#leishmania

Researchers in Brazil who analyzed samples from a 46-year-old patient in the Northeast state of Maranhão found an amphotericin B-resistant strain of the parasite Leishmania amazonensis circulating for the first time in the country. Amphotericin B is widely used to treat cutaneous leishmaniasis, a skin infection caused by sandfly bite.

The disease is characterized by skin lesions that persist for months but can be cured. In the case in question, however, the patient had the diffuse form of cutaneous leishmaniasis, which is rare, hard to treat, and associated with an inadequate immune response by the organism.

The patient also had HIV, which causes AIDS, making his condition even harder to combat. He had previously received treatments that were unsuccessful. The parasite was refractory to a therapeutic regimen involving the main drugs used against leishmaniasis in Brazil: meglumine antimoniate (preferred for several decades despite low efficacy) and amphotericin B (one of the few options available in Brazil for treating diffuse cutaneous leishmaniasis).

The researchers decided to find out how resistant the strain isolated from this patient was to amphotericin B by means of in vitro and in vivo trials. “We used mice infected by the isolated parasite for the in vivo model. We treated the mice with amphotericin B and two other drugs to which the patient had not been exposed: miltefosine and paromomycin,” says Adriano Cappellazzo Coelho, principal investigator for the study and a professor at the State University of Campinas’s Institute of Biology (IB-UNICAMP) in São Paulo state. 

Finished coloured pencil illustration - portrait of a man with leishmaniasis - by @claire_carswell

Plug and Parasitise

Responsible for leishmaniasis, a disease that can cause severe skin lesions or affect internal organs, Leishmania parasites use biting phlebotomine sand flies as vectors to move between hosts. To maximise transmission into a new victim, they produce a thick fluid, the promastigote secretory gel (PSG), which obstructs the flies’ digestive system. Looking inside an infected fly, using micro-computed tomography, reveals how the mass of parasites and PSG distends the midgut (in green, with ingested blood in red), and forces a valve, lying between the foregut and midgut, to open more widely. This makes it more difficult for flies to take in blood, causing them to feed for longer than usual when they next bite, and so increasing the chance of parasites being regurgitated. If infected flies do manage to get another meal, parasite numbers grow and the volume of the PSG plug increases, further boosting transmission during later bites.

Written by Emmanuelle Briolat

Image from work by Martin JR Hall and colleagues

Natural History Museum, London, UK

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in PLOS Pathogens, August 2021

This flesh-eating parasite is one of the most deadly in the world. Can a vaccine protect us?

Holo Victory

Put on your 3D glasses now! Here a 3D effect known as an anaglyph mimics how the parasite Leishmania mexicana swims with different speeds and trajectories – some may be coming straight at you by way of a stereoscopic illusion. The video is actually based on research using another 3D technique – holograms. By comparing light patterns around the wriggling parasites, holographic microscopy tracks their movement in 3D – reconstructing (and here simulating) how their tails, or flagella, propel them through human blood. Researchers find that infectious forms of L. mexicana adapt their swimming style to follow a chemical to trail straight towards macrophages, immune cells that usually destroy pathogens. In fact, the parasites use macrophages to spread their infection – but with these new insights scientists may be able to intervene and stem the spread of diseases like leishmaniasis.

Written by John Ankers

Video from work by Rachel C Findlay and colleagues

York Biomedical Research Institute, Department of Biology, and Department of Physics, University of York, York, UK

Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in eLife, June 2021

Yakarca Sineği ve Leishmania Paraziti: Tehlike ve Korunma Yöntemleri Manisa Celal Bayar Üniversitesi Tıp Fakültesi Öğretim Üyesi Prof. Dr. Ahmet Özbilgin, yakarca sineklerinin taşıdığı Leishmania adlı parazitin ciddi sağlık riskleri oluşturduğuna dikkat çekti. Bu sineklerin insanlara ölümcül olabilen hastalıklar bulaştırabildiğini ve özellikle Manisa bölgesinde tropikal hastalıkların yaygınlaşma…