More than 220 people have been killed by two mosquito-borne viruses in India's largest state in the last three months.
Mosquitoes are spreading disease
Health officials said on Tuesday that the northern state of Uttar Pradesh had recorded 926 cases of encephalitis and 384 cases of dengue fever since August.
Dr Awdhesh Srivastava, of the state's health directorate, said at least 205 people had died of encephalitis, while 18 people had died of dengue fever.
The unusually strong monsoon season, which ended several weeks ago, has been blamed for the outbreak of disease.
This has led to the creation of many stagnant pools of water - ideal breeding grounds for the mosquitoes which carry both viruses.
More than 7,400 cases of dengue have been reported across India, according to the Federal Health Ministry.
Symptoms of dengue include fever and, in severe cases, some patients suffer bleeding from their internal organs and need blood transfusions. Some die of shock or heart failure.
Encephalitis begins like flu with headache, fever, weakness and gastrointestinal problems.
In about one of every 200 cases, the illness progresses to inflammation of the brain, with more than half of those cases ending in permanent disability or death.
The High Court in Lucknow, the state capital, has reprimanded city officials for failing to maintain adequate sanitation.
But Dr HP Kumar, the head of the Uttar Pradesh's health services, said that several parts of Lucknow were being fumigated to kill the mosquitoes.
He said: "The number of infections could rise as heavy monsoon rains have left pools of stagnant water, which serve as breeding grounds for mosquitoes."
Monalisa Chaudhry, the chief spokeswoman for the federal Sanjay Gandhi Post Graduate Institute of Medical Sciences in the city, said patients were being turned away from the hospital.
This was because of a shortage of a blood component called platelets, which are needed to treat dengue.
Local officials in Lucknow are appealing to residents to maintain clean neighbourhoods.
Dengue fever is indigenous to parts of Asia and the Caribbean. The World Health Organization has estimated that dengue infects nearly 100m people world-wide each year. About 5% die.