He cautioned that ribavirin has never been used on West Nile virus infections and has been known to produce some side effects, particularly anemia when used in high doses in other disease treatments. Therefore, physicians should monitor ribavarin treatments very closely. The increased disease incidence, combined with increased frequency of epidemic dengue cause by multiple virus serotypes, has increased the risk of epidemic dengue haemorrhagic fever, one of the leading causes of hospitalisation and death among children in Southeast Asia. Other factors responsible for such increases include a greater than usual number of tropical storms and increasing urbanisation. Dengue fever is an acute viral illness with severe flu-like symptoms often accompanied by a rash on the feet or legs beginning three to four days after onset of fever.
More severe forms are dengue haemorrhagic fever and dengue shock syndrome.
Vascular collapse and hemoconcentration may require vigorous fluid replacement with a crystalloid solution such as lactated Ringer's, but over-hydration must be avoided. Since 1993, Aventis Pasteur researchers have been developing an attenuated tetravalent dengue vaccine. T-cell assays suggest priming to all the dengue viruses among the tetravalent vaccine recipients. Clinical studies of various tetravalent dengue vaccines are in progress in Thailand.