FEATURE ARTICLE
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.
主文-蚊子與氣候變遷
馬來西亞因為優越的地理位置，被稱為被幸運之神眷顧的國家，很少發生天災；但是全球氣候變遷在不知不覺影響著馬來西亞人周邊的生活。
2018年政府間氣候變化專門委員會 (IPCC)的特別報告指出，氣候變遷可能會增加東南亞地區健康相關影響；此外攝氏1.5度到2度的變暖，預計會增加某些媒介傳播疾病的風險，例如瘧疾和骨痛熱症，包括其地理位置的改變。
虽然全球氣候變遷最常让人联想到画面的是兩極的冰山融化，但它從來不是一個遙不可及的課題。其實小至每天晚上在你我耳边嗡嗡作響的「蚊子」，都與氣候變遷息息相關。
很多人投訴近期的蚊子特別多，身上總是出現大小不一的咬痕，防不勝防，有沒有想過是我們所居住的環境因氣候的改變，促進了蚊子的繁殖。
衛生部環境衛生研究中心氣候變遷主任羅海達醫生證實，在理想的溫度下，蚊子會變得更加活躍地叮人，也繁殖地更快，因此蚊子的數量會變多。
她舉例，黑斑蚊在低溫下都不咬人，但在攝氏28度時最活躍，而雌蚊在攝氏26度至35度時，攻擊的速度更快。
「蚊子一般上從卵，到孑孓到成為一隻蚊子，需要7日的時間，而較高的溫度會縮短蚊子的發育週期。」
她指出，蚊子完成發育所需的溫度以攝氏32度為最佳，而蚊子在攝氏14度和38度時的死亡率最明顯。
根據大馬氣象局網站最新的年度報告，2019年大馬的平均溫度是攝氏27.63度，比起1981年至2010年的平均溫度26.94度，高出0.69度。
2019年的平均最高溫度約為攝氏32.67度，比过去平均温度高0.71度，而2019年的平均最低溫度為24.24度，比平均高0.66度。
根據氣象網站，以梳邦機場地區的氣溫為例，在2000年有248天的溫度在攝氏32度以上，而來到2020年則有超過300天出現攝氏32度以上的高溫。
总的来说，一切迹象都显示我國近期平均溫度在提升, 我們貌似在不知不覺中，為蚊子提供更好的生長環境。
Graph: https://public.flourish.studio/resources/embed.js
副文 1—骨痛熱症和瘧疾與氣候變遷
很多人很難將氣候變遷和人類健康做聯想，就連羅海達醫生坦言，即使是醫學界的同事或者其他領域的科學家，也很難理解氣候變遷和人類健康的關係，因為兩者之間的關係充滿其他可能性。
氣候變遷對人類的生活和健康帶來了威脅，相較他國因為熱浪而致死的情況，大馬在氣候變遷下面對的健康課題，主要是由蚊子傳播的瘧疾和骨痛熱症。
她解釋，儘管城市化和氣候因素如降雨、濕度和溫度的確與骨痛熱症傳播和爆發有關，但氣候因素和骨痛熱症的關係不一致， 因此不足以將氣候變遷作為導致骨痛熱症病例增加的主因。
不過，在合適的溫度範圍內，會加速複製在黑斑蚊內的骨痛熱症病毒，此外蚊子在較高溫度下比较活跃而缩短了將病毒傳染給另一個宿主的時間。
照理來說，我国近年提升的气温應該會增加蚊子傳播的疾病病例，但是我國在2020年骨痛熱症病例却呈現大幅度下降趨勢。
羅海達表示，骨痛熱症病例下跌可能與人群的流動有關係。我國去年实施的行動管制令或是降低骨痛熱症傳播的關鍵因素之一。
至於瘧疾，我國的本土感染人類瘧疾病例更是從2018年起已經清零，不過還有一些動物性瘧疾和輸入性瘧疾病例。
她指出，衛生部在瘧疾和骨痛熱症的管控付出很多努力，其中包括國家消除瘧疾策略計劃以及國家骨痛熱症策略計劃，都旨在針對這兩種疾病做出的綜合管理和監測。。
她也說，骨痛熱症病例的減少也有賴於跨部門以及地方政府的合作，以及社會意識的提升。
副文 2- 骨痛熱症倖存者
骨痛熱症一直是馬來西亞積極打擊的媒介傳播式疾病，在2020年有逾9萬人受到骨痛熱症折磨，其中有145人不幸死亡。
來自芙蓉的羅奕瑩曾經在四年內兩度感染骨痛热症，她说每次感染後康复都犹如死里逃生，而要面對的後遺症更是讓人後怕。
她指出，自己住在骨痛熱症黑區，有很多居民都曾受骨痛熱症所苦，也說到所住的社區非常炎熱，儘管氣溫顯示攝氏32度，但是感覺起像是攝氏35度。
「我們那邊也沒有什麼積水，真是不知道為什麼會有那麼多蚊子？」
大馬流传的骨痛熱症主要有四種類型，分別是DENV1至4血清型病毒，然而感染其中一种骨痛熱症血清型病毒，並不能提供長期的交叉保護性免疫。
這意味著，一個人可能會重複感染不同類型的骨痛熱症。令人擔憂的是一个人因感染了其中一种骨痛热症病毒而長生的免疫，竟會加劇他对另一种骨痛热症血清型病毒的反应。
28歲的羅奕瑩在2017年8月首次患上骨痛熱症，然後在2021年1月不幸再度感染。
她表示，骨痛熱症的症狀會因人而異，自己首次感染時不斷發燒，血小板下跌，第二次則是手腳酸痛，感到無力。
「自己第二次感染時，化驗結果竟然是對骨痛熱症呈陰性反應，最後醫生追溯所有發病症狀，才確定感染骨痛熱症。」
她提到，其母親也是兩度感染骨痛熱症，而在第二次感染時的症狀是連續3天嘔吐不止，然後變得十分虛弱。
羅奕瑩也分享，自己兩次感染後所面臨的各種骨痛熱症後遺症。
「第一次感染骨痛熱症後，經歷了嚴重脫髮，近乎禿頭的地步，直到半年後才好轉。」
她表示，第二次感染的後遺症更嚴重，用時超過1個月才恢復力氣，即使是現在還是影響著身體的機能，生理期失調、牙齦出血、容易疲倦、喘不上氣、沒有胃口等等。
「整個人的免疫力因為一次又一次的骨痛熱症而降低。」
經歷了兩次慘痛的感染和康復過程後，她說會竭盡所能避免經歷第三次的骨痛熱症。
「我現在出門盡量穿長褲，我已經很怕了，不想再中第三次，感覺上真的會死掉。」
English translation:
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.
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