In June 1935 we observed in the intestine of an Indian squirrel, Sciurus sp.1, a coccidium which, since it has tetrazoic tetra-sporocystid oocysts, must be placed in the genus Wenyonella recently created by Hoare (1933).2

Four specimens of the pika (Ochotona rufescens Gray) were captured, and on dissection three of them were found to be heavily infested with a Nematode worm in the large intestine.

Claparède (1869) established the genus Myocoptes for a mite, found upon a house-mouse (Mus musculus musculus L., 1758), which had been described by C. L. Koch (1844) under the name Sarcoptes musculinus (syn. Listrophorus larisi Vorobiov, 1938). In this genus sexual dimorphism is pronounced; the female has legs iii and iv modified and provided with processes with which it can maintain a firm grasp on the fur of its host. In the male this modification is only present on legs iii.

Most animals are concurrently infected with multiple parasites, and interactions among them may influence both disease dynamics and host fitness. However, the sublethal costs of parasite infections are difficult to measure and the effects of concomitant infections with multiple parasite species on individual physiology and fitness are poorly described for wild hosts. To understand the costs of co-infection, we investigated the relationships among 189 European eel (Anguilla anguilla) from Mar Menor, parasites (richness and intensity) and eel's ‘health status’ (fluctuant asymmetry, splenic somatic index and the scaled mass index) by partial least squares regression. We found a positive relationship with 44% of the health status variance explained by parasites. Contracaecum sp. (Nematoda: Anisakidae) was the strongest predictor variable (44·72%) followed by Bucephalus anguillae (Platyhelminthes: Bucephalidae), (29·26%), considered the two most relevant parasites in the analysis. Subsequently, 15·67 and 12·01% of the response variables block were explained by parasite richness and Deropristis inflata (Platyhelminthes: Deropristiidae), respectively. Thus, the presence of multiple parasitic exposures with little effect on condition, strongly suggests that eels from Mar Menor tolerate multiparasitism.

Owing to the courtesy of Dr G. M. Vevers I have had the opportunity of examining a marine Ichthyobdellid leech, taken by Dr F. A. Phillipps from the cloaca of a shark, 7 feet long, caught between the islands of Aore and Santu, New Hebrides. The leech resembles Pontobdella superficially in being covered by warty tubercles. It possesses, however, certain peculiarities described below which justify its recognition not only as a new species but also as a representative of a new genus.

The oocysts studied were concentrated from the contents of the colon and caecum of the cottontail rabbit. The concentration method of Benbrook (1929) has been found to serve best.

Mounting an antibody response capable of discriminating amongst and appropriately targeting different parasites is crucial in host defence. However, cross-reactive antibodies that recognize (bind to) multiple parasite species are well documented. We aimed to determine if a higher inoculating dose of one species, and thus exposure to larger amounts of antigen over a longer period of time, would fine-tune responses to that species and reduce cross-reactivity. Using the Plasmodium chabaudi chabaudi (Pcc)–Nippostrongylus brasiliensis (Nb) co-infection model in BALB/c mice, in which we previously documented cross-reactive antibodies, we manipulated the inoculating dose of Pcc across 4 orders of magnitude. We investigated antigen-specific and cross-reactive antibody responses against crude and defined recombinant antigens by enzyme linked immunosorbent assay, Western blot and antibody depletion assays. Contrary to our hypothesis that increasing exposure to Pcc would reduce cross-reactivity to Nb, we found evidence for increased avidity of a subpopulation of antibodies that recognized shared antigens. Western blot indicated proteins of apparent monomer molecular mass 28 and 98 kDa in both Nb and Pcc antigen preparations and also an Nb protein of similar size to recombinant Pcc antigen, merozoite surface protein-119. The implications of antibodies binding antigen from such phylogenetically distinct parasites are discussed.

To model the colonization of a novel host by fleas, Synosternus cleopatrae and Xenopsylla ramesis, we established experimental lines maintained for 15 generations on a principal or a novel host (either co-occurring with a flea or not). We compared the blood meal size and the energy expended for digestion by fleas from the 15th generation of each line on these hosts between hosts within a line and between lines within a host asking (a) whether fleas adapt to a novel host (increased blood consumption/decreased energy expended for digestion); (b) if yes, whether this adaptation leads to the loss of ability to exploit an original host, and (c) whether the success of adaptation to a novel host depends on its ecological co-occurrence with a flea. The blood consumption and digestion energetics of fleas fed on the principal host differed from those on other hosts. The effect of the principal host on feeding performance differed between fleas, with S. cleopatrae consuming less blood and expending more energy for digestion on the principal than on any other host, whereas the opposite was true for X. ramesis. No changes in feeding performance on a novel host over generations were found. We propose several explanations for the lack of adaptation to a novel host over time. We explain the poor performance of S. cleopatrae on its principal host via its immune response mounting pattern. We argue that the principal host of a parasite is not necessarily the host on which the parasite demonstrates the best performance.

This study assessed the role of historical processes on the geographic isolation, molecular evolution, and morphological diversification of host-parasite populations from the southern Brazilian coast. Adult specimens of Scleromystax barbatus and Scleromystax macropterus were collected from the sub-basin of the Nhundiaquara River and the sub-basin of the Paranaguá Bay, state of Paraná, Brazil. Four species of Gyrodactylus were recovered from the body surface of both host species. Morphometric analysis of Gyrodactylus spp. and Scleromystax spp. indicated that subpopulations of parasites and hosts could be distinguished from different sub-basins and locations, but the degree of morphological differentiation seems to be little related to geographic distance between subpopulations. Phylogenetic relationships based on DNA sequences of Gyrodactylus spp. and Scleromystax spp. allowed distinguishing lineages of parasites and hosts from different sub-basins. However, the level of genetic structuring of parasites was higher in comparison to host species. Evidence of positive selection in mtDNA sequences is likely associated with local adaptation of lineages of parasites and hosts. A historical demographic analysis revealed that populations of Gyrodactylus and Scleromystax have expanded in the last 250 000 years. The genetic variation of parasites and hosts is consistent with population-specific selection, population expansions, and recent evolutionary co-divergence.

Leishmania mutants have contributed greatly to extend our knowledge of this parasite's biology. Here we report the use of the mariner in vitro transposition system as a source of reagents for shuttle mutagenesis and targeted disruption of Leishmania genes. The locus-specific integration was achieved by the disruption of the subtelomeric gene encoding a DNA-directed RNA polymerase III subunit (RPC2). Further inactivation of RPC2 alleles required the complementation of the intact gene, which was transfected in an episomal context. However, attempts to generate a RPC2 chromosomal null mutant resulted in genomic rearrangements that maintained copies of the intact locus in the genome. The maintenance of the RPC2 chromosomal locus in complemented mutants was not mediated by an increase in the number of copies and did not involve chromosomal translocations, which are the typical characteristics of the genomic plasticity of this parasite. Unlike the endogenous locus, the selectable marker used to disrupt RPC2 did not display a tendency to remain in its chromosomal location but was targeted into supernumerary episomal molecules.

The present study was conducted to evaluate the anti-parasitic activity of a pure compound from Streptomyces sp. HL-2-14 against fish parasite Ichthyophthirius multifiliis, and elucidate its chemical structure. By electron ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectrum (1H NMR and 13C NMR), the compound was identified as amphotericin B (AmB). The in vitro trials revealed that AmB can effectively kill the theronts and tomonts of I. multifiliis with the median lethal concentration (LC50) of 0·8 mg L−1 at 30 min for the theronts and 4·3 mg L−1 at 2 h for the tomonts, respectively. AmB at 5 mg L−1 significantly reduced I. multifiliis infectivity prevalence and intensity on grass carp (Ctenopharyngodon idella), and consequently decreased fish mortality, from 100% in control group to 30% in treated group. The 72 h acute toxicity (LC50) of AmB on grass carp was 20·6 mg L−1, but fish mortality was occurred when exposure to 13·0 mg L−1. These results indicated that AmB was effective in the therapy of I. multifiliis infection, but the safety concentration margin is relatively narrow. Further efforts aiming to decrease the toxicity and improve the therapeutic profile remain to be needed.

A new species of Trypanosoma, T. (Megatrypanum) hoarei, is described from shrews of the genus Sorex (S. trowbridgii, S. vagrans, S. ornatus, and S. palustris) in California. Four body types are found in adult populations of T. hoarei, two common and two rare, as well as intermediate stages, indicating a tendency to-ward polymorphism in this species. Multiplication is discontinuous, with a reproductive and growth period characterized by moderate numbers of diverse and bizarre developmental forms in the blood and high coefficients of variation for total length (20–30 %), succeeded by an adult phase with few trypanosomes in the blood and lower coefficients of variation for total length (7–12 %). The method and site of multiplication in T. hoarei is unknown but evidence indicates that reproduction by multiple fission or binary fission of amastigote forms may occur in tissue capillaries, with the production of large, rounded amastigote individuals. The latter develop, without intervention of epimastigote stages, into large, rounded trypomastigote individuals from which a wide variety of other developmental forms proceed, including certain distinctive, very long ribbon-like trypanosomes. A review of the literature on mole and shrew trypanosomes suggests that T. hoarei of Sorex, T. petrodromi from Petrodrorrms, and T. talpae from Talpa are related, primitive insectivore forms, clearly distinguishable from the lewisi-type trypanosomes also found in insectivores.

On the skin of the dorsal surface, and particularly on the dorsal fins of Scyllium canicula at Plymouth, occurs a parasite which appears to be identical with Paracotyle caniculae Johnstone 1911. In British waters it was first noticed by Scott (1906) who queried it as a species of Epibdella. Johnstone (1911) gave an account of the species but his specimens were immature, being in the male phase of their development and considerably smaller than those found at Plymouth.

Using foot-pad infection of female C57BL/6, DBA/2J and NMRI-IVIC mice as an animal model for American cutaneous leishmaniasis (ACL), we evaluated the inhibitory effect of Formycin B (FoB) on the infection produced by 7 different Leishmania isolates. When treatment was initiated some days, or even some weeks, after infection a significant leishmanistatic effect was detected on mice infected with all Leishmania isolates, which reached 30–55 weeks for some isolates. The optimal dose schedule was 1·25 mg/kg body weight/day, injected intraperitoneally for 20 consecutive days. Significant differences in the sensitivity of various Leishmania spp. to FoB were found, either in vivo, or in vitro where a high [3H]FoB incorporation rate was found only for certain Leishmania isolates. The low toxicity of this drug and the sensitivity of the 7 Leishmania isolates tested suggest that FoB could be useful in the treatment of ACL.

A preliminary report on the results of our studies on the comparative efficacy of different culicifuges under laboratory conditions has been published (Roy, Ghosh & Chopra, 1942).

Volume conducted potentials were recorded from schistosomula of Schistosoma mansoni transformed mechanically (MS) and by skin penetration (SS). The spontaneous electrical activity recorded consisted of bi and triphasic transients ranging from 20 to 200 μV in amplitude and 10 to 300 msec in duration. Low amplitude potentials occurred at a much greater frequency than large amplitude potentials, which appeared to correlate with peristaltic-like contractions of the schistosomulum's musculature. Electrical activity in the schistosomulum was highly sensitive to a number of agents believed to affect metabolic pathways, the neuromuscular system or the host/parasite interface of adult schistosomes. Among the most reactive substances were potassium antimony tartrate, eserine, poly-L-arginine and potassium cyanide. Over a wide range of experimental treatments, electrophysiological responses in schistosomula transformed from cercariae by mechanical decaudation and skin penetration were remarkably similar, supporting the notion that MS are suitable material for in vitro immunochemical, biochemical and physiological study. Some treatments, however, were more or less effective in altering electrophysiological activity and motility in the schistosomulum than in adult S. mansoni. This suggests that significant physiological alterations may occur during development from skin stage to adult parasites concomitant with immunochemical and morphological changes already known to occur.

The development of T. lewisi in the blood of the rat is accompanied by a division of the nucleus which is more like an amitosis than a mitosis.

The division of the blepharoplast, always preceded by the division of a karyosome-like granule, might be called a promitosis (sensu: Nägler, 1909).

It is not proved that autogamy or parthenogenesis takes place in rats' blood or in cultures. The evidence brought forward by Prowazek and by Moore, Breinl and Hindle proves only the existence of chromidia; neither are Schilling's recent proofs suggestive.

Under abnormal conditions hypertrophy takes place affecting the nucleus and the blepharoplast, with subsequent formation of chromidia and final fragmentation. Similar stages found in the rat-louse have been described as sexual cells.

Considering these results in connection with previous observations of Strickland and myself, we may conclude that as yet nothing whatever indicates the occurrence of any sexual process in the life-cycle of T. levrisi, both in the vertebrate and invertebrate hosts.

Cortisone appears to enhance the production of some humoral agent in the serum of infected mice which, when injected in extremely small quantities into experimental, infected animals, produces a decrease in the parasitaemia in the peripheral blood. This effect is not produced by clean serum, and only slightly, if at all, by the serum from infected mice which have received no cortisone.