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What is the impact of Covid-19 on neglected tropical diseases?

The question is raised by researchers from the Unicamp Biology Institute in an article in Trends in Parasitology

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It is estimated that 1 billion people in the world are affected by so-called neglected tropical diseases (NTDs), such as leishmaniasis and Chagas disease. What has been the impact of Covid-19 on these already vulnerable populations, who traditionally suffer from precarious health, sanitation and economic conditions? This is a question posed by researchers from Unicamp, in an article in Trends in Parasitology (Cell group), one of the most respected magazines in the area. The authors survey articles published about the pandemic since its beginning in March 2020 and discuss its possible medium and long-term effects on NTD control and eradication programs on the planet.

The researchers highlight the co-infections of severe acute respiratory syndrome (Sars-Cov-2) with ectoparasites, helminths and protozoa described in the literature, and the urgent need to understand the conditions of these associated pathologies in order to continue the measures that have been adopted for decades in the control of neglected parasites. "The pandemic has been dragging these populations into even more extreme poverty. According to estimates by the World Bank, this economic crisis, which lasts from one to two years, will generate a cycle that fuels the emergence and makes it difficult to eradicate these diseases. Several of them are difficult to eradicate, but others were in the process of being controlled", says professor Danilo Ciccone Miguel, from the Institute of Biology (IB) at Unicamp.

Danilo Ciccone Miguel, parasitologist professor at the Institute of Biology (IB): economic crisis will generate a cycle that fuels the emergence and makes it difficult to eradicate these diseases
Danilo Ciccone Miguel, parasitologist professor at the Institute of Biology (IB): economic crisis will generate a cycle that fuels the emergence and makes it difficult to eradicate these diseases

Danilo Miguel has been a professor hired for the area of ​​parasitology since 2013 and researcher responsible for the Leishmania Infection Biology Study Laboratory (Lebil) since 2015. "At Lebil, we work with protozoa, mainly in the search for drugs for diseases caused by them, with an emphasis on Leishmania. I teach classical parasitology for several courses at Unicamp, currently coordinating the discipline for undergraduates at the Faculty of Medical Sciences."

The article in Trends in Parasitology, highlights the researcher, points out guidelines listed to control or try to eradicate many NTDs by 2030, but which will suffer from the impact of Covid-19. "The British government has already warned that around 90% of its investment in assistance policies to control these diseases will be cut, which will drastically impact former colonies such as India and Kenya, where they are accompanied by mass treatment, mainly of children. Around 250 million children receive treatment each year. Countries generally working in partnership with non-governmental organizations will have more limited resources from now on."

The drama of hunger, which worsens and alters the nutritional status of these populations, leads the authors of the article to raise a flag of attention to the medical and scientific community, especially in Brazil, which does not have permanent policies to control NTDs. "Our policies change from government to government. We had, for example, mass treatment policies for schistosomiasis in the Northeast and intense surveillance of malaria in the Amazon. There are no systematic policies for leishmaniasis itself, which in recent decades has become heavily urbanized, leaving of being a rural disease and coming closer to us. NTD treatments are difficult, expensive, toxic and do not always lead to a clinical cure."

For the IB professor, in relation to parasites, an interesting aspect is that some decreased with Covid-19 and others increased, with cases of patients that still need to be better understood, as one year is the deadline for observation. "Covid-19 has imposed lockdown and social isolation and we hope this will reflect on diseases transmitted through physical contact. A study in Argentina showed that lice infestation, pediculosis, decreased in Buenos Aires [from 70% to 43%], because children stopped attending school. On the other hand, there was an explosion of scabies cases in Turkey, because people left work in the cities and crowded into homes in peripheral regions, with more family members and less hygiene conditions; scabies is a mite that spreads easily and hospitals were unable to even change bed linen due to the high demand for beds."

Macrophage infected with the protozoan that causes leishmaniasis, a neglected tropical disease studied by the Lebil group
Macrophage infected with the protozoan that causes leishmaniasis, a neglected tropical disease studied by the Lebil group

Main NTDs

Miguel explains that the term neglected tropical diseases (NTD) was coined in the 1970s, at the Rockefeller Foundation, and in the early 2000s it was accepted and incorporated by Doctors Without Borders (MSF) and then by the World Health Organization (WHO). , becoming the official term for diseases that affect the poorest and most vulnerable populations on the planet. "They are generally chronic, debilitating and often fatal, while we have very poor, outdated medication options, in addition to the lack of vaccines. There are many NTDs, which are divided by the types of pathogens that cause them."

In his area of ​​protozoa, the researcher recalls that malaria left the list of neglected diseases due to the increase in financial support, which does not mean that it no longer has a global impact, as it still affects a large proportion of children and pregnant women on the African continent. "Malaria is transmitted by an insect of the genus Anopheles and in its history it has already affected areas that are not so tropical, such as swampy regions in Europe and Washington DC. These countries managed to control malaria over time, with the development of antimalarials and mass drug distribution policies. The Bill and Belinda Gates Foundation, for example, supports campaigns to distribute mosquito nets in Africa, which has had a huge impact and still does."

NTDs include diseases caused by protozoa such as leishmaniasis (both cutaneous and visceral), Chagas disease (caused by trypanosoma cruzi) and sleeping sickness (or African trypanosomiasis), caused by subspecies of Trypanosoma brucei in Africa. There are also amoeba and helminthiasis infections transmitted by contaminated soil (with eggs and/or worm larvae). Flea, lice and tick infections are called infestations. Among the viruses, dengue and yellow fever deserve to be highlighted. Among the main bacterial infections is trachoma, which affects the eyes and is one of the main causes of blindness in the world; There are also infections caused by fungi.

Pay attention to possible interactions between parasites and their hosts in situations of co-infection with Sars-Cov-2
Pay attention to possible interactions between parasites and their hosts in situations of co-infection with Sars-Cov-2

Coinfection in Brazil

Danilo Miguel informs that Brazil has records of Sars-Cov-2 co-infection for Chagas disease, with patients with chronic Chagas cardiomyopathy responding worse to Covid, so much so that they are now in the special group for vaccination. "We do not yet know whether or not in the case of visceral leishmaniasis, with systemic infection, the modulated immune response can alter the course of the Sars-Cov-2 infection. What we propose to scientists and laboratories is that they study these infections, paying attention to the profile of co-infection. How will an already established Sars-Cov-2 infection occur in a region endemic for NTDs due to the parasite, and vice versa? In these endemic regions with circulating parasites, what happens with the arrival of Sars-Cov -2? Does each NTD manifest itself differently? Each case needs to be studied individually and, most importantly, reported."

In this sense, the IB professor draws attention to the population made up of immigrants, refugees and tourists, even though restrictions on air traffic and tourism may have impacted the transport of parasites. "It's not a simple equation, it depends on the population affected, and refugees and immigrants continue to leave in search of better living conditions. Before the pandemic, Japan, Australia and Germany were very concerned about the transit of Latin American immigrants, because they carry along with the trypanosoma cruzi, which affects almost 7 million people on the continent and, without knowing that they have Chagas disease, they can donate blood or even organs, "donating" the parasite to individuals from other countries."

Another point made in the article concerns immunosuppressants that are being used against Covid-19 to control inflammation, but depending on the type of medication, such as corticosteroids, they can stimulate the reproduction of some parasites. "This is already well known in the case of a worm called strongyloides: when a person is treated with corticosteroids, these parasites begin to change much more quickly and cause a disseminated infection, which is quite serious; We are talking about a disease that is highly neglected and spread throughout the world."

The postgraduate students and co-authors of the article: Nathalia Grazzia, Letícia Rosa, Karen Minori and Mariana Brioschi
The postgraduate students and co-authors of the article: Nathalia Grazzia, Letícia Rosa, Karen Minori and Mariana Brioschi

Confinement and vaccination

It is part of the complex equation, adds the Unicamp researcher, to know whether or not the confinement caused by Covid-19 brought benefits to the containment of neglected tropical diseases. "If there is a positive aspect for our area in the face of so much tragedy, we can mention vaccination. Some technologies that have been developed against Covid-19 are not new, they are already there, used mainly in animals and in human tests, with platforms using recombinant DNA and RNA technology. Soon we will be able to have vaccine models for protozoa, for example, using these technologies. It is as if the gate has been opened. I believe that in the next five or ten years many new developments will emerge in terms of vaccines against these parasites ."

Against Covid-19, however, the message at the end of the article in Trends in Parasitology is that Brazil was very ineffective in controlling the disease, like India and African, Caribbean and Middle Eastern countries. "Vaccination coverage needs to be reinforced, mainly because these populations are the ones that suffer most from neglected tropical diseases. The situation seems very chaotic to me. Our warning, in this review, is exactly that control programs do not stop, or we will back to square one. We were doing well, with diseases that would be eradicated or with few isolated outbreaks in the world by 2050. There is an imminent risk of them returning."

Danilo Ciccone Miguel signs the article "The impact of Covid-19 on neglected parasitic diseases: what to expect", with four IB postgraduate students: Mariana BC Brioschi, Letícia B. Rosa, Karen Minori and Nathalia Grazzia, all Capes scholarship holders. "Students live under enormous threat of losing their scholarships, given the dismantling of science, which will impact the training of new scientists. We have a scandalous reflection of how the difficulty we face in managing Covid-19 can impact our lives, as individual and collective level. We have relatives and friends dying and a collapsed economy. But as I tell the students, we can't just think about the parasite: the person who has elephantiasis and can't get up because of swelling in the leg, won't be able to work either , support the family and generate wealth."

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The question is raised by researchers from the Unicamp Biology Institute in an article in Trends in Parasitology

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