Human adenovirus spread, rainfalls, and the occurrence of gastroenteritis cases in a Brazilian basin.

Climate variables may interfere with the environmental persistence and spread of pathogenic microorganisms. This study aimed to investigate the occurrence of human adenovirus (HAdV) and total and thermotolerant coliforms in treated and untreated water and report gastroenteritis cases in seven cities located in the hydrographic basin of the Sinos River (HBSR), Southern Brazil. The data on water quality from samples collected at catchment areas of HBSR from March to December 2011 were compared with precipitation records, virus detection rates and viral loads, and information on enteric diseases among residents of the region. There was a marked increase in precipitation intensity in April, July, and August and a decrease in May and November. The number of HAdV genome copies (gc) in untreated water ranged from 2.1×10(8) gc/L in June to 7.8×10(1) gc/L in December, and in treated water, from 6.3×10(4) gc/L in September to 4.1×10(1) gc/L in November. The most probable number (MPN) of total coliforms ranged from 5×10(1) MPN/100 mL in December to 2.4×10(5) MPN/100 mL in July, and thermotolerant coliforms ranged from 1×10(1) MPN/100 mL in August to 6.9×10(4) MPN/100 mL in July. A total of 79 hospital admissions due to gastroenteritis were registered in the cities studied. The results for coliforms in untreated water demonstrate deficits in sanitation and wastewater treatment. These findings also indicate a possible relationship between the occurrence of rainfalls after dry periods and an increase in the number of gastroenteritis cases and in HAdV load quantified in surface water collected for conventional potabilization.