The patients had both consumed potentially contaminated raw date palm sap, a known risk factor for contracting the virus.
Having tools to identify outbreaks early is crucial for containing outbreaks for both dangerous pathogens.
The patients are from the same district, and both had consumed raw date juice, a known risk factor.
The initial trial will likely last 18 months, with the next phase expected to take place in a Nipah-affected country.
Deaths are at the country's highest level in 7 years.
The bats were tested as part of the response to a Nipah virus outbreak in Kozhikode district, where spillovers have been reported before.
Tests on samples from bats, bat droppings, and fruit from the village and forested area where the first patient lived turned up no positives.
The list of contacts grows to 950 people, including 213 in the high-risk category, of whom 21 are hospitalized.
Among 5 Nipah cases, 2 have proved fatal, and officials are following up with 77 high-risk contacts.
Two people, relatives of one of the deceased patients, are hospitalized with Nipah infections.