Gujarat recorded 25 Chandipura virus deaths in about five weeks.
Authorities confirmed 39 infections among children across Gujarat and Rajasthan.
Gujarat had reported 225 suspected cases by August 10.
Cases were detected across 12 Gujarat districts and three Rajasthan districts.
More context
More than 1,000 sandfly, mosquito and tick samples tested negative.
The outbreak showed no clear geographic clusters.
Researchers are investigating other insects and possible animal reservoirs.
Children under 15 face particular risk from rapid neurological deterioration.
A national response team is supporting surveillance, investigation and containment.
Health teams expanded testing, door-to-door monitoring and insecticide spraying.
No specific antiviral treatment or vaccine is currently available.
Early supportive medical care is considered critical.