In Bolivia's worst national outbreak in a decade, 19 people have died from dengue fever since January and 31,000 people have been affected, official estimates showed Thursday.

Twelve people died from the disease in the tropical eastern region of Santa Cruz, three others died in central Bolivia, two others in the Andean west and one in the capital city of La Paz, according to an official toll cited by ATB television.

A Bolivian national died on arriving in neighboring Peru, and Health Minister Ramiro Tapia said that one additional death brought the overall death toll to 19.

A total of 30,870 dengue cases have been counted, 71 percent of them in Santa Cruz, -- the region most affected by the outbreak, where authorities have declared a health emergency, Beni, Pando and Cochabamba departments. More than 15,000 troops have been mobilized to assist health teams.

Transmitted by the Aedes aegypti, or yellow fever mosquito, dengue is the most widespread tropical disease after malaria. The highly infectious disease causes high fever, headaches and joint pain.

Its deadly hemorrhagic variant is much more dangerous than the classic type because it causes violent internal bleeding and swift fluid loss, which can lead to a quick, painful death if not treated in time.

Tapia said that 88 confirmed dengue cases were from the hemorrhagic variant.

Several countries, including Brazil, Cuba, Paraguay, Venezuela, Spain and Japan have sent help to La Paz in the form of donations, experts or fumigating equipment.

The World Health Organization (WHO) estimates that 50 million people worldwide each year are affected by dengue, a disease that has grown in recent decades, in part due to global warming.

The virus has made a major comeback on the American continent, where some 900,000 cases were counted in 2007, including 20,000 under the hemorrhagic variant.