Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Drug resistance of parasite which causes river blindness could lead to resurgence

15.06.2007
Development of drug resistance in the parasite which causes river blindness could lead to breakouts of the disease in communities where it has been brought under control, conclude authors of an Article published in this week’s edition of The Lancet.

River blindness (onchocerciasis) is caused by the filarial nematode Onchocerca volvulus, a parasite transmitted by Similium blackflies. Around 37 million people worldwide are suspected to be infected. Ivermectin, in the form of an annual dose, is the drug that has been widely used for river blindness (onchocerciasis) since 1987, and due to this long-term use a study into resistance to its effects is timely. Although invermectin does not kill substantial numbers of adult O. volvulus at standard doses, it prevents them releasing microfilariae and keeps skin counts of microfilariae low.

Professor Roger Prichard, Institute of Parasitology, McGill University, Montreal, Quebec, Canada, and colleagues studied 2,501 people in 20 communities in Ghana, West Africa. Of these, 19 had been receiving between 6-18 annual doses of ivermectin, while one community had never been given ivermectin.

In the first phase of the study, all the participants were tested for levels of microfilarial load by taking 2mm skinsnips (skin samples) prior to their 2004 annual ivermectin dose, and 30 days after treatment to determine the effect of the ivermectin. For the second phase, skin snips were taken from 342 individuals from ten communities, who had tested positive at pre-treatment assessment, at 90 and 180 days after treatment.

The researchers found that microfilaria prevalence ranged from 2.2% to 51.8%, and community microfilarial load in treated communities ranged from 0.06-2.85 microfilariae per snip. Despite treatment, prevalence rate doubled in two communities between 2000 and 2005.

Although ivermectin clears 100% of microfilariae in 99% of those treated, 90 days later four of 10 communities had significant microfiliarae repopulation, ranging from 7-21% of pre-treatment counts. This rose to nearly 54% by day 180. In the other six communities studied, microfilariae repopulation was controlled as expected.

The authors conclude: “Ivermectin remains a potent microfilaricide. However, our results suggest that resistant adult parasite populations, which are not responding as expected to ivermectin, are emerging. A high rate of repopulation of skin with microfilariae will allow parasite transmission, possibly with ivermectin-resistant O. volvulus which could eventually lead to recrudescence of the disease.”

In an accompanying Comment, Dr Peter Hotez, President, Sabin Vaccine Institute and Department of Microbiology, Immunology, & Tropical Medicine, George Washington University, Washington, DC, USA, says there is a moral imperative to continue ivermectin treatment to control river blindness.

He says: “We need to anticipate the possibility of further ivermectin resistance and greatly increase our current level of effort and support to develop and test a new generation of control tools for onchocerciasis.”

He concludes: “Now is the time for global health leaders to build on the strengths of community-directed treatment with ivermectin, and advocate and support the development, testing, and distribution of a new generation of onchocerciasis-control tools.”

Tony Kirby | alfa
Further information:
http://www.thelancet.com/webfiles/images/clusters/thelancet/press_office/Onchocerca.pdf

More articles from Health and Medicine:

nachricht Laser activated gold pyramids could deliver drugs, DNA into cells without harm
24.03.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

nachricht What does congenital Zika syndrome look like?
24.03.2017 | University of California - San Diego

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>