Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacteria cause river blindness

08.03.2002


Bacteria find safe-haven inside worms in return for helping them reproduce.
© Science


Inflammation clouds the transparent cornea, leading to cataract-like blindness.
© WHO


Microbes, not the worms that carry them, aggravate the immune system.

Stowaway bacteria inside parasitic worms, and not the worms themselves, cause river blindness, according to new research. The finding could lead to better ways of preventing or treating the debilitating disease.

River blindness, or onchocerciasis, affects some 17 million people throughout central Africa and in parts of Arabia and South America. Sufferers develop inflammatory conditions. When inflammation occurs in the eyes it clouds the transparent cornea, leading to cataract-like blindness.



The minute offspring of filarial nematode worms, called microfilaria, were thought to cause the disease. Fragments of dead microfilaria were believed to cause the immune system to overreact.

Not so: Wolbachia microbes probably play a major role, say Eric Pearlman of Case Western Reserve University in Cleveland, Ohio, and colleagues. Working with a genetically modified mouse mimic of human river blindness, they have now found that it is these bugs that aggravate the immune system1.

Worm turn

Bacterium-free worm extract doesn’t cause severe disease in the mice; Wolbachia-laden worms do. What’s more, Pearlman’s group found a molecular receptor in the eye that is particularly sensitive to Wolbachia. This receptor is crucial to eliciting an inflammatory immune response.

"It’s a very significant finding - it gives us a more precise idea of what’s happening," says Alexander Trees of the Liverpool School of Tropical Medicine in England. Trees’ group recently showed that filarial nematodes need Wolbachia bacteria to reproduce; antibiotics to kill Wolbachia can sterilize adult worms2.

"The more we know about this disease the better," agrees Juliet Fuhrman, who studies river blindness at Tufts University in Medford, Massachusetts. Wolbachia’s interaction with the immune system might provide a target for vaccines or other drugs to quell the disease itself, rather than the worms, Fuhrman hopes. "These may be our best chance," she says.

That Wolbachia are found in filarial nematodes is not so surprising. These bacteria live within numerous insects, where they specialize in manipulating their host’s reproduction. Researchers are keen to control them as they are essential to many harmful insects, including mosquitoes and crop pests3.

River blindness is currently managed with chemicals to stop adult filarial nematodes from reproducing and with insecticides to kill the black flies that carry the worms. These have curbed the disease quite successfully, but "the job isn’t done yet", warns Pearlman,

Antibiotics could be a good alternative, if Wolbachia is the culprit. Trials have begun, but widespread antibiotic use is difficult to enforce and runs the risk of the bacteria subsequently adapting to the drugs. "We’re all living in terror of resistance developing," says Fuhrman.

References

  1. Saint Andre, A. V. et al. The role of endosymbiotic Wolbachia bacteria in the pathogenesis of river blindness. Science, 295, 1892 - 1895, (2002).
  2. Langworthy, N. G. et al. Macrofilaricidal activity of tetracycline against the filarial nematode Onchocerca ochengi: elimination of Wolbachia precedes worm death and suggests a dependent relationship. Proceedings of the Royal Society B, 267, 1063 - 1070, (2002).
  3. Knight, J. Meet the Herod bug. Nature, 412, 12 - 14, (2001).


TOM CLARKE | © Nature News Service

More articles from Health and Medicine:

nachricht New malaria analysis method reveals disease severity in minutes
14.08.2017 | University of British Columbia

nachricht New type of blood cells work as indicators of autoimmunity
14.08.2017 | Instituto de Medicina Molecular

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New bioimaging technique is fast and economical

21.08.2017 | Medical Engineering

Silk could improve sensitivity, flexibility of wearable body sensors

21.08.2017 | Materials Sciences

On the way to developing a new active ingredient against chronic infections

21.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>