Since it became a global issue during World War II, researchers and scientists have been struggling to develop a vaccine for Dengue fever. To date, there has been no success in eradicating this disease. Before we get to the specifics of the challenges this disease presents, let’s cover the symptoms related to this tropical disease.
Dengue fever is a viral disease that is typically transmitted through a mosquito bite. It thrives in warm, wet climates, hence the greater number of reported cases in Malaysia, Mexico, the Caribbean and, in more recent times, Florida. It is characterized by a fever, headache, muscle/joint pain and a skin rash similar to that of the measles. Dengue is rarely fatal, but because there is currently no vaccine, standard treatment simply consists of IV fluids to prevent dehydration and, in some cases, a blood transfusion.
Why has it been so hard to come up with a vaccine? Being a viral disease, it has mutated over time to its current form that involves four different serotypes. Infection with one serotype generates antibody production for life-long protection, but only against that particular strain. The patient will experience only short-term protection against the other three serotypes. The research community believes that this is most likely due to viral interference. Thus, a vaccine must be tetravalent and offer strong resistance to all four strains simultaneously to be effective.
Current studies around the development of a vaccine include chimerization with yellow fever 17D vaccine strain, combinations of defined mutations/deletions and chimeras and chimerization with dengue 2 PDK53 virus, attenuated by cell culture passage. Due to the fact that it may take up to twelve (12) months for sufficient antibody response, three-part immunization schedules have been developed. Unfortunately, one inoculation will not protect an individual from all four serotypes and could actually enhance the disease if infection occurs between the first and last immunization.
The World Health Organization estimates ~30 million new cases of Dengue fever every year, with a fair percentage of those infected being children. Eradicating this disease through immunization has become somewhat of a Holy Grail for today’s modern scientist.