If I have had dengue fever before, should I avoid traveling to countries with prevalent dengue as a rule to avoid hemorrhagic fever?
Yes. Dengue is caused by any one of four related viruses transmitted by mosquitoes. Recovery from infection by one provides lifelong immunity against that particular serotype. However, cross-immunity to the other serotypes after recovery is only partial and temporary. Subsequent infections by other serotypes increase the risk of developing severe dengue.
Mosquito control. For 100% certainty, avoiding travel to areas with dengue is all you can do. However, "avoid" is relative, depending on the reason and importance of travel. In dengue areas, the main thing is to be very compulsive about preventing mosquito bites with proper clothing, good repellant (DEET or picaridin, nothing else is reliable), and night time mosquito nets in some settings, e.g. sleeping in tents.
How does thrompocytopenia result in Hemorrhage? . Whats the Main role of plateles that gets hampered due to dengue fever?
See below. Platelets are the first line of defense in plugging any hole in a blood vessel. Microscopic holes happen with natural activity. Lack of platelets allows bleeding. Thrombocytopeina in Dengue occurs to due a combination of issues. You may consult this site for information. http://www.who.int/csr/resources/publications/dengue/012-23.pdf. Read more...