Rise of dengue in rural Bangladesh stokes fears of outbreak cycle

The magnitude of the dengue fever outbreak in the rural areas from the epicentre in Dhaka has sparked concerns among experts about a possible cycle of spate of the mosquito-borne viral disease in the villages.

The disease was first found in the country in 2000 when 93 people died in an outbreak, but no-one outside the city was even infected by the virus until 2016. The number of hospitalised dengue patients outside Dhaka was only 37 among 6,060 while the ratio dropped to five to 10,148 last year.

But out of the around 70,000 patients hospitalised with dengue fever in Bangladesh so far this year, nearly 42 percent cases have been reported outside the capital, according to the Directorate General of Health Services. 

The total number of such patients this year has exceeded the combined totals in the past 19 years.

Out of the 189 fatal cases reported by doctors and hospital authorities, 48 have been outside Dhaka while the number was only three in total out of 298 in around two decades.

Dengue is mostly caused by Aedes aegypti mosquito which is prevalent in Dhaka city.

As the dengue spreads outside Dhaka, people fear the presence of Aedes albopictus, another vector in dengue outbreak, can aggravate the situation.

Aedes aegypti plays 95 percent role in spreading the virus while the rest is done by Aedes albopictus in an epidemic condition, according to Professor Kabirul Bashar, an entomologist at Jahangirnagar University’s zoology department.

“I think it (Aedes albopictus) has gained vectorial capacity this time and that is the reason behind the spread of dengue in rural areas,” he told bdnews24.com.

Another dangerous side of Aedes albopictus is, Prof Kabirul pointed out, dengue virus transfers to the mosquito’s eggs.

“So dengue fever can rise in the rural areas next year. Because the mosquitos now have the virus and the cycle will continue,” he said.   

Dr Meerjady Sabrina Flora, director of the government’s disease control agency, said the authorities and the people now need to take steps to contain dengue outside Dhaka as well as inside the city.

The director of the Institute of Epidemiology Disease Control And Research or IEDCR said Aedes mosquito can also breed in rural areas with sources like tree holes, broken and abandoned pots and other things where clean rainwater can gather.

Local Government and Rural Development Minister Md Tazul Islam told bdnews24.com that the government will work to raise awareness against Aedes mosquito in the union level because people’s participation is most important in preventing dengue fever.

Dr ASM Alamgir, a senior scientist at the IEDCR, had earlier warned of the possibilities of the disease’s spread outside Dhaka, noting that Aedes albopictus is prevalent in rural areas.

“If this mosquito bites a dengue patient who travelled from Dhaka, then the disease can spread in those areas,” he had said, suggesting treatment of patients inside mosquito net.

Former director of IEDCR Prof Mahmudur Rahman sees the situation “a cause for concern”.

“We have seen the presence of dengue outside Dhaka even in the past. But this year it just flared up,” he had told bdnews24.com, adding that due to urbanisation Aedes aegypti mosquito can be found in Upazilas as well.

“Aegypti is more virulent than albopictus,” he had said.

Dr BN Nagpal, senior entomologist of WHO Southeast Asia region, however, disagrees on the fears about the presence of albopictus.

Albopictus can play a 0.5 percent to 1 percent role when a large number of cases are in rural settings, according to the WHO expert. “Then only few cases can be generated by the albopictus,” he had said.