SAO PAULO (AFP) - Cases of dengue fever are on the rise in Sao Paulo, with a nearly eight-fold increase that saw 24 people die in Brazil's most populous state so far this year, the health ministry said.

The mosquito-borne infectious tropical disease comes as Sao Paulo state and the southeast of the country suffer water shortages in the wake of the worst, months-long drought in living memory.

"In many regions, owing to a lack of water, people were stocking supplies at home. That helped add to the proliferation of mosquitoes," which spread the disease, Health Minister Arthur Chioro explained.

A total of 94,623 cases were registered state-wide in January and February, 82,747 more than in the same period last year, according to ministry figures.

The state, home to 40 million of Brazil's 200 million inhabitants, accounted for just over half of the nationwide total of 174,676 cases in the first two months of the year, a 139 per cent rise on 2014.

Overall fatalities in Brazil reached 39 - although that was down from 62 for the same period last year.

But the worst may still be to come, as the March to May period traditionally sees the largest spread of the disease, Chioro warned, adding that Brazil would invest an extra 150 million reais (S$69 million) to combat the problem.

Sao Paulo is the third-worst affected federal state behind Acre, bordered by the Amazon, and the central state of Goias.