A common fungus could be the newest
weapon in the fight against malaria, researchers have
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
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
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.
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
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
If the insect is killed during this
time, then it would have no opportunity to pass malaria
Professor Andrew Read, of the University
of Edinburgh, who worked on the research, stated:
"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 Thomas 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
Dr Joe Lines of the London School
of Hygiene and Tropical Medicine stated: "It is always
great to have something new, and the way this works
He said the fungus was unusual because
it attacked adult mosquitoes - most control measures
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