Answer to Case 558

Answer toParasite Case of the Week 558:Plasmodium falciparummalaria,>10% parasitemia. NEGATIVE rapid antigen.Sowhy is the rapid antigen test negative???As noted by our readers, there are many possible reasons for apositive blood smear and negative rapid malaria antigen test (RDT). Here are our options, along with the reasons why each is or isn't a likely explanation in this case:This is babesiosis, and not malaria. This is a very important consideration given the morphologic similarities betweenBabesiaspp. andPlasmodium falciparum.However, the moprhologic features in this case are highly consistent withP. falciparum, including the presence of relatively-homogenous rings, without the size and shape pleomorphism usually seen withBabesiaspp. There are also applique forms and headphone forms (arrows, below) which are characteristic, but not definitive, forP. falciparuminfection. There may also be a hint of hemazoin (malaria pigment), but it is not obvious. Overall, we can rule out babesiosis based on the microscopic morphology.The negative RDT is due to deletion of theP. falciparum histidine rich protein II repeat region in the parasite infecting this patient. This deletion has been reported in some African and South American countries, including Kenya where this patient had recently traveled. While this is a good thought, it would not explain why the pan-malaria antigen band (in this case, aldolase) is also absent, resulting in a completely negative RDT result. Thus...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs

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In this study we analyze the distribution of apicomplexans across a range of both host-associated and free-living environments. Using publicly available small subunit (SSU) rRNA gene databases, high-throughput environmental sequencing (HTES) surveys, and our own generated HTES data, we developed an apicomplexan reference database, which includes the largest apicomplexan SSU rRNA tree available to date and encompasses comprehensive sampling of this group and their closest relatives. This tree allowed us to identify and correct incongruences in the molecular identification of apicomplexan sequences. Analyzing the diversity a...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
Answer to Parasite Case of the Week 554:Babesiaspecies. Without a travel history, the differential diagnosis includesPlasmodium falciparummalaria given that only ring forms are seen and there is a high parasitemia; however, the following features are supportive of babesiosis:1. Multiple (4) small forms within a single cell that are not a clear schizont form ofPlasmodium.2. Easily-identified extracellular forms.3. Lack of malaria pigmentAs Blaine mentioned, the rings are not thin and delicate as would normally be seen withP. falciparuminfection. While thicker rings are commonly seen in'older'blood (i.e., blood that was>2...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs
Publication date: Available online 19 July 2019Source: Veterinary ParasitologyAuthor(s): Mohamed Abdo Rizk, Shimaa Abd El-Salam El-Sayed, Sabry El-Khodery, Naoaki Yokoyama, Ikuo IgarashiAbstractThere is an innovative approach to discovering and developing novel potent and safe anti-Babesia and anti-Theileria agents for the control of animal piroplasmosis. Large-scale screening of 400 compounds from a Malaria Box (a treasure trove of 400 diverse compounds with antimalarial activity has been established by Medicines for Malaria Venture) against the in vitro growth of bovine Babesia and equine Babesia and Theileria parasites ...
Source: Veterinary Parasitology - Category: Veterinary Research Source Type: research
In this study, the 400 compounds in the Pathogen Box provided by the Medicines for Malaria Venture foundation were screened against Babesia bovis, Babesia bigemina, Babesia caballi, and Theileria equi. A fluorescence-based method using SYBR Green 1 stain was used for initial in vitro screening and determination of the half maximal inhibitory concentration (IC50). The initial in vitro screening performed using a 1 μM concentration as baseline revealed nine effective compounds against four tested parasites. Two “hit” compounds, namely MMV021057 and MMV675968, that showed IC50  100 were selected. The IC50s ...
Source: International Journal for Parasitology: Drugs and Drug Resistance - Category: Parasitology Source Type: research
Abstract Babesia divergens is an intra-erythrocytic parasite that causes malaria-like symptoms in infected people. As the erythrocyte provides the parasite with the infra-structure to grow and multiply, any perturbation to the cell should impact parasite viability. Support for this comes from the multitude of studies that have shown that the sickle trait has in fact been selected for because of the protection in provides against a related Apicomplexan parasite, Plasmodium that causes malaria. In this paper, we examine the impact of both sickle cell anemia and sickle trait RBC environment on different aspects of th...
Source: Haematologica - Category: Hematology Authors: Tags: Haematologica Source Type: research
Abstract Although Babesia represents an important worldwide veterinary threat and an emerging risk to humans, this parasite has been poorly studied as compared to Plasmodium, its malaria-causing relative. In fact, Babesia employs highly specific survival strategies during its intraerythrocytic development and its intricate journey through the tick vector. This review introduces a substantially extended molecular phylogeny of the order Piroplasmida, challenging previous taxonomic classifications. The intriguing developmental proficiencies of Babesia are highlighted and compared with those of other haemoparasitic Ap...
Source: Trends in Parasitology - Category: Parasitology Authors: Tags: Trends Parasitol Source Type: research
Evaluation of 4-amino 2-anilinoquinazolines against Plasmodium and other apicomplexan parasites in vitro and in a P. falciparum humanized NOD-scid IL2Rγnull mouse model of malaria. Antimicrob Agents Chemother. 2018 Dec 17;: Authors: Gilson PR, Nguyen W, Poole WA, Teixeira JE, Thompson JK, Guo K, Stewart RJ, Ashton TD, White KL, Sanz LM, Gamo FJ, Charman SA, Wittlin S, Duffy J, Tonkin CJ, Tham WH, Crabb BS, Cooke BM, Huston CD, Cowman AF, Sleebs BE Abstract A series of 4-amino 2-anilinoquinazolines optimized for activity against the most lethal malaria parasite of humans, Plasmodium falciparum, w...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
Publication date: Available online 7 August 2018Source: International Journal for Parasitology: Drugs and Drug ResistanceAuthor(s): Marie Jalovecka, David Hartmann, Yukiko Miyamoto, Lars Eckmann, Ondrej Hajdusek, Anthony J. O'Donoghue, Daniel SojkaAbstractBabesiosis is a tick-transmitted zoonosis caused by apicomplexan parasites of the genus Babesia. Treatment of this emerging malaria-related disease has relied on antimalarial drugs and antibiotics. The proteasome of Plasmodium, the causative agent of malaria, has recently been validated as a target for anti-malarial drug development and therefore, in this study, we invest...
Source: International Journal for Parasitology: Drugs and Drug Resistance - Category: Parasitology Source Type: research
Abstract Babesia is a tick-borne intraerythrocytic parasite that is clinically and diagnostically similar to malaria parasite, conferring risk of misdiagnosis in areas where both parasites are endemic. Data on Babesia in humans in Africa are lacking, despite evidence that it is present in regional animal populations. Samples that were collected in November 2014 to July 2015 in Kilosa district, Tanzania, were evaluated for evidence of malaria and Babesia infection. Clinical data and laboratory samples (i.e., hemoglobin, rapid diagnostic testing [RDT] for malaria, peripheral blood smear, and dried blood spots) from ...
Source: The American Journal of Tropical Medicine and Hygiene - Category: Tropical Medicine Authors: Tags: Am J Trop Med Hyg Source Type: research
In conclusion, seroreactive antigen 5-1-1, a member of the BMN1 protein family, is expressed on the outer surface of B. microti and is a promising candidate antigen for the early diagnosis of babesiosis. rBmSA5-1-1 ELISA and ICT methods show good potential for detecting specific antibodies in mice at different stages of infection. PMID: 29559329 [PubMed - as supplied by publisher]
Source: Acta Tropica - Category: Infectious Diseases Authors: Tags: Acta Trop Source Type: research
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