Date Data Philippines Dengue Trends
Aug-10 1.000 Google Dengue Trends
Sep-10 0.912 July Aug Sept Oct
Aug-10 0.882 0.486 1.000 0.912 0.381
Aug-11 0.871 0.390 0.882 0.845 0.381
Sep-10 0.845 0.386 0.871 0.674 0.346
Aug-10 0.753 0.486 0.753 0.548 0.337
Aug-11 0.725 0.390 0.725 0.499 0.313
Sep-10 0.674 0.386 0.634 0.459 0.311
Aug-11 0.634 0.319 0.580 0.448 0.296
Aug-10 0.580 0.494 0.430
Sep-10 0.548 0.443 0.403
Sep-11 0.499 0.367 0.361
Aug-10 0.494 0.325 0.333
Jul-10 0.486 0.320 0.324
Sep-06 0.459
Sep-06 0.448
Aug-11 0.443
Sep-06 0.430
Sep-11 0.403
Jul-10 0.390
Jul-10 0.386
Oct-10 0.381
Aug-05 0.367
Sep-11 0.361
Oct-06 0.346
Oct-12 0.337
Sep-05 0.333
Aug-05 0.325
Sep-11 0.324
Aug-05 0.320
Jul-10 0.319
Oct-06 0.313
Oct-12 0.311
Oct-06 0.296

During the rainy months of August to September, the prevalence of Dengue is the highest in the Philippines.

About Dengue fever from Wiki:

Dengue fever is a mosquito-borne tropical disease caused by the dengue virus.Symptoms typically begin three to fourteen days after infection. This may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash. Recovery generally takes two to seven days. In a small proportion of cases, the disease develops into the life-threatening dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs.
Dengue is spread by several species of mosquito of the Aedes type, principally A. aegypti.

The virus has five different types; infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others. Subsequent infection with a different type increases the risk of severe complications A number of tests are available to confirm the diagnosis including detecting antibodies to the virus or its RNA.
A novel vaccine for dengue fever has been approved and is commercially available in a number of countries.

Other methods of prevention are by reducing mosquito habitat and limiting exposure to bites. This may be done by getting rid of or covering standing water and wearing clothing that covers much of the body.

Treatment of acute dengue is supportive and includes giving fluid either by mouth or intravenously for mild or moderate disease. For more severe cases blood transfusion may be required. About half a million people require admission to hospital a year.

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen should not be used.
Dengue has become a global problem since the Second World War and is common in more than 110 countries.

Each year between 50 and 528 million people are infected and approximately 10,000 to 20,000 die.

The earliest descriptions of an outbreak date from 1779. Its viral cause and spread were understood by the early 20th century.  Apart from eliminating the mosquitoes, work is ongoing for medication targeted directly at the virus. It is classified as a neglected tropical disease.