Brazil’s attempt to save the Olympic Games : Radiation in fight against Zika-virus

POSTED: 02/29/16 6:07 PM

St. Maarten News – While the Zika-virus has not affected the Dutch side of St. Maarten all that much, with just one confirmed case, and while there are now seven confirmed cases on the French side, the war on the Aedes aegypti mosquito has gone to the next level in Brazil, the country where the Zika-outbreak in the region originates.

With the Olympic Games in August rapidly approaching, the International Atomic Energy Agency (IAEA) is shipping a machine to host country Brazil that sterilizes male mosquitoes through radiation. This infertile swarm must prevent that female mosquitoes in the Zika-area reproduce.

This so-called cobalt-60 irradiator has the size of a bookcase. It is currently still in Madeira, Portugal where the machine has been used to combat fruit flies. The Brazilian government still has to issue a permit for the use of the machine. Once that is done, the IAEA will ship the irradiator to Juazeiro, a town in the northeastern Brazilian state of Bahia.

This is the first time the method is used to combat the Zika-virus, Pieter Hotse Smit reported in the Volkskrant yesterday, adding that the method is not new. In the sixties and seventies of last century the same method was used to combat insect plagues with the objective to protect crops in for instance the United States. In Sudan the method has been used to combat malaria mosquitoes.

“It is comparable to the human contraceptive for birth control,” says Kostas Bourtzis, a molecular biologist at the IAEA in a report by press agency Reuters.

In Brazil, the agency wants to use the method to combat the Aedes aegypti mosquito that transfers the Zika-virus,

Gamma radiation in the machine kills every week the sperm of 12 million bred male mosquitoes. The sterilized mosquitoes are released in the Zika-area to couple with wild female mosquitoes.

The offspring they produce is not viable due to the radiation treatment of the male mosquitoes. Because the female mosquitoes have only one chance to reproduce, they will not get any offspring. The fewer mosquitoes, the smaller the chance of transferring the Zika-virus. At least, that is the theory.

Mosquito expert Sander Koenraadt of Wageningen University is enthusiast about the method, but he also has marginal comments. “Brazil hopes of course that this is the silver bullet to terminate Zika,” he says. “But in practice, this method is not one hundred percent effective.”

The IAEA also acknowledges that the method is not perfect. “It’s like cars in the 1890s: they work but they still had to be developed further and improved,” Bourtzis says. According to Koenraadt radiation has to be one of the weapons in the fight against the Zika-virus.

A similar method is already in use in Brazil. Genetic modification gives mosquitoes a gene that causes larvae not to develop fully. But just like with the radiated mosquitoes, it is not at all certain that these male mosquitoes will have the same attraction for female mosquitoes as fertile mosquitoes do.

Brazil also uses pesticides to eradicate mosquitoes but the disadvantage of this method is that the insects become resistant.

Koenraadt says that providing information is important. “The mosquito larvae do well in stagnant water. It is important that Brazilians realize they should not leave rainwater in their yards in barrels, old care tires or even bottle caps.”

To smother mosquitoes there is yet another option: little fish who eat the larvae before they become full-blown mosquitoes.

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