1. The occurrence of Adelina cryptocerci in the host, Cryptocercus punctulatus, and its probable means of natural transmission are discussed.

2. Artificial infection experiments were carried out and furnished material for determination of succession of stages in the life cycle of the organism. The cycle is briefly as follows:

(a) Mature cysts are ingested by the hosts with tissues of infected roaches. Sporozoites enter the host's tissues by passing through the midgut wall.

(b) The first schizogony, in which merozoites are produced, ocurs in the fat-bodies between the sixteenth and twenty-fifth days after ingestion of cysts.

(c) In the second schizogonial generation two types of schizogony produce merozoites and gametoblasts, respectively, between the twenty-fifth and twenty-ninth days following infection. There is evidence that both male and female gametoblasts are formed from a single schizont.

(d) Male and female gametoblasts become associated during the growth period of the latter. When fully grown, they are surrounded by a membrane, the gametocyst. The male gametoblast undergoes 2 divisions, forming 4 microgametes, of which 1 fertilizes the macrogamete and the other 3 lie unused between the gametocyst and the first oocyst, which is formed shortly after fertilization. A second oocyst is formed before the first division of the synkaryon.

(e) By repeated divisions of the synkaryon a multinucleate sporont is formed. This divides into uninucleate sporoblasts. Each sporoblast divides once, forming a sporocyst containing 2 sporozoites. Mature cysts occurred in experimentally infected roaches from 40 days onwards.

3. The stages in the life cycle are described in detail.

4. Evidence for zygotic meiosis in Adelina cryptocerci is presented.

5. The effect of the parasite on the host is discussed.

This investigation has been made at the suggestion of Dr Harold Kirby, Jr., and under his direction and that of Dr C. A. Kofoid. I wish to express here my grateful appreciation to both for their interest and many valuable suggestions and criticisms.

Histomonas meleagridis is a protozoan parasite of various galliform birds causing a type of enterohepatitis termed histomonosis or ‘blackhead disease’. Due to the ban of chemotherapeutic substances and an increase in free-range poultry production, histomonosis is currently a re-emerging disease. So far limited molecular knowledge is available. In the present work, mRNAs coding for antigenic proteins of H. meleagridis were identified. For this purpose, a cDNA expression library was constructed from a mono-eukaryotic culture of H. meleagridis. The library was screened with polyclonal rabbit serum raised against purified H. meleagridis trophozoites. Polyclonal rabbit serum specifically recognized the same major H. meleagridis antigens as chicken and turkey sera originating from animal trials, but displayed a significantly lower bacteria-dependent background signal. After 2 rounds of screening, a total of 95 positive clones were sequenced. Bioinformatics analyses were performed on nucleotide and deduced amino acid sequences, identifying 37 unique clones. Based on the homology to other protozoan parasites, mostly Trichomonas vaginalis, the clones were grouped according to functional aspects: structural proteins, possible surface proteins, oxygen reducing proteins, ribosomal proteins, protein kinases and various other intracellular proteins.

To study the infection dynamics of metacercariae of the digenean Cryptocotyle lingua, wild living Atlantic cod, Gadus morhua, were caged for 18 months close to the shore. Here they were exposed to naturally occurring transmission stages of the parasite. First, both the abundance and the variance to mean ratio of metacercariae increased, but during the second half of the study the abundance levelled out, and the variance to mean ratio showed a significant decrease. Host mortality was negligible throughout the study. Based on the relationship between pigment spots and metacercariae observed by skin digestion, there was no indication of density-dependent parasite mortality. We conclude that the infrapopulations of metacercariae on the caged cod probably were regulated by density-dependent host responses acting against the cercariae.

The community structure of monogeneans on the gills of a catfish Pimelodus albicans, in the Río de la Plata, was studied and compared with previous findings on P. maculatus. Six Monogenea species belonging to 3 genera were found: Demidospermus majusculus Kritsky & Gutiérrez, 1998; Demidospermus armostus Kritsky & Gutiérrez, 1998; Demidospermus idolus Kritsky & Gutiérrez, 1998; Demidospermus bidiverticulatum (Suriano & Incorvaia, 1995) Kritsky & Gutiérrez, 1998; Scleroductus yuncensi Jara & Cone, 1989; and Unibarra paranoplatensis Suriano & Incorvaia, 1995. The relationships between selected host and helminth variables; the interactions between the worms and the patterns obtained from the species abundance were analysed employing appropriate statistical methodology. The results obtained revealed the following common patterns within the monogenean communities of P. maculatus and P. albicans: (a) most monogenean species belonged to the genus Demidospermus; (b) S. yuncensi was a secondary species in both communities; (c) 1 of the 3 species common to both hosts was a core species (D. bidiverticulatum); (d) the selected variables of both hosts (weight and length) were not related to the number of monogeneans or species richness; (e) the dominant species in both communities showed the highest proportion of monogeneans in more than 40 % of the infracommunities; (f ) in both communities the dominant species accounted for 40–80 % of the total number of monogeneans at component community level; (g) the number of worms correlates positively with the species richness; (h) few cases of interaction among species were found; (i) a high degree of order exists among the infracommunities compared. Finally, the proportion of common species and the phylogenetic and ecological resemblances between the hosts, P. maculatus and P. albicans support a hypothesis of co-speciation among monogeneans and pimelodids in Río de la Plata. It seems improbable that these parasite communities are recent species assemblages formed by chance. The phylogenetic resemblance of the host–monogeneans system in Río de la Plata suggests that there is a single community pattern that can be observed in congeneric and sympatric hosts.

Trichinella spiralis (T.spiralis) muscle-larva (ML) excretory–secretory proteins (ESPs) contain antitumour-active substances. ESPs have been shown to inhibit tumour growth. To explore the effects of these proteins on small cell lung cancer cells and the possible mechanisms of their antineoplastic action, H446 SCLC cells were co-cultured with different concentrations of T. spiralis ML ESPs for 12, 24 and 48 h. Our results showed that T. spiralis ML ESPs significantly inhibited H446 cell proliferation, which was dose-and time-dependent. The results of flow cytometry testing indicate a clear apoptosis trend in H446 cells co-cultured with ESPs for 24 h. Reverse transcription polymerase chain reaction and Western blotting results showed increased expression of pro-apoptosis genes Bax, Cyt-C, Apaf-1, caspase-9 and caspase-3, compared with the negative control group, and decreased the expression of anti-apoptosis genes Bcl-2 and Livin. Our results suggest that T. spiralis ML ESPs can induce apoptosis in H446 cells through a mitochondrial pathway, which may be a mechanism of antineoplastic action in T. spiralis ML ESPs.

The economic importance of Trematode infections of mammals has been, and is still, felt even in this country. Epidemic liver-rot in cattle and sheep is probably one of the most serious epidemic diseases with which veterinarians have had to deal and its ravages have, on occasion, been severe. Bilharziasis in cattle is possibly of considerably less importance and, so far as I am aware, has never become endemic in this country. As pathogenic agents the Amphistomes are of third-rate importance.

Presently, no effective anthelmintic drugs have been used to treat and control paramphistomosis, a severe disease of ruminants. In this study, we have investigated the in vitro anthelmintic effect of the leaves of Terminalia catappa L. crude extract (TcCE) and albendazole (ABZ) on adult Fischoederius cobboldi after incubating the flukes in RPMI-1640 medium containing the TcCE at various doses and times. The TcCE-treated flukes at all dosages exhibited rapid decrease of motility, and the relative motility (RM) values were decreased sharply from start to 3 h. Worms were killed after 6 and 12 h of treatment with 1000, 1500 and 2000 µg mL−1 as well as 500 µg mL−1 of TcCE, respectively. By light microscopy examination, the flukes exhibited the earliest alteration in a limited area of the tegument. At scanning electron microscopy level, the flukes’ tegument showed similar sequence of morphological alterations after treatment with ABZ and TcCE that consisted of swelling of ridges and folds, followed by blebbing and rupturing of the blebs, leading to the erosion, lesion and disruption of the tegument. Hence, in vivo studies should be performed to examine whether the TcCE may serve as a powerful anthelmintic drug for treatment of paramphistomosis.

An experiment was conducted to examine, under laboratory conditions, the pathophysiology of chronic ovine haemonchosis. In the present study, groups of Merino and Scottish Blackface lambs were maintained on a low plane of nutrition and infected with 50 Haemonchus contortus larvae/kg live weight. The parasitized lambs along with respective breed controls were examined over a 27-week period. In addition to the body weight, haematological and parasitological parameters, erythrokinetic, metabolic, digestibility and nitrogen balance studies were conducted in the early stages of the infection. The results demonstrated that a low level of infection with H. contortus in lambs on a poor plane of nutrition caused the development of a normochromic normocytic anaemia which was associated with a modest but significant increase in abomasal blood loss and slightly elevated erythropoiesis in both breeds relative to the controls. The level of anaemia, hypoproteinaemia and pathophysiological changes were more marked in the Merino lambs and they also had higher faecal egg counts than the Blackface lambs.

The search for nested subset patterns has become a powerful tool for understanding the processes shaping parasite communities. Here, we re-examine the results of past studies on nestedness in parasite communities, to assess how sensitive they are to the analytical method used. Using the metric N and the null model RANDOM1, the first method available to study nested patterns, early studies concluded that nestedness was infrequent in parasite communities. In contrast later studies, using instead the metric T and the nestedness temperature calculator (NTC), found that nested subset patterns were very common in parasite communities. Recently, a new algorithm, the binary matrix nestedness temperature calculator (BINMATNEST), has been proposed to quantify nestedness. Using data on 31 helminth communities of fish hosts, we show that applying the NTC yields consistently more significant nested patterns than when N and RANDOM1 are used on the same data. The use of BINMATNEST produced results that depend on the choice of the null model. To provide a benchmark, a straightforward comparison between the observed frequencies of co-occurrences of species with those expected from their prevalence under random assembly was also made for each community. This test indicates that random structure occurs in practically all communities, even those where one of the nestedness analyses found a significant pattern. We demonstrate that the probability of finding a nested pattern in a parasite community depends entirely on the metric and null model chosen for analysis.

Human population increases, with greater food demands, have resulted in a rapid evolution of livestock food systems, leading to changes in land and water use. The scale of global livestock systems mean that changes in animal health status, particularly in parasite levels, have impacts that go beyond farm and sector levels. To quantify the true impact of parasites in livestock, frameworks that look at both resources and services valued in markets and those that have no true market value are required. Mitigating the effects of parasitic disease in livestock will not only increase productivity, but also improve animal welfare and human health, whilst reducing the environmental burden of livestock production systems. To measure these potential benefits, a One Health approach is needed. This paper discusses the types of methods and the data collection tools needed for a more holistic perspective and provides a framework with its application to coccidiosis in poultry. To build a body of knowledge that allows the ranking of parasite diseases in a wider animal health setting, such One Health frameworks need to be applied more frequently and with rigour. The outcome will improve the allocation of resources to critical constraints on parasite management.

Studies investigating parasite diversity have shown substantial geographical variation in parasite species richness. Most of these studies have, however, adopted a local scale approach, which may have masked more general patterns. Recent studies have shown that ectoparasite species richness in mammals seems highly repeatable among populations of the same mammal host species at a regional scale. In light of these new studies we have reinvestigated the case of parasitic helminths by using a large data set of parasites from mammal populations in 3 continents. We collected homogeneous data and demonstrated that helminth species richness is highly repeatable in mammals at a regional scale. Our results highlight the strong influence of host identity in parasite species richness and call for future research linking helminth species found in a given host to its ecology, immune defences and potential energetic trade-offs.

A 482 base pair gene fragment from samples of amoebae E. histolytica and E. dispar was amplified by PCR. The amplification products of fragments from the 2 species of amoebae presented differences in mobility in non-denaturing polyacrylamide gel, probably due to sequence-dependent conformational alterations in the DNA fragments. The method described here permits E. histolytica and E. dispar to be distinguished with greater sensitivity and rapidity.

The failure of Boophilus microplus to be cleansed of Babesia bigemina while the ticks were growing on non-bovine hosts, as well as the infection of the non-bovine hosts, was demonstrated in experiments in which infected ticks were released on a number of sheep, a goat and a horse.

Seven of ten batches of ticks, collected from six non-bovine hosts, retained their babesia-infection.

Blood subinoculated into cattle from seven of nine sheep and from the horse showed that these animals carried B. bigemina whilst the ticks were feeding on them. This suggested that ticks may have become reinfected from the non-bovine hosts, a possibility supported by the finding of B. bigemina in blood smears from two of the sheep.

This work was performed at the Animal Research Institute, Yeerongpilly, and in the Department of Parasitology, University of Queensland, and supported by funds from both organizations. I am indebted to Mr G. D. Daly for technical assistance, to Professor J. F. A. Sprent and Dr H. M. D. Hoyte for their interest and help.

Oocysts of Eimeria maxima inoculated into guinea fowl do not develop. Infection occurs when intestinal mucosa or liver tissue from guinea fowl given E. maxima is transferred to susceptible chickens. By transferring material at different times after inoculation, it was shown that most of the stages are lost between 6 and 12 h and few, if any, survive to 48 h.

Sporozoites of E. tenella had low infectivity after 48 h contact in vitro with peritoneal macrophages from guinea fowls and turkeys. Sporozoites of E. grenieri from the guinea fowl appeared to be destroyed within macrophages taken from chickens.

Coccidiosis occurs sporadically in lambs at about 6 weeks of age when oocyst output is very high in healthy as well as in diseased lambs. These experiments were designed to throw light on the source of infection and to correlate oocyst output in lambs and ewes with performance in lambs. In two experiments, one indoors on deep litter the other in outdoor paddocks, oocyst output (of different coccidial species), body weight and clinical state of lambs were recorded weekly. Oocyst output in ewes was also recorded, starting 1–4 weeks before lambing. Monensin was included in the concentrates of ewes and/or lambs, up to lambing or before and after lambing. No periparturient rise was detected in the oocyst output of ewes. Monensin drastically reduced oocyst output in animals receiving it. Oocyst output in lambs appeared to be little affected by the output of ewes around the lambing period, but was reduced if the ewes' output was kept low after lambing. Lambs receiving monensin tended to produce drier faeces but their weight gain was not significantly greater than that of controls. Eimeria crandallis was the predominant species in the lambs, followed by E. ovinoidalis and E. ovina.

In an earlier paper (1933) the writer drew attention to the inadequacy of the only existing description of Uncinaria lucasi, given, under the name of Uncinaria sp., by Stiles & Hassall (1899). Through the kindness of Dr E. C. Dougherty, it has now been possible to examine specimens of an Uncinaria from the type-host of U. lucasi (the Alaskan fur-seal, Callorhinus alascanus). These were collected by Dr V. B. Scheffer, of the United States Fish and Wildlife Service, from the small intestine of a furseal pup at Polovina, St Paul Island (Pribylov group), in the Bering Sea in July 1945. There seems to be no reasonable doubt that they are of the same species as those originally described by Stiles & Hassall, the principal evidence being the identity of the host and locality, and the length of the spicules of the male worms. A new description is therefore presented, which it is hoped will place the species on a more satisfactory footing.

Strongyloides venezuelensis is a parasitic nematode of rodents that is frequently used to obtain heterologous antigens for immunological diagnosis of human strongyloidiasis. The aim of this study was to identify antigens from filariform larvae of S. venezuelensis for immunodiagnosis of human strongyloidiasis. Soluble and membrane fractions from filariform larvae of S. venezuelensis were obtained in phosphate saline (SS and SM) and in Tris–HCl buffer (TS and TM), and were analysed by Western blotting. Different antigenic components were recognized by IgG antibodies from the sera of strongyloidiasis patients. Highest recognition was observed for a 30–40 kDa mass range present in all antigenic fractions. The band encompassing this mass range was then excised and subjected to mass spectrometry for protein identification. Immunoreactive proteins identified in the soluble fractions corresponded to metabolic enzymes, whereas cytoskeletal proteins and galectins were more abundant in the membrane fractions. These results represent the first approach towards identification of S. venezuelensis antigens for use in immunodiagnostic assays for human strongyloidiasis.

Current control of plant parasitic nematodes often relies on highly toxic and environmentally harmful nematicides. As their use becomes increasingly restricted there is an urgent need to develop crop varieties with resistance to nematodes. The limitations surrounding conventional plant breeding ensure there is a clear opportunity for transgenic resistance to lessen current dependence on chemical control. The increasing use of molecular biology techniques in the field of plant nematology is now providing useful information for the design of novel defences to meet the new needs. Plant responses to parasitism are being investigated at the molecular level and nematode gene products that could be targets for a direct anti-nematode defence are being characterized. The potential of an anti-feedant approach to nematode control has been demonstrated. It is based on the transgenic expression of proteinase inhibitors. The rational development of this strategy involves characterization of nematode proteinase genes and optimization of inhibitors by protein engineering. Durability of the resistance can be enhanced by stacking transgenes directed at different nematode targets.

Little is known about the trematode fauna of India. Hitherto no species has been described from an Indian tortoise except Polystomum kachugae Stewart. In the present paper I describe a new genus Spinometra from a tortoise, and in the systematic account of the family Lepodermatidae I include new observations on other genera which I have studied and which I shall describe in subsequent papers.

Laelaps giganteus and Laelaps muricola (Mesostigmata; Laelapidae) are widespread and locally abundant host generalists on small mammals in southern Africa. The large host range and complex life history of these ectoparasites may allude to possible intraspecific cryptic diversity in these taxa. To assess genetic and morphological diversity in L. giganteus and L. muricola, we sampled 228 rodents at eight localities in South Africa. This sample included nine previously recorded host species and on these, L. muricola was only recorded from Mastomys natalensis and Micaelamys namaquensis while L. giganteus was found on Rhabdomys dilectus and Lemniscomys rosalia. Phylogenetic analyses of partial mtDNA cytochrome oxidase subunit I (COI) and nuclear ITS1 data strongly supported the recognition of L. giganteus and L. muricola, a scenario partly supported by the Tropomyosin intron. Strong support for evolutionary distinct lineages within L. giganteus is found: L. giganteus lineage 1 is confined to R. dilectus and L. giganteus lineage 2 is confined to L. rosalia. These host specific monophyletic lineages were also separated by 9·84% mtDNA sequence divergence and 3·44% nuclear DNA sequence divergence. Since quantitative morphometric analyses were not congruent with these findings, these two lineages more than likely represent cryptic species.