did not significantly retard application run-off on citrus leaves. The combination of Nu-Film-P® and Zeba®, however, was able to significantly retard sedimentation, increasing the average number of nematodes deposited on 2-cm2 leaf discs by 10 nematodes. In an aqueous suspension, nematodes settle rapidly to the bottom, resulting in an uneven distribution of nematodes. Xanthan gum, at a concentration of 0.2%, was highly effective at retarding sedimentation, with 72% of the initial nematode number still in suspension after 1 h. Zeba®, at a concentration of 0.3%, despite not being as effective as Xanthan gum, nevertheless still retarded sedimentation significantly. This is the first report of the potential of Nu-Film-P® and Zeba® to improve EPN performance against P. citri when used above ground in citrus orchards.

Confusion exists over the species status and host-specificity of the tapeworm Rodentolepis (= Hymenolepis) nana. It has been described as one species, R. nana, found in both humans and rodents. Others have identified a subspecies; R. nana var. fraterna, describing it as morphologically identical to the human form but only found in rodents. The species present in Australian communities has never been identified with certainty. Fifty one human isolates of Rodentolepis (= Hymenolepis) nana were orally inoculated into Swiss Q, BALB/c, A/J, CBA/CAH and nude (hypothymic) BALB/c mice, Fischer 344 and Wistar rats and specific pathogen free (SPF) hamsters. Twenty four human isolates of R. nana were cross-tested in flour beetles, Tribolium confusum. No adult worms were obtained from mice, rats or hamsters, even when immunosuppressed with cortisone acetate. Only one of the 24 samples developed to the cysticercoid stage in T. confusum; however, when inoculated into laboratory mice the cysticercoids failed to develop into adult worms. The large sample size used in this study, and the range of techniques employed for extraction and preparation of eggs provide a comprehensive test of the hypothesis that the human strain of R. nana is essentially non-infective to rodents.

A comparison of the characteristics of two strains of S. haematobium in experimental infections in hamsters is made. A limited study of these strains is also made in Mastomys.

Growth changes in male and female adult worms are compared, as are changes in the uterine egg counts.

The quantitative distribution of eggs in the tissues of the hamster is recorded. The approximate mean daily egg output per female worm for each strain is calculated at specified time intervals, and for the entire period of observations.

The recorded characteristics of the two strains of parasite are compared with those described for other strains of S. haematobium.

It is considered that the hamster provides a useful model for such studies provided that standardised infection procedures are employed.

It is considered that differences in host characteristics and susceptibility of individual animals account for the apparent variability recorded with regard to growth of parasites and egg depositions.

Water quality greatly influences the population density of aquatic biota, including parasites. In order to evaluate the relationship between fish parasites and water quality in Kashmir Himalayas, we assessed helminth parasite densities in Schizothorax niger Heckel, 1838 (an endemic cyprinid fish of Kashmir) from three lakes, namely Anchar, Manasbal and Dal, which reflected the varied stages of eutrophication. The overall prevalence of helminth infections was higher in the hypertrophic Anchar Lake (prevalence = 18.6%) compared to Manasbal Lake, which was the least eutrophied (prevalence = 6.4%). Furthermore, mean prevalence of monoxenous and heteroxenous parasites was higher in lakes containing higher levels of water degradation (Anchar and Dal). The mean number of helminth species per fish host was the highest in the hypertrophic lake (1.3 ± 0.3) in comparison to the least eutrophic lake (0.2 ± 1.5). Variability of calculated infection indices (prevalence, mean intensity and mean abundance) revealed that helminth parasite composition in the fish was affected by the lakes' environmental stress (degraded water quality). Therefore, data on the density of helminth parasites in fish can provide supplementary information on the pollution status of a water body.

Eosinophil counts, interleukin 5 (IL-5) concentrations in peripheral blood and larval recovery after infection with Toxocara canis were compared between IL-5 transgenic (Tg) and nontransgenic counterparts, C3H/HeN mice. In Tg mice characterized by a constant high level of peripheral eosinophils, eosinophils in peripheral blood fell to the lowest level on day 4 of a T. canis infection and then returned to the preinfection level on day 14. Serum IL-5 level fell to the lowest level on day 4 of infection, then recovered rapidly and peaked on day 14 postinfection. In contrast, the eosinophil and IL-5 levels in the peripheral blood peaked on days 11 and 7 of infection, respectively in C3H/HeN mice. The degree of eosinophil infiltration into the lung 4 days after infection was far more pronounced in Tg than C3H/HeN mice. The highest number of larvae recovered from the lungs of infected Tg and C3H/HeN mice occurred on day 4 postinfection. Strains of Tg and C3H/HeN mice vaccinated with excretory and secretory (ES) antigens of T. canis larvae were infected with T. canis and the recovery of larvae on day 21 analysed. There were no significant differences in the mean number of larvae recovered from nonvaccinated Tg and C3H/HeN mice or vaccinated Tg and C3H/HeN mice. However, significant differences were demonstrated in the mean total number of larvae recovered from vaccinated and nonvaccinated Tg or C3H/HeN mice. These results suggest that immunocompetent cells other than eosinophils may play a significant role in the expulsion and killing of T. canis larvae in infected mice.

The development of the parasitic stages of O. ostertagi is described and illustrated by a series of figures.

Out of a total of 282 soil samples obtained from public areas, 58 samples contained Toxocara spp. eggs. This gave an overall prevalence of 20.6%. Highway rest areas were contaminated and childrens sand boxes had the highest percentage of recovery of all.

In the Chambezi-Luapula area of the Northern Province of Northern Rhodesia, 2,575 Africans were examined for intestinal helminths and 2,017 for urinary helminths. The examinations were carried out in situ in the native villages in widespread localities representing different topographical parts of the area.

The average infection rates of the helminthic infections found were as follows: hookworm, 52.2%; Strongyloides, 13.3%; Ascaris lumbricoides, 3.7%; Enterobius vermicularis, 0.85%; Trichuris trichiura, 0.3%; Trichostrongylus sp., 0.1%; Schistosoma haematobium, 14.7%; S. mansoni, 6.99%; Hymenolepis nana, 0.09%; H. diminuta, 0.04%; Taenia sp., 0.04%.

The survey revealed regions or foci of relatively high and relatively low incidence in the case of each of the major species. The relationship of this to topographical and other factors is discussed.

Examination of 459 Africans for Mf. bancrofti revealed three positives, but none of these had definitely contracted the infection in N. Rhodesia. Mf. Perstans was found in 5.4% of those examined; this infection is endemic in the country.