“We are still investigating why the cases are high in Mindanao. Cases usually shoot up there are new serotype strains. There is a possibility that the older serotype 2 strain has been replaced with a new one, making the populace more vulnerable,” Tayag explained.
Of the 4 “serotype” strains or variation of dengue viruses, types 2 and 3 are the most common in the country.
According to DOH, those who get infected with the common dengue serotypes develop immunity from these strains until the following year. If serotype 4, for instance, will spread as a predominant strain in an area, this will make most people susceptible to the disease.
Among the areas in Mindanao, Zamboanga City is apparently vulnerable to dengue fever since DOH discovered all serotypes there.
“During the 2010 outbreak, it was confirmed that dengue serotype 4, which increases the chances of fatality among those infected with disease, was already existing in Zamboanga City,” said Dr Norvie Taruc-Jalani of the DOH's Regional Epidemiology and Surveillance Unit. (www.rappler.com)