Dengue fever carrier

Question

Sparked by a Dengue infection on two of my off-site colleagues in India, I read up a little on this virus.

Reading the Wikipedia article on Dengue fever, I saw that 80% of the infected people are asymptomatic but also that the incubation period varies from 3 to 14 days and that person-to-person transmission is very unusual.

Also when reading a news article on a peak increase of Dengue reports in Telangana, India, I saw that 80% have mild or no symptoms, but are carrier. And that the 'infection season' there will probably hold until October or November, which is interesting for me as I am planning a visit before the end of this year.

My question is what being a carrier in this context means. Am I correct in thinking that 80% of the infected is just lucky and that being a carrier is just temporary and bears no significant meaning? (As long as they are not infected by a different serotype of the virus later on, which could increase their risk on a more severe decease.)

Answer 1

The virus transmits not person-to-person, but person-to-mosquito-to-person. The carriers may be bitten by mosquitos who up until that point weren't infecting people, and afterwards can.

The World Heath Organization says:

Once infected, humans become the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. The virus circulates in the blood of an infected person for 2-7 days, at approximately the same time that the person develops a fever. Patients who are already infected with the dengue virus can transmit the infection via Aedes mosquitoes after the first symptoms appear (during 4-5 days; maximum 12).

In humans recovery from infection by one dengue virus provides lifelong immunity against that particular virus serotype. However, this immunity confers only partial and transient protection against subsequent infection by the other three serotypes of the virus. Evidence points to the fact that sequential infection increases the risk of developing severe dengue. The time interval between infections and the particular viral sequence of infections may also be of importance.

Your information that 80% of those infected are just carriers for a few weeks means that even if you are bitten by a mosquito carrying the disease, you may not end up feeling ill. If doesn't give you any information about your chances of being bitten by a mosquito carrying the disease, and your best efforts to prevent being bitten by mosquitos are still the only way to prevent getting the disease if you travel somewhere it is circulating.