SAO PAULO - Drones fly high above Sao Paulo in search of mosquito-ridden puddles in an effort to tackle the spike in dengue cases around Brazil, as experts say current vaccine supplies will not be enough to fully curb infections any time soon.

Cases of the mosquito-borne illness have surged during Brazil's hot, rainy season causing authorities nationwide to take emergency measures. On Tuesday, Sao Paulo's state department of health declared a state of emergency, estimating 300 cases for every 100,000 inhabitants.

"Vaccination is one more tool for controlling the disease. But unfortunately, we won't be able to achieve this with the number of doses planned for the next five years," said Dr. Renato Kfouri, an infectious diseases expert at the Brazilian Immunization Society.

"We have six million doses this year and 50 million doses over five years," he said. Two doses of the vaccine are needed to inoculate one person.

"To vaccinate 25 million Brazilians in five years, just over 13% of our population, is not enough to control the disease or change dengue figures in the country."

The drones are being used to find areas that might contain standing water in which mosquitoes breed. Ideally, mosquito control personnel find and target mosquito egg-laying sites to kill the larvae before the insects emerge as flying blood-feeding adult females that can spread disease.

Dengue is now present in 85% of Brazil's municipalities, Kfouri added, spreading into regions where it was never seen before.

Dengue symptoms include a high fever, headache, vomiting, muscle and joint pain that can be so severe the disease has been called breakbone fever, and an itching skin rash. In some cases, the disease can cause a more severe hemorrhagic fever, resulting in bleeding that can lead to death.

The Health Ministry's latest weekly bulletin cited some 1.3 million "possible cases" of dengue nationwide and 299 confirmed deaths related to the disease this year. REUTERS