1. Between November 1936 and February 1937, ninety-six rabbits were examined, whilst between August 1937 and July 1938, 446 rabbits were examined for cestode parasites. The rabbits were obtained from the same area.

2. The rabbits were infected with the following cestodes to the extent given, for the two periods respectively:

3. Two species of the genus Hymenolepis are recorded for the first time from the rabbit, and they are briefly described.

4. The seasonal fluctuations in the incidence of the above cestodes are discussed.

5. The span of life of both Cittotaenia pectinata and C. denticulata is seen to be not greater than 10 months, and evidence is given to show that the intermediate host of C. denticulata is available between April and December, and that of C. pectinata from August to April.

6. Evidence of host and age resistance is demonstrated in Cysticercus pisiformis.

Trophically transmitted parasites must trade-off own growth on one hand and energy drain from the intermediate host on the other hand, since killing the host before transmission to the next host is a dead end for both parasites and hosts. This challenge becomes especially intriguing when multiple parasites find themselves within the same individual host. The tapeworm Schistocephalus solidus may gain more than 98% of its final body mass within few months infecting its three-spined stickleback (Gasterosteus aculeatus) intermediate host. During these months the tapeworms may achieve a mass even larger than its host. We studied virulence of single and multiple infections of S. solidus, by comparing body condition of wild stickleback hosts in two perennial stickleback populations located at high latitudes, and each population was studied in two different years. Our results demonstrated multiple compared with single infections to be a highly significant predictor of the condition of stickleback hosts, with multiple-infected hosts having relatively higher body condition. However, this applied only after adjusting for parasite mass, which was another significant predictor for host condition. Thus, our results suggested that, at a given parasite mass, S. solidus was more harmful towards their host's body condition in single compared with multiple infections.

Eukaryotic 5S rRNA, synthesized by RNA polymerase III (Pol III), is an essential component of the large ribosomal subunit. Most organisms contain hundreds of 5S rRNA genes organized into tandem arrays. However, the genome of the protozoan parasite Leishmania major contains only 11 copies of the 5S rRNA gene, which are interspersed and associated with other Pol III-transcribed genes. Here we report that, in general, the number and order of the 5S rRNA genes is conserved between different species of Leishmania. While in most organisms 5S rRNA genes are normally associated with the nucleolus, combined fluorescent in situ hybridization and indirect immunofluorescence experiments showed that 5S rRNA genes are mainly located at the nuclear periphery in L. major. Similarly, the tandemly repeated 5S rRNA genes in Trypanosoma cruzi are dispersed throughout the nucleus. In contrast, 5S rRNA transcripts in L. major were localized within the nucleolus, and scattered throughout the cytoplasm, where mature ribosomes are located. Unlike other rRNA species, stable antisense RNA complementary to 5S rRNA is not detected in L. major.

Sarcocystis neurona is an apicomplexan parasite that causes severe neurological disease in horses and marine mammals. The Apicomplexa are all obligate intracellular parasites that lack purine biosynthesis pathways and rely on the host cell for their purine requirements. Hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT) and adenosine kinase (AK) are key enzymes that function in two complementary purine salvage pathways in apicomplexans. Bioinformatic searches of the S. neurona genome revealed genes encoding HXGPRT, AK and all of the major purine salvage enzymes except purine nucleoside phosphorylase. Wild-type S. neurona were able to grow in the presence of mycophenolic acid (MPA) but were inhibited by 6-thioxanthine (6-TX), suggesting that the pathways involving either HXGPRT or AK are functional in this parasite. Prior work with Toxoplasma gondii demonstrated the utility of HXGPRT as a positive-negative selection marker. To enable the use of HXGPRT in S. neurona, the SnHXGPRT gene sequence was determined and a gene-targeting plasmid was transfected into S. neurona. SnHXGPRT-deficient mutants were selected with 6-TX, and single-cell clones were obtained. These Sn∆HXG parasites were susceptible to MPA and could be complemented using the heterologous T. gondii HXGPRT gene. In summary, S. neurona possesses both purine salvage pathways described in apicomplexans, thus allowing the use of HXGPRT as a positive-negative drug selection marker in this parasite.

Nosema leptinotarsae Lipa, 1968 is a microsporidian pathogen of the Colorado potato beetle, Leptinotarsa decemlineata Say. (Coleoptera: Chrysomelidae). To determine the phylogenetic status of N. leptinotarsae, the 16S SSU rRNA gene was sequenced (GenBank Accession No. MN841279) and compared phylogenetically against 21 microsporidian 16S SSU rRNA sequences using neighbour-joining and maximum-parsimony methods. The per cent identities of the N. leptinotarsae and other members of the Nosema–Vairimorpha clade ranged from 78.1 to 98.5%. Pairwise phylogenetic distances between the N. leptinotarsae and other species ranged from 0.009 to 0.320. Phylogenetic analysis shows clearly that N. leptinotarsae is a member of the Vairimorpha clade rather than the Nosema clade. The sequence divergence and morphological traits separated the N. leptinotarsae from other species in the Vairimorpha complex. As a result, a new assignment of Vairimorpha leptinotarsae comb. nov. has been implemented for N. leptinotarsae according to the phylogenetical positioning in the present study.

We are developing Tetrahymena thermophila as a delivery system for recombinant vaccines against parasitic protozoa, including the common fish parasite, Ichthyophthirius multifiliis. T. thermophila cell lines expressing I. multifiliis genes under the control of a cadmium-inducible metallothionein gene promoter conferred strong protection against a lethal parasite challenge when administered parenterally to naïve fish. Nevertheless, given that heavy metals can be toxic to parasites, a question arose as to whether protection resulted from Cd residues carried over with the vaccine, rather than acquired immunity per se. To address this issue, we examined the sensitivity of I. multifiliis to Cd in vitro and determined Cd concentrations in different host tissues following i.p. injection of juvenile channel catfish with the recombinant vaccine. We found that CdCl2 at concentrations [ges ]50 ppb were lethal to I. multifiliis theronts in vitro. Furthermore, Cd concentrations were clearly elevated in fish tissues and reached levels equivalent to 74 ng/g wet weight (74 ppb) in the skin within 14 days of injection with recombinant T. thermophila. Nevertheless, fish injected with non-transformed Tetrahymena grown in the presence or absence of CdCl2 showed no significant difference in either relative survival or parasite load following direct challenge with I. multifiliis.

Electrophysiological techniques were used to obtain recordings of extracellular electrical activity from the anterior end of live adult females of Brugia pahangi. Stimulation with 100mM, 10mM and 1mM acetylcholine resulted in an increase in spike activity which was concentration dependent, whereas stimulation with phosphate-buffered saline and 0·1mM acetylcholine gave no increase in activity. The delay in response was not concentration dependent. The action of possible host cues was investigated. Stimulation with heat-inactivated foetal calf serum (IFCS) and 10mM glutathione gave an increase in spike activity but exposure to 5mg/dl haemoglobin elicited no response. The response to IFCS was found to be suppressed completely by pre-incubation for 30min in ivermectin.

In the mouse pinworm, Aspiculuris tetraptera, the basic features of the process of osmotic regulation is similar to the process in other nematodes such as Parascaris equorum, Rhabditis terrestris and Hammerschmidtiella diesingi. The ability to osmoregulate is, however, utilized more effectively in a hypertonic than in a hypotonic solution.

The body fluid is isotonic with 35 % sea water. The relative accuracy of this value is confirmed by direct measurements of the depression of freezing point of the body fluid. This is approximately 0.68–0.69 °C, which is approximately 0.12 % NaCl, which is higher than the value for Ascaris (= 0.655 °C).

My thanks are due to Dr D. L. Lee for helpful discussions on some aspects of this study.

A cDNA clone codifying ribosomal protein L25 was isolated from a Leishmania braziliensis cDNA gene library. The alignment of the amino acid sequence deduced from this gene with other proteins revealed that this protein is related to the L23/25 ribosomal protein family. This is so because this protein shows, in its C-terminal end, the rRNA binding domains characteristic of these proteins and at the N-terminal end the NLS sequence necessary for its entry into the nucleus. Southern blot analysis showed 2 copies of gene L25 per genome arranged in tandem position and pointing in the same direction. Northern blot analysis showed that this gene is transcribed in 2 mRNAs when parasite promastigotes are in the logarithmic phase. In order to analyse the antigenic properties of L. braziliensis RPL25, it was purified as a recombinant protein and ELISA-tested against cutaneous, mucocutaneous and Chagasic sera. The results indicate that the recombinant RPL25 from L. braziliensis presents a non-specific reaction that disqualifies it for the diagnosis of cutaneous leishmaniasis. In contrast, some of the synthetic peptides derived from its sequence may serve as promising tools for the diagnosis of this disease.

The genus Diaphanocephalus was erected by Diesing in 1851 to contain certain species included in Rudolphi's Synopsis in the old genus Strongylus. The species in question were Strongylus galeatus Rud., 1819, re-named Diaphanocephalus strongyloides by Diesing, and subsequently indicated as the type-species of the genus; S. costatus; and possible S. viperae Rud., which Diesing listed as a species inquirenda. In deciding upon the necessity for the new genus Diesing seems to have been influenced largely by the characters of the head. His diagnosis shows that he considered the supporting rays of the buccal capsule to be four only in number, regarding two of these as divided each into two distinct processes. Molin (1861) gave an emended diagnosis of Diesing's genus and proposed the new genus Kalicephalus for certain other strongyle parasites in reptiles. It has already been pointed out (Baylis and Daubney) that the generic characters used by Molin are unreliable and that Railliet and Henry (1909) were justified in abolishing Kalicephalus in favour of the older genus, Diaphanocephalus. Recently, Skrjabin (1916) has given a diagnosis of the genus. Through the kindness of Dr H. A. Baylis the writer has been able to examine specimens in the collection of the British Museum (Natural History), and the Wellcome Bureau of Scientific Research. The material examined includes four specimens of the genus Diaphanocephalus.

The major surface immunodominant antigen (P30) of Toxoplasma gondii was purified by two methods (i) SDS–PAGE and (ii) immunoaffinity chromatography. The secondary elements within this protein were assessed by circular dichroism and spectra obtained were compared to those proposed by Manavalan & Johnson (1983). The results allowed us to determine an all β protein status for this antigen. This experimental result was in agreement with the predicted secondary structures deduced from the P30 primary sequence. Modifications in conformation according to pH and temperature were recorded without any change in immunoactivity. The epitope, which was always recognized by a monoclonal antibody against P30, could be a linear epitope.

The object of this paper is to draw attention to certain grave sources of error underlying the present mode of differentiating Anoplura and more especially species of the sub-order Siphunculata. I am unable to say if the criticisms herewith advanced apply equally to the methods employed in differentiating members of the sub-order Mallophaga, because I am not familiar with the latter group, but the two sub-orders mentioned are in many respects so closely allied that it appears difficult to avoid the suspicion that the considerations herein contained may apply equally in both cases.

Mycoses of the gypsy moth, Lymantria dispar (L.) by two species of entomogenous fungi, Metarrhizium anisopliae (Metschnikoff) Sorokin and Paecilomyces fumoso-roseus (Wize) Brown and Smith were experimentally established. Infected larvae revealed complete disintegration of viscera within 95 h post-inoculation with M. anisopliae and within 120 h with P. fumoso-roseus. Avian safety studies confirmed the tolerance of large dosages of spore suspensions of both species. Some body weight loss was recorded but all other indicators were not significantly different from the control birds.

A list of the genera of the family Caryophyllaeidae known from India is given. Crescentovitus biloculus gen.nov., sp.nov. from the coelom of the siluroid fish, Heteropneustis fossilis, is described and its systematic position discussed. An up-to-date key to the genera of the subfamily Lytocestinae is included.

I desire to express my deep gratitude to Professor M. A. Moghe for his helpful criticism in the preparation of this paper, and to Mr N. A. Shastri, Principal M.M. College of Science, Nagpur, for the kind co-operation extended to me. My thanks are due to Mr S. C. Theophilus, Head of Botany Department, Hislop College, Nagpur for helping me in various ways.

Intra-erythrocytic stages of malaria parasites can alter the surface of their host cells and release toxins which induce the production of cytokines, which in turn can up- or down-regulate the expression of adhesion receptors on the surface of microvascular endothelial cells. New adhesion receptors on endothelial cells provide the parasite with increased chances of survival despite an increasing level of host immunity. In order to take advantage of these new opportunities for survival, the parasite itself needs to make best use of its considerable ability to vary its surface antigens and adherent molecules. The paper describes the various players in this survival game and articulates a working hypothesis to explain how it may all fit together.

Oncomelania nosophora (Gastropoda: Pomatiopsidae) is the intermediate host of Schistosoma japonicum in Japan. Although most of the snails were eliminated during the 20th century, they are still found in two areas in Japan. One area is in the Kofu Basin, including Nirasaki City, in Yamanashi Prefecture. The other is the Obitsu River Basin in Kisarazu City, Chiba Prefecture. Snails collected in Nirasaki and Kisarazu were exposed to 3 geographical strains of S. japonicum originating from Japan, China, and the Philippines. Both isolates of O. nosophora showed high susceptibility to the Japanese strain of S. japonicum (74·0%–82·2% for the Nirasaki isolate and 58·0%–56·0% for the Kisarazu isolate) and low susceptibility to the Chinese strain (0·0%–1·3% and 1·4%–7·9% respectively). In contrast, the susceptibility of the snails to the Philippine strain was significantly different (P<0·01) between the isolates (3·3%–6·6% for the Nirasaki isolate and 31·9%–75·9% for the Kisarazu isolate). To examine the differences in infectivity in detail, we conducted histological observations of snails exposed to the Philippine strain at 3 h, 1, 3, and 15 days after miracidial exposure. We found differences in the development of the parasite between the isolates of snails from early after exposure.

Glossina pallidipes Austen have been successfully reared in the adult stage in the laboratory. The flies fed readily on the belly of guinea-pigs, and the latter did not seem to be worried by the attentions of the flies.

Immediately after adult emergence the flies were kept individually in tubes at four different temperatures (20°, 22°, 24° and 28 °C), at a relative humidity of 40 ± 5%, and they were offered guinea-pigs daily. Fifty per cent of the flies reared at temperatures of 20° and 28 °C died during the first 5 days, 50% of those reared at 24 °C died during the first 10 days, and 50% of those reared at 22 °C lived for more than 50 days.

Few flies reared at 20° or 28 °C fed at all, and those that did had only four or five meals in their life-time; most of the flies reared at 22° or 24 °C did feed, but those reared at 24° took only a few meals. Most of these meals were ‘full’ ones, but a considerable proportion of meals taken by flies reared at 20 °C were ‘partial’ ones. The interval between meals was usually 3 or 4 days; but the time taken between adult emergence and time of first meal was shorter, except for the flies reared at 20 °C.

When tsetse flies are reared at 22 °C the first six blood-meals are smaller than subsequent ones. The size of the meals and the rate of body growth do not seem to be related to the gonadotrophic cycles. On the other hand, the terminal phase of growth in both sexes shows a steady increase in body weight.

The factors that might influence feeding, growth, and the longevity of adult tsetse flies are discussed.

Thanks are extended to Mr J. M. B. Harley of the East African Trypanosomiasis Research Organization for sending me tsetse pupae, to Miss Caroline Walter and Mr John Boro for technical assistance, and to the Rockefeller Foundation for a research grant.

1. There can be no doubt that Ankylostomiasis has obtained a very firm hold in the coastal districts of North Queensland, and every effort should be made to arrest its spread, and if possible eradicate it.

2. Experience in other parts of the world, notably the United States and Germany, has demonstrated the great difficulty of coping with the disease, even with the most energetic of preventive measures.

3. The disease gives rise to much sickness and inefficiency especially amongst children, and although competent medical treatment is usually efficacious the most satisfactory and permanent results are to be expected in the direction of prevention.

4. The chief preventive measures are individual cleanliness and thorough and rapid destruction of night soil and deposits of faecal material.

5. In the presence of a properly organised sanitary system, intelligently utilised, there should be little or no risk of infection. It is the promiscuous distribution of excreta that is the chief source of the spread of infection.

6. If the indiscriminate deposit of faecal material be not prevented, the matter resolves itself into a problem of considerable difficulty.

7. The more commonly used disinfectants, if thoroughly employed, would render the faecal material comparatively innocuous, but their use is not less laborious than the proper removal of the faecal material and its disposal in properly constructed receptacles.

8. Common table salt has a decidedly injurious effect upon the hook-worm eggs but it requires to be brought into very intimate contact with the infected material. The process of merely sprinkling the surface is almost futile unless the salt be used in enormous quantities.

9. When mixed with faecal matter, sand promotes the development of hook-worm larvae, but when used as a covering of a certain depth it arrests development.

10. Exposure to direct sunlight of sufficient intensity kills hook worm eggs and larvae very rapidly.

An unusual new species of bopyrid parasite is described: unlike other bopyrids, the new species is attached on the dorsal surface of the abdomen of its host, a pontoniinid shrimp Periclimenes hertwigi Balss. A new genus has been erected for the parasite, Filophryxus dorsalis. It is distinguished from other genera by the presence of pereiopods I and II on the longer side of the body and pereiopods I, IV-VI on the shorter side, by three pairs of uniramous pleopods and no uropods on the abdomen. The specimen was collected off the Coast of Queensland, Australia, at a depth of 275 m.