Blog Post BIOL1040- s41885581 – Claire Doig
BREAKING NEWS; Possibility of Dengue Fever vaccine near at hand!!!
There has been a great deal of anxiety amongst the general public regarding the possibility of a dengue fever outbreak in Townsville. But why would such an outbreak be so troublesome?
Each year approximately 100 million people are infected with the dengue virus, including approximately 20, 000 people who die from its more severe form[1]. Thus, the idea of there being a dengue fever epidemic can be quite frightening and therefore making the attempts to develop a vaccine against the mosquito transmitted virus tremendously important.
But why is it so hard to develop a vaccine against the virus? The main answer to this is that there are four separate strains of the virus, Dengue 1, Dengue 2, Dengue 3 and Dengue 4[2]. The initial infection that a person may develop from one of the strains is not usually very serious. However, it is only possible for a person to develop immunity to the strain of the virus which they have already been infected with, thus making them susceptible to one of the other three strains[3]. Furthermore, when a person is infected with a different strain of the virus to what they had previously, the chance of them developing the extremely serious dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS) immediately increases[4]. As a result, it is necessary to develop a vaccine which can create immunity to the four strains the virus at the same time.
The National Institute of Allergy and Infectious Diseases (NAID) researchers have developed a vaccine for two of the strains of the virus, dengue 1 and dengue 4. These two potential vaccines appear to create a relatively high level of immunity to these two strains of the virus. The researchers have also developed possible vaccine candidates for the dengue 2 and dengue 3 strains of the virus; however these are still undergoing clinical trials[5].
Another obstacle to the development of a vaccine is that the researchers have been unable to find an animal which develops the same clinical signs and conditions that appear in humans when they contract the virus. As a result, the discoveries that are made with vaccines tested on animals such as monkeys do not necessarily apply to the human response to the virus.
There have been very promising results shown in recent clinical trials of the vaccines in which the vaccines have reduced the transmission of the virus from people to mosquitoes[6]. However, the suitability of all four vaccines to be included in the tetravalent vaccine is still uncertain. BUT, will it only be a matter of time until a safe and reliable vaccine is produced???
[1]Modified Mosquitoes Could Save People from Dengue Fever, National Institute of Allergy and Infectious Diseases , http://www3.niaid.nih.gov/topics/DengueFever/Researcg/Prevetntion/modSkeetersDengue.htm , (4/11/08)
[2] Dengue Fever, Infant Immunity, National Institute of Allergy and Infectious Diseases, http://www3.niaid.nih.gov/topics/DengueFever/Research/Prevention/infantImmunity.htm , ( )
[3] Ibid.
[4] NIAID Scientists Use Reverse Genetics to Develop Potential Dengue Fever Vaccine, National Institute of Allergy and Infectious Diseases , http://www3.niaid.nih.gov/topics/DengueFever/Research/Prevention/infantImmunity.htm , (1/1/09)
[5] ibid
[6] Ibid.
