Journal of Helminthology

For the sensitive detection of eggs ofEchinococcus multilocularisin fox faeces by PCR we have evaluated a method based on the previous concentration of helminth eggs by a combination of sequential sieving of faecal samples and flotation of the eggs in zinc chloride solution. The eggs were microscopically detected in the fractions retained in 40 and 20µm mesh sieves. DNA of the taeniid eggs retained in the 20 µm sieve was obtained after alkaline lysis and PCR was performed usingE. multilocularisspecies-specific primers. Compared to the parasitological findings after examination of the small intestines of the foxes, the specificity of the PCR was 100% (no false-positive result with 20 foxes free ofE. multilocularis) and the sensitivity was 94% (33 positive results from total 35 foxes proven to be infected withE. multilocularis). Both false-negative results were obtained with faeces from foxes harbouring immature worms. Using faecal volumes between 2 and 20 ml, no inhibition of PCR was observed as was demonstrated by the amplification of size-modified target in parallel reactions. The tests were undertaken with fresh faeces stored in 70% ethanol, but egg detection by PCR was also possible after inactivation of eggs by freezing the faeces at −80°C for one week or by incubation at +70°C for 2 h.

The reliability of different egg counting methods for estimating the intensity of Trichostrongylus tenuis infections in red grouse, Lagopus lagopus scoticus, was investigated in the autumn, when grouse may harbour high parasite intensities. Possible limitations to the use of these methods were also examined. Faecal egg counts were found to accurately estimate T. tenuis worm intensities, at least up to an observed maximum of c. 8000 worms. Two egg counting methods (smear and McMaster) gave consistent results, although the exact relationship with worm intensity differed according to the method used. Faecal egg counts significantly decreased with increasing length of sample storage time, but egg counts were reliable for estimating worm intensity for three weeks. The concentration of eggs in the caecum was also found to reliably estimate worm intensity. However, egg counts from frozen gut samples cannot be used to estimate worm intensities. These results conclude that, despite some limitations, faecal and caecum egg counts provide useful and reliable ways of measuring T. tenuis intensities in red grouse.

Laboratory experiments were designed to select nematophagous fungi that were able to survive in vitro conditions simulating passage through the gastro-intestinal tract of cattle. All of the tests were conducted at 39°C. In a primary stress selection step in diluted rumen fluid, 21 isolates were obtained. Each of the primary stress selected isolates was tested in synthetic saliva, rumen fluid simulating the activity in the rumen, rumen fluid followed by pepsin-hydrochloric acid treatment simulating the additional effect of ruminal and abomasal activity, pepsin-hydrochloric acid solution simulating conditions in the abomasum and finally in a trypsin solution as an example of enzyme activity in the gut. The effect of the rumen fluid alone, or rumen fluid followed by pepsin-hydrochloric acid treatment, were responsible for the reduction in surviving fungal isolates. Only six of thirteen isolates belonging to the genus Arthrobotrys survived while seven of eight isolates of the genus Duddingtonia survived. Fourteen isolates were tested for their predatory capacity in a dung pat bioassay. Fungi of the genera Arthrobotrys and Duddingtonia reduced the development of Ostertagia ostertagi third stage larvae by approximately 75% and 96% respectively compared to the number of larvae that developed from fungus-free control pats.

Three nematode-trapping fungi, oneArthrobotrys oligosporaand twoDuddingtonia flagransisolates, were fed toOstertagia ostertagi-infected calves to test their ability to destroy larvae of this parasite in faeces and consequently to reduce the transmission of infective larvae to herbage. The fungi had previously been selected for their capability to pass the alimentary tract of cattle without losing growth and nematode-trapping potentials. Dung was collected from three calves each fed one of the three fungi and placed as 1-kg cow pats on a parasite-free grass plot together with control cow pats from a calf that was not given fungi. The cow pats contained comparable concentrations of parasite eggs. The twoD. flagransisolates were highly effective in that they reduced herbage larval infectivity by 74–85%. In contrast,A. oligosporadid not show any effect in the present experiment. Field experiments will demonstrate ifD. flagransrepresents a potential organism for biological control of bovine gastrointestinal nematodes under practical agricultural management conditions.

Infection with Oesophagostomum sp. appears to be extremely common in man in northern Togo and Ghana Adult specimens were recovered from the intestinal lumen by treatment with pyrantel pamoate and the morphological characteristics of oesophagostomes of man could for the first time be compared with information available on the morphology of oesophagostomes of monkeys. The observations and measurements demonstrated that the species involved is Oesophagostomum bifurcum and that the eggs of this species cannot be differentiated from those of Necator americanus. Both infections occur simultaneously in the population involved. The L₁ larvae, too, cannot be differentiated from hookworm L₁ larvae. The L₃ however, are characteristic. Diagnoses of human Oesophagostomum infections is based on the detection of these larvae in coprocultures. In the present paper, the eggs, the L₁ and L₃ larval stages and the adults, carefully described and photos are given.

The activity, infectivity and fat content of ageing infective larvae of Ancylostoma caninum were investigated at regular intervals.

The reduction in activity and fat content was found to occur at a similar rate.

Sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochromecoxidase subunit 1 (cox1) and NADH dehydrogenase subunit 4 (nad4), and internal transcribed spacer (ITS) of rDNA among and within three cestodes,Spirometra erinaceieuropaei,Taenia multicepsandTaenia hydatigena, from different geographical origins in China was examined. A portion of thecox1 (pcox1),nad4 genes (pnad4) and the ITS (ITS1+5.8S rDNA+ITS2) were amplified separately from individual cestodes by polymerase chain reaction (PCR). Representative amplicons were subjected to sequencing in order to estimate sequence variability. While the intra-specific sequence variations within each of the tapeworm species were 0–0.7% for pcox1, 0–1.7% for pnad4 and 0.1–3.6% for ITS, the inter-specific sequence differences were significantly higher, being 12.1–17.6%, 18.7–26.2% and 31–75.5% for pcox1, pnad4 and ITS, respectively. Phylogenetic analyses based on the pcox1 sequence data revealed thatT. multicepsandT. hydatigenawere more closely related to the other members of theTaeniagenus, andS. erinaceieuropaeiwas more closely related to the other members of theSpirometragenus. These findings demonstrated clearly the usefulness of mtDNA and rDNA sequences for population genetic studies of these cestodes of socio-economic importance.

In the First Report of the W. H. O. Expert Committee on Bilharziasis (1953) it was stated: “Infection with Schistosoma is often well tolerated and without clinical signs, however this relative benignity appears to vary considerably from country to country, without the cause of these variations being as yet thoroughly understood”. This statement refers to the relative absence of serious manifestations of schistosomiasis as has been reported by various investigators working in Africa, e.g. Ramsay (1934) working in Nigeria, Dixon (1934) and Fisher (1934) in the Congo, Gelfand (1950) in Southern Rhodesia, Mackey (1953) in Tanganyika, Manson-Bahr (1958) in Kenya and Nelson (1959) in Uganda as compared with the situation reported in Egypt and South America.

The humoral immune response in the two eel species,Anguilla japonicaandAnguilla anguillaagainst two fractions of antigens inAnguillicola crassuswere studied.Within species, both eel species showed significantly elevated titres compared with controls when immunized with antigens fromAnguillicola crassus.In interspecific comparison,Anguilla japonicashowed significantly elevated titres in comparison withAnguilla anguilla. Immunization ofAnguilla anguillacaused a significantly decrease in the plasma levels of protein in comparison with control fish and all groups ofAnguilla japonica.In contrast,Anguilla japonicashowed significantly lower plasma levels of Ig in all groups compared withAnguilla anguilla.The different susceptibilities toAnguillicola crassusbetween the natural host,Anguilla japonica, and the naı¨ve,Anguilla anguilla, is partly due to differences in the ability of the two eel species to mount a humoral immune response.