There is a 60% global shortfall in funds for malaria control, according to a report by UK and African experts.
Researchers found only 21 out of 93 countries where malaria is common have received enough money to implement effective control measures.
African countries have seen the biggest funding increases but billions are still needed elsewhere, the experts say in the Lancet medical journal.
The Roll Back Malaria Campaign warned $4.9bn (£3.1bn) was needed this year.
The researchers, led by Professor Bob Snow of Oxford University and Kenya's Kenyatta National Hospital, found that annual international funding had increased by 166% - from $730m to $1.94bn - since 2007.
They said: "Any decline in malaria-funding commitments will run the risk of a resurgence of malaria in countries that have enjoyed the benefits of this funding to provide protection from malaria since 2002.
"Sustained funding in these countries is crucial or $9.9bn invested since 2002 will have been in vain."
While financing for malaria control has increased as part of international efforts to reach the Millennium Development Goals, the amount received from domestic sources varies greatly.
Twenty-one countries, 12 of them in Africa, now receive adequate donor money, according to the research.
But a further 50, including Niger and Sierra Leone, as detailed in the Lancet paper, do not get enough from the international community.
Professor Snow said: "Poor countries with inadequate donor assistance and large sectors of their population at risk of malaria must remain the focus of attention if global ambitions for malaria control are to be realised.
"The challenge will now be on finding more money, making sure funding is linked to performance and putting pressure on malaria-endemic countries with large domestic incomes to do more for themselves.
"A failure to maintain the momentum will mean money spent so far will have been for nothing."
The authors also argue that some countries like China and India, which have their own space programmes, could perhaps contribute funds to help other countries rather than being recipients, thereby increasing the financial support available.
But the work only assesses external funding.
Commenting on the study, Professor Anne Mills, from the London School of Hygiene and Tropical Medicine in the UK, said that external funding may be low because a country may be funding its own malaria programmes.
Cerebral malaria may have passed from gorillas to us
DNA analysis
To study the DNA of infections in wild apes, you cannot use blood samples. So the team collected 2,700 samples of faecal material from two species of gorilla - western and eastern - and from common chimpanzees and bonobos, also known as pygmy chimpanzees.
They tried sequencing Plasmodium DNA from the faeces with techniques that use a large sample, and drew a genetic family tree to see which parasites were related. Dr Hahn said "When we did conventional sequencing, the tree didn't make any sense, because each sample contained a mixture of parasites."
They diluted the DNA so that they had just one parasite's genome represented in a single sample, and then amplified the DNA from there. This means they were able to separate the DNA from different species of the parasite much more effectively.
They then found the tree made much more sense. But they also found some surprising results.
The human Plasmodium was not very closely related to chimpanzeePlasmodium, as had been thought - but it was very closely related to one out of three species of gorilla Plasmodium from western gorillas in Central and West Africa.
There was more genetic variety in the gorilla parasites than in human parasites, and Dr Hahn said this means the gorilla is likely to be the "reservoir" - the origin of the human parasite.
"Other studies have just looked at chimps, so didn't find the gorilla parasite," said Dr Hahn. She added that some studies have looked at animals in captivity - so it is possible any parasites have "jumped" from their human keepers.
Cross-infection
The researchers, who report their findings in Nature, are now going to investigate further to see exactly how different the gorilla and human parasites are. Dr Hahn says that it is possible they are even the same species, and that cross-infection between humans and gorillas may be going on now.
Members of the team Dr Martine Peeters and Dr Eric Delaporte of the University of Montpelier in France are working with hunters and loggers in Cameroon, who spend a lot of time in the forests.
They will investigate whether these workers carry malaria parasites from the gorillas, which would suggest that new infections from other species can still happen.
They also do not yet know how badly apes are affected by malaria. Dr Hahn said that the team would now like to find out whether apes are able to catch the malaria parasite, without getting ill or dying in the way that humans do.
Scientists say they have genetic proof malaria spread by mosquitoes jumped species from chimpanzees to humans.
By looking at blood samples, a US team discovered all world strains of the human malaria parasite falciparum stem from a malaria parasite in chimps.
They tell Proceedings of the National Academy of Sciences how the species shift probably happened 10,000 years ago when humans turned to agriculture.
Man's encroachment upon the natural forest habitat of chimps is blamed.
It brought the two species into close contact and the deforestation created pools of stagnant water and other conditions favourable for mosquito breeding.
"Today, human encroachment into the last forest habitats has further extended, leading to a higher risk of transfer of new pathogens, including new malaria parasites," the researchers warn.
Species jump
Previously, malaria's origin in humans had been unclear.
But this latest work suggests malaria, like HIV, has jumped species from one of our closest relatives.
Although chimps were known to harbour a parasite - Plasmodium reichenowi - that is closely related to the most common of the human malaria parasites, Plasmodium falciparum, many scientists had assumed that the two had co-existed separately.
But blood tests on 94 wild and captive chimpanzees in Cameroon and the Ivory Coast suggest falciparum evolved from reichenowi.
Francisco Ayala, of the University of California, Irvine, and colleagues found eight new strains of reichenowi that had striking similarities to falciparum and were genetic precursors to the human disease.
The leap could have happened as early as two to three million years ago, but most likely to our Neolithic ancestors as recently as 10,000 years ago.
The scientists hope their discovery will help others looking for new drugs and vaccines to stop human malaria.
Professor Brian Greenwood, a malaria expert at the London School of Hygiene and Tropical Medicine, said: "This is interesting work.
"There has been dispute about how long falciparum has been around for and as genetic techniques get better we can get a more accurate idea."
Malaria-proof mosquito engineered
Scientists in the US have succeeded in genetically engineering a malaria-resistant mosquito.
The researchers, from the University of Arizona, introduced a gene that affected the insect's gut, meaning the malaria parasite could not develop.
They report the advance, which also reduced the insects' lifespan, in the journal PLoS Pathogens.
They say that the ultimate goal is to introduce malaria-resistant mosquitoes into the environment.
"Before we do this, we have to somehow give the mosquitoes a competitive advantage over the disease-carrying insects," explained Professor Michael Riehle from the University of Arizona a principle investigator on the project.
In the study the researchers altered a gene that codes for a "signalling molecule".
This molecule, a protein, enables the mosquito's cells to communicate with each other, and is crucial for parasite development inside the mosquito.
The genetic tweak artificially increased its production, disrupting the whole process, and also shortened the insect's lifespan.
The team was able to add a fluorescent tag to the gene, to ensure that it had been successfully "expressed" by the mosquito larvae.
Professor Riehle said: "This is the first time that we've been able to completely block the parasite from developing in the mosquito."
Gareth Lycett, a malaria researcher from Liverpool School of Tropical Medicine in the UK, said it was an important advance.
"They have tested it on the most harmful of the malaria parasites, Plasmodium falciparum," he told BBC News. "It is another step on the journey towards potentially assisting malaria control through GM mosquito release."
But Dr Lycett pointed out that the this work had not been carried out specifically on theAnopheles gambiae mosquito. "That is the major vector of malaria in Africa where the disease is most prevalent," he explained.
This study was a collaborative project with the University of California Davis and the University of Georgia funded by the National Institutes of Health.
Slim, Gates and Spain pledge $150m to fight disease
Two of the world's richest men and the Spanish government have pledged $150m (£101.7m) to battle disease and improve health in Central America and Mexico.
Carlos Slim and Bill Gates are to fund a project jointly with Spain aimed at improving nutrition and maternal health and fighting dengue fever and malaria.
The two men and Spain's Princess Cristina announced the project in the Mexican capital, Mexico City.
The project also aims to reduce infant mortality and boost vaccination rates.
The "2015 Meso-American Health Initiative" will benefit Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua and Panama.
The three parties will each donate $50m.
Worth an estimated $53.5bn, Mr Slim - a Mexican telecom mogul - is the world's richest man, according to this year's Forbes magazine "rich list". Mr Gates, founder of Microsoft, is said to be worth $53bn.
