[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/8804\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003EDry season parasite behaviour could provide new route for malaria treatment\u003C\/h2\u003E\u003Cp\u003EMalaria is not caused by a bacteria or a virus, but by a single-celled protozoa called \u003Cem\u003EPlasmodium \u003C\/em\u003Ethat parasitises humans. When a person is bitten by an infected mosquito, a few parasites flow in and journey towards their liver. They multiply there and eventually, in a new guise, the parasite bursts from liver cells and this time seeks out red blood cells.\u003C\/p\u003E\n\n\u003Cp\u003EThe parasite squeezes into a blood cell, multiplies and then breaks out to infect more cells. As it multiplies in the blood, a person may suffer symptoms of malaria, which include fever, headache and chills. If a mosquito bites this infected individual, it can suck up the parasite, which reproduces in the insect\u2019s gut, and infects whoever gets bitten next by the mosquito. The more people with parasite in their blood, the more mosquitoes will carry and pass on malaria to other people. \u0026nbsp;\u003C\/p\u003E\n\n\u003Cp\u003EThe most common and severe form of malaria is caused by the species \u003Cem\u003EPlasmodium falciparum. \u003C\/em\u003EIn areas where malaria is endemic, adults usually develop immunity to a level where they can keep parasite numbers down and not suffer symptoms.\u0026nbsp;\u003C\/p\u003E\n\n\u003Cp\u003E\u2018The parasite is tricky,\u2019 said Dr Richard Thomson-Luque, a parasitologist at Heidelberg University Hospital, Germany. \u2018You can develop some immunity, but you need several rounds of infection.\u2019 Children under the age of five, however, have little or no immunity and they account for 67% of all deaths from malaria.\u003C\/p\u003E\n\n\u003Cp\u003E\u003Cstrong\u003EDry season\u003C\/strong\u003E\u003C\/p\u003E\n\n\u003Cp\u003EMalaria hits Africa hardest. The continent was home to 94% of malaria cases and deaths in 2019, \u003Ca href=\u0022https:\/\/www.who.int\/news-room\/fact-sheets\/detail\/malaria\u0022 rel=\u0022noopener noreferrer\u0022 target=\u0022_blank\u0022\u003Eaccording to the World Health Organization\u003C\/a\u003E. In some parts of Africa, illness and death from malaria only occur during the six months of the rainy season. There are few, if any, mosquitoes around during the dry season, and no new infections or illnesses. But somehow the parasite lives on.\u003C\/p\u003E\n\n\u003Cp\u003EDr Silvia Portugal, a parasitologist at Germany\u2019s Max Planck Institute for Infection Biology in Berlin, has been investigating what happens during the dry season by studying blood samples taken from children in a village in Mali. This is part of \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/759534\u0022 rel=\u0022noopener noreferrer\u0022 target=\u0022_blank\u0022\u003Ea five-year research project\u003C\/a\u003E called DrySeasonPf, looking at the behaviour of \u003Cem\u003EPlasmodium falciparum \u003C\/em\u003Ein the dry season\u003Cem\u003E.\u003C\/em\u003E\u003C\/p\u003E\n\n\u003Cp\u003EDr Thomson-Luque, who had worked in her lab, travelled to Mali during the dry season in March 2018, as part of a related project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/839998\u0022 rel=\u0022noopener noreferrer\u0022 target=\u0022_blank\u0022\u003ENotToKill-NotToDie\u003C\/a\u003E. This is a time when people do not suffer from malaria symptoms. \u2018People are not sick during the dry season, from January to May,\u2019 Dr Thomson-Luque explained. \u2018Only when the rain starts.\u2019\u003C\/p\u003E\n\n\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018People are not sick during the dry season, from January to May. Only when the rain starts.\u2019\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Richard Thomson-Luque, Heidelberg University Hospital, Germany \u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\n\n\u003Cp\u003E\u003Cstrong\u003ESticky grabber\u003C\/strong\u003E\u003C\/p\u003E\n\n\u003Cp\u003EWith no mosquitoes around during the dry season, the parasite must live for up to six months inside people. This should offer the human immune system an opportunity to eliminate this parasitic foe, for example by filtering blood in the spleen to remove any misshapen cells that are infected with the parasite.\u003C\/p\u003E\n\n\u003Cp\u003ETo grow inside a person, the parasite usually folds itself into red blood cells and pops out a protein \u2013 like a sticky grabber \u2013 that attaches the infected cell to the walls of blood vessels. This allows the parasite to multiply and resist going through the spleen, where it would risk being removed.\u0026nbsp;\u003C\/p\u003E\n\n\u003Cp\u003EDr Portugal observed that the parasite drops to low numbers in the blood of infected children during the dry season. This seems like good news, but \u003Ca href=\u0022https:\/\/www.nature.com\/articles\/s41591-020-1084-0\u0022 rel=\u0022noopener noreferrer\u0022 target=\u0022_blank\u0022\u003Eher lab, including Dr Thomson-Luque, reported\u003C\/a\u003E that this might be a strategy used by the parasite to keep a low profile, when no mosquitoes are around to transmit it to new people.\u003C\/p\u003E\n\n\u003Cp\u003EThe parasite\u2019s trick seems to be to pop out different grabbers during the dry season, that do not stick so well to the walls of blood vessels. This allows more parasite to be filtered out by the spleen, meaning they stay in circulation for a shorter period of time and keep numbers low, which is one way to avoid immune attention. \u2018The immune system seems not to see really low numbers of the parasite. It is just not bothered,\u2019 Dr Portugal said.\u003C\/p\u003E\n\n\u003Cp\u003EThe \u003Cem\u003EPlasmodium \u003C\/em\u003Eparasite has about 5,500 genes, offering it far more options than, say, a virus when choosing proteins to show the body. This includes about 60 genes for the main grabber protein, which means 60 versions of the protein. This makes it harder for the body to recognise and build immunity to its foe.\u003C\/p\u003E\n\n\u003Cp\u003E\u003Cstrong\u003EDeck of cards\u003C\/strong\u003E\u003C\/p\u003E\n\n\u003Cp\u003EDr Portugal suspects that the parasite also uses these 60 genes like a deck of cards: it pulls out its stickiest protein first, which helps its numbers shoot up initially, but once the immune system responds and blocks that, it shuffles through dozens of grabber proteins that are less and less sticky. Dr Thomson-Luque\u2019s project focused on these changes in the stickiness of infected blood cells and will report on this in a scientific publication soon.\u003C\/p\u003E\n\n\u003Cp\u003EEventually, in the dry season, the parasite \u003Cem\u003EPlasmodium falciparum\u003C\/em\u003E uses a card that hits a sweet spot \u2013 a protein sticky enough to adhere to blood vessels and allow the parasite to reproduce, but which allows most progeny to be filtered out in the spleen. That way, numbers are kept low and the immune system mostly ignores the parasite.\u003C\/p\u003E\n\n\u003Cp\u003EOnce the rains come, and a mosquito siphons parasites from infected blood, the next person will get a form of the parasite with the deck stacked so that it adheres strongly to blood vessels and multiplies rapidly inside a new host. If this new person is under five, then the child can become severely ill and even die.\u003C\/p\u003E\n\n\u003Cp\u003EFor this reason, protective drugs are given to younger children during the transmission season in Africa. This makes sense, as they are the most vulnerable to malaria.\u003C\/p\u003E\n\n\u003Cp\u003EBut Dr Portugal wonders if it might be useful to give prophylactic drugs to older children and adolescents during the dry season, when their parasite numbers are low. \u2018During the dry season, you have a much lower prevalence of infected people \u2013 15 to 25%,\u2019 she explained. \u2018Whereas during the transmission season, you can have close to 80% of people infected.\u2019\u003C\/p\u003E\n\n\u003Cp\u003EThis could be an opportunity to treat children and young adults to try kill off the parasite during the dry season. Then, when the mosquitoes return with the rains, there would be a lower reservoir of parasite to begin with. This strategy is as yet unproven. But it illustrates how, by better understanding the strategies of this ancient human foe, researchers can devise new ways to outwit the parasite and push down the terrible burden of malaria. \u0026nbsp;\u003C\/p\u003E\n\n\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. 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