Plasmodium Cathemerium Research Articles

Haemosporidian parasites in the ash-breasted Sierra finch (Geospizopsis plebejus): insights from an Andean dry forest population.

Haemosporidian genera Plasmodium, Haemoproteus and Leucocytozoon, responsible for avian malarial infections, are highly diverse and have a wide range of health effects and predictors, depending on the host and its environmental context. Here, we present, for the first time, detailed information on the identity, prevalence and parasitaemia of haemosporidians and other haemoparasites that infect the ash-breasted Sierra finch, Geospizopsis plebejus, in an Andean dry forest. We study the consequences of infection in the host body and health conditions and explore the environmental and intrinsic factors that influence infection status and parasitaemia. We conducted diagnoses by cytochrome b (cytb) sequencing and morphological identification, and estimated the levels of parasitaemia based on microscopy. We identified 6 cytb lineages infecting G. plebejus. Two of them were new lineages: Haemoproteus sp. GEPLE01 and GEPLE02. We also detected Haemoproteus sp. ZOCAP08, Haemoproteus sp. AMAVIR01, Plasmodium homopolare BAEBIC02 and Plasmodium cathemerium ZONCAP15. By microscopy, we detected Haemoproteus coatneyi, Haemoproteus erythrogravidus, P. homopolare and other unidentified species of Haemoproteus, Plasmodium, Babesia sp. and 1 microfilaria. We found no evidence of Leucocytozoon. Additionally, we detected several coinfections by sequencing and microscopy. The prevalence of haemosporidian infections was high (87.7%), and the mean parasitaemia was 61.65 infected cells per 10 000 erythrocytes examined. Prevalence and parasitaemia were higher for Haemoproteus than for Plasmodium. Haemoproteus sp. AMAVIR01 showed the highest prevalence (43.1%) and mean parasitaemia (94.39/10 000 erythrocytes) and might be associated with H. coatneyi. Immature individuals showed a lower prevalence than adults, supporting previous findings.

Vector incrimination and transmission of avian malaria at an aquarium in Japan: mismatch in parasite composition between mosquitoes and penguins

BackgroundCaptive populations of penguins outside of their natural distributions are often maintained in outdoor facilities, such as zoos and aquariums. Consequently, such penguins in captivity are constantly exposed to mosquito vectors and risk of avian malarial infection during their active period from spring to autumn, which can be lethal to these naïve birds. Previous studies have investigated parasite prevalence in mosquitoes or penguins, but simultaneous investigations, which would be crucial to monitor the transmission dynamics and cycle within a facility, have not been done. To identify dominant lineages and trends, multiple-year surveys are recommended.MethodsAvian malaria parasites (Plasmodium spp.) and related haemosporidia were tested in penguins and mosquitoes at an aquarium in Japan through multiple years from 2011 to 2018. Prevalence and dynamics were confirmed, and molecular analyses targeting the protozoal cytb gene were used to reveal the transmission cycle. Blood meals of mosquitoes were also identified using molecular methods.ResultsParasite detection in penguins tended to fluctuate within an individual. Two Plasmodium lineages were consistently detected in mosquitoes that had fed on penguins and wild birds observed around the aquarium. Plasmodium lineage CXPIP09 was detected from both mosquitoes and penguins, suggesting active transmission at this facility. However, Plasmodium cathemerium PADOM02 was only detected in mosquitoes, which may be due to host, vector or parasite-related factors, or detection methods and their limits. Additionally, Haemoproteus larae SPMAG12 was detected from penguins, suggesting active transmission via biting midges.ConclusionsThe mismatch in parasite composition between penguins and mosquitoes shows that multiple aspects such as captive birds, wild birds and vector insects should be monitored in order to better understand and control avian malarial infection within ex-situ conservation facilities. Furthermore, morphological analyses would be needed to confirm competency and infection dynamics of avian malaria parasites.

Vector-Borne Blood Parasites of the Great-Tailed Grackle (Quiscalus mexicanus) in East-Central Texas, USA.

Great-tailed grackles (Quiscalus mexicanus) have dramatically expanded into North America over the past century. However, little is known about the blood that parasites they support. Here, for the first time, we document an assemblage of trypanosome, haemosporida, and filarial nematodes co-circulating in invasive great-tailed grackles. Between February and July, 2015, 61 individuals were captured in an urban environment of College Station, Texas. Field microscopy and molecular diagnostics indicate that 52% (24/46) were visually infected with filarioid nematodes, 24% (11/46) with avian trypanosomes, and 73% (n = 44/60) with haemosporida parasites, such as Haemoproteus (Parahaemoproteus) and Plasmodium cathemerium. Overall, 87% of great-tailed grackles were infected with blood parasites. Although 50% of individuals hosted parasites from multiple phylum, no patterns of parasite assembly were observed. Results indicate that great-tailed grackles can support a relatively high level of blood parasitism. However, the consequences for avian health remain to be determined.

Morphological and molecular characterization of Plasmodium cathemerium (lineage PADOM02) from the sparrow Passer domesticus with complete sporogony in Culex pipiens complex.

Avian malaria is a mosquito-borne disease caused by Plasmodium spp. protozoa. Although these parasites have been extensively studied in North America and Eurasia, knowledge on the diversity of Plasmodium, its vectors and avian hosts in Africa is scarce. In this study, we report on natural malarial infections in free-ranging sparrows (Passer domesticus) sampled at Giza Governorate, Egypt. Parasites were morphologically characterized as Plasmodium cathemerium based on the examination of thin blood smears from the avian host. Sequencing a fragment of the mitochondrial cytochrome b gene showed that the parasite corresponded to lineage PADOM02. Phylogenetic analysis showed that this parasite is closely related to the lineages SERAU01 and PADOM09, both of which are attributed to P. cathemerium. Experimental infection of Culex pipiens complex was successful, with ookinetes first detected at 1-day post infection (dpi), oocysts at 4 dpi and sporozoites at 6 dpi. The massive infection of the salivary glands by sporozoites corroborates that Cx. pipiens complex is a competent vector of PADOM02. Our findings confirm that Plasmodium lineage PADOM02 infects sparrows in urban areas along the Nile River, Egypt, and corroborate that Cx. pipiens complex is a highly competent vector for these parasites. Furthermore, our results demonstrate that this lineage corresponds to the morphospecies P. cathemerium and not P. relictum as previously believed.

Epidemiology, hematology, and unusual morphological characteristics of Plasmodium during an avian malaria outbreak in penguins in Brazil.

Avian malaria is a mosquito-borne disease caused by Plasmodium spp. protozoa, and penguins are considered particularly susceptible to this disease, developing rapid outbreaks with potentially high mortality. We report on an outbreak of avian malaria in Magellanic penguins (Spheniscus magellanicus) at a rehabilitation center in Espírito Santo, southeast Brazil. In August and September 2015, a total of 89 Magellanic penguins (87 juveniles and 2 adults) received care at Institute of Research and Rehabilitation of Marine Animals. Over a period of 2weeks, Plasmodium infections were identified in eight individuals (9.0%), four of which died (mortality = 4.5%, lethality = 50%). Blood smears and sequencing of the mitochondrial cytochrome b gene revealed the presence of Plasmodium lutzi SPMAG06, Plasmodium elongatum GRW06, Plasmodium sp. PHPAT01, Plasmodium sp. SPMAG10, and Plasmodium cathemerium (sequencing not successful). Two unusual morphological features were observed in individuals infected with lineage SPMAG06: (a) lack of clumping of pigment granules and (b) presence of circulating exoerythrocytic meronts. Hematological results (packed cell volume, plasma total solids, complete blood cell counts) of positive individuals showed differences from those of negative individuals depending on the lineages, but there was no overarching pattern consistently observed for all Plasmodium spp. The epidemiology of the outbreak and the phylogeography of the parasite lineages detected in this study support the notion that malarial infections in penguins undergoing rehabilitation in Brazil are the result of the spillover inoculation by plasmodia that circulate in the local avifauna, especially Passeriformes.

Avian malaria co-infections confound infectivity and vector competence assays of Plasmodium homopolare

Currently, there are very few studies of avian malaria that investigate relationships among the host-vector-parasite triad concomitantly. In the current study, we experimentally measured the vector competence of several Culex mosquitoes for a newly described avian malaria parasite, Plasmodium homopolare. Song sparrow (Melospiza melodia) blood infected with a low P. homopolare parasitemia was inoculated into a naïve domestic canary (Serinus canaria forma domestica). Within 5 to 10 days post infection (dpi), the canary unexpectedly developed a simultaneous high parasitemic infection of Plasmodium cathemerium (Pcat6) and a low parasitemic infection of P. homopolare, both of which were detected in blood smears. During this infection period, PCR detected Pcat6, but not P. homopolare in the canary. Between 10 and 60 dpi, Pcat6 blood stages were no longer visible and PCR no longer amplified Pcat6 parasite DNA from canary blood. However, P. homopolare blood stages remained visible, albeit still at very low parasitemias, and PCR was able to amplify P. homopolare DNA. This pattern of mixed Pcat6 and P. homopolare infection was repeated in three secondary infected canaries that were injected with blood from the first infected canary. Mosquitoes that blood-fed on the secondary infected canaries developed infections with Pcat6 as well as another P. cathemerium lineage (Pcat8); none developed PCR detectable P. homopolare infections. These observations suggest that the original P. homopolare-infected songbird also had two un-detectable P. cathemerium lineages/strains. The vector and host infectivity trials in this study demonstrated that current molecular assays may significantly underreport the extent of mixed avian malaria infections in vectors and hosts.

Outbreak of avian malaria associated to multiple species of Plasmodium in magellanic penguins undergoing rehabilitation in southern Brazil.

Avian malaria is a mosquito-borne disease caused by Plasmodium spp. Avian plasmodia are recognized conservation-threatening pathogens due to their potential to cause severe epizootics when introduced to bird populations with which they did not co-evolve. Penguins are considered particularly susceptible, as outbreaks in captive populations will often lead to high morbidity and rapid mortality. We used a multidisciplinary approach to investigate an outbreak of avian malaria in 28 Magellanic penguins (Spheniscus magellanicus) at a rehabilitation center during summer 2009 in Florianópolis, Brazil. Hemosporidian infections were identified by microscopic and molecular characterization in 64% (18/28) of the penguins, including Plasmodium (Haemamoeba) tejerai, Plasmodium (Huffia) elongatum, a Plasmodium (Haemamoeba) sp. lineage closely related to Plasmodium cathemerium, and a Haemoproteus (Parahaemoproteus) sp. lineage closely related to Haemoproteus syrnii. P. tejerai played a predominant role in the studied outbreak and was identified in 72% (13/18) of the hemosporidian-infected penguins, and in 89% (8/9) of the penguins that died, suggesting that this is a highly pathogenic parasite for penguins; a detailed description of tissue meronts and lesions is provided. Mixed infections were identified in three penguins, and involved P. elongatum and either P. tejerai or P. (Haemamoeba) sp. that were compatible with P. tejerai but could not be confirmed. In total, 32% (9/28) penguins died over the course of 16 days despite oral treatment with chloroquine followed by sulfadiazine-trimethoprim. Hemosporidian infections were considered likely to have occurred during rehabilitation, probably from mosquitoes infected while feeding on local native birds, whereas penguin-mosquito-penguin transmission may have played a role in later stages of the outbreak. Considering the seasonality of the infection, rehabilitation centers would benefit from narrowing their efforts to prevent avian malaria outbreaks to the penguins that are maintained throughout summer.

Blood parasites, body condition, and wing length in two subspecies of yellow wagtail (Motacilla flava) during migration

Blood parasites of migrating yellow wagtails of two subspecies--Motacilla flava feldegg and Motacilla flava flava-were studied on a sample of 473 birds caught in spring and autumn periods in Bulgaria. We controlled eight "migration waves" (flocks captured in different evenings) of yellow wagtails for four parameters--average body mass, average fat level, average wing length, and average prevalence of different hematozoan species. Gametocytes or meronts of a total of six species of hematozoa belonging to three genera were identified-Haemoproteus motacillae, Haemoproteus anthi, Plasmodium relictum, Plasmodium subpraecox, Plasmodium cathemerium, and Tryponosoma avium. Mixed infections were detected in 31 cases, of which 14 were of H. anthi/H. motacillae type. Parasite species composition was similar in the two studied subspecies of M. flava. We did not find any significant differences in the overall infection prevalence or number of infecting parasites between M. f. flava and M. f. feldegg. Parasite prevalence and the number of co-infecting parasites in spring were much higher than in fall. Season had a strong influence on the prevalence of H. anthi and H. motacillae, and for both, there was a marginally significant interaction between subspecies and season, but not a season-independent influence of subspecies. Males of M. f. feldegg had a significantly higher overall blood parasite prevalence and prevalence of H. anthi than females. Sex-related differences in the prevalence of other parasites were not significant. Migration waves of yellow wagtails differed in overall infection status and in H. motacillae prevalence, but not for H. anthi prevalence. We also found significant differences in fat score, weight, and wing length between the studied migration waves of the yellow wagtails. Fat scores of birds infected with different hematozoa were lower compared with those of the non-infected birds. This only marginally was true for body weight and was not the case for wing length. Overall, infected birds were in worse condition (estimated as the residual weight after regression with wing length) compared with the non-infected birds, but after controlling for seasonal effects, the differences in condition appeared to be due to migration season and did not significantly differ between infected and non-infected birds caught in the same season.

Polymerase chain reaction-based identification of Plasmodium (Huffia) elongatum, with remarks on species identity of haemosporidian lineages deposited in GenBank

Numerous lineages of avian malaria parasites of the genus Plasmodium have been deposited in GenBank. However, only 11 morphospecies of Plasmodium have been linked to these lineages. Such linking is important because it provides opportunities to combine the existing knowledge of traditional parasitology with novel genetic information of these parasites obtained by molecular techniques. This study linked one mitochondrial cytochrome b (cyt b) gene lineage with morphospecies Plasmodium (Huffia) elongatum, a cosmopolitan avian malaria parasite which causes lethal disease in some birds. One species of Plasmodium (mitochondrial cyt b gene lineage P-GRW6) was isolated from naturally infected adult great reed warblers (Acrocephalus arundinaceus) and inoculated to one naive juvenile individual of the same host species. Heavy parasitaemia developed in the subinoculated bird, which enabled identification of the morphospecies and deposition of its voucher specimens. The parasite of this lineage belongs to P. elongatum. Illustrations of blood stages of this parasite are given. Other lineages closely related to P. elongatum were identified. The validity of the subgenus Huffia is supported by phylogenetic analysis. Mitochondrial cyt b gene lineages, with GenBank accession nos. AF069611 and AY733088, belong to Plasmodium cathemerium and P. elongatum, respectively; these lineages have been formerly attributed to P. elongatum and P. relictum, respectively. Some other incorrect species identifications of avian haematozoa in GenBank have been identified. We propose a strategy to minimise the number of such mistakes in GenBank in the future.

Bayesian analysis of new and old malaria parasite DNA sequence data demonstrates the need for more phylogenetic signal to clarify the descent of Plasmodium falciparum

Molecular systematic studies published during the last 15 years to clarify the phylogenetic relationships among the malaria parasites have led to two major hypotheses on the descent of Plasmodium falciparum: One supports an avian origin as a result of a relatively recent host switch, and another one favours the evolutionary development of P. falciparum together with its human host from primate ancestors. In this paper, we present phylogenetic analyses of three different Plasmodium genes, the nuclear 18 small sub-unit (SSU) ribosomal ribonucleic acid (rRNA), the mitochondrial cytochrome b (cyt b) and the plastid caseinolytic protease C (ClpC) gene, using numerous haemosporidian parasite DNA sequences obtained from the GenBank as well as several new sequences for major malaria parasites including the avian one Plasmodium cathemerium, which has never been considered in molecular phylogenetic analyses before. Most modern and sophisticated DNA substitution models based on Bayesian inference analysis were applied to estimate the cyt b and ClpC phylogenetic trees, whereas the 18 SSU rRNA gene was examined with regards to its secondary structure using PHASE software. Our results indicate that the data presently available are generally neither sufficient in number nor in information to solve the problem of the phylogenetic origin of P. falciparum.

Plasmodium (Haemamoeba) cathemerium gene sequences for phylogenetic analysis of malaria parasites

The DNA sequence information on avian malaria parasites of the genus Plasmodium is quite limited. At present, sequences of only 6 out of 34 valid species are available. However, sequence data of avian malaria parasites are particularly important with regard to the resolution of the phylogenetic relationships of the most virulent human malaria agent, Plasmodium falciparum. The question as to whether P. falciparum originates from avian or from mammalian parasites would contribute to our understanding of its biology and would probably facilitate the interpretation of experimental results. To add to the body of molecular data, we sequenced three genes (cytochrome b, 18 SSU rRNA, caseinolytic protease C) of different organellar origin of one of the most widespread avian malaria parasites, Plasmodium (Haemamoeba) cathemerium, which once used to be an important laboratory in vivo model in human malaria research. The analysis of the new P. cathemerium sequences in direct comparison with the rodent parasite P. berghei and the four human malaria parasites by pairwise distance calculation do not suggest a closer relationship of P. cathemerium to P. falciparum than to the other species involved.

The Development of Plasmodium gallinaceum Brumpt in the Hemocoels of Refractory Culex pipiens pipiens Linn. and Susceptible Aedes aegypti (Linn.)

The extent and rate of development of Plasmodium gallinaceum Brumpt in the hemocoel of the refractory mosquito Culex pipiens pipiens L. and in that of the susceptible mosquito Aedes aegypti (L.) have been determined. Infected blood, with a high gametocyte count, was injected into the hemocoel of the mosquitoes and the development of the parasites in both hosts was compared with each other and with the natural exogenous cycle. Serial sections of the infected mosquitoes were used in these experiments. It was concluded that (1) the parasites develop at the same rate in the hemocoel of the injected susceptible mosquito as on the stomach wall of the naturally infected host; (2) development of the parasites in the hemocoels of both susceptible and refractory mosquitoes was parallel for the early stages until the 3rd day; (3) oocysts in the refractory host deteriorated and receded from the host tissues after the 4th day; (4) adequate metabolites were available to support development in the resistant host for the first 3 days but undetermined toxic factors were probably responsible for the resultant deterioration and death of the parasites. The relations between the exogenous stages of malaria and the invertebrate host, especially those between the parasite and the tissues, are poorly understood. Each species of Plasmodium finds favorable environments for development only in certain species of mosquitoes, whereas development may be restricted in part or completely suppressed in numerous other species of mosquitoes. The developmental stages of most malaria parasites in susceptible mosquito species have been known in detail since they were first described. We know very little, however, about the extent of development of the exogenous stages in resistant or refractory species of mosquitoes. Little is known about the relationship between extent of development and the innate resistance of such mosquitoes to malaria. One of the earliest investigations in this regard was reported by Huff (1927). He traced the development of Plasmodium cathemerium Hartman in Aedes sollicitans (Walker) which is resistant to the parasite and in Culex pipiens L. which is susceptible, and found that development to the ookinete stage was about equal in both species. He did not find differences in the rates of digestion of the blood meals or in the appearance of the parasites in the stomachs of these mosquitoes, and factors responsible for susReceived for publication 7 June 1968. *This investigation was supported in part by Public Health Service research Grant AI 05253, from the NIAID. c ptibility were not recognized. In 1934 Huff showed that ookinetes of P. cathemerium may form in the stomachs of a resistant strain of C. pipiens but they degenerated and died without penetrating the stomach wall. There had been no attempt to determine the possibility of parasites developing beyond the stomach phases in either refractory or susceptible species until one of us (Weathersby, 1952) injected parasites directly into the hemocoel of the mosquitoes. The stomach wall was thus bypassed. Susceptibility was not altered by this technique since the susceptible mosquitoes became infected and the refractory mosquitoes did not. It was demonstrated (Weathersby, 1952, 1954) that the factors g verning innate susceptibility of mosquitoes to malaria were systemic and not restricted to, or localized in, the stomach wall. In those experiments the progress of the development of the parasites was not observed in detail but susceptibility was evaluated on evidence of subsequent sporozoites in the mosquitoes' salivary glands and on the ability of the mosquitoes to infect susceptible vertebrate hosts. The purpose of this study is to show the daily development of exogenous forms in the hemocoel of refractory mosquitoes, in comparison to the development in the hemocoel of susceptible mosquitoes, and to determine the relations of such development to the innate susceptibility, or more specifically the immunity, of certain mosquitoes to malaria.

The Effect of Lowered Temperatures of the Host on the Reproductive Activity of Plasmodium cathemerium*

SYNOPSIS. Experiments were carried out to determine if the course of infection with Plasmodium cathemerium was changed when the temperature of incubation of the duck embryo host was lowered. At 30° C. the infection developed more slowly and never reached the peak seen in infected embryos incubated at 37° C. If infected embryos at 30° were returned to 37° C. the resultant parasitemia developed similarly to that usually seen in this host at the latter temperature. Studies of the periodic behavior of the parasite at 30° C. and 38° C. revealed no differences in the time of segmentation. Merozoite counts were unchanged. The reduced parasitemia in embryos at 30° C. may result from reduced ability of the parasite to penetrate new host cells.

The Reproductive Behavior of Plasmodium cathemerium in Duck and Chick Embryos

Boyd (1925, 1929, 1933) and Stauber (1939) have shown that this inherent tendency of the parasite is profoundly affected by environmental conditions. All attempts to solve the problem of the relation of environmental factors to periodicity of parasitic reproduction have been seriously hampered, however, by the impossibility of securing completely controlled environmental conditions in the vertebrate host. If a host could be found in which the malaria parasite could successfully establish itself and whose environment is subject to a minimum degree of fluctuation, a closer approach could be made to the relation which these influences surrounding the host bear to activities of the parasite itself. In an attempt to find such a host bird embryos have been used for the avian plasmodia. Wolfson (1940) and Stauber and Van Dyke (1945) succeeded in obtaining an infection in duck embryos with Plasmodium cathemerium. In this study we have made use of their discovery to study the parasite's behavior, particularly with regard to reproduction, in a host whose environment normally remains more or less constant in relation to such fac

The effects of hypoxia on infections with Plasmodium cathemerium.

Received for publication January 31, 1955. The authors wish to acknowledge substantial aid from Parke, Davis and Co. in support of this study. * Present address: Department of Biochemistry and Pharmacology, Indiana University School of Medicine, Indianapolis, Indiana. considerations led us to the study of the effects of hypoxia produced by a simulated high altitude, or lowered tension of oxygen on the natural resistance of the canary towards infections with P. cathemerium, as well as on the effect of an oxygen-deficient environment on the effectiveness of chemotherapy of the same infection.

The Blood Protozoa of Seventeen Species of Sparrows and Other Fringillidae

SUMMARY. A total of 1037 birds, belonging to 17 species of Fringillidae (order Passeres) and nearly all collected in or near Syracuse, N. Y., were examined for blood parasites. Of the species of avian malaria, Plasmodium cathemerium occurred most frequently, followed by P. hexamerium, P. relictum, P. elongatum, and P. circumflexum. Other species were not seen, although some (e.g. P. nucleophilum, P. polare, P. vaughani) are known to occur in Central New York.A number of song, chipping, and field sparrows were given experimental inoculations of Plasmodium vaughani‐infected blood and liberated. A few were recaught at varying intervals, but none were infected, suggesting that these species are insusceptible to this type of avian malaria.Malaria in song sparrows, which were caught in large numbers, is common and probably endemic, not varying greatly in frequency from year to year. But the incidence shows a sharp peak in the spring, most cases apparently being low‐grade relapses, which probably serve to reestablish the infection in the new crop of mosquitoes. There are indications that Haemoproteus and Leucocytozoon behave similarly.Infection with these last two parasites occurred in most of the species examined, but the incidence varied greatly, being especially high in white‐throated and white‐crowned sparrows. Reproductive stages of Haemoproteus were observed in the lungs of song and chipping sparrows.

Further studies on the cultivation of the avian malaria parasites.

Summary Experiments involving the cultivation of three species of avian plasmodia, Plasmodium cathemerium, P. hexamerium and P. relictum, on the Harvard medium show the medium to be best adapted to the requirements of P. hexamerium. Although the Growth Index (defined as the ratio of parasites per unit number of red cells at the end of a given period of cultivation to that at the start) was numerically not as high as that obtained with some other species of avian plasmodia, it represents a relatively better result because this species has a much slower rate of natural increase. Viability tests and staining reactions of cultured parasites confirm this conclusion. Relatively good results were also obtained in subculture. Nevertheless even this species does not show a rate of multiplication in culture approaching that observed in vivo. Of the other two species, P. relictum (as previously reported) does moderately well in primary cultures, but little more than survival occurs in subcultures. P. cathemerium shows even less multiplication in primary cultures, and virtually none in subculture.

The effect of antibiotics on experimental malaria (Plasmodium cathemerium and Plasmodium berghei).

Summary and ConclusionsCertain antibiotics derived from various types of Streptomyces possess definite antimalarial properties. Against Plasmodium cathemerium in the canary, aureomycin and terramycin have marked prophylactic effect and even afford complete protection in some instances when administered for 10 days or longer. Aureomycin has a suppressive effect equal to that of quinine, and terramycin a relatively poor suppressive effect against the blood parasites. Chloramphenicol has a meager prophylactic and suppressive effect only in maximum tolerated doses. None of these drugs proved to be curative, either alone or in combination with quinine. Dihydrostreptomycin, neomycin, rimocidin, thiolutin, and two Brucella-active lyophilized broths were totally ineffective.The same three antibiotics, aureomycin, terramycin, and chloramphenicol, show a suppressive effect in P. berghei infections in the white mouse. Aureomycin is again nearly equivalent to quinine, while terramycin and chloramphenicol both have rather low quinine equivalents of 0.16 and 0.17 respectively. Neomycin had no suppressive effect on P. berghei infections.The marked prophylactic effect of certain of these antibiotics, confirming previous reports of such activity by others indicates further search for more effective preparations in this group. To our knowledge, causal prophylaxis is demonstrated by only two other compounds against P. cathemerium infections—metachloridine (Wiselogle, 1946) and Endochin (unpublished observations). As this type of antimalarial activity may be interpreted as bearing chiefly on the exo-erythrocytic forms of the parasite, there is a possibility that among the antibiotics or a combination of one of them with another antimalarial will be found a less toxic curative agent for vivax malaria.

Drug, host and parasite interrelationships in the treatment of avian malaria (Plasmodium cathemerium in canaries).

Journal Article Drug, Host and Parasite Interrelationships in the Treatment of Avian Malaria (Plasmodium Catiiemerium in Canaries) Get access Russell O. Hanson, Russell O. Hanson Department of Pharmacology and Toxicology, University of Wisconsin, Madison, Wisconsin Search for other works by this author on: Oxford Academic PubMed Google Scholar Arthur L. Tatum Arthur L. Tatum Department of Pharmacology and Toxicology, University of Wisconsin, Madison, Wisconsin Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Infectious Diseases, Volume 90, Issue 2, March 1952, Pages 105–109, https://doi.org/10.1093/infdis/90.2.105 Published: 01 March 1952 Article history Received: 18 June 1951 Published: 01 March 1952

Observations on the pre-erythrocytic stages of Plasmodium relictum, Plasmodium cathemerium, and Plasmodium gallinaceum in various birds.

During the course of our earlier efforts to elucidate the nature of that portion of the life cycle of avian malarial parasites occurring before patent parasitemia and later during various experiments involving studies of the pre-erythrocytic stages of these parasites, numerous observations were made on the preerythrocytic stages of Plasmodium relictum, Plasmodium cathemerium and Plasmodium gallinaceum which remain unpublished. These observations include (1) success or failure to observe pre-erythrocytic stages in a variety of avian hosts and (2) details of morphology and development of these stages hitherto unrecorded. Some generalizations follow these observations.