SciDev.Net

Leptospira bacteria viewed with an electron microscope

CDC

Researchers have developed a new way to rapidly assess the risk of developing a severe disease called leptospirosis from contact with water.

The approach, which has been tested in Peru, can gauge whether water contains the bacteria that cause the disease and, if so, how many are present.

PLoS Medicine published the findings by Joseph Vinetz of the University of California in San Diego and his colleagues online this week. They will also appear in the September issue of the journal.

Vinetz says the research has direct policy implications for health departments monitoring the safety of water for drinking, bathing, cleaning and swimming.

Leptospirosis causes severe jaundice, kidney failure and bleeding in the lungs. It is found worldwide but particularly in the tropics and can kill up to 25 per cent of people infected.

Bacteria called Leptospira cause the disease — also known as Weill's disease. It is spread through the urine of infected animals such as livestock and rodents.

The disease varies in severity depending on which of various types of Leptospira are present. Standard laboratory methods are time-consuming, laborious and usually fail to distinguish the disease-causing strains.

The researchers used a technique called polymerase chain reaction to rapidly amplify tiny pieces of bacterial DNA.

This allowed them to assess which types of Leptospira were present in water from gutters, wells, puddles and streams in rural and urban parts of Iquitos, in Peru's Amazon region.

The researchers say their approach could also be used to identify the risk of other waterborne diseases, such as those caused by the bacteria Shigella, Salmonella, and Escherichia coli.

The Peruvian study suggests that reducing sources of standing water and clearing away rubbish in urban areas might reduce the number of cases of severe leptospirosis.

Reference PLoS Medicine doi: 10.1371/journal.pmed.0030308 (2006)