Latin America scrambles to squash Zika-spreading mosquito

RIO DE JANEIRO -- With no hope for a vaccine to prevent Zika in the near future, authorities are focusing on the most effective way to combat the virus: killing the mosquito that carries it.

Fumigation is one method; another is seeking out and draining standing water where the insect lays its eggs.

Other strategies are possible, including larvae-devouring fish, genetically modified insects and even lasers.

But officials agree it won't be easy.

The battle is focused on Aedes aegypti, a formidable foe. It carries not only Zika, but other diseases such as dengue, yellow fever and chikunguya.

Well adapted to humans, it lives largely inside homes and can lay eggs in a bottlecap's worth of stagnant water.

The dishes beneath potted plants are a favorite spot, as are abandoned tires, bird feeders and the little puddles of rainwater that collect in the folds of plastic tarps.

"This mosquito really is a bear to deal with," said Thomas Scott, professor of entomology and epidemiology at the University of California, Davis. "It's almost like a cockroach of the mosquito world."

Scientists are also trying to determine whether, and how easily, Zika could be spread by sex or by blood transfusions. But the virus usually is transmitted through mosquito bites.

Brazil's first case of Zika -- a virus that first was identified in Uganda in 1947 and subsequently spread to parts of Asia -- was recorded in the middle of last year.

Researchers don't know exactly how it made the jump, but two theories suggest it may have arrived with tourists visiting the country for the 2014 World Cup soccer tournament or an international canoeing competition the same year.

Thanks to Aedes aegypti, the disease spread quickly across Brazil and to more than 20 countries in the region, the Caribbean and beyond, leading the World Health Organization this week to declare an international emergency.

The concern is not the disease itself -- Zika's immediate effects are mild, consisting mostly of a moderate fever and a rash, and only a fifth of those afflicted notice any symptoms.

But Brazilian authorities said they have detected a spike in cases of microcephaly, which leaves infants with unusually small heads and can result in brain damage and a host of developmental and health problems.

The link between Zika and microcephaly is as yet unproven.

Brazil is pouring money into the development of a vaccine against Zika.

But a viable vaccine is years away, and public-health experts say for now, slashing the mosquito population is key.

The country had success against Aedes once before, when a nationwide campaign to drain standing waters and spray the insecticide DDT led to a steep fall in dengue and yellow fever in the late 1950s.

But as the crusade faded, the insect drifted back in from neighboring countries.