First record of natural infection by Angiostrongylus cantonensis (Nematoda: Metastrongyloidea) in Tanychlamys indica (Godwin-Austen, 1883) in the city of São Paulo, Brazil.

Background: Tanychlamys indica (Godwin-Austen, 1883) was reported as a serious pest in India. The snails are voracious and feed on a wide range of commercial crops. It has also been identified as an intermediate nematode host of Angiostrongylus cantonensis in Bombay, India. T. indica was recently introduced in Brazil by international trade of citrus fruit seedlings. First in the State of Santa Catarina and then in Paraná. Recently, it has been detected in the city of São Paulo threatening to spread to other Brazilian states.

Objectives: We report the first record, in Brazil, of the natural infection by L3 larvae of A. cantonensis isolated from T. indica collected in the Vila Leopoldina neighbourhood, located in the west zone of São Paulo city.

Methods: In January 2023, a team from LABFAUNA and UVIS Lapa collected 36 molluscs identified as T. indica in Vila Leopoldina, São Paulo city. Of these, 20 molluscs were subjected to individual parasitological analysis at the Instituto Adolfo Lutz, using the modified Rugai methodology.

Findings: A total of 145 larvae were identified morphologically and classified according to Ash's criteria. These larvae were identified as third - stage larvae (L3) of A. cantonensis by real time polymerase chain reaction (PCR).

Main conclusions: It is evident that further research is imperative to map the distribution of T. indica in Brazil and to assess its potential as an intermediate host for the nematode A. cantonensis, as well as the economic risks to agriculture. Over the past two decades, human cases of neuroangiostrongyliasis have been documented in the Southeast, North, Northeast, and South regions of Brazil. Additionally, there are records of natural infection with A. cantonensis in molluscs and rodents.