Dengue Symptoms

[David Beasley]

In article <Pine.SUN.3.91.950928091456.10830A-100000 at alsys1>, Peter Charles <pcharles at aecom.yu.edu> says:

[SNIP]

>Immunity to any one of the 4 serotypes (by previous exposure)
>does not confer protection against the other 3, and is in fact thought to 
>exacerbate the disease upon exposure to one of the other serotypes (a 
>phenomenon known as "immune enhancement" of disease).  This is thought to 
>be one of the mechanisms by which simple dengue fever becomes dengue 
>hemorrhagic fever/shock syndrome (DHF/SS). To my knowledge, there are no 
>strains (ie, D1-D4) that specifically *cause* DHF/SS.

Several "risk factors" for DHF/DSS have been identified.  Around 90% (?) of
haemorrhagic fever cases occur during secondary infections (hence the
immune enhancement theories), and a secondary infection with dengue 2 is
more likely to cause haemorrhagic fever than a secondary dengue 1, 3 or 4
infection.  A number of other factors such as age, sex and immune status 
have also been implicated.