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Plasmodium vivax causes heavy burdens of disease across malarious regions worldwide. Mature P. vivax asexual and transmissive gametocyte stages occur in the blood circulation, and it is often assumed that accumulation/sequestration in tissues is not an important phase in their development. Here, we present a systematic study of P. vivax stage distributions in infected tissues of nonhuman primate (NHP) malaria models as well as in blood from human infections. In a comparative analysis of the transcriptomes of P. vivax and Plasmodium falciparum blood-stage parasites, we found a conserved cascade of stage-specific gene expression despite the greatly different gametocyte maturity times of these two species. Using this knowledge, we validated a set of conserved asexual- and gametocyte-stage markers both by quantitative real-time PCR and by antibody assays of peripheral blood samples from infected patients and NHP ( Aotus sp.). Histological analyses of P. vivax parasites in organs of 13 infected NHP ( Aotus and Saimiri species) demonstrated a major fraction of immature gametocytes in the parenchyma of the bone marrow, while asexual schizont forms were enriched to a somewhat lesser extent in this region of the bone marrow as well as in sinusoids of the liver. These findings suggest that the bone marrow is an important reservoir for gametocyte development and proliferation of malaria parasites. IMPORTANCE Plasmodium vivax malaria continues to cause major public health burdens worldwide. Yet, significant knowledge gaps in the basic biology and epidemiology of P. vivax malaria remain, largely due to limited available tools for research and diagnostics. Here, we present a systematic examination of tissue sequestration during P. vivax infection. Studies of nonhuman primates and malaria patients revealed enrichment of developing sexual stages (gametocytes) and mature replicative stages (schizonts) in the bone marrow and liver, relative to those present in peripheral blood. Identification of the bone marrow as a major P. vivax tissue reservoir has important implications for parasite diagnosis and treatment. Plasmodium vivax malaria continues to cause major public health burdens worldwide. Yet, significant knowledge gaps in the basic biology and epidemiology of P. vivax malaria remain, largely due to limited available tools for research and diagnostics. Here, we present a systematic examination of tissue sequestration during P. vivax infection. Studies of nonhuman primates and malaria patients revealed enrichment of developing sexual stages (gametocytes) and mature replicative stages (schizonts) in the bone marrow and liver, relative to those present in peripheral blood. Identification of the bone marrow as a major P. vivax tissue reservoir has important implications for parasite diagnosis and treatment.

Haemogregarines (Adeleorina) have a high prevalence in turtles. Nevertheless, there is only one Hepatozoon species described that infects Testudines so far; it is Hepatozoon fitzsimonsi which infects the African tortoise Kinixys belliana. Colombia harbours a great diversity of chelonians; however, most of them are threatened. It is important to identify and characterize chelonian haemoparasite infections to improve the clinical assessments, treatments and the conservation and reintroduction programs of these animals. To evaluate such infections for the Colombian wood turtle Rhinoclemmys melanosterna, we analysed blood from 70 individuals. By using the morphological characteristics of blood stages as well as molecular information (18S rRNA sequences), here we report a new Hepatozoon species that represents the first report of a hepatozoid species infecting a semi-aquatic continental turtle in the world. Although the isolated lineage clusters within the phylogenetic clades that have morphological species of parasites already determined, their low nodal support makes their position within each group inconclusive. It is important to identify new molecular markers to improve parasite species identification. In-depth research on blood parasites infecting turtles is essential for increasing knowledge that could assess this potential unknown threat, to inform the conservation of turtles and for increasing the state of knowledge on parasites.

Background Blood parasites have been the subject of much research, with numerous reports of the presence of microfilariae in the peripheral blood (circulating microfilariae) of birds belonging to many orders. Current limitations in molecular characterization methods and species identification using morphological characters of circulating microfilariae are major obstacles to improving our understanding the biology of Filarioidea species, particularly in wildlife. The aim of this study was to partially fill these gaps, with particular emphasis on morphological features of microfilariae, which are the most readily accessible stages of these pathogens. Methods Peripheral blood samples of 206 birds belonging to genera Acrocephalus (five species) and Sylvia (five species) were examined using the buffy coat method to process the blood samples for the presence of microfilariae. Positive birds were dissected to collect adult nematodes. Microfilariae and adult nematodes were described, and sequences of their mitochondrial cytochrome c oxidase subunit I and nuclear 28S rDNA gene fragments were obtained and used for molecular characterization and Bayesian phylogenetic inferences. Results Overall prevalence of microfilariae was 2.9%. Microfilariae were found in the blood samples from six birds (2 Acrocephalus scirpaceus and 1 each of A. arundinaceus , Sylvia atricapilla , S. borin and S. curruca ), which were dissected. All parasite species observed were new. Eufilaria acrocephalusi sp. n. and Eufilaria sylviae sp. n. were present in subcutaneous, peritracheal and periesophageal connective tissues in A. scirpaceus and S. borin, respectively. Splendidofilaria bartletti sp. n. was found in finger joins of S. atricapilla. Illustrations of microfilariae and adult nematodes are shown, and morphological and phylogenetic analyses identified the DNA barcode haplotypes that are associated with these species. Phylogenetic analysis places the parasites of different genera in different closely related clades. Conclusions Adult nematode morphological characters, which have been traditionally used in the taxonomy of Filarioidea species, have a phylogenetic value. Importantly, in our study parasites of different genera were readily distinguishable based on the morphology of their microfilariae. The link between molecular and morphology data requires more study in Filarioidea species research, particularly because this approach provides new knowledge on species identity using only readily accessible blood stages (microfilariae), thereby avoiding host dissection and thus minimizing harm to wildlife during research. Graphical Abstract

Background and Aim: Tick-borne pathogens such as Babesia canis, Hepatozoon canis, and Ehrlichia canis can cause serious disease in canines. Each blood parasite can be associated with different hematological characteristics in infected dogs. Identification of hematological alterations during routine laboratory screening of blood samples from dogs displaying clinical signs is essential for diagnosing blood parasitic infections. This study aimed to evaluate parasitic infections and hematological alterations in blood samples of infected dogs in Southern Thailand. Materials and Methods: A total of 474 blood samples were collected from dogs presented at the Veterinary Teaching Hospital of the Prince of Songkla University between 2016 and 2019. An automatic hematology analyzer was used to establish hematological values; peripheral blood films were screened for blood parasites and their detection was associated with hematological alterations to determine the odds ratio (OR). Results: This study found that E. canis (n=127) was the most common blood parasite infecting dogs in southern Thailand, followed by H. canis (n=100) and B. canis (n=24). Hematological alterations caused by Ehrlichia infections included anemia, thrombocytopenia, monocytosis, and eosinophilia (OR=14.64, 17.63, 20.34, and 13.43, respectively; p<0.01). The blood samples of Hepatozoon-infected dogs were characterized by anemia, thrombocytopenia, leukocytosis, neutrophilia, and monocytosis (OR=6.35, 3.16, 12.80, 11.11, and 17.37, respectively; p<0.01). Anemia, thrombocytopenia, eosinopenia, and lymphopenia (OR=10.09, 33.00, 20.02, and 66.47 respectively; p<0.01) were associated with B. canis-infected dogs. Conclusion: These data support the fact that hematological abnormalities are a hallmark for the identification of tick-borne infections. The hematological values, hereby reported, can be used as a guideline for the clinical diagnosis of canine blood parasitic infections in Southern Thailand.

Parasitic protozoa such as Lankesterella and Isospora are common in avian hosts, particularly in passerines. Despite their high prevalence, the diversity of these parasites within avian populations remains poorly understood. This study aimed to assess the diversity of Lankesterella and Isospora in passerine birds, using the SSU rRNA gene to characterize and compare the genetic variation in both parasites across multiple avian host species. For Isospora, the extraintestinal blood stages and oocysts from feces were compared. Minimum spanning networks were constructed to visualize haplogroups in relation to host specificity and to reveal the identity of various developmental stages. A total of 122 sequences from eight passerine species were used to generate a haplotype network for Lankesterella, and a total of 103 sequences (64 from blood and 39 from feces) was used for Isospora. We detected a total of 36 haplotypes for Lankesterella and 33 haplotypes for Isospora. In Lankesterella, we confirmed that the sedge warbler has its own specific lineages, whereas other warbler species share lineages belonging to three haplogroups; blue, great, marsh and willow tits have their own unique groups of lineages. Isospora is less host-specific than Lankesterella in avian hosts; nevertheless, Isospora sequences from blood and feces were identical in their respective hosts. Our findings provide insights into the diversity and host specificity of blood coccidians; moreover, we molecularly characterized the developmental stages of Isospora.

To investigate intestinal and blood parasites in people who have a history of traveling abroad during the Coronavirus disease-2019 pandemic and returning to Turkey. In this study, 104 patients with gastrointestinal system and/or fever complaints who had traveled abroad during the pandemic period and returned to Turkey were included. Parasitic agents were investigated by taking blood and stool samples from the patients. Additionally, urine samples were obtained from patients with hematuria or dysuria with the suspicion of schistosomiasis. A direct microscopic examination, the Crypto-Giardia immunochromatographic test, and ELISA methods were used in the examination of the stool samples. In order to detect species, blood samples were examined by preparing both the rapid diagnostic test and thick drop and thin smear preparations. One or more parasite species were detected in 38 (38.5%) of 104 patients included in the study. While intestinal parasites were detected in 16 (32%) of 50 patients who traveled to Iran and 16 (33.3%) of 48 patients who traveled to Northern Iraq, blood parasites were not found. was detected in all 5 of the patients with a history of traveling to Sudan. was detected in 1 patient who traveled to the African continent. It is vital to take precautions to prevent parasitic diseases, such as malaria and schistosomiasis, during travels to African countries. During travels to neighboring countries of Turkey, such as Northern Iraq and Iran, hygiene should be paid attention to, so as to prevent contracting intestinal parasitic diseases. In addition, it was concluded that people who plan to travel abroad should have information about the endemic parasitic diseases of the country that they are going to.

Birds are hosts to a diverse assemblage of vector-transmitted haemosporidian parasites. However, the true genetic diversity and many host–parasite interactions are still unknown, particularly in under-represented species groups such as wild doves and pigeons (Columbiformes). In this study, we examined the prevalence and lineage diversity of haemosporidian genera Plasmodium, Leucocytozoon, and Haemoproteus in three species of wild columbids, sampled in Germany. Examinations were performed by applying molecular methods (nested PCR and one-step multiplex PCR) and blood smear examination, and their respective advantages and disadvantages are discussed. In the case of the European Turtle Dove Streptopelia turtur, samples were collected along a west–east gradient throughout Germany, covering migratory birds from the Western and Central-Eastern flyway of this species. Although no infection was detected in the Stock Dove Columba oenas samples, 53% of Turtle Dove and 86% of Common Woodpigeon Columba palumbus harbored a parasite of at least one haemosporidian genus, revealing previously unknown lineage–host interactions. We were not able to demonstrate a correlation between infection status (presence or absence of infection based on PCR results) and parasitemia with condition based on the heterophil to lymphocyte ratio (H/L ratio). Neither lineage occurrence nor prevalence of infection followed any geographically specific patterns. Thus, haemosporidian lineages found in Turtle Doves could not be used as a marker of geographic origin that would allow the tracking of their nonbreeding distribution.

Avian malaria (Plasmodium) and related genera (Haemoproteus and Leucocytozoon) are diverse and widespread parasites. Despite the extent of knowledge on avian haemosporidian parasites, information about domestic and wild bird's blood parasites is overall insufficient in Iran. Prevalence of the haemosporidian parasites’ and phylogenetic relationship of lineages are studied by using molecular and morphological results of 152 examined hosts belonging to 17 species. Molecular analysis for haemosporidian detections demonstrated overall prevalence 22.36%. Inspected hosts mostly belonging to Common Pigeons (Columba livia) parasitized by Haemoproteus spp., and Hooded Crows (Corvus cornix) and Carrion Crow (C. corone) were identified as hosting Plasmodium spp. Detected lineages COLIV03, COQUI05, LINN01, ROFI04 and SGS01 are identified as new reports from Iran. We detected no evidence of Leucocytozoon lineages, while the high prevalence of H. columbae was found in Common Pigeons. Such investigation on avian blood parasites contributes to providing new information on the prevalence, epidemiology and geographical distribution of haemosporidian parasites circulating in domestic, pets and wild birds. Despite the extent of knowledge on avian haemosporidian parasite, information about domestic and wild bird's blood parasites is overall insufficient in Iran. Prevalence of the haemosporidian parasite' and phylogenetic relationship of lineages was estimated by molecular and morphological results of 152 examined hosts belonging to 17 species.

The aim of this research was to identify and to find out the prevalence of blood parasites in cattle in Kutalimbaru Subdistrict, Deli Serdang Regency. This research was conducted in Kutalimbaru Subdistrict, Deli Serdang Regency from December 2018 to February 2019. Normal/healthy cattle of different breeds were randomly selected from five locations, namely Sei Mencirim village, Sawit Rejo village, Silebo-lebo village, Sampe Cita village and Pasar X village. A total of 150 blood samples were collected for blood smears. Diagnostic techniques were tested using Giemsa's staining technique. The blood parasites were then identified and their prevalence was determined. The results showed that one species of blood parasite was successfully identified, all belonging to the blood parasite, namely, Theileria sp. with a prevalence of 33%. In addition, there were no species of blood parasite from the Anaplasma, Trypanosoma, and Babesia. This study suggests that theileriosis is spreading to even the other region in North Sumatera. To reduce the infection, follow up surveys of the blood parasites of the livestock, assess their distribution and infection rates of possible vectors are recommended and plans control measures against should be focused on reducing transmission to highly susceptible animal species.

Malaria killed over 600,000 people in 2022, a death toll that has not improved since 2015. Additionally, parasites and mosquitoes resistant to existing interventions are spreading across Africa and other regions. Vaccines offer hope to reduce the mortality burden: the first licensed malaria vaccines, RTS,S and R21, will be widely deployed in 2024 and should substantially reduce childhood deaths. In this Review, we provide an overview of the malaria problem and the Plasmodium parasite, then describe the RTS,S and R21 vaccines (the first vaccines for any human parasitic disease), summarizing their benefits and limitations. We explore next-generation vaccines designed using new knowledge of malaria pathogenesis and protective immunity, which incorporate antigens and platforms to elicit effective immune responses against different parasite stages in human or mosquito hosts. We describe a decision-making process that prioritizes malaria vaccine candidates for development in a resource-constrained environment. Future vaccines might improve upon the protective efficacy of RTS,S or R21 for children, or address the wider malaria scourge by preventing pregnancy malaria, reducing the burden of Plasmodium vivax or accelerating malaria elimination.In this Review, Duffy et al. examine the malaria vaccine landscape, showcasing both achievements and setbacks over the past decades. They discuss approaches and assays for different parasite stages, summarize recent advancements, propose a decision-making process for the field and identify future priorities to address unmet needs.