Cases of dengue have soared in Brazil where the disease has caused 229 fatalities this year, the Health Ministry said Monday, as authorities try to combat its spread using transgenic mosquitos.

The health ministry said it had logged 745,900 cases nationwide in the first 15 weeks of the year -- an annual increase of 234 percent.

That equates to 367.8 people infected per 100,000 residents, which falls into the category of an epidemic under parameters used by the World Health Organization.

The number of dengue deaths has climbed 44 percent from the same period last year, and most of the diagnosed cases have occurred in business hub Sao Paulo.

In all, Sao Paulo has seen 169 fatalities and 401,564 cases this year -- a high since records began in 1990.

Cases of the mosquito-borne infectious tropical disease increased in the wake of a serious drought last year, the worst in living memory.

Severe water shortages led residents to store what they could in open receptacles, which facilitated the spread of dengue.

Last Thursday the city of Piracicaba, located 160 kilometers (100 miles) west of Sao Paulo, released its first batch of 100,000 transgenic male mosquitos in reaction to the growing crisis.

The genetically modified mosquitos pass on a modified gene during procreation that makes offspring incapable of reaching sexual maturity, causing the overall population to decline steadily.

Piracicaba authorities and British firm Oxitec last year opened a facility at Campinas, near Sao Paulo, able to produce 550,000 modified mosquitoes weekly.

Dengue symptoms include severe abdominal pain, persistent vomiting and circulatory system failure.