First record of natural infection by (Nematoda: Metastrongyloidea) in and in an urban area of São Paulo city, SP, Brazil.

, a rat lungworm, is one of the leading causes of eosinophilic meningitis in humans. Infection in humans occurs by the ingestion of intermediate hosts, undercooked paratenic hosts or contaminated vegetables and fruits by mucus from infected molluscs. This zoonosis is widespread in tropical and subtropical areas of Southeast Asia, it has also been reported in the Pacific Islands as well as in other regions of Americas. In Brazil, human cases of angiostrongyliasis have been reported since 2007 in Southeast, Northeast, and South regions. In January 2011, we collected a batch of 30 slides in a neighborhood of São Paulo city (Parque Fernanda). Six of them were used for identifying species, and the others (24) were used in parasitological tests through digestion in peptic solution and then larvae isolation by the Rugai method. A total of 250 larvae were obtained and they had morphological traits of lus spp. Later, four Golden hamsters () were infected with 38 larvae that allowed the recovery of young worms from the brain and lungs of rodents on the 21 and 30 day of infection. In this same neighborhood we captured rodents () that, after necropsy led us to recovery of 22 adult worms in the pulmonary arteries (14 males and 8 females) in May 2011. The larvae and worms obtained from natural infection were evaluated by morphological and morphometric parameters, as well as biological behavior patterns and molecular profile. All methodologies identified the parasite as . In this way, we report for the first time, the natural infection by in intermediate () and definitive () hosts in a new urban region of Brazil.