Half of the world’s population is at risk of getting malaria – about 3.3 billion people – according to the World Health Organziation (WHO). And although prevention and control measures have led to a reduction in mortality rates, WHO estimates that 660,000 people died of this disease in 2010.

Malaria is particularly prevalent in Africa’s poorest countries. In 2010, 90% of all malaria deaths were in this area, and mostly among children under the age of 5.

It can be hard to imagine that something as tiny as a mosquito can be such a big threat to human populations – and even then, the mosquito is just the carrier. The even tinier Plasmodium parasite causes the disease, characterized by high fevers, headaches, chills and vomiting.

There are four species that cause malaria in humans:

  • P. falciparum
  • P. vivax
  • P. malariae
  • P. ovale.

Of the four, P. falciparum and P. vivax are the most common, with P. falciparum being the most deadly.

New research from Harvard School of Public Health (HSPH) and University of Perugia (UNIPG), in Italy, targets the carrier of the disease – the female Anopheles gambiae mosquito – and even more specifically, her ability to produce eggs, in an attempt to conquer the spread of this killer disease.

The researchers claim to have found a molecular switch in female mosquitoes that is triggered by a male’s hormone delivered during sex, prompting her to produce eggs. They argue that blocking this switch will prevent the mosquitoes reproducing, and therefore stop the spread of the disease.

Reporting their findings in PLOS Biology, the researchers say this may be a viable strategy for controlling malaria in the future.

The researchers found that the male mosquitoes transferred a steroid hormone called 20-hydroxy-ecdysone – or 20E – to the female during mating, and it then interacts with a Mating-Induced Stimulator of Oogenesis (MISO) protein. The interaction between the two stimulates oogenesis, or egg production.

They also found that this interaction boosted the build-up of fat in the female’s ovaries, leading to more rapid and more successful egg production.

“This is the first time, in any insect species, that a male hormone has been shown to directly interact with a female protein and alter the ability of the female to reproduce,” said Francesco Baldini, co-author and a UNIPG graduate student who performed part of the analyses as a visiting scientist at HSPH.

Associate professor of immunology and infectious diseases at HSPH and UNIPG, Falminia Catteruccia says:

“These findings represent a significant step forward in our understanding of how these devastating malaria vectors reproduce.”

When the researchers suppressed MISO’s functioning in the females using a chemical, they found that they produced fewer eggs.

Catteruccia continues:

How males contributed to egg development had been previously unknown; with the identification of the molecular players of this male-female interaction we can now find ways to switch off the signal and prevent females from reproducing.”

The researchers are optimistic that these findings will help in the development of new tools for controlling Anopheles mosquitoes.

Research into malaria control and prevention continues. Earlier this year Medical News Today reported on the continuing success of a vaccine trial in sub-Saharan Africa.