July has turned out to be the deadliest month since the outbreak of the mosquito-borne disease in the country way back in 2000.

Dengue has claimed the lives of 200 people this month till yesterday, which is the highest number of deaths recorded in one month alone in the last 22 years.

The number of dengue deaths this month is also nearly twice that of the previous July months combined -- 103.

A total of 247 dengue patients have died so far this year. Last year, it was 281, the highest number of dengue deaths the country ever recorded. And the number of total dengue deaths over the years is 729, according to the data of the Directorate General of Health Services (DGHS).

Expressing concern, experts and doctors attributed this year's unusually high death rate to delays in hospitalisation, patients getting infected multiple times, and the presence of dengue strains Den-2 and Den-3.

Tahmina Shirin, director at the Institute of Epidemiology, Disease Control and Research, said when the number of patients increases, deaths also go up.

Second-time dengue infection with a different strain is one of the reasons for the increasing number of deaths this year, she added.

HM Nazmul Ahsan, associate professor at Shaheed Suhrawardy Medical College Hospital, said there were a large number of patients getting admitted to the hospital who are already suffering from dengue shock -- a critical stage of the disease.

The number has increased so much that these patients are now visiting his Mirpur private chamber, where they are advised immediate hospitalisation.

"This is for the first time I and my colleagues are seeing this…," Nazmul added.

There are many who cannot tell that they're having the symptoms and end up not getting hospitalised. These patients are most like to go into shock, he added.

Prof Nazmul said severe stomach aches, breathing difficulties, severe weakness, bleeding from gums or nose, and vomiting are the signs that a patient needs to be hospitalised immediately.

"If a patient is not hospitalised within 24 hours, they may go to the stage of dengue shock syndrome," he said.

There are two types of dengue shocks -- compensated shocks and decompensated shocks. If a patient is hospitalised  immediately after their compensated shock, they don't reach decompensated shock, where the chance to be cured is only 50 percent, he said.

"The patient's blood pressure may remain normal during a compensated shock, which is why many don't realise it. Some of the signs of compensated shock may include a drop in body temperature, increased heart rate, and increased breathing rate," Prof Nazmul added.

There are four types of dengue strains -- Den-1, Den-2, Den-3, Den-4 -- of which Den-2 and Den-3 are mostly active this year and the severity of these two types is high. This is also a reason for so many deaths this year, he said.