{"id":281457,"date":"2019-04-16T15:03:41","date_gmt":"2019-04-16T18:03:41","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/?p=281457"},"modified":"2019-04-17T09:58:29","modified_gmt":"2019-04-17T12:58:29","slug":"from-monkeys-to-people-2","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/from-monkeys-to-people-2\/","title":{"rendered":"From monkeys to people"},"content":{"rendered":"

In 1966, Le\u00f4nidas Deane (1914\u20131993), a parasitologist from Par\u00e1 State who at that time was a professor at the University of S\u00e3o Paulo Medical School (FMUSP), described the first known case of human malaria caused by the protozoan Plasmodium simium<\/em>. Previously, this parasite species was thought to cause the disease only in monkeys. The protozoan was found in the blood of a park ranger who collected mosquitoes for researchers from the forest canopy at the Horto Florestal Park in the city of S\u00e3o Paulo, which is a wild area in which no case of malaria had been previously recorded. The possibility that mosquitoes that had bitten infected monkeys could transmit this form of malaria to people could not be demonstrated at the time when the case appeared. Half a century later, a team from the Oswaldo Cruz Foundation (Fiocruz) returned to Deane\u2019s hypothesis and proposed a sixth form of human malaria that was transmitted by mosquitoes infected with P. simium<\/em> after biting contaminated monkeys. This hypothesis has not been confirmed by other studies and recognized by international bodies.<\/p>\n

Malaria is transmitted to humans by mosquitoes of genus Anopheles<\/em> contaminated with infectious agents\u2014protozoa of genus Plasmodium<\/em>. The forms of malaria are differentiated by microscopic identification of Plasmodium<\/em> species that multiply in red blood cells. Although the initial symptoms are similar, including fever, chills, headache, and body aches, progression of the disease depends on its causative agent. For instance, P. vivax<\/em> causes a milder form of malaria, whereas P. falciparum infection is more severe (see the table<\/a><\/em>). One form (caused by P. knowlesi<\/em>) was described in 1965 in Malaysia as the first type of malaria transmitted to humans by mosquitoes infected after biting monkeys; this form is a zoonotic disease involving animals, which function as reservoirs of the infectious agent. P. knowlesi<\/em> was described in 1932 in monkey blood and is easily confused with P. malariae<\/em> and P. falciparum<\/em>. This variant is responsible for a growing number of cases in Malaysia (703 in 2011 and 996 in 2013), Thailand, Indonesia, Vietnam, and the Philippines.<\/p>\n

The conclusion that monkeys can serve as a reservoir for the protozoa that cause malaria in Brazil was reached after analysis of blood samples from three animals and 28 residents in the mountain region of Rio de Janeiro. \u201cWe initially believed they were cases of malaria caused by P. vivax<\/em>, the most common form in Brazil and in the region,\u201d says parasitologist Cl\u00e1udio Tadeu Daniel-Ribeiro, a Fiocruz researcher in Rio de Janeiro. \u201cSince the symptoms were slightly different, we considered the possibility that it might be the monkey malaria described by Deane.\u201d<\/p>\n

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P. vivax<\/em> and P. simium<\/em> are very similar in microscopic blood tests. The Fiocruz team distinguished the two types by identifying two different stretches of the mitochondrial DNA from each species and considered the possibility that P. simium<\/em> infection could explain outbreaks in Rio de Janeiro\u2019s Atlantic Forest regions. The researchers identified P. simium<\/em> in 28 of the 49 autochthonous (local) cases of malaria recorded in the region in 2015 and 2016. This work was performed by Fiocruz parasitologist Patr\u00edcia Brasil and described in an October article published in Lancet Global Health<\/em> warning of the risk of malaria in areas far from the Amazon, which accounted for 99% of the 131,000 cases recorded from January to September 2017 according to the Brazilian Ministry of Health. The World Health Organization registered 214 million cases of malaria and 438,000 deaths from the disease in 95 countries in 2015.<\/p>\n

A Fiocruz team in Minas Gerais state also used molecular analysis to identify P. simium<\/em> in nine of a group of 65 brown howler monkeys (Alouatta guiariba<\/em>) and robust capuchin monkeys (Sapajus<\/em> spp.) living in captivity or in areas of the Atlantic Forest in the city of Indaial, Santa Catarina State, as reported in a 2014 study published in Mem\u00f3rias do Instituto Oswaldo Cruz<\/em>. The muriqui (Brachyteles <\/em>spp.) is another primate species that can harbor this parasite; the protozoan was identified in 1951 in a monkey from a forest near the city of S\u00e3o Paulo and described for the first time by the parasitologist Fl\u00e1vio Oliveira Ribeiro da Fonseca (1900\u20131963), who was a native of Rio de Janeiro State and professor at FM-USP. P. simium<\/em> has also been found in the blood of monkeys in the states of S\u00e3o Paulo, Esp\u00edrito Santo, and Paran\u00e1 according to biologist Cristiana Ferreira Alves de Brito, who is a researcher at Fiocruz in Belo Horizonte.<\/p>\n

\u201cMalaria in humans outside of the Amazon region is much more lethal, because doctors in cities in the south and southeast of the country do not suspect that the high fever and anemia could be symptoms of malaria,\u201d says Brito. \u201cWe need to warn doctors and health centers to make the correct diagnosis, because the treatment is efficient.\u201d In November 2010, one traveler from Nigeria and another from the Ivory Coast died of malaria in S\u00e3o Paulo after seeking care in hospitals where doctors did not diagnose the disease (see<\/em> Pesquisa FAPESP, issue No. 186<\/em><\/a>). The S\u00e3o Paulo State Center for Epidemiological Surveillance registered eight autochthonous cases of malaria in humans in 2016 and five as of October 2017, mostly in coastal cities near forested areas.<\/p>\n

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\u201cBecause it is difficult for physicians outside the Amazon region to recognize the disease, the description of malaria cases in Rio de Janeiro as a zoonotic disease is a major challenge for control of this disease,\u201d says biologist Silvia Di Santi, a researcher at the Endemic Diseases Oversight Office (SUCEN) and the Institute of Tropical Medicine at FM-USP. \u201cTo better understand this situation, it is essential to broaden the areas of study in regions with the same epidemiological profile and describe the complete transmission cycle with mosquitoes, monkeys, and infected humans.\u201d<\/p>\n

The cases of malaria transmitted in areas of the Atlantic Forest along the coast are a benign form of the disease according to Di Santi. Inhabitants of the mountainous region of Rio de Janeiro State infected with P. simium<\/em> exhibit similar but milder symptoms than those caused by P. vivax<\/em> and respond to treatment with a combination of chloroquine and primaquine. Two patients who were unable to take primaquine received only chloroquine and had not relapsed as of 18 months later. According to Ribeiro, the fact that malaria did not reappear in these people is an indication that P. simium<\/em>, unlike P. vivax<\/em>, cannot maintain dormant forms of the parasite in the liver, which are usually eliminated by primaquine.<\/p>\n

According to Ribeiro, the infection could be caused by P. simium<\/em> or P. vivax<\/em> that adapted to the monkey and reached humans via mosquitoes, adding, \u201cWe will only know when we have sequenced their complete genomes.\u201d There is no expert consensus regarding whether P. vivax<\/em> and P. simium<\/em> are even different species or variations of the same species. In a 2005 article in PNAS, researchers from the University of California at Irvine argued that at least two transfers of P. vivax from monkeys to humans or vice versa may have occurred over the past several thousand years. \u201cIn Africa,\u201d says Brito, \u201cvivax and falciparum came from monkeys to humans.\u201d<\/p>\n

Scientific articles<\/strong>
\nBRASIL, P. et al<\/em>. Outbreak of human malaria caused by Plasmodium simium in the Atlantic Forest in Rio de Janeiro: A molecular epidemiological investigation<\/a>. Lancet Global Health<\/strong>. v. 5, i. e1038-1046. 2017.
\nCOSTA, D. C. Plasmodium simium\/Plasmodium vivax infections in southern brown howler monkeys from the Atlantic Forest<\/a>. Mem\u00f3rias do Instituto Oswaldo Cruz<\/strong>. v. 109 (5), i. 641-53. 2014.
\nLIM, C. S. et al<\/em>. Plasmodium vivax: Recent world expansion and genetic identity to Plasmodium simium<\/a>. PNAS<\/strong>. v. 102 (43), i. 15523-28. 2005.<\/p>\n","protected":false},"excerpt":{"rendered":"A Fiocruz team suggests a sixth form of malaria that is transmitted by mosquitoes infected after biting wild primates in the Atlantic Forest","protected":false},"author":17,"featured_media":281458,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[156],"tags":[],"coauthors":[5968],"class_list":["post-281457","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cover"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/281457","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=281457"}],"version-history":[{"count":4,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/281457\/revisions"}],"predecessor-version":[{"id":283546,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/281457\/revisions\/283546"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media\/281458"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=281457"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=281457"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=281457"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=281457"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}