WHO tackles rabies, snake bites and scorpion stings

Jan 9 2007

Although more than 12 million people each year are bitten by dogs or snakes, or stung by scorpions, the world's capacity to treat them is inadequate.

Effective treatment for these conditions is critically dependent on therapeutic sera1, but this essential drug is often unavailable or unaffordable in the countries where it is most needed.

To address this neglected public health issue, the World Health Organization (WHO) is creating a five-year plan to boost production in developing countries, help authorities forecast market needs and strengthen regulatory capacity. On 10 January, the health agency will bring together the top experts in the area as well as recipient and donor countries, international organizations and manufacturers to agree to a global action plan.

Production of therapeutic sera in industrialized countries is dropping due to inadequate profitability, linked to uncertainty about the quantities needed. In developing countries, affordability is an issue, and production is also quantitatively limited and often does not reach the quality standard required to make these treatments effective and safe. WHO estimates its plan to boost access to treatment will cost US$ 10 million.

"We need to boost local manufacturers' capacity and improve the delivery of products to remote rural areas," said Dr Howard Zucker, WHO Assistant Director-General for Health Technologies and Pharmaceuticals. "There are effective solutions that could save millions of lives."

Rabies is the tenth most common cause of death due to infections in humans. It is 100% fatal but 100% preventable when post-exposure treatment using therapeutic sera is readily available. An estimated eight million people need to receive anti-rabies serum each year after being exposed to animals suspected of carrying rabies. Almost half of those requiring the therapeutic sera and those dying of rabies are children less than 15 years old. More than 99% of all human deaths from rabies occur in Africa and Asia.

Close to five million snake bites and scorpion stings are recorded each year in the world (mostly in Africa, Asia and Latin America), 50 to 75% of which need treatment with therapeutic sera to prevent death, amputation or severe neurological disorders. The main populations affected are young agricultural workers and children. Available epidemiological data on the incidence of snake bites, including the degree of associated mortality and long-term morbidity are largely hospital-based and therefore underestimate the true scale of the problem. A majority of snake-bite victims seek traditional treatment and may die at home unrecorded.

Since the 1970s, the number of manufacturers of anti-venoms against African snake bites has dropped dramatically. It is estimated that there are one million snake bites each year in Africa alone resulting in over 20,000 deaths and a much higher incidence of chronic disability resulting from neurological sequelae and physical handicap from necrotic effects requiring amputation.

Over 10 million vials of anti-venom sera would be needed to treat snake and scorpion bites worldwide, with an estimated 2 million vials required for Africa alone. An estimated 16 million vials of anti-rabies serum would be needed each year if current international guidelines for post-exposure prophylaxis were to be fully implemented.

The crisis in the availability of therapeutic sera calls for an international effort to facilitate the transfer of technology to affected countries and address major logistic problems in distribution, particularly in ensuring maintenance of a cold chain. In addition, a lack of knowledge about the correct medical management of bites and stings from venomous animals, including the appropriate use of sera, further compromises the efficient clinical use of the limited quantity of product available.

WHO is planning the following actions, which will be discussed at the 10 January meeting:

• Define a global standard for the production, quality control, and regulation of therapeutic sera to be used as guidance by local regulatory authorities and manufacturers;
• Conduct regional educational workshops to help the implementation of quality and safety requirements for production of therapeutic sera following the principles of good manufacturing practices;
• Train inspectors and manufacturers on the critical parameters of the production of therapeutic sera;
• Facilitate transfer of technology to developing countries;
• Establish a therapeutic sera pre-qualification scheme based on WHO experience in pre-qualification of other therapeutic products;
• Develop guidance and training materials on the prevention, diagnosis and management of diseases treatable by therapeutic sera.

1 A therapeutic serum is a pharmaceutical preparation that contains antibodies against one or more specific antigens. These therapeutic sera are manufactured by fractionating plasma collected from animals (typically horses) that have been immunized against relevant antigens and that as a result develop neutralizing antibodies. The plasma is pooled in batches of tens to hundreds of litres, and processed to extract the active immunoglobulin fraction.

For more information contact:

Dr Ana Padilla
WHO Scientist
Telephone: +41 22 791 3892
Mobile: +41 79 793 0786
Email: [email protected]

Charlotte Wiback
Media Officer
Telephone: +41 22 791 1346
Email: [email protected]

Jacqueline Sawyer
External Relations Officer
Telephone: +41 22 791 3921
Mobile: +41 79 509 0649
Email: [email protected]