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In New York eight years ago, the West Nile virus showed up and infected many. People affected severely would go on to develop encephalitis, which is a swelling of the brain. Deaths occurred.
In 1937 Uganda, the West Nile virus was discovered. Usually, it is found in Africa and the Middle East.
Experts now believe that there is potential for a severe outbreak of the virus in Colorado this year. Mosquitoes collected in several areas, especially North-Central Colorado, have been found to be carriers. However, chances for another big outbreak of West Nile are lessened in areas that have already experienced such an incident.
Scientists cannot explain the phenomenon.
In 2003, there was a West Nile outbreak in Colorado in which over 60 people died.
Scientists are studying why outbreaks do not usually occur in the same area twice as well as a vaccine. Most of this research is being conducted at the Centers for Disease Control and Prevention in Fort Collins.
"Well, it certainly will be several years before a West Nile Virus vaccine will be available for use in humans," says CDC medical epidemiologist Dr. Marc Fischer.
Several private companies are working on the vaccine. Acambis has the most advanced version, which is in phase II trials right now. The trials are being conducted on horses, which when vaccinated, very rarely develop the disease.
Before any vaccine can be used in humans, there must be three successful trial phases.
The West Nile vaccine is a live virus type however; some DNA based vaccines are being studied. No significant delays in development are preventing the distribution, once the third trial phase is successfully completed.
Efforts to develop the vaccine did not begin until 1999, when the virus appeared in the U.S.
The DNA vaccine is promising and easy to produce. Genetic material from the virus is placed into harmless E. coli bacteria.
DNA vaccines are “much simpler than live virus vaccine,” says Dr. Jeff Chang of the Fort Collins CDC. However, the DNA vaccines are just in clinical trials.
Because about 80% of those infected with West Nile suffer little effect of the disease and about 20% get a nasty illness but recover, the CDC is also studying how to best use such a vaccine. Only about 1% becomes severely ill.
The CDC presumes that the West Nile vaccine may be used like the flu vaccine, where specific risk groups are targeted for the shot.
The vaccine is still several years away from production.
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