As an expat blogger I quite often receive questions about mosquitoes and dengue. These originate from travelers as well as people wanting to relocate their young families to Sri Lanka. Apart from responding with my own personal experience regarding living with mosquitoes in the tropics, I also point them in the direction of this National Dengue Control Unit website and the website for the Sri Lankan Epidemiology Unit of the Ministry of Health.
Interestingly, when you do some research into the facts (i.e. recorded dengue statistics) Sri Lanka is actually doing better in terms of the dengue fatality rate than in some of its worst years. The fatality rate takes into account the total number of dengue cases and the number of deaths caused by dengue. Over the past seven consecutive years, Sri Lanka has achieved a continuing downward trend in the dengue fatality rate despite the high numbers of dengue cases.
I was reading an article posted back in September 2015 that references results of the Health Ministry's investigations into dengue deaths. In the article, the Health Services Director General was quoted stating "Health authorities who investigated dengue deaths in Sri Lanka found that the majority of dengue deaths were due to patients not seeking prompt medical treatment. A person with fever for more than two days should take prompt medical treatment from a state hospital."
The takeaway from the above findings of the Health Services inspections is to act swiftly if you have been bitten and develop a severe flu-like fever by heading to the nearest hospital for diagnosis and treatment. Based on the high number of total dengue cases reported annually and the declining dengue fatality rate, one could conclude that the medical treatment for dengue in Sri Lanka has been somewhat effective, and the medical profession should be commended for this result.
A Neighborhood Perspective
A few days ago I was at my local kade or corner shop and while I was waiting for my turn to be served I couldn't help but hear the conversation among a few of my neighbors. It went something like this:
Neighbor #1: "Aney, so much bother over dengue these days"
Neighbor #2: "They come with police and bang on my gate for home inspections"
Neighbor #3: "Yes, they inspected the garden a few times this year and they can't find anything because I don't have anything that would collect, not even a coconut shell"
Neighbor #1: "I am old and alone, I don't like how they come with police and demand entry like I have committed a crime"
Neighbor #3: "Sorry to hear Aunty. Did you hear the news that said they will no longer ask permission to come into your home?"
Neighbor #1: "What is this you talk about son?"
Neighbor #3: "The news reports are saying the inspectors will come in by force. No need to ask our permission to enter our homes."
Neighbor #2: "And government is increasing fines from Rs.1,500 up to Rs.25,000."
Neighbor #1: "This is terrible. How can they force entry to my home? I don't breed mosquitoes in my home. And I don't want strangers coming to look at my things. I don't know if they are good or bad people. But, if they find something wrong, how can I pay Rs.25,000. I am really scared of this"
Neighbor #2: "I'm also worried about the dengue people they send. Some are not to be trusted. It's easy for them to pick a fault and ask for money instead of issuing a fine."
Neighbor #3: "This is possible. They could ask for a pay off that is less than the fine. But what can we do?"
I didn't participate in the conversation, but I found it extremely insightful to get a local neighborhood perspective. When I returned home I looked up a few things to confirm some of what they were talking about, such as the increase in fine and entry to your property. In an article published on 12 December 2016, sources at the Health Ministry confirmed that "Arrangements will be made to issue a gazette notification increasing the fine to Rs. 25,000 for mosquito breeding. The inspectors in the future will not require the permission of premises owners to carry out inspection activities to detect mosquito breeding sites, the sources added."
Many fines in Sri Lanka seem to be increasing to Rs.25,000, including motor vehicle and dengue. My neighbor's comments about the fear of corruption are nothing new. There has been much chatter over the internet and in social settings around the implications of an increase in fines to Rs.25,000. There was even an article titled "Rs 25,000 fine will lead to more corruption" that was published in Ceylon Today.
It also seems both alarming and invasive (and seemingly illegal) if no notice or permission is required for inspectors in Sri Lanka to enter your property. In other jurisdictions undertaking dengue control, for example Singapore, the health inspectors make a couple of attempts to inspect in person and then try to make contact by phone or letter, but if you are not at home or have not responded, then the process in place requires a written letter and legal notice to be posted to ensure a lawful entry before an inspection can be undertaken.
Dengue Statistics and Trends
I'm a bit of a numbers person, so when you give me statistics I can't help but to automatically want to graph it and look for obvious trends. The graph below shows the Dengue Trends for Sri Lanka plotting the total number of dengue cases alongside the dengue fatality rate. On quick perusal, in terms of the dengue fatality rate, 2016 is tracking very similarly (0.2%) against the last few years despite the swings and roundabouts with the total number of dengue cases. It also compares favorably against the spikes in dengue fatality rate recorded in 1996 (5%) and 2009 (1%).
|Data sources - Epidemiology Unit, Sri Lanka Ministry of Health and World Health Organization|
Over the years the total number of dengue cases in Sri Lanka has definitely trended upwards, particularly from 2009 onward. Obviously, you'd ask why the number of cases has leaped so high since 2009? Could it be due to increased awareness of medical facilities for treating dengue, changes to the reporting and recording of dengue cases, significant changes in weather affecting the island etc. I don't have a definitive answer, but something significant (or a combination of factors) has contributed to the spike in total dengue cases since 2009.
Dengue occurs in urban and suburban settings with higher transmission rates happening during the rainy season. The two peak seasons in Sri Lanka for the dengue epidemic to spread are October to December and May to July annually. We are currently at the end of one of the peak seasons for dengue.
If you look at the graph below that shows the monthly trend from 2010 to 2016, the surge in the number of dengue cases generally occurred in accordance with the peak season for dengue.
|Data source - Epidemiology Unit, Sri Lanka Ministry of Health|
Natural Disasters and Dengue
In an article dated 14 December 2016, a Health Ministry official told the publication that "The numbers are much higher this year. This is mainly due to the floods in June. We are trying our best to control the situation". If you've lived in Sri Lanka for a few years you will have noted the extreme weather conditions that have included both droughts and floods. Following along the same lines as the comment from the Health Ministry official, I looked into the correlation between the surge in dengue cases and natural disasters, such as floods, landslides, monsoons and torrential rains, over the past seven years.
The following is a summary of how Sri Lanka has been affected annually by natural disasters, particularly heavy torrential rains and flooding, since 2009.
- Mid-November 2010 a low-pressure area developed over Colombo resulting in the highest amount of rainfall in 18 years causing widespread damage and flooding in the area. The heavy rains displaced over 260,000 people in Colombo and suburbs;
- 1 million affected by Sri Lanka massive floods due to two weeks of heavy torrential rains in January 2011 described by the government as the worst natural disaster since the 2004 tsunami;
- Deadly floods stuck rain-soaked Sri Lanka killing at least 25 people and leaving more than a quarter of a million marooned in their homes. Heavy rains battered the island for much of mid-December 2012. Most of the deaths were due to landslides engulfing homes. The floods are some of the worst in Sri Lanka since early 2011;
- At least 503,406 people have been affected by monsoon floods and landslides in Sri Lanka over January 2013. The worst affected area is that of the Eastern Province because it is most exposed to torrential rains;
- With the arrival of Southwest monsoon, the southern region of Sri Lanka received heavy rainfall with high winds, floods and landslides within a short period of time in early June 2014. The floods and landslides caused 27 deaths and a total of 104,476 people were affected in eleven out of the country's 25 districts;
- An estimated 1.1 million people in Sri Lanka were affected by torrential rainfall, widespread floods, landslides, mudslides and high winds that began around 19 December 2014;
- Continuous heavy rain since mid-September 2015 in the southern regions resulted in floods and landslides, causing eight deaths and nine injuries.
- On 14 May 2016 a low pressure area over the Bay of Bengal caused torrential rain to fall across Sri Lanka, causing floods and landslides which affected half a million people.
Mosquitoes thrive in areas with standing water, including puddles, water tanks, containers and old tires. Lack of reliable sanitation and regular garbage collection also contribute to the spread of the mosquitoes. When natural disasters strike the island there is an immediate pressure placed on the existing environmental and waste management infrastructure and systems.
If the existing infrastructure and systems have been destroyed, damaged or reached capacity, then the overall situation is compounded. Additionally, there is a flow on effect if faced with more than one natural disaster per year as existing resources are strained beyond capacity. Even with relief or emergency aid, there are still challenges. All of this can exacerbate the dengue situation in Sri Lanka, particular if natural disasters coincide with the peak season for dengue, which it has in many of the years.
During the recent 2016 floods, UN Resident Coordinator in Sri Lanka Una McCauley explained in a UN Central Emergency Response Fund article that, “In some highly populated urban areas flooding destroyed much of the water and sanitation infrastructure, which must be urgently addressed. We are also concerned that any remaining stagnant water could lead to serious public health issues”.
Dengue Prevention and Management
Since there is no antiviral drug or vaccine to protect from dengue, mosquito control is the only alternative.
In a 2014 published statement by the World Health Organization South-East Asian regional office, it referred to dengue as "a climate-sensitive disease and its vector dynamics are strongly influenced by environmental factors, population dynamics and climate change." It also called for an integrated approach that addressed "good environmental management, effective solid waste management and better management of water resources are key elements of mosquito control" due to the fact that "no single approach works on the mosquitoes".
So the questions for Sri Lanka are: "How good is environmental management?"; "Is there effective solid waste management?"; and "Has better management of water resources been implemented?". If you live here, then you know there are shortcomings across all three areas, with environment and waste management being particularly problematic. All you have to do is visit an urban public space in Colombo to see evidence of environmental issues such as excessive plastics and other waste; or just have a look down one of the suburban streets and you'd see evidence of household rubbish piling up by the roadside. Sri Lanka is considered one of the five worst offenders when it comes to plastic pollution, according to a study published in Science. There have been many articles published on Colombo's waste management issues. Some examples include, "No Solution in Sight For Colombo’s Garbage Problems" or "Solid waste no more waste but like gold".
Sri Lanka's approach to dengue control and prevention entails an integrated vector management process consisting of vector surveillance and vector control. The latter is where most of the attention seems to be focused with environmental management, biological methods, chemical methods - larvicides and adulticides, intersectoral coordination and social mobilization, and law enforcement against offenders.
Chemical fogging or space spraying is widely used for dengue control in the Sri Lankan dengue eradication programme. It seems to be rolled out to the main provinces that have high cases of dengue, but it is not clear whether it is targeted primarily at most productive-breeding locations or places that have previously been problematic.
There was this article published on dengue in which a World Health Organization (WHO) dengue scientist Raman Velayudhan highlighted that “It is not just about looking for breeding sites, but also targeting the most productive ones. An unused tyre may have hundreds of larvae versus a small coconut shell.” This raises a few questions when it comes to target areas and emergency chemical fogging.
The Health Ministry website states "space spraying is recommended for vector control only in emergency situations to suppress ongoing epidemics or to prevent an incipient one. The objective of space spraying is the massive, rapid destruction of adult vector populations, both indoors and outdoors. In space spraying, a suitable insecticide is mixed with kerosene oil and released to the environment in the form of very tiny droplets. Once these droplets get contacted with the vector mosquitoes, the mosquitoes get knocked down and die. In order for the fog to reach the interior of the premises, the doors and windows should be kept open while fogging, however, food and water should be kept covered to prevent contamination with the insecticide."
I was curious as to what insecticides are used in Sri Lanka and found that a 2012 Weekly Epidemiological Report on "Fogging in Dengue Control" that lists the following - "Insecticides -mainly Organophosphates and Pyrethroids- such as Malathion, Fenitrothion, Deltamethrin, Etofenprox, λ-Cyhalothrin, Permethrin, Cyphenothrin etc are widely used in fogging."
I've done some reading on the challenges and concerns regarding chemical fogging in dengue control. It makes for some very eye-opening reading, and not to be taken lightly. Some useful articles published in India, Malaysia and Singapore that are worth a read - see "Does Smoke really help in the fight against dengue"; "Seven reasons why fogging will not kill the mosquitoes"; and "Widespread fogging may do more harm than good";
If you're not familiar with insecticides used in dengue control, then this blog post might help to illuminate things for you. No doubt it'll make you think twice about this urgent chemical fogging programme being rolled out in Sri Lanka, and whether you are willing to be exposed to chemicals that are physically harmful (given you are required to leave your windows and doors open while the fogging is undertaken). In addition, the chemicals are said to cause harm to insects and animals (i.e. birds, cats etc) in your garden, not to mention the impact on fruit and vegetables that are grown at home as the chemicals are said to seep into the soil and contaminate ground water.
I'm no expert on dengue, but I've read some interesting research in other countries. One particularly interesting one relates to the use of genetically modified mosquitoes to reduce the risk of dengue in Brazil. A year-long trial was conducted in Juazeiro, Brazil that was successful in reducing the population of the disease-carrying insects by 95%. See this article as well as the study report.
I've also had discussions with various peer groups, colleagues and friends who have a myriad of ideas in tackling some of the causes for mosquito breeding that relate to environmental management and waste management. I thought one of the most effective suggestions was imposing a plastics tax or levy in Sri Lanka. Given Sri Lanka is one of the worst offenders, alongside China, Indonesia, the Philippines, and Vietnam, it would make sense to influence and change the behavior of Sri Lankan residents towards plastic.
Another suggestion related to improving existing infrastructure in Sri Lanka, including water drainage systems (i.e. improve open drains that carry wastewater in urban areas and the drains located in high-risk areas prone to flooding etc). With regard to waste management, straightforward improvements to implement more regular garbage collections or ways to how garbage is stored and collect would significantly improve the situation. More targeted public awareness and educational programmes regarding environmental management would also be useful.
There are many more ideas and suggestions, some that cost little and some that cost a whole lot more and all of which require a coordinated and cohesive approach.