By Lim Ann Gee
*This story has been originally produced in Mandarin as part of the ‘PANAS! Climate Change Stories in Malaysia’ aimed at producing Malaysian climate change stories in English, Bahasa Malaysia, Mandarin and Tamil. Scroll down for the ENGLISH version.
副文 2- 骨痛熱症倖存者
PART I: Mosquitoes and climate change
Malaysia is known as a country blessed with an enviable geographical location where natural disasters rarely occur. But global climate change is affecting the lives of Malaysians, albeit sometimes in subtle ways.
The 2018 Intergovernmental Panel on Climate Change (IPCC) special report pointed out that health-related impacts from climate change could rise particularly in Southeast Asia.
If global temperatures rise from 1.5°C to 2°C, the risk of vector-borne diseases is projected to increase too. Changes are expected in the range of diseases transmitted by mosquitoes, such as malaria and dengue fever.
Although global climate change is most commonly associated with polar caps melting, it has never been a distant subject. In fact, the mosquitoes buzzing by our ears every night are closely related to climate change.
We often complain that mosquitoes and mosquito bites have increased recently. Have you ever thought that mosquitoes are now breeding faster because our environments have been changed by the climate?
Dr. Rohaida Ismail, Head of Climate Change Unit at the Environmental Health Research Center of the Ministry of Health, says that at ideal temperatures, mosquitoes turn more active – they bite people more and reproduce faster. So, mosquito numbers will increase.
She gives an example. Aedes mosquitoes do not bite at low temperatures, but are most active at 28 °C , while female mosquitoes feed more at 26°C to 35 °C 。
“It usually takes 7 days for a mosquito to go from an egg to a larva to become a mosquito, and a higher temperature will shorten the mosquito’s development cycle,” says Rohaida.
She points out that 32 °C is the best temperature for mosquitoes to complete their development, and the death rates of mosquitoes are most significant at 14 °C and 38 °C
According to the latest annual report on the Malaysia Meteorological Department website, the average temperature in Malaysia in 2019 was 27.63 °C , which was 0.69 °C higher than the normal temperature (average temperature from 1981-2010) of 26.94 °C .
The average maximum daily temperature in 2019 is about 32.67 °C , which was 0.71°C higher than normal, while the average minimum daily temperature in 2019 was 24.24 °C , which was 0.66°C higher than normal.
According to the weather website, taking the temperature in the Subang Airport area as an example, there were 248 days of temperatures above 32 °C in 2000, and more than 300 days of high temperatures above 32 °C in 2020.
In short, all trends show that Malaysia’s recent temperatures have been rising. Without much warning, global warming seems to turn Malaysia into a better environment for mosquitoes to grow.
PART II: Dengue Fever, Malaria and Climate Change
Climate change poses threats to human life and health. While other countries are hit with lethal heat waves, Malaysia worries about climate change changes to malaria and dengue fever. These diseases are transmitted by mosquitoes.
Many people struggle to link climate change with human health. Dr. Rohaida admits that even medical colleagues or scientists cannot understand the relationship between climate change and human health because there are many confounding factors between the two.
She explains that urbanization and climatic factors such as rainfall, humidity and temperature are associated with dengue transmission and outbreak. But the links between these climatic factors and dengue fever are inconsistent. Therefore, there is often insufficient evidence to say climate change is the main reason for the increase in dengue fever cases.
However, suitable temperatures can accelerate the replication of dengue virus in the mosquitoes. And at higher temperatures, the mosquitoes turn more active, which shortens the time for the virus to be transmitted to another host.
In theory, Malaysia’s rising temperatures should also increase the number of mosquito-borne disease cases. But the number of dengue fever cases in Malaysia dropped in 2020.
Rohaida says that the decline in dengue cases last year may be related to the movement of humans. The movement control order implemented in Malaysia for most of 2020 might have been one of the key factors in reducing the spread of dengue fever.
As for malaria, Malaysia had no locally transmitted human malaria cases since 2018, but there are still some imported cases and infections from animal malaria。
She points out that the Ministry of Health has worked hard on implementing integrated vector management and surveillance of malaria and dengue fever, including executing the National Malaria Elimination Strategic Plan and the National Dengue Fever Strategic Plan. .
She adds that the reduction of dengue cases also depends on the cooperation of inter-agencies and local authorities, and raising community awareness.
PART III: Story of a Dengue Fever Survivor
Malaysia has been fighting dengue fever for decades. In 2020, this disease transmitted by mosquitoes infected more than 90,000 people in the country and killed 145.
Loh Yi Ying from Seremban contracted dengue fever twice in four years. Both times felt like an escape from the clutches of death, she says. Even more terrifying were the sequelae.
She says that her neighbourhood is a dengue hotspot where many residents have suffered from dengue fever. She describes the area as very hot, and often feels warmer than what the thermometer shows.
“We don’t really see stagnant water here. I really don’t know why there are so many mosquitoes?” says Loh.
There are four serotypes, or varieties, of dengue fever namely DENV1 to 4. All four occur in Malaysia. While infection of one serotype grants lifelong immunity against that serotype, it doesn’t provide immunity against other serotypes.
This means that a person may be repeatedly infected with different types of dengue fever. What is even more frightening is that a person who has developed immunity against one serotype would show more severe reactions if he later contracts another serotype of dengue virus.
Twenty-eight-years old Low Yi Ying first contracted dengue fever in August 2017, and in January 2021.
She says that the symptoms of dengue fever vary from person to person. The first time she was infected, she had fever and her blood platelet levels fell. The second time, she had sore hands and feet and felt weak.
“When I was infected for the second time, the test result turned out to be negative for dengue fever. After the doctor traced all my disease symptoms, he confirmed that I was infected with dengue fever.”
She mentions that her mother also had dengue fever twice – in the second infection, her mother vomited for 3 consecutive days and became very weak.
Low also shared the various sequelae of dengue fever she faced after each infection.
“After the first infection with dengue fever, I experienced severe hair loss, almost baldness. It didn’t get better until half a year later.”
She said that the sequelae of the second infection were more serious, and it took her more than 1 month to regain strength: menstrual disorders, bleeding gums, fatigue, shortness of breath, loss of appetite, etc.
“My immunity is weakened by dengue fever again and again.”
After two painful experiences with dengue fever, she does her best now to prevent a third time.
“I try to wear long pants when I go out now. I am scared. I do not want it to hit a third time. It feels like I might die.”
*This story has been originally produced as part of the ‘PANAS! Climate Change Stories in Malaysia’ project organised by Science Media Centre (SMC) Malaysia, in collaboration with British High Commission Kuala Lumpur and EcoKnights. It was first published on 12th May 2021 in Oriental Daily. Link here: https://www.orientaldaily.com.my/news/features/2021/05/12/411005
**Read more about PANAS! here: https://sciencemediacentremalaysia.com/panasclimatechangestories/
Lim Ann Gee is a Mandarin-writing journalist at Oriental Daily, covering topics on politics, parliament, court, government and national issues. Ann Gee is also a host for a Facebook Live Program called Oriental Cloud Talk. She believes in positive thinking and encourages others to work hard and succeed. Passionate about life, Ann Gee believes that “if you never try, you will never know”, working hard to achieve her dreams.