The country has already seen the death of 12 dengue patients before the beginning of the monsoon, while 1,261 others were hospitalised till yesterday. The numbers indicate alarming signs of a massive dengue outbreak this year.

The head of the World Health Organization warns that the Zika outbreak would likely worsen before nations besieged by the mosquito-borne virus linked to thousands of birth defects in Brazil see relief.

The Zika virus may be particularly adept at entrenching itself in parts of the body that are shielded from the immune system, making it harder to fight off and possibly lengthening the timeframe in which it can be transmitted, top US experts say.