Why does reinfection with dengue fever often become more severe?

Doctor Bach Thi Chinh, Medical Director, VNVC Vaccination System, said as above, adding that this phenomenon is closely related to immunity. There are four serotypes of dengue fever: Den-1, Den-2, Den-3 and Den-4. That is, a person can get the disease 4 times with 4 different types.

“The second infection can cause severe illness and the death rate is many times higher than the first infection,” said Dr. Chinh.

This phenomenon is called “antibody-dependent enhancement” (ADE). That is, after contracting dengue fever for the first time, the body creates long-term specific antibodies against the type of Dengue virus that has just been contracted. This antibody can cross-protect with other types but not for a long time (about 6 months), after this time the patient is at risk of a second dengue infection with another type of Dengue virus.

At this time, the old antibodies bind to the new dengue virus type but do not neutralize it to destroy it. On the contrary, they make it easier for the virus to penetrate immune cells, causing a stronger inflammatory response, leading to severe complications such as severe bleeding and shock.

Some other factors can also make dengue fever worse a second time, including: age, health status, virus type… Accordingly, children and the elderly are at risk of more severe disease. People with underlying diseases such as diabetes, cardiovascular disease, liver disease, kidney disease… are also more susceptible to dangerous complications. Some strains of Dengue virus are highly virulent and will cause more severe disease upon first infection.

Some dangerous complications of the disease include hemorrhagic shock, pleural effusion, coma, heart failure, kidney failure, premature birth and miscarriage. Patients may experience long-term symptoms including bone and joint pain, weakness, dizziness, nausea, hair loss, arm weakness, bleeding gums, private areas…

Like Ms. Nguyet (51 years old, Binh Tan, Ho Chi Minh City), she had dengue fever twice. The first time was when I was 13 years old and had symptoms of fever and fatigue, so I was only treated at home. The second time in 2022, she had a high fever that did not go away, then symptoms of bleeding from her gums and private areas appeared, so she had to be hospitalized. At this time, the condition became worse, the platelet index decreased sharply, requiring aggressive treatment.

Similarly, Hoang Duong (24 years old, Phu Nhuan, Ho Chi Minh City), from 2023 to now, has had dengue fever twice. The first time, Duong took care at home and recovered after 7 days. In September this year, he was infected for the second time, had a high fever for three consecutive days, severe bone pain, vomiting a lot, bleeding gums… Duong had to stay in the hospital for 10 days, receive fluids, blood tests, and mineral supplementation. .

According to Dr. Chinh, the phenomenon of worsening dengue re-infection is warned every year, at the peak of the disease. With proper medical care and early detection, the death rate from dengue hemorrhagic fever is less than 1%.

To reduce the severity of dengue fever when reinfected, Dr. Chinh recommends that patients pay attention to monitoring signs of the disease and proactively prevent it.

Warning signs of worsening disease include severe abdominal pain, continuous vomiting, bleeding gums, tooth roots, vomiting blood… At this time, the family and patient need to immediately go to a medical facility for timely treatment. . Families should not buy medication at home because it can make the disease worse and lead to death.

Prevent the disease by getting vaccinated, killing mosquitoes (larvae) and avoiding mosquito bites. In particular, the vaccine helps prevent all 4 serotypes of Dengue virus, with protective effectiveness of up to more than 80% and prevention of hospitalization up to 90%.

The injection is indicated for children 4 years of age and older and adults for people who have had and have not had the disease, and do not need to be screened for previous Dengue infection. Two-dose vaccination schedule, each dose three months apart. Currently, the vaccine is distributed at nearly 200 VNVC centers nationwide.

To prevent mosquitoes from breeding, families close the lid of the tank and water containers, and release fish to kill larvae in the tank and rockery. Pots, flower vases and unused water containers should be turned upside down and waste materials and natural water holes should be removed. Sleep under mosquito nets even during the day, wear long-sleeved clothes, use mosquito spray, mosquito scent…

According to statistics from the Ministry of Health, in the first 9 months of this year, Vietnam recorded 79,727 cases of dengue fever, of which 12 deaths. In 2023, the country will have more than 172,000 cases of dengue fever, of which 43 people died.