BANGKOK — More than 20,000 people in Thailand have been infected with dengue fever since January, 25 of whom have died, disease control officials said.

Suwanchai Watthanayingcharoenchai, disease control department chief, said the number of infections has doubled compared to the same period in 2018.

In Bangkok alone, nearly 900 cases of dengue and one mortality were reported from January to March, according to the Bangkok Health Department.

Most patients are children aged 5 to 15 years old, but adults are also at risk. Statistics show that the disease is particularly endemic in areas by the Chao Phraya River such as Thonburi, Khlong San, Bang Kho Laem and Yannawa Districts.

“Children are more at risk because they don’t protect themselves from mosquitoes as adults do,” Sant Muangnoicharoen, expert and doctor at the Hospital for Tropical Diseases said. “They are unaware that they need to ward off mosquitoes or stay indoors.”

“They also have less immunity to the symptoms because they have been less exposed to dengue,” he added.

Four types of dengue viruses have been found in Thailand. After getting infected with one kind of dengue, an individual is immune to it but remains susceptible to the other types.

Earlier this month, the disease control department also issued an announcement warning the public of other diseases common during the monsoon season.

“These diseases are more common during this season because viruses grow better in colder temperatures,” Sant said. “Mosquitoes, carriers of dengue and malaria, also breed faster as heavy rain leaves stagnant water where they lay eggs.”

Among the 11 diseases listed in the announcement, dengue, leptospirosis, influenza, diarrhea and conjunctivitis are most prevalent in urban areas. Some of these diseases can be deadly if left untreated.

Sant recommends staying healthy through a balanced diet, adequate sleep and regular exercise as general precautions. Vulnerable groups such as children and elders should be vaccinated against influenza.

Maintaining personal hygiene can also mitigate risks. Stay away from floods, but immediately wash up if you can’t avoid plodding through floodwaters.

“If a fever reaches high temperatures or a wound is infected, you should seek immediate medical attention,” Sant added.