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 New antibody analysis accelerates rational vaccine design
09.08.2018 | Scripps Research Institute

nachricht Distrust of power influences choice of medical procedures
01.08.2018 | Johannes Gutenberg-Universität Mainz

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: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>