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Last Updated: Sunday, 23 April 2006, 23:10 GMT 00:10 UK
Hope for tropical disease vaccine
Image of an African village
Leishmaniasis is common across the African continent
Scientists hope they can create a new vaccine for a tropical disease which kills about 60,000 people a year.

Leishmaniasis, or black fever, attacks the spleen, bone marrow and liver and destroys the immune system. Untreated it is nearly always fatal.

Swiss researchers say in the journal, American Chemical Society Chemical Biology, they have designed a jab that could protect animals and humans.

Several other potential vaccines for the disease are also being developed.

This candidate vaccine may be of use not only in humans but also for pet vaccines
Professor Peter Seeberger

But despite a World Health Organization push no vaccine yet exists for the disease which affects 500,000 people worldwide a year - mostly in India, Bangladesh, Nepal, Sudan and Brazil.

The team at the Laboratory for Organic Chemistry at the Swiss Federal Institute of Technology (ETH) in Zurich are the only scientists known to be trying to design a carbohydrate-based vaccine.

This new type of vaccine uses synthetic forms of carbohydrates taken from the parasite or bacteria responsible for the disease.

They work by stimulating the patient's own immune system to deploy a protective shield against the disease.

Carbohydrate vaccines are already used in everyday medicine to protect against meningitis and other bacterial infections.

Research leader Dr Peter Seeberger explained that the immune system already has a means of fighting the parasite.

Tests in animals

What the vaccine he is trying to create does is to "educate the human body" to make an immune response to it, he says.

It also uses a deactivated flu virus as a means of boosting that natural response.

He added: "This candidate vaccine brings something new to the table and may be of use not only in humans but also for pet vaccines.

"Dogs get leishmaniasis, particularly in Southern Europe and a vaccine is urgently needed there, as well."

Laboratory studies have shown that this possible vaccine produces a protective action against leishmaniasis, so now the Swiss team are moving on towards tests in animals.

But Professor Seeberger acknowledges that a final vaccine is at least five years off.

'Extremely serious'

He says animal tests will take in the order of two years and pre-clinical trials another two to three years.

The WHO has made the development of a vaccine for leishmaniasis disease a high priority because of the current lack of any effective treatment.

The most common drugs used to treat leishmaniasis have serious side-effects and are expensive.

Immunisation, vaccines and biologicals expert at the WHO Melinda Henry said the vaccine development was in an early stage.

She said: "There are about half a million new cases of visceral leishmaniasis occurring each year.

"Leishmania-endemic regions have expanded in recent years and Leishmania/HIV co-infection has emerged as an extremely serious, increasingly frequent new disease.

"Given this situation, a safe, effective vaccine against visceral leishmaniasis would prevent a great deal of suffering and death due to a disease, which, if untreated, is very deadly."

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