Another case of a life-threatening bacterial disease scarcely seen in North America has been documented in the US. It remains a mystery how these four cases – including two that were fatal – emerged in the US.
The Centers for Disease Control and Prevention (CDC) announced in late June they were investigating three cases of melioidosis in Kansas, Texas, and Minnesota, one of which was fatal. On August 9, the CDC announced another fatal case was identified in Georgia.
Melioidosis is caused by Burkholderia pseudomallei, a bacterium found in the soil of tropical and subtropical climates, predominantly Southeast Asia and northern Australia. The only places this bacteria can occur naturally in the US are Puerto Rico and US Virgin Islands. Approximately a dozen cases of melioidosis are documented annually in the US, but are typically in people coming from locations where the disease is prevalent.
Most unusually, no patients in this recent outbreak have recently traveled outside the US, leaving health authorities stumped as to how they came into contact with the bacteria.
To further investigate, the CDC has taken samples from over 100 samples from household products, soil, and water in and around the patients’ homes. Genetic analysis of the bacteria shows the four cases share a potential common source of exposure. The bacteria also appear to be closely related to strains found in Asia, especially South Asia, which could be a possible lead for the investigation.
Sniffing out the culprit is no easy feat, as the pathogen can take two to three weeks to make someone sick. By the time the illness has emerged and been identified, health authorities have up to three weeks of evidence to trawl through for a possible origin. This particular outbreak is also tough to solve as all of the cases are separated by a significant distance.
To make matters even hazier, melioidosis symptoms are vague and easily mistaken for other diseases. Infection in the lungs can cause a cough, chest pain, a high fever, and headache. In a bloodstream infection, the symptoms are similar but often include joint pain and disorientation. People are at especially high risk of falling severely sick with the disease if they also suffer from diabetes, liver diseases, renal disease, thalassemia, chronic lung disease, cancer, or another immune-suppressing condition not related to HIV.
Fortunately, melioidosis can be treated with intravenous antibiotics administered directly into a vein.
The bacteria Burkholderia mallei has previously been used as a biological weapon during war, with a whole section on the CDC website explaining how the bacteria is a possible bioterrorism threat. However, there is currently no evidence that this is a concern.