Has the Changing Climate caused the recent outbreak of Melioidosis in Sri Lanka? 

The Sri Lanka Medical Association recently announced a warning to the general public regarding the Spread of Melioidosis also known as Whitmore’s disease. This is caused by a bacteria called Burkholderia pseudomallei present in contaminated soil and water. Humans acquire the infection by ingesting contaminated water and soil-contaminated food or other contact with contaminated soil, especially through skin abrasions. 

Climate Fact Checks investigated this possible future epidemic following the claims stating that Melioidosis is a disease susceptible to Climate Change. We spoke to Dr Mahen Kothalawala, Specialist Clinical Microbiologist and Infection Prevention Professional at the Teaching Hospital, Kandy. We wanted to find out the severity of the risk Sri Lanka may face with Melioidosis. 

Dr Kotelawala mentioned that the recent outbreak of Melioidosis in Sri Lanka was detected in the Batticaloa region. This bacteria is commonly detected in the Eastern Province which concludes that it is abundantly found within this area. With the irregular rainfall patterns and monsoons a research done in 2021 in the Eastern Province warns that there is a risk for more infected clusters to appear from different parts of the country in the future. Access the full research paper here. 

What is Melioidosis and how serious is it? 

Melioidosis is an infectious disease that can infect humans and animals which spreads through direct contact with soil or water contaminated with the Burkholderia pseudomallei bacteria. This is a disease known to spread in tropical climates. 

• Transmission 

Melioidosis is rarely transferred from one human to another, but not unheard of. However, it is primarily transmitted from contaminated dust or water droplets, ingestion of contaminated water, and ingestion of soil-contaminated food or other contact with contaminated soil, especially through skin abrasions. Recently tropical freshwater fish have been found susceptible to the disease. The other animals include,Sheep, Goats, Swine, Horses, Cats, Dogs and Cattle. 

• Signs and Symptoms 

Melioidosis has a wide range of symptoms, it can easily be mistaken for other diseases like Tuberculosis and Pneumonia. The several types of infections include, localized infection, pulmonary infection, bloodstream infection and disseminated infection. The incubation period of melioidosis is not clearly defined; it can vary from 1 day to several years. But generally symptoms appear 2 to 4 weeks after exposure. 

• Risk of Exposure 

Though cases of Melioidosis have been reported from all over the world South East Asia and Northern Australia are main areas it is abundantly found. Farmers are more susceptible to the disease due their close contact with contaminated soil or water. 

• Treatment and Prevention 

There are treatments to cure the disease however, the course of treatment can result in long term outcomes. Cover the open wounds with bandages, those working in the agricultural field wear boots and gloves, medical caretakers take necessary precautions when treating melioidosis can prevent the infection from spreading. 

Dr Kotelawala said that approximately 50-60 patients are reported from Sri Lanka annually. 

History of Melioidosis in Sri Lanka

Sri Lanka lies within the tropics and farming using traditional methods is still very common in the country. Sri Lanka (1927)  along with Malaysia, Singapore (1921) and Vietnam (1925)  were the first countries to report the infection after its first description at Rangoon, Burma  in 1912. Following 7 decades after the first reports of Melioidosis in Sri Lanka, reports started to surface in 2004, 2006 and 2008. A surveillance system for melioidosis was then commences. Between 2006 and March 2017, 250 culture-positive cases of melioidosis were identified by the surveillance programme. Read more about the history of melioidosis  here. 

Dr Kotelawala stated that in the past many infected patients would have existed but undiagnosed, and treated for their symptoms focusing on pneumonia and other lung infections. He mentioned that now, with the special attention given to the surveillance of the disease, more numbers are detected yet these numbers would have been the same in the past. 

How does Climate Impact the growth of Melioidosis bacteria 

The association between climate change and melioidosis has long been established after multiple researches showed a correlation between the frequency of the disease occurrence and rainfall patterns. They also proposed that levels of cloud cover corresponds to the levels of soil moisture that provides suitable conditions for the bacteria’s survival. Extreme weather conditions (heavy rainfall, typhoons and storms) have also been associated with the increase in the number of Melioidosis patients. 

Has Climate Change increased the prevalence of Melioidosis 

Climate Change is mostly associated with increased temperature, human induced global warming and rising sea levels. These environmental conditions have proved to trigger the emergence of new diseases that were previously unseen. However, in the case of melioidosis the increasing temperature alone cannot influence the rapid spread of the infectious organism. There needs to be sufficient increased rainfall. It was observed that hotspots of melioidosis change with the changing rainfall patterns as it moves from one location to another based on the presence of disease-causing bacteria. However, in preparing for such epidemics the normal rainfall patterns have now become unpredictable leaving areas  with less time to prepare. 

“Diseases like Melioidosis are Multifactorial” said Dr Kotelawala, its prevalence depends on multiple different causes and it cannot be pointed alone at Climate Change. But he also added that there is an increase in Melioidosis reports in the country in the last few years with global warming and other weather conditions. Yet there are several other confounding factors, the medical history of the patient whether they are suffering with diabetes, asthma, cholesterol or other non communicable diseases. And factors that cause such diseases. 

On the other hand, predictions of annual rainfall by the near-term multi-model Intergovernmental Panel on Climate Change (IPCC) suggest a likely decrease in rainfall between 20 and 40 degrees latitude and general increases outside this zone. This means that the already wet tropics and moist mid-latitudes will likely receive more rain. More rain will be delivered to all areas by more intense extreme weather events, increasing the opportunities for B. pseudomallei exposure Increases in maximum rainfall in the tropics will further increase melioidosis risk while increased rain outside the tropics will expand the B. pseudomallei-receptive regions. 

In a Nutshell 

Based on our investigation, we don’t have to be alarmed about the disease Melioidosis becoming a serious pandemic. But we need to keep in mind that the bacteria Burkholderia pseudomallei which causes Melioidosis exist in the local environment hence, changes in the environment and climate can impact its rate of spread. In addition, it is essential to be aware of the prevalence of such diseases so we can easily notice the symptoms and avoid transmission. 

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