Parasitaemia data and molecular characterization of Haemoproteus catharti from New World vultures (Cathartidae) reveals a novel clade of Haemosporida

Background

New World vultures (Cathartiformes: Cathartidae) are obligate scavengers comprised of seven species in five genera throughout the Americas. Of these, turkey vultures (Cathartes aura) and black vultures (Coragyps atratus) are the most widespread and, although ecologically similar, have evolved differences in morphology, physiology, and behaviour. Three species of haemosporidians have been reported in New World vultures to date: Haemoproteus catharti, Leucocytozoon toddi and Plasmodium elongatum, although few studies have investigated haemosporidian parasites in this important group of species. In this study, morphological and molecular methods were used to investigate the epidemiology and molecular biology of haemosporidian parasites of New World vultures in North America.

Methods

Blood and/or tissue samples were obtained from 162 turkey vultures and 95 black vultures in six states of the USA. Parasites were identified based on their morphology in blood smears, and sequences of the mitochondrial cytochrome b and nuclear adenylosuccinate lyase genes were obtained for molecular characterization.

Results

No parasites were detected in black vultures, whereas 24% of turkey vultures across all sampling locations were positive for H. catharti by blood smear analysis and/or PCR testing. The phylogenetic analysis of cytochrome b gene sequences revealed that H. catharti is closely related to MYCAMH1, a yet unidentified haemosporidian from wood storks (Mycteria americana) in southeastern USA and northern Brazil. Haemoproteus catharti and MYCAMH1 represent a clade that is unmistakably separate from all other Haemoproteus spp., being most closely related to Haemocystidium spp. from reptiles and to Plasmodium spp. from birds and reptiles.

Conclusions

Haemoproteus catharti is a widely-distributed parasite of turkey vultures in North America that is evolutionarily distinct from other haemosporidian parasites. These results reveal that the genetic diversity and evolutionary relationships of avian haemosporidians are still being uncovered, and future studies combining a comprehensive evaluation of morphological and life cycle characteristics with the analysis of multiple nuclear and mitochondrial genes will be useful to redefine the genus boundaries of these parasites and to re-evaluate the relationships amongst haemosporidians of birds, reptiles and mammals.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2165-5) contains supplementary material, which is available to authorized users.

Malaria Diagnosis Using Automated Analysers: A Boon for Hematopathologists in Endemic Areas

BACKGROUND

Haematological abnormalities are common in acute febrile tropical illnesses. Malaria is a major health problem in tropics. In endemic areas especially in the post monsoon season, it is not practical to manually screen all peripheral blood films (PBF) for malarial parasite. Automated analysers offer rapid, sensitive and cost effective screening of all samples.

AIM

The study was done to evaluate the usefulness of automated cell counters analysing their histograms, scatter-grams and the flaggings generated in malaria positive and negative cases. The comparison of other haematological parameters were also studied which could help to identify malaria parasite in peripheral blood smear.

MATERIALS AND METHODS

The blood samples were analysed using Beckman coulter LH-750. The abnormal scatter grams and additional peaks in WBC histograms were observed diligently & compared with normal controls. Haematological abnormalities were also evaluated.

STATISTICAL ANALYSIS

Statistical analysis was done by using software Epi-Info version 7.1.4 freely available from CDC website. Fisher exact test was applied to calculate the p-value and value < 0.05 was considered as significant. Final identification of malarial parasite species was done independently by peripheral blood smear examination by two pathologists.

RESULTS

Of all the 200 cases evaluated abnormal scatter grams were observed in all the cases of malaria while abnormal WBC histogram peaks were noted in 96% cases demonstrating a peak at the threshold of the histogram. The difference between number of slides positive for abnormal WBC scatter gram and abnormal WBC histogram peaks were statistically highly significant (p=0.007). So abnormal WBC scatter gram can better give idea of malarial parasite presence. Of the haematological parameters thrombocytopenia (92% cases) emerged as the strongest predictor of malaria.

CONCLUSION

It is recommended for haematopathologists to review the haematological data and the scatter plots on the analyser along with peripheral blood smear examination.

Erythritol predicted to inhibit permeation of water and solutes through the conducting pore of P. falciparum aquaporin

Plasmodium falciparum aquaporin (PfAQP) is a multifunctional channel protein in the plasma membrane of the malarial parasite that causes the most severe form of malaria infecting more than a million people a year. This channel protein facilitates transport of water and several solutes across the cell membrane. In order to better elucidate the fundamental interactions between PfAQP and its permeants and among the permeants, I conducted over three microseconds in silico experiments of atomistic models of the PfAQP-membrane system to obtain the free-energy profiles of five permeants (erythritol, water, glycerol, urea, and ammonia) throughout the amphipathic conducting pore of PfAQP. The profiles are analyzed in light of and shown to be consistent with the existent in vitro data. The binding affinities are computed using the free-energy profiles and the permeant fluctuations inside the channel. On this basis, it is predicted that erythritol, a permeant of PfAQP itself having a deep ditch in its permeation passageway, inhibits PfAQP's functions of transporting water and other solutes with an IC50 in the range of high nanomolars. This leads to the possibility that erythritol, a sweetener generally considered safe, may inhibit or kill the malarial parasite in vivo without causing undesired side effects. Experimental studies are hereby called for to directly test this theoretical prediction of erythritol strongly inhibiting PfAQP in vitro and possibly inhibiting P. falciparum in vivo.