Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New approach assesses risk of water-borne pathogen disease

22.08.2006
Researchers at the University of California, San Diego (UCSD) School of Medicine, along with colleagues at the University Peruana Cayetano Heredia in Lima, Peru, have developed a novel approach for assessing the risk to humans of acquiring leptospirosis – a severe, water-borne disease that is the common cause of severe jaundice, renal failure and lung hemorrhage in urban areas throughout the developing world – from environmental water exposure.

The approach, which uses advanced molecular methods to measure risk for infection, may also be applicable to other water-borne bacterial diseases. The findings will be published on line August 21 in advance of the September issue of the journal Public Library of Science (PLoS) Medicine.

"What we found supported our hypothesis that severe leptospirosis in the Peruvian Amazon is associated with higher concentrations of more virulent forms of the bacteria at sites of exposure and transmission," said Joseph Vinetz, M.D., Associate Professor of Medicine in UCSD's Division of Infectious Diseases..

This approach to risk assessment of environmental surface waters is globally applicable, and can connect the presence of water-borne pathogens to the risk of mild versus severe human disease, according to the researchers. Scientists will be able to determine if a sample of water contains Leptospira, as well as quantify how many of the bacteria are present. More densely contaminated water sources would be more likely to cause human disease than water with a lower concentration of Leptospira.

"This can have direct policy implications for health departments in monitoring the safety of water for bathing, cleaning and swimming – all ways that diseases are spread, not just by drinking contaminated water," Vinetz said, adding that the next step is to intervene and clean up the water sources, and assess the impact of cleanup on the incidence rate of human leptospirosis.

The researchers successfully used a powerful molecular technology called polymerase chain reaction (PCR) to measure and compare levels of Leptospira in environmental surface waters at urban and rural sites in the Peruvian Amazon region of Iquitos. Leptospirosis, caused by bacteria of the genus Leptospira, is the most common disease in the world transmitted from animals to humans.

Annually, tens of millions of human cases of leptospirosis occur worldwide, and fatality rates can range as high as twenty to twenty-five percent in some regions. It occurs in both industrialized and developing countries, but is particularly prevalent in tropical countries where poor people live under highly crowded conditions, or in rural areas where people are exposed to water contaminated by the urine of Leptospira-infected mammals such as livestock or rats. Transmission also appears to coincide with warm weather and the occurrence of flooding, which washes soil contaminated with animal urine into water sources such as wells and streams.

Recent outbreaks worldwide among adventure athletes, military personnel and travelers highlight the risk for acquiring leptospirosis in tropical environments. Noted risk factors include the use of well or stream water, minding livestock, walking barefoot and the presence of rats and cats in the home.

Previous data from the Peruvian Amazon region indicated that the overall incidence of human leptospirosis was similar in urban and rural sites. However, the severe form of the disease had only been observed in urban areas. Vinetz and his research team tested two hypotheses: first, that concentration of more virulent Leptospira would be higher in urban than in rural environmental surface waters; and that the concentration and species of disease-causing Leptospira in the water would be associated with both the risk of acquiring the disease and its severity.

Standard lab culture-based methods of identifying Leptospira in water and soil sources are time-consuming, laborious, and usually unable to identify pathogenic Leptospira at all. To overcome these limitations, the scientists analyzed relatively small quantities of surface water – for instance water from gutters, wells, puddles and streams – using quantitative real-time PCR assays that amplify small amounts of DNA. By measuring DNA, the researchers were able to effectively describe and quantify the amount of pathogenic bacteria present in the water samples.

The scientists then were able to connect the molecular identification of the bacterial pathogens in the water samples to those actually infecting people and causing acute leptospirosis in rural and urban areas. This approach allowed for a precise mechanistic connection between source of infection and human disease, allowing the researchers to measure the environmental risk for bacterial infection – an approach never used before.

"This study is important because we have connected clinical and basic science to provide a quantitative risk assessment for water-borne diseases," said Vinetz. "This method of risk assessment for infection may also be applicable to other water-borne diseases such as those caused by Shigella, Salmonella, Cryptosporidium, and E. coli."

Debra Kain | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>