Incidence of Vibrio cholerae O1 was studied in 2,585 samples from different aquatic environments and 91 from foods in Pernambuco State, northeastern Brazil, from 1992 to 1994. A total of 193 (7.21%) samples of V. cholerae were isolated with a higher prevalence of the Inaba serovar (183-94.8%) than the Ogawa serotype (10-5.1%). All isolates were classified as biotype El Tor, and resistance patterns to antibiotics showed that all strains were susceptible tetracycline. Some 70 random samples of Vibrio cholerae proved toxigenic, including all the Ogawa serovars. Incidence of V. cholerae O1 in river water and sewage (86.0%) pointed to fecal contamination as the most common source and vehicle for rapid spread of the microorganism in the aquatic environment. The vibrio was isolated in 2.1% of all food examined, which was less than expected.

After the worldwide cholera epidemic in 1993, permanent environmental monitoring of hydrographic basins was established in Pernambuco, Brazil, where cholera is endemic. After a quiescent period, 4 rfbN (serogroup O1) positive water samples that were culture negative were detected by multiplex single-tube nested PCR (MSTNPCR); 2 of these were also ctxA (cholera toxin) positive. From May to June 2012, 30 V. cholerae O1 isolates were obtained by culturing samples. These isolates were analyzed for the presence of virulence genes by PCR, intergenic spacer region 16S-23S PCR (ISR-PCR), and pulsed field gel electrophoresis (PFGE). The isolates were positive for the rfbN gene and negative for the assessed pathogenic genes and were classified into 2 groups by ISR and the same profile by PFGE. Close genetic similarity was observed between them (2012) and environmental strains from 2004 to 2005, indicating the permanence of endemic V. cholerae O1 in the region.