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 Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>