The resistance to infection by Ostertagia spp. of three groups of lactating ewes was compared with an unbred control group. Group 1 was fed a full diet of hay and a concentrate ration ad lib. Groups 2 and 3 were fed the same quantitatively inadequate diet and in addition group 3 received daily injections of thyroxine sodium. All the animals were infected regularly with Ostertagia larvae and killed 6 weeks after lambing.

While the unbred sheep were highly resistant, all three groups of lactating ewes carried significant numbers of worms. Group 2 and 3 had significantly more than group 1, the additional worms being present as adults. The effect of hyperthyroidism in group 3 was not significant.

It is concluded that the immuno-suppressant effect of lactation is probably not due to protein depletion although the latter may be an important secondary factor.

Stunkardia minuta sp. n. was recovered from the small intestine and rectum of 5 box-tortoises (Cuora amboinensis) in Malaysia. The average body size (L × W) is 11·42 × 2·35 mm; oral sucker 1·51 × 1.02; oral pouches 0·21 × 0·18; ventral sucker 1·67 × 1·43; oesophageal bulb 0·54 × 0·54; ant. testis 0·95 × 0·98; post. testis 0·94 × 0.94; seminal vesicle 0·82 × 0·24; ootype 0·21 × 0·41; ovary 0·41 × 0·34; and egg 121 × 83 μm. Although morphologically similar to S. dilymphosa, S. minuta is distinct from any other reported member of the Paramphistomidae.

Early in June, 1933, the writer received two vials of caterpillars, to which nematodes were attached, from Mr. A. M. Adamson of the Pacific Entomological Survey with a request, supported by Mr. E. P. Mumford, the Director of the Survey, that an examination and identification of the helminths would be much appreciated.

Nondenatured and denatured total RNA from the tapeworm Diphyllobothrium dendriticum (Cestoda) was analysed by agarose gel electrophoresis. It was found that the large subunit ribosomal RNA (lrRNA) is 28.0S and the small subunit ribosomal RNA (srRNA) is 19.5S. Following denaturation the 28.0S rRNA was disrupted into a 19.5S subfragment and a 20.7S subfragment due to the presence of a centrally located hidden break. By hybridization of Northern blot membranes with oligonucleotide probes specific for the 5′- and 3′-ends of the lrRNA respectively, we have shown that the 19.5S sub-fragment is from the 5′-end (the α-subfragment) and the 20.7S subfragment from the 3′-end (the β-subfragment) of the 28.0S rRNA of D. dendriticum.

Pharmacological studies carried out on protoscoleces in vitro to standardize conditions that would permit a preliminary estimate of the efficacy of drugs with potential activity against Echinococcus granulosus are reported. Media such as PBS and Hanks solution, maintenance temperature, different pH values and concentrations of various solvents have been tested to check the effects on protoscolex survival in tubes in vitro. Mebendazole has been used as the pharmacological standard reference. Changes in the viability of protoscoleces have been used to demonstrate pharmacological activity. Best conditions were obtained employing Hanks solution and propylene glycol at low concentrations. Mebendazole was not completely effective at the concentrations achievable in human therapy. Linear, reproducible results demonstrated that Hanks solution provides an ideal medium for pharmacological studies. Among tested solvents, propylene glycol and dimethyl sulphoxide showed no lethal activity at low concentrations. At concentrations similar to those normally obtained in human sera, mebendazole, as in vivo, demonstrated only partial lethality for protoscoleces. The present study represents a new experimental approach to chemotherapy of hydatid disease.

A post-parturient rise in worm egg count was seen in ewes which lambed in the autumn following ovulation induced by hormone treatment. Similarly treated ewes in the same flock which proved to be barren showed only a slight increase in egg count. There were indications that hormone treatment may be associated with egg count rises which differ in intensity and duration from those reported in ewes which ovulate spontaneously.

Larvae of Syngamus trachea pass from the intestine to the lungs of the definitive host via the blood stream. They have been recovered from blood taken from the auricles of the heart and from the posterior vena cava.

The condition of the lungs heavily infected with larvae is described.

A condition of ‘Syngamus pneumonia’ occurs in the wild state among poults of partridges and pheasants.

Promising results in the colorimetric assay of potato-root eelworm hatching factor have been obtained with picric acid and with 3: 5- dinitrobenzoic acid. Both of the reagents are used for the assay of cardiac glycosides with which the hatching factor may have affinities.

A gelatin-agar bolus, designed and developed for the administration of metacercariae of the liver fluke Fasciola hepatica, was evaluated in adult Holstein Friesian cattle. The metacercariae, enclosed within a gelatin capsule, were placed inside the bolus and delivered to each animal using an oesophageal balling gun. At slaughter, 13 weeks after challenge, an average of 25% of the challenge dose was recovered from each liver. This percentage recovery is similar to that obtained with other known methods. The new bolus, however, offers improved handling qualities. In addition, the bolus also has potential for improving a number of other techniques including those for the administration of other parasites, compounds or chemotherapeutic agents.

A successful peritoneal transplant of 5 Cardiofilaria nilesi adult worms, 3♀ Symbo; and 2♂ Symbo; is reported. Microfilaraemia in the recipient chicken was found on the 6th day after the transplant. The count rose to 4/20 c.mm., from 1/20 c.mm. in 19 days after the transplant. The highest count recorded was 14/20 c.mm. The microfilaraemia persisted for 63 days.

Experiments were carried out to obtain additional data concerning the role of IgM antibodies, specific for the cuticular surface of the microfilariae (mf) of A. viteae, in clearing microfilaraemia from high-and low-responder mice infected by transplanted adult worms. Although BALB/c mice, which sustain a chronic microfilaraemia, produced IgM mf surface-specific antibodies, the binding to target mf was weak when compared to that of antibodies from the serum of the resistant C57BL/10 mice. Furthermore, antibodies from BALB/c mice were not as efficient as those from C57BL/10 mice in promoting the adherence of immune or control leukocytes to mf in vitro. Evidence is provided to show that mf shed surface bound antibody. Although the results do not establish conclusively the mechanism underlying the contrasting response phenotypes of C57BL/10 and BALB/c mice, they provide support for the involvement of antibody in controlling microfilaraemia and suggest that quantitative and qualitative differences in the amount and affinity of IgM antibody specific for the mf surface, together with the natural tendency of the mf to shed surface bound antibody at 37°C. may combine to allow the former strain to clear microfilaraemia efficiently whilst the latter sustains a chronic infection.

RAPD technique was used to differentiate individuals of Anisakis simplex obtained from Merluccius merluccius, Phycis blennoides, Conger conger and Lepidorhombus boscii, from the North Atlantic Ocean. The amplification patterns of the host DNA controls were markedly different from those obtained for the parasitic material. No variation within the same host was detected. The amplification patterns for larvae obtained from fish of the same genus were somewhat different. The amplification patterns of A. simplex isolates from M. merluccius, P. blennoides, C. conger and L. boscii, were different. These results suggest the possible existence of two populations with a considerable high genetic variability and a different adaptation to different host species.

In order to characterize GATA transcription factors in Echinococcus granulosus, a PCR-based cloning strategy was developed. Degenerate oligonucleotides were designed for the most conserved sequence in GATA proteins that include 20 amino acids of the zinc domain. A 60 bp fragment was isolated that had high homology among this sequence and those reported in other species. An analogous sequence was obtained by performing the same procedure with DNA from the free living platyhelminth Dugesia tigrina. High stringency Southern blotting experiments confirmed the presence of this sequence in the parasite genome.

An attempt was made to identify the human hookworm involved in failed-treatment cases using abnormal hosts and scanning electron microscopy. Thirty-seven, 2 to 6 month old Chinese hamsters (Cricetulus griseus) from a closed, outbred, conventional colony, were each given between 20 and 120 filariform larvae per os. The larvae were cultured from faeces from mebendazole (Vermox®) 500 mg single-dose, failed-treatment cases living in the lowveld farming area of the Transvaal Province, South Africa. About 60 to 78 days after inoculation, the animals were killed and adult worms were removed from their small intestines. Eleven (30%) of the 37 hamsters harboured a total of 31 adult worms (19 males and 12 females), while 26 hamsters were refractory to infection. The greatest number of worms recovered from a single animal was six. A total of 27 worms (17 males and 10 females) were subjected to examination by scanning electron microscopy. Micrographs showed male and female worms to be morphologically all of the Necator americanus species, as identified by a pair of ventral and dorsal cutting plates, a dorsal tooth and the fused terminus of spicules in the male bursa. The transverse cuticular striations were distinct and smooth. Several points of interest arose from the results of this study and are discussed.

It was observed in laboratory experiments that the lethal action of dilute solutions of calcium cyanamide on the larvae of Heterodera schachtii was more rapid when these solutions were rendered slightly acid. This might be due to the rate of decomposition of calcium cyanamide in aqueous solutions of varying þH. The changes which cyanamide undergoes in acid and alkaline media have been described by Crowther & Richardson (1932). Solutions of commercial calcium cyanamide are moderately alkaline because of their lime content, and in this alkalinity any free cyanamide which is formed tends to polymerise to dicyanodiamide. Experiments with solutions of dicyanodiamide showed that this substance has very little toxic action on H. schachtii larvae. In acid solution, on the other hand, cyanamide is hydrolysed to urea. This substance becomes toxic when it decomposes to ammonia, but in the slightly acid solutions used the change would be a slow process. It is probable, therefore, that the degree of toxicity of calcium cyanamide solutions would be greatest where the cyanamide radicle could be retained unchanged for the longest period.

One of the peculiarities of the eelworm Heterodera schachtii which makes it a very difficult parasite to control is the length of time it can survive in a dormant condition in the soil. In this state the embryonated eggs are protected by the resistant cyst wall, and, in the case of the potato strain of the eelworm, the larvae only hatch in large numbers in the presence of the host plant. On account of this property, land infected with the parasite remains infected even though the host plant is not grown. It is however well known that if “potato sick” land is rested from potatoes for a few years it is then sometimes possible to grow a potato crop giving a fairly good yield and showing little or no sign of sickness in the overground parts. In these cases, however, it is often found that the roots of the plants are heavily infested with eelworm. These and other observations have led to suggestions that other factors may be associated with H. schachtii in giving rise to the condition known as “potato-sickness.” Such factors may be due wholly or in part to soil conditions, climate, fungal attack or the time of attack by the eelworm. In some cases more than one factor may operate in addition to the nematode, and in different cases it is probable that different factors come into play.

1. Skrjabinotaenia cricelomydis n.sp. is described from 18 specimens taken from Cricetomys gambianus Waterhouse, near Ibadan, Nigeria.

2. Apolytic proglottides are described and also some details of development of the eggs.

3. Details of the anatomy are given and their significance in deciding the relationship with other genera and species is discussed.

4. The regrouping of a number of species into the genus Skrjabinotaenia is proposed.

5. The diagnostic features of the genera Catenotaenia and Skrjabinotaenia are restated.

Echinococcus granulosus sensu stricto is regarded to have the highest zoonotic potential of all Echinococcus taxa. Globally, human infection due to this species constitutes over 88.44% of the total cystic echinococcosis (CE) burden. Here, we report a CE infection in a Nigerian camel caused by E. granulosus G1 genotype. To the best of our knowledge, this report is the first encounter of the G1 genotype in the West Africa sub-region where the G6 genotype is reportedly prevalent, suggesting that the epidemiology of this highly zoonotic group could have a wider host range and distribution in the sub-region, and emphasizes the need for further investigation into the genetic diversity of Echinococcus spp. in Nigeria and across the sub-region.

This paper presents a new haploporid digenean that expands the number of species of Saccoccoelioides to 27. The new species, Saccocoelioides kirchneri n. sp. was collected from the intestine of Cnesterodon decemmaculatus (Poeciliidae: Cyprinodontiformes) from Lago del Bosque, La Plata, Argentina. The new species possesses the diagnostic features for Saccocoelioides: a sac like ceca; the vitellarium confined in two irregular groups of follicles distributed between the ventral sucker and the anterior margin of the testis; and a uterus confined largely in the hind-body, but encroaching into the range of the ventral sucker. The new species is differentiated from the 26 congeners by the body size, pharynx size, ventral sucker size, posterior extent of ceca, posterior extent of uterus and egg size. S. kirchneri n. sp. also is supported by the molecular analysis.