Dengue danger returns with monsoon

Most disasters strike without warning. But dengue fever which spreads when infected mosquitos breed in monsoon puddles, is largely predictable and preventable. Densely populated Kathmandu with stagnant pools of water has all the ingredients for another outbreak like the deadly one in 2022.

Last year there were about 55,000 infections and 88 fatalities officially reported across Nepal in its biggest dengue outbreak yet, the real figure is probably higher. Hospitals were out of capacity, over-medication was rampant, and almost every house in Kathmandu had multiple members struck down with infection.

This year, Nepal had already seen over 1,000 dengue infections by end-June. Starting in Dharan where one person has already died, the disease has now reached most of the 77 districts. Even so, many cases are never reported, and many recuperate at their homes. Furthermore, 80% of dengue cases are asymptomatic.

“We are not even at the peak of the dengue season, and cases are already surging. It is very likely that this will further increase as rains begin to dwindle post-monsoon,” warns Sher Bahadur Pun, virologist at the Sukraraj Tropical and Infectious Disease Hospital in Kathmandu. “Nepal’s poor surveillance and record keeping also means diseases like dengue are seriously under-reported.” 

Lack of public awareness about dengue management and prevention adds to the problem. A third of dengue patients admitted to Teku Hospital last year did not even know that the disease is mosquito-borne and spreads in the daytime. 

“At least this wasn’t the case with Covid-19, but with dengue, people struggled to adopt the correct precautions due to lack of knowledge,” explains Pun. “Even more alarming: once infected, people took strong medications like painkillers and antibiotics unaware that they are ineffective and often even harmful in dengue.” 

Although there is no specific medication for dengue, doctors recommend paracetamol to ease the fever and enough fluids to replenish the body. Dengue has no cure. 

Dengue was first reported in Nepal in 2004, but it was not until 2019 that it spread like wildfire in major urban centres. Two years of Covid lockdowns significantly reduced the caseload after the 2019 outbreak, but last year, it struck again. 

Read also: New dengue outbreak likely this monsoon, Sonia Awale

But even as dengue starts to spread in Kathmandu Valley, elected local officials do not seem to be too concerned. When the Ministry of Health and Population called on all local unit representatives in the Valley to discuss the outbreak on 9 July, 12 out of the 18 units avoided the meeting altogether.

Although there are some fumigation and dengue search and destroy campaigns set to be launched in Kathmandu soon, with the monsoon already started, it may be a case of too little too late. It should have started before the onset of the monsoon.

“Though not as many as last year, we are already seeing a worrying number of mosquitoes near areas with stagnant water. And when they fly into homes, chances are the virus is already spreading from those infected,” explains Pun. 

This negligence and delay in action comes despite repeated warnings from experts. Officials knew far in advance that last year’s virus is still in mosquito larvae, waiting for the monsoon, and yet, preventive measures, emergency preparedness, and capacity building were ignored.

The risk of dengue fever will rise in the coming months of August and September, although some public health experts say serious dengue outbreaks seem to happen after a gap of two years. With climate change, mosquitos are moving up the mountains in Nepal, bringing mosquito-borne disease like malaria, encephalitis and dengue higher.

The number of cases officially recorded between January and June this year is nine times higher than last year. Districts like Sankhuwasabha are on the top-ten list for most cases reported, even though it is in the high mountains, and indicating how global warming is pushing mosquito breeding grounds further north. Bagmati is once again the hardest-hit province, possibly due to higher population density.

Read also: Dengue days are here to stay, Sonia Awale

Tackling Dengue: what does it really take?

Ugonnaya Caleb-Ugwuowo recalls treating children and pregnant women struck down with dengue fever in a local hospital in Lagos. The Nigerian doctor and public health expert specialises in managing outbreaks, and says she often felt helpless at being unable to correctly diagnose and treat them due to lack of facilities.

Nepal could learn from Nigeria's experience. Dengue fever is endemic in almost all states in Nigeria. “Although the country is still struggling, the challenges and epidemics Nigeria has faced over the years have shaped our understanding of what it takes to tackle outbreaks like the ones Nepal faced last year and in 2019,” says Ugonnaya. 

It starts with surveillance, she says, adding: “The government in Nepal should, as a matter of urgency, conduct dengue surveys in all provinces to assess the proportion and magnitude of different dengue serotypes circulating freely. Following this, dengue should be made reportable from all local health institutions directly into the national health information system."

Dengue fever for the first time, though debilitating, often does no harm. But getting it a second time with a different serotype poses a significantly higher risk of the disease progressing to haemorrhagic fever, where blood thins out and can start leaking from veins, causing potentially fatal internal bleeding. This is what makes serotype surveys so important.

A study aiming to report dengue serotypes seen in Kathmandu during last year’s outbreak showed DEN-1 and DEN-3 to be the dominant serotypes, with only negligible cases of DEN-2 reported. But such studies should be conducted nationwide, so that the risk of infection with other serotypes can be correctly determined.

Sri Lanka and Bangladesh, both of which have reported elevated levels of dengue infections this year, have direct flights into Nepal. “Although the inflow of infected tourists also poses a great threat, the greater concern should be the mosquitoes in and around places where these tourists go, like airports, temples and major tourist sites,” warns Pun.

If barring flights is not an option, vector control is the best way to minimise transmission. For this, fumigation and dengue search and destroy efforts should be concentrated in tourist sites first. Simple source reduction strategies like covering open water containers, using insecticides in canals, parks and fields exist, but deploying genetically modified mosquitoes to reduce the population of disease carriers can also control vector-borne diseases.

Caleb-Ugwuowo adds that Nepal already has a decentralised framework of healthcare, so proper surveillance is possible. More importantly, the two previous outbreaks have given experts an idea of what needs to be done: capacity building in hospitals, sanitation and drainage facilities, public awareness, and emergency preparedness before the disease strikes.

Pun agrees: “We must learn from other countries as well as from our own past experience, and act to contain this outbreak. Things will get progressively worse in the next few weeks, so there is no time to beat around the bush, especially with dengue already knocking at our doors.”

Read also: Mosquitoes move up mountains as the earth warms, Sonia Awale