Secondary dengue infection turns severe in Bangladesh

The risk of secondary dengue infection has been increasing in the country with a large number of people are contracting the mosquito-borne disease every year as more than one of its four serotypes are infecting people at the same time.

Virologists and physicians suspect that already a number of people are contracting secondary infection which means getting dengue infected more than once as this year three serotypes are active at the same time.

Hospitals currently have no diagnostic mechanism to make sure on their own whether a patient has been infected for the first time, or was infected by the disease earlier too, and have to depend on the accounts shared by the patients themselves about their disease history.

A large number of dengue patients reported that it was not their first-time dengue, said physicians.

Bangabandhu Sheikh Mujib Medical University former vice-chancellor and virology professor Nazrul Islam said that those who were infected for the second time were certainly attacked by different serotypes that were more virulent than the ones that infected patients for the first time.

He said that different serotypes could be present at the same time particularly in a situation heavily lacking effective mosquito control measures.

An Institute of Epidemiology Disease Control and Research’s latest virus surveillance report shows that of the four dengue virus serotypes, three—DENV-2, DENV-3 and DENV-4 are spreading the infection this year.

Institute director professor Tahmina Shirin, referring to a recent surveillance report completed in October, said that this year DENV-2 serotype dominated with infecting 70 per cent of total patients. Serotype DENV-3 is found in 20 per cent patients, while and DENV-4 is diagnosed among the rest 10 per cent.

Virologists say that a particular serotype of a virus cannot usually infect the same patients twice in their life time due to the immunity system active in the human body, and so for a patient to contract the same disease it needs different serotypes of the same virus.

Professor Nazrul Islam has put the significantly higher dengue deaths down to the secondary infection. 

‘The presence of three dengue serotypes at the same time is making the disease more fatal, raising the death toll,’ he added.

He also blamed people’s careless attitude in taking preventive measures for the rising dengue morbidity, urging all to take self-motivated measures amid the lack of mosquito control initiatives by the government. 

According to the Directorate General of Health Services, so far 42,470 people were hospitalised, while 214 died, including 660 hospitalisation and four deaths in the past 24 hours till Sunday morning, of dengue since January this year.

Dengue killed 1,705 people and sent 3,21,179  people to hospital in 2023 alone, while 853 deaths and 2,44,246 hospitalisations were recorded between 2000 and 2022, the DGHS data showed.

Dengue hospitalisations had been reported at 28,429 and 62,382, respectively, in 2021 and 2022, when the outbreak in the country caused 105 and 281 deaths respectively.

In 2019, over 1,01,354 dengue patients were hospitalised and over 276 deaths were reported. In 2020 during the Covid-19 pandemic, 1,405 people were hospitalised and seven died of dengue.

Experts suspect the actual number of dengue infection is much higher than the reported cases as the health directorate collects information from major healthcare facilities only.

According to the DGHS data, dengue fatality rate is 0.50 per cent this year which was 0.34 per cent in 2020.

Physicians said that with the rise in dengue infection burden, the fatality risk was also increasing.

Physicians have also reported that the patients’ fighting capability against dengue is reducing, which they attribute largely to secondary infection and comorbidity.

‘After admission, a significant number of patients deteriorate within just 2-3 days,’ said Md Kamruzzaman Mazumder, a medicine department associate professor at Ibn Sina Medical College Hospital.

This year, of the deaths, 14 died in January, three in February, five in March, two in April, two in May, eight in June, 12 in July, 27 in August, 80 in September, and 47 in the first 12 days of October.

Of the hospitalisations this year, 1,055 were reported in January, 339 in February, 311 in March, 504 in April, 644 in May, 798 in June, 2,669 in July, 6,521 in August, 18,097 in September, and 10,872 in the first 12 days of October.

A dengue outbreak was first officially reported in the country in 2000 when 93 people died and 5,551 patients were hospitalised, according to the DGHS data.

Entomologists observed that dengue patients are on the rise largely due to the inactivity of the authorities concerned.

Dengue is likely to peak early November, according to prediction by experts.