Fungus 'may help malaria fight' article

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Fungus 'may help malaria fight'

http://news.bbc.co.uk/2/hi/health/4074212.stm

A common fungus could be the newest weapon in the fight against

malaria, researchers have suggested.

A UK team found that it can prove fatal to mosquitoes which come into

contact with the fungus when it is sprayed onto surfaces.

The study in Science showed over 90% of mosquitoes were killed within

14 days of being infected.

However, other experts cautioned there would be difficulties in

ensuring the fungus was widely used.

Malaria kills at least one million people each year.

It is an extremely difficult disease to treat, as the parasite easily

becomes resistant to the drugs used to treat it, and the mosquitoes

develop resistance to the pesticides designed to kill them.

The University of Edinburgh and Imperial College, London researchers

looked at whether there was a way of halting the mosquitoes in their

tracks.

After the insects have fed on human blood, they find somewhere to rest

for a few hours - usually a nearby ceiling or wall.

The researchers wanted to identify something which could infect them

during this period.

'No resistance'

They tested a type of fungus from the species Beauveria bassiana by

applying inert spores directly, and as a spray, onto cage mesh.

When a mosquito touches the spores, the fungus germinates, penetrates

the mosquito and grows within it, eventually killing the insect.

Not only were over 90% of mosquitoes killed within 14 days of being

infected with the fungus, it effectively overwhelmed their body,

slowing the insects down so that in their last few days of life they

were less able to fly, and thus spread disease.

In laboratory tests, fungal infection reduced malaria transmission in

the laboratory by 98%.

The key is to infect the insect as soon as possible after it has fed

on infected blood.

It takes about two weeks after this for parasite levels in the insect

to reach the point where they can infect another person bitten by the

same insect.

If the insect is killed during this time, then it would have no

opportunity to pass malaria on.

Professor Read, of the University of Edinburgh, who worked on

the research, told the BBC News website: " It seems this fungus is

eating them up from the inside. "

He said the formulation of fungal sprays used to protect fields from

locusts could be the model for anti-mosquito sprays.

Dr Matt of Imperial College, who led the study, said: " There is

no evidence that insects can develop resistance to fungi.

" However, even if mosquitoes were to become resistant, it is extremely

unlikely that they would also be resistant to chemical pesticides.

" It should be possible to use the chemical and biological pesticides

together or in rotation to prolong their usefulness " .

People 'need convincing'

A second paper in Science, by researchers from the Ifakara Health

Research and Development Centre in Tanzania, the Swiss Tropical

Institute in Basel and Wageningen University in The Netherlands found

mosquitoes which rested on fungus-impregnated sheets in houses became

infected and died.

Researcher Kija Ng'habi said: " This technology needs to be developed

to be manageable and affordable. "

Dr Joe Lines of the London School of Hygiene and Tropical Medicine

told BBC News website: " It is always great to have something new, and

the way this works is exciting. "

He said the fungus was unusual because it attacked adult mosquitoes -

most control measures tackle larvae.

But he said the fact that using the fungus would confer benefit on the

community, rather than the individual, would mean that people may need

a lot of convincing to use it themselves.

" When mosquitoes come into the house, some are young and will bite a

person, getting malaria to pass on to somebody else.

" Other mosquitoes will be old, and have already got malaria from other

people, and will give it to you. "

" So the fungus wouldn't prevent you getting malaria from the

mosquitoes which were already infected. "