Melioidosis Surge: Deadly Bacteria Spikes After Flooding – What You Need to Know

Melioidosis is a rare but potentially life-threatening bacterial infection that significantly increases in cases after floods and heavy rainfall. As Tropical Cyclone Alfred approaches Queensland, health authorities have issued warnings about this disease, which is caused by exposure to contaminated soil and water. This article explores melioidosis, its causes, symptoms, impact on human health, and why extreme weather conditions contribute to its outbreak.

Understanding Melioidosis: The Silent Killer

Melioidosis is caused by the bacterium Burkholderia pseudomallei, which is commonly found in soil and water in tropical and subtropical regions. The bacteria usually remain deep in the soil but can be brought to the surface due to flooding and heavy rains. Humans typically get infected through direct contact with contaminated water or soil, inhaling the bacteria, or consuming contaminated water.

The disease has a high fatality rate if not diagnosed and treated quickly. In severe cases, it can cause pneumonia and sepsis, leading to multiple organ failure. While healthy individuals may have mild symptoms or none at all, those with pre-existing health conditions such as diabetes, kidney disease, or weakened immune systems are at higher risk.

Why Do Cases Spike After Flooding and Cyclones?

1. Increased Exposure to Contaminated Water

During floods and cyclones, water levels rise and mix with soil, spreading Burkholderia pseudomallei over a larger area. People wading through floodwaters, especially those with open wounds, are at high risk of infection.

2. Soil Disturbance and Aerosolization

Heavy rainfall disrupts the natural balance of soil bacteria. As the soil is disturbed, the bacteria become airborne, increasing the chances of inhalation. Studies have shown that strong winds and heavy rains during cyclones can lead to the spread of melioidosis-causing bacteria through aerosolization.

3. Higher Contact with Contaminated Drinking Water

Flooding often contaminates drinking water supplies. People in affected areas might consume water carrying Burkholderia pseudomallei, leading to infection through the digestive tract.

4. Increased Risk in Vulnerable Populations

Regions like Queensland have a large elderly population, many of whom have diabetes or other chronic conditions. These individuals are at higher risk of developing severe melioidosis when exposed to the bacteria.

Symptoms of Melioidosis

Melioidosis is often called “the great mimicker” because its symptoms resemble those of other infections, making it difficult to diagnose. Some common symptoms include:

• Fever and Chills: The infection often presents with a high fever, similar to flu or pneumonia.
• Severe Respiratory Issues: Many cases manifest as a severe chest infection, leading to cough, shortness of breath, and chest pain.
• Skin Abscesses and Ulcers: The bacteria can cause painful abscesses on the skin, especially in people with open wounds.
• Joint Pain and Muscle Weakness: Some patients experience joint inflammation and muscle pain.
• Sepsis and Organ Failure: If left untreated, the infection can spread to the bloodstream, causing septicemia and multiple organ failure, which can be fatal.

How is Melioidosis Diagnosed and Treated?

Diagnosing melioidosis is challenging because its symptoms mimic other bacterial infections. Doctors rely on laboratory tests, such as blood cultures and PCR tests, to detect Burkholderia pseudomallei.

Treatment includes:

• Intravenous Antibiotics: The first phase of treatment lasts for 10-14 days, using strong antibiotics such as ceftazidime or meropenem.
• Oral Antibiotics: Patients must continue oral antibiotics like trimethoprim-sulfamethoxazole for 3 to 6 months to prevent recurrence.
• Hospitalization: In severe cases, patients require intensive care, especially those with pneumonia or sepsis.

Despite treatment, the mortality rate can be as high as 20%, especially among patients with underlying health conditions.

How Many Cases Have Been Reported in 2025?

As of March 5, 2025, Queensland Health has reported 119 cases of melioidosis, with 16 deaths. The majority of these cases (106) occurred in the flood-affected regions around Cairns and Townsville.

The surge in cases this year is alarming, as it is three times higher than the cases recorded in the same period in 2024. Experts attribute this increase to extreme weather conditions and the resulting environmental changes.

Does Melioidosis Spread from Person to Person?

Unlike many bacterial infections, melioidosis does not usually spread from person to person. Instead, infections occur due to environmental exposure. However, in rare cases, transmission has been reported between individuals through contaminated medical equipment or prolonged close contact.

Can Tropical Cyclone Alfred Make Melioidosis Worse?

Tropical Cyclone Alfred is expected to bring heavy rainfall and potential flooding to southeastern Queensland. While the highest risk remains in northern Queensland, extreme weather events can contribute to bacterial spread in unexpected ways.

Possible effects of the cyclone on melioidosis include:

• Flooding and Water Contamination: As floodwaters recede, they may leave behind contaminated mud and water sources.
• Aerosolized Bacteria: Strong winds could disperse Burkholderia pseudomallei over wider areas, increasing the risk of inhalation.
• Increase in Other Flood-Related Diseases: Apart from melioidosis, cyclone-hit areas may see a rise in mosquito-borne diseases, fungal infections, and gastroenteritis.

How to Stay Safe After Flooding

Given the dangers associated with melioidosis, Queensland Health has issued safety guidelines to reduce the risk of infection. These include:

1. Avoid Direct Contact with Floodwaters: If possible, stay away from floodwaters, as they may carry harmful bacteria.
2. Wear Protective Gear: Use waterproof boots and gloves when cleaning up after a flood to prevent bacteria from entering through cuts or wounds.
3. Cover Open Wounds: Ensure any cuts or sores are properly covered with waterproof bandages.
4. Disinfect Drinking Water: Boil or purify water before drinking to kill harmful bacteria.
5. Practice Good Hygiene: Wash hands thoroughly after handling soil or water, especially before eating.
6. Seek Medical Attention for Symptoms: Anyone experiencing fever, chills, or respiratory issues after flood exposure should seek immediate medical care.

Climate Change and the Growing Threat of Melioidosis

The increase in melioidosis cases after floods is a growing concern worldwide. Climate change is expected to contribute to more frequent and severe storms, increasing the likelihood of bacterial spread. Some experts believe that as global temperatures rise, Burkholderia pseudomallei may expand its range beyond tropical regions.

Long-term measures to combat melioidosis include:

• Improving Flood Management: Better drainage systems can prevent water from stagnating and spreading bacteria.
• Public Awareness Campaigns: Educating at-risk populations about melioidosis can lead to earlier diagnosis and treatment.
• Developing Vaccines: Research is underway to develop a vaccine against Burkholderia pseudomallei, but it is still in early stages.
• Melioidosis is a serious bacterial disease that thrives in floodwaters and wet soil, posing a heightened risk after natural disasters like cyclones and heavy rains. The recent surge in cases in Queensland underscores the need for greater awareness and preventive measures.

With Tropical Cyclone Alfred approaching, the risk of infection may rise further, making it crucial for residents to take precautions. Protective clothing, proper wound care, and water hygiene are key to preventing exposure.

As climate change leads to more extreme weather events, the threat of melioidosis is expected to grow. While medical advancements may improve treatment in the future, awareness and preparedness remain the best defense against this potentially deadly disease.