In 2021, in US states far removed from one another, numerous cases of melioidosis (Whitmore's disease) sprang up, some with a fatal outcome. What is the common factor linking all of those affected? A search for evidence was begun.
No Common Journeys
Between March and July 2021, cases of the bacterial infectious disease sprung up in Georgia, Kansas, Minnesota, and Texas. The disease was fatal for two of those affected. Usually, cases of melioidosis occur in the US after the patient has traveled to regions where the pathogen is prevalent. However, none of the patients had undertaken any previous international travel.
When the genomes of the bacterial strains (Burkholderia pseudomallei) were sequenced, they showed a high level of concordance, suggesting a common source of infection. The bacterial strain resembles those that are found in South East Asia. An imported product from that region was considered as the potential trigger.
The Centers for Disease Control and Prevention (CDC) examined blood samples from the patients, as well as samples from the soil, water, food, and household items around the patients' homes.
An Aroma Spray
In October 2021, the cause of the melioidosis was finally identified in the house of the patient from Georgia as an aromatherapy spray. The genetic fingerprint of the bacterial strain matched with that from the other patients. The common trigger was thus discovered.
The contaminated spray, with a lavender-chamomile scent for room fragrancing, was sold between February and October in some branches of Walmart, as well as in their online store. The product was therefore recalled, and authorities checked whether the ingredients were also being used in other products.
The CDC requested physicians to consider melioidosis if they were presented with acute bacterial infections that did not respond to normal antibiotics and to inquire whether the affected room spray had been used.
What Is Melioidosis?
Melioidosis is an infectious disease affecting humans and animals. The trigger is the bacteria B. pseudomallei. The disease appears predominantly in tropical regions, especially in South East Asia and northern Australia.
The bacteria can be found in contaminated water and soil. It is disseminated between humans and animals through direct contact with the infectious source, such as through inhaling dust particles or water droplets, or through consuming contaminated water or food. Human-to-human transmission is extremely rare. Tropical saltwater fish were identified recently as potential carriers.
Melioidosis has a wide range of symptoms, which can cause it to be confused with other diseases such as tuberculosis or pneumonia. Melioidosis has different forms, each with different symptoms.
Localized pain and swelling
Loss of appetite
Stomach or chest pain
Muscle or joint pain
The incubation time is not clearly defined and can be from 1 day to several years. The symptoms mostly emerge 2 to 4 weeks after exposure, however. The risk factors include diabetes, high alcohol consumption, chronic pulmonary or kidney disease, and immunodeficiencies.
Diagnosis based on the symptoms is often difficult, since the clinical picture is similar to that of more common conditions.
If melioidosis is identified, it can be treated with only mildly effective antibiotics, since it has a natural resistance to many commonly used antibiotics. The type of infection and the course of treatment also affects the long-term outcome. Without treatment, 90% of the infections have a fatal outcome. With appropriate treatment, the mortality rate still lies at 40%.
Therapy generally begins with intravenous antibiotic therapy for at least 2 to 8 weeks (ceftazidime or meropenem). Oral antibiotic therapy then follows for 3 to 6 months (trimethoprim-sulfamethoxazole or amoxicillin/clavulanic acid). If the patient is allergic to penicillin, alternative antibiotics can be used.
Use as a Bioweapon
The CDC classifies B. pseudomallei as a potential pathogen for biological attack (class-B candidate). They list the potential reasons for use as a bioweapon as the following:
The pathogen can be found naturally in certain regions.
The triggered disease can take a serious course and ultimately be fatal without appropriate therapy.
In the past, the US has used similar pathogens in wars as bioweapons.
In a potential attack, the pathogen could be spread through air, water, or food, thus exposing many people. Any contact with the bacteria can result in melioidosis. As the bacteria cannot be seen, smelled, or tasted, the biological attack would not be recognized for some time. A certain amount of time can also pass until the pathogen is identified, once fever and respiratory diseases have developed.
In such an emergency, the CDC would collaborate with other federal and local authorities to supply specialized testing laboratories and provide the public with information.
This article was translated from Coliquio.
Lead image: iStock/Getty Images
Medscape Medical News © 2022
Cite this: Christoph Renninger. What Caused a Series of Cases of Melioidosis? - Medscape - Aug 12, 2022.