Major setback in the fight against malaria

Dar es Salaam. Hope that we can defeat malaria, the number one killer disease in Africa, is fading following the discovery of a deadly new parasite known scientifically as plasmodium vivax.
Though this new parasite has been around for years,The Citizen has learnt,  it did not infect Africans because of natural immunity in our blood.
But this immunity appears to have worn off  with changing lifestyles in many African countries due to rapid urbanisation. This has paved the way for this new type of malaria parasites to attack millions in Tanzania and the rest of Africa.
This being the  case,  doctors in Africa will have to confront two types of malaria—the regular  plasmodium parasitis and vivax.
Until now, there was a belief that Africans were  protected from vivax malaria because of the presence of a protein in their blood that  blocked the parasite from entering the red blood cells.
But a recent American Society of  Tropical Medicine and Hygiene meeting held in the US was told that vivax parasites, which are more dangerous  because of their ability to hide in the liver and bloodstream, are now infecting more and more Africans.
“We discovered previously unknown genetic mechanisms in the P. vivax parasite that could give it other ways to invade red blood cells and help explain why we are seeing these vivax malaria infections in [Africans] who are Duffy-negative”, said Dr Peter Zimmerman of Case-Western Reserve University. He is co-author of two new studies to be published on November 21 and December 5 in the journal PLOS Neglected Tropical Diseases.
Officials from the National Institute of Medical Research (NIMR) and the National Malaria Control Programme (NMCP) say  the emergence of vivax malaria could reverse all the gains in the fight against the killer disease. Dr Zimmerman  added, though,  that  more research would have to be done to establish the veracity of the findings.
According to Dr Renata Mandike, the deputy programme manager at the  NMCP,  the emergence of vivax malaria could throw scientists off balance because they have all along focused on the  malaria caused by  falciparum parasites. Still, researchers are working on establishing whether the vivax plasmodium is growing in Tanzania.
According to a principal research scientist at NIMR, Dr Julius Massaga, vivax malaria has been  found at very low levels in Africa and it is hard to pin down why it is rising.  “We know that there is a growing number of the parasite, but it is too early for us to say why,” Dr Massaga said. “More research will be done.”
Dr Fredros Okumu, a scientist and researcher at Ifakara Health Institute, said  different types of plasmodium can occur in different places even in the same country.  In the southern part of the country, such as Kilombero, there is a high level of plasmodium malariae.
 “The plasmodium found in Kilombero had infected at least four per cent of the population but later disappeared,” he added.
Vivax malaria is difficult to cure because the country has only one drug  for it—and it is  very toxic. “In some people, you need to detect the genetic factor, which  poses even more of a challenge,” he added.
Nevertheless, the institution is making an effort to ensure malaria is eradicated. 
Vivax malaria threatens the health of some 2.49 billion people worldwide,  but that number  maybe higher if the blood type is not as fully protective as previously believed. Although both types of  malaria are caused by the mosquito,  vivax is harder to cure.
Symptoms of P. vivax malaria are similar to those of other types of malaria and include cyclical fever and chills, headache, weakness, vomiting and diarrhoea. The most common complication is enlargement of the spleen.
According to scientists, P. vivax malaria is rarely fatal but relapses often occurring months to years after treatment because some of the parasites have become dormant in the liver. Special medication can be taken to kill the dormant parasites. “If vivax establishes itself in Africa,” Dr Zimmerman said, “it will undo a lot of the malaria progress we’ve made.”
Dr Kevin Baird, an expert in vivax malaria at the Eijkman-Oxford Clinical Research Unit in Indonesia, described the expanding reports of vivax malaria in Duffy-negative individuals as “alarming”.
The research done in Madagascar found that  over 50 percent of  the 189 sample tested from Cambodia had the vivax parasite.
According to the researchers, one possibility is that in such split populations, the Duffy-positive individuals keep parasites circulating in their communities, allowing them to frequently attempt to infect  individuals who are Duffy-negative. Such repeated encounters increase the chances that a P. vivax parasite could develop a new way to penetrate red blood cells.  The ASTMH annual meeting is the premier international gathering of those working on malaria, noted ASTMH President David Walker, and  is reputed to have in recent years significantly added to efforts to raise the visibility and understanding of the global burden of vivax malaria. 
“These studies are sure to generate robust discussions among attendees on the future of vivax in sub-Saharan Africa, particularly given the recent progress against falciparum malaria,” he said.
 Human malaria is caused by four different species of Plasmodium: P. falciparum, P. malariae, P. ovale and vivax malareae.
According to the World Health Organisation, cases of severe P. vivax have recently been reported among populations living in sub-tropical countries or areas at risk. P. vivax and P. ovale can remain dormant in the liver.