Research into cattle parasite could improve treatment of river blindness in humans
13 January 2011
A team at the University of Liverpool, including a BBSRC-funded PhD student, has discovered how a parasitic worm that causes a skin complaint in cattle survives due to an advantageous relationship with a type of bacteria that protects it from the body's immune system. The parasite - a tiny worm called Onchocerca ochengi - is very closely related to the worm that causes river blindness in humans. This research therefore has the potential to improve both animal and human health.
The team found that a bacterium inside the worm acts as a 'disguise' for the parasite, resulting in the immune system reacting to it in an ineffective way. The bacteria protect the worm from the body's natural defences, but once the bacteria are removed with antibiotics, the immune system responds appropriately, releasing cells, called eosinophils, that kill the worm.
Antibiotics are successful against the river blindness parasite, but the long treatment regime means that it has limited use across whole communities. These new findings suggest that if medics could prime the immune system to recognise the worm, a shorter duration of antibiotic treatment may be sufficient to overcome its bacterial defences.
Both the cattle and human diseases are caused when insects that breed in rivers deposit the larvae of a worm via their bite. In humans, the infection leads to severe itching of the skin and lesions of the eye which can result in blindness. It affects millions of people in developing countries, particularly in West and Central Africa. In cattle, the closely related parasite causes lumps to appear on the animal's skin but does not cause blindness or any other illness.
Dr Ben Makepeace, from the University's Institute of Infection and Global Health, explains: "Our team has already shown that removing the bacteria with antibiotics results in the death of the worm, but until now we were unaware of how the bacteria protected the parasite in the first instance. Antibiotics can rid the parasite of the bacteria, allowing the immune system to respond properly, but it is a long treatment process, lasting up to six weeks.
"Now we can begin to look for a way to 'prime' the body into reacting to the parasite more efficiently. Currently there is no vaccine for river blindness, but if a candidate could be identified this may help boost the immune system ahead of antibiotic treatment and reduce the length of time patients have to take the drug. It is essential that whole communities are cured of the infection and the more we know about the mechanisms the parasite uses to survive in the body, the further we can progress with finding a practical treatment that kills adults worms and not just the larval stages".
The research is also funded by Pfizer Animal Health, and the European Commission. It is published in Proceedings of the Royal Society B.
About the University of Liverpool
The University of Liverpool is a member of the Russell Group of leading research-intensive institutions in the UK. It attracts collaborative and contract research commissions from a wide range of national and international organisations valued at more than £110M annually.
BBSRC is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £470M in a wide range of research that makes a significant contribution to the quality of life in the UK and beyond and supports a number of important industrial stakeholders, including the agriculture, food, chemical, healthcare and pharmaceutical sectors.
BBSRC provides institute strategic research grants to the following:
- The Babraham Institute
- Institute for Animal Health
- Institute of Biological, Environmental and Rural Sciences (Aberystwyth University)
- Institute of Food Research
- John Innes Centre
- The Genome Analysis Centre
- The Roslin Institute (University of Edinburgh)
- Rothamsted Research
The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.
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