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How dengue complicates Southeast Asia’s COVID-19 fight

Healthcare systems in the region face a two-front war

Southeast Asia is experiencing high numbers of rainy season dengue fever cases. This comes at a time when the region is still combating a devastating coronavirus pandemic that has left healthcare systems reeling and local economies in deep recession. Dengue fever is a mosquito-borne viral disease endemic in tropical and subtropical regions. Severe cases can be fatal. Just as with COVID-19, no vaccine or drug can prevent dengue. The alarming spread of dengue alongside COVID-19 can only increase pressure on fragile regional healthcare systems.

Dengue fever report card

In Southeast Asia, Singapore, Malaysia, Indonesia, and Thailand are all grappling with a high seasonal dengue burden.

Singapore has seen a big spike in cases. The city-state recorded 1,793 dengue cases in the week ending 25 July 2020, the highest number of weekly cases ever recorded in Singapore. Latest data for the week ending 8 August shows only a slight improvement of 1,668 dengue cases. The National Environment Agency (NEA) expects Singapore to surpass its previous annual record of 22,170 dengue fever cases set in 2013. Amid warnings of a possible acceleration of the dengue outbreak, the government has responded with harsher penalties on households and construction sites that let mosquitos breed.

Weekly Dengue Cases in Singapore, 2016-20

Weekly Dengue Cases in Singapore, 2016-20
Note: E-week = end week
Source: Communicable Diseases Division, Ministry of Health, Singapore

In Malaysia, the situation is more in line with the country’s typical dengue cycle, and fewer dengue cases have been reported overall this year. In week 30, Malaysia suffered a total of 1,298 dengue cases for a year-to-date total of 62,625 cases as of 25 July 2020, down from the 75,913 cases reported in the same period of last year. There have been 105 deaths so far in 2020.

2019 was a bad year for Southeast Asia’s most populous country with 137,761 dengue fever infections, more than double the year before, according to Indonesia‘s Ministry of Health. The ministry reported 70,418 dengue cases and 458 disease-related deaths to 1 July this year, fewer than that in the same period in 2019, when it logged 105,222 cases and 727 deaths. The relatively low death toll is mainly due to better therapeutic standards.

Thailand's Bureau of Epidemiology reported 41,415 cases and 31 deaths in the year to 25 July, a major surge in cases over the past four weeks ( 1 ). 

Thailand: Chikungunya cases top 6,000, Dengue cases top 40K Go to source

Chaiyaphum, Mae Hong Son, Rayong, Nakhon Ratchasima and Khon Kaen provinces have seen the highest incidence of the mosquito-borne viral disease. Thailand is simultaneously struggling to contain the Chikungunya virus, which is also transmitted by the bite of Aedes mosquitoes.

In the Philippines, the week of July 5-11 saw only 454 new dengue cases and three deaths reported,  97% down over the same period in 2019 (14,492) ( 2 ).

Dengue Situation Update Number 599, Western Pacific, WHO

In the year to 11 July, there were a total of 54,941 dengue cases in the Philippines with 196 deaths reported, 63% lower compared to the 146,766 cases in the same period in 2019.

Dengue versus COVID-19 cases, 2020 year to date*

Dengue versus COVID-19 cases, 2020 year to date Image
COVID-19: year to 16 August; Dengue: Thailand – year to 11 July, Indonesia – year to 1 July, Philippines – year to 11 July, Singapore – year to 25 July, Malaysia – year to 25 July
Sources: national ministries of health and environmental agencies.

Why the surge in cases?

The COVID-19 epidemic did not slow the onset of dengue fever. The lockdowns that require people to stay at home for their safety exposes them to Aedes mosquitoes breeding in local neighbourhoods. This disrupts the pathogen-host-vector-environment interface, increasing the risk of new clusters (see figure below). As cases spike, a vicious cycle takes hold as uninfected mosquitoes bite infected individuals, causing cases to spiral. Because more urban residents are stuck indoors during home quarantine routine ‘fogging’ to eliminate mosquito breeding grounds can be disrupted. People worried about seeking out medical assistance at hospitals over fears they might be exposed to COVID-19 are delaying medical treatment for dengue, a situation that can only add to the number of missed cases.

Longer-term, the effects of global warming could newly expose as many as a billion people to disease-carrying mosquitoes by the end of the 21st Century. Within Southeast Asia, changing patterns of rainfall, humidity and temperature linked to climate change, are leading to longer mosquito breeding spells and shorter disease incubation ( 3 ).

Climate change and Asia’s deadly dengue fever outbreaks Go to source

These trends will cause dengue epidemics to become much more unpredictable in terms of their scale, and when and where they occur, with the potential to overwhelm health systems.

The pathogen-host-vector-environment interface

Long-term control or even disease elimination requires the interruption of human–vector contact through the use of bed nets, personal protection (e.g. insect repellent), and the use of insecticides.

Source: https://doi.org/10.1371/journal.pntd.0008302.g002

Similar symptoms and misdiagnosis

The challenge for doctors, pharmacists and other frontline healthcare professionals is that the early symptoms of dengue fever and those of COVID-19 are strikingly similar. These include fever, headaches and muscle aches (see table below). Appropriate treatments and referrals for this seasonal infection are different from those for COVID-19. There are documented cases of coronavirus patients initially misdiagnosed with dengue fever, and some patients have received the wrong treatment.

COVID-19 vs Dengue Symptoms

COVID-19 vs Dengue Symptoms image
Note: * less common symptoms; severe COVID-19 symptoms include difficulty breathing and chest pain
Sources: Dengue symptoms – Singapore’s National Environment Agency; COVID-19 symptoms – WHO

mClinica Pharmacy Solutions

The concurrence of the COVID-19 pandemic and unusually high rates of seasonal dengue is complicating the work of frontline medical workers and stressing already stretched healthcare systems across Southeast Asia. Digital education resources such as mClinica’s SwipeRx pharmacy network are urgently needed to respond quickly and nimbly to these emerging medical threats. Beleaguered pharmacy professionals need all the support they can get to assess and refer their clients properly.

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