IRVINE, California, January 20, 2010 (ENS) – The parasite that causes malaria in humans has been found in gorillas, along with two new species of malaria parasites, reports a study by French and American scientists.
Co-authored by University of California, Irvine biologist Francisco Ayala, the study, published Tuesday, confirms a recent discovery by Ayala and colleagues that human malignant malaria, caused by Plasmodium falciparum, originated from a closely related parasite found in chimpanzees in equatorial Africa.
Malignant malaria is an infectious disease that puts the sick person through cycles of chills, fever, and sweating. It is transmitted to humans by the bite of a female anopheles mosquito infected with P. falciparum.
Malaria caused by this parasite is a leading cause of death and disease globally, particularly among young children. P. falciparum is responsible for 85 percent of malignant malaria infections in humans and nearly all deaths from the disease.
The researchers cautioned that increased contact between primates and humans, mostly due to logging and deforestation, creates a greater risk of new parasites being transmitted to humans.
Increased contact also could further jeopardize endangered ape populations by spreading diseases to them.
Finding P. falciparum in gorillas also complicates the challenge of eradicating malaria, the researchers said.
“Hundreds of billions of dollars are spent each year toward ridding humans of malignant malaria. But success may be a pyrrhic victory, because we could be re-infected by gorillas – just as we were originally infected by chimps a few thousand years ago,” said Dr. Ayala.
The researchers analyzed fecal samples from 125 wild chimpanzees and 84 gorillas in Cameroon and tested blood samples from three gorillas in Gabon.
They identified two new closely related species of malaria parasites – Plasmodium GorA and Plasmodium GorB – that infect gorillas.
The animals also were found to harbor P. falciparum, previously thought to only infect humans.
In August 2009, Dr. Ayala and colleagues published a study reporting that P. falciparum had been transmitted to humans from chimpanzees perhaps as recently as 5,000 years ago – and possibly through a single mosquito. Before their study, malaria’s origin had been unclear.
Chimpanzees were known to carry the parasite Plasmodium reichenowi, but most scientists assumed the two parasites had existed separately in humans and chimpanzees for the last five million years.
The discovery could aid the development of a vaccine for malaria, which each year causes two million infant deaths and sickens about 500 million people, mostly in sub-Saharan Africa.
“When malaria transferred to humans, it became very severe very quickly,” said Ayala last August. “The disease in humans has become resistant to many drugs. It’s my hope that our discovery will bring us closer to making a vaccine.”
The discovery also furthers understanding of how infectious diseases such as HIV, SARS, and avian and swine flu can be transmitted to humans from animals.
In addition to Ayala, French scientists Franck Prugnolle, Patrick Durand, Cecile Neel, Benjamin Ollomo, Celine Arnathau, Lucie Etienne, Eitel Mpoudi-Ngole, Dieudonne Nkoghe, Eric Leroy, Eric Delaporte, Martine Peeters and Francois Renaud worked on the gorilla study.
Funding was provided by France’s Institute of Research for Development, National Center for Scientific Research, Ministry of Foreign Affairs and National Agency for Research on AIDS, as well as Gabon’s International Center for Medical Research in Franceville.
The findings were published this week in the journal “Proceedings of the National Academy of Sciences.”
Simultaneously, a group of Australian researchers has published a study identifying a group of proteins that could form the basis of an effective vaccine against malaria.
Dr. James Beeson, Dr. Freya Fowkes and Dr. Jack Richards from the Walter and Eliza Hall Institute, along with Dr. Julie Simpson from the University of Melbourne, have identified proteins produced by malaria parasites during the blood-stage that are effective at promoting immune responses that protect people from malaria illness.
Funded by the National Health and Medical Research Council of Australia and a Victorian Government Operational Infrastructure Support grant, their is published today in the international journal PLoS Medicine.
“As well as presenting an enormous health burden, malaria also has a major impact on social and economic development in countries where the disease is endemic,” Dr. Beeson said. “Vaccines are urgently needed to reduce the burden of malaria and perhaps eventually eradicate the disease.
“A malaria vaccine that stimulates an efficient immune response against the proteins that malaria parasites use to burrow into red blood cells would stop the parasite from replicating and prevent severe illness.”
Dr. Fowkes said the review of existing studies illustrates how little is known about blood-stage malaria proteins and their suitability for use in vaccine development.
“Only about six blood-stage malaria proteins have been well studied out of a potential 100 proteins,” she said. “There is an urgent need for malaria researchers to better coordinate their research efforts on these proteins. This will take us one step closer to developing an effective vaccine.”
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