Chikungunya and Dengue

The Aedes aegypti mosquito is responsible for the spread of viral infections like Dengue, Chikungunya and Zika.The vector control strategies may work best right now.

If anyone has suffered from Chikungunya once, they are immune for lifetime. Chikungunya disease is caused by one serotype and the chances of repeated infection caused by the same serotype is minimum. The fatalities observed in case of Chikungunya cannot be solely related to it but the concurrent underlying other medical conditions like sepsis, kidney injury and pneumonia in the patient.

Whereas,Dengue is caused by 4 closely related serotypes of the virus. After recovery, a Dengue patient develops life long immunity from one serotype of virus, from which he got sick. Cross immunity to other serotypes is partial and temporary after recovery. Second time infection from other serotypes makes the patient’s condition worse and often turns fatal. This is the biggest challenge in inventing the vaccine for Dengue. 

A vaccine to prevent dengue (Dengvaxia®) is licensed and available in some countries for people ages 9-45 years old. The World Health Organization recommends that the vaccine only be given to persons with confirmed prior dengue virus infection.The vaccine manufacturer, Sanofi Pasteur, announced in 2017 that people who receive the vaccine and have not been previously infected with a dengue virus may be at risk of developing severe dengue if they get dengue after being vaccinated.

As, Dengue vaccine has attenuated or weak virus, which acts very much, like a natural infection, without making the recipient sick. But, if the vaccinated person is infected with the virus again in life, the immune system treats it as a second infection that has much severe consequences. This drawback prohibits the use of the vaccine in children below 9 yrs as they may be the ones who are most likely to be untouched by the prior Dengue infection.

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