The disease is most commonly seen in Bangladesh, Sudan, India, Nepal, and Brazil. The spleen is the organ to be first affected followed by the bone marrow and liver. Progressively, with worsening of the disease, the immune system is eventually destroyed. It is associated with a significant risk of mortality if left unattended to.
Despite the best efforts of the World Health Organization, no vaccine has been developed so far. The lack of proper available treatment for the disease has made the design of a safe and effective vaccine the utmost priority of the WHO. The currently employed drugs for treatment of leishmaniasis are very expensive and have serious side-effects.
'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,' remarked Melinda Henry, Immunisation, vaccines and biologicals expert at the WHO.
Active research is being conducted at the moment to design potential vaccines to combat the disease. The latest carbohydrate-based vaccine, being developed by researchers at the Swiss Federal Institute of Technology (ETH) in Zurich offers a new ray of hope.
Synthetic (artificial) carbohydrates derived from the bacteria or parasite causing the disease is used in the production of the vaccine. It stimulates the infected person's immune cells to install a protective shield against the disease. Such type of carbohydrate vaccines have been developed previously to protect against meningitis (inflammation of the brain coverings) and other similar bacterial infections.
The immune system has an intrinsic ability to fight against the disease. The vaccine would educate the human body to trigger an immune response. Attempts have also been made to exploit a deactivated flu virus to induce a natural immune response. The results of this study have been published in the American Chemical Society Chemical Biology journal.
'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,' said Dr Peter Seeberger, lead researcher of the vaccine development trial.
Studies based on laboratory experiments have shown that the vaccine might be able to produce an adequate immune response. Inspired by this clue, the research team would now move forward to testing the vaccine formulation on animals. This would take approximately 2 years to complete. If the results of the vaccine trial are successful, it can then be extended to the pre-clinical stage.