Cantaloupe grown in Australia and found to be responsible for a deadly Listeria outbreak there was exported to at least nine other countries, the World Health Organization reported this week.
The public health organization said there are likely outbreak cases in those other countries. However, diagnosis, confirmation testing and reporting to international authorities could take several weeks. Also, the incubation time for listeriosis, which can be as long as 70 days, complicates the identification of outbreak cases.
The outbreak has sickened 20 people in Australia, killing seven of them.
The cantaloupe, or rockmelons as they are called in Australia, came from a single grower. In addition to distribution in Australia, the grower shipped the fruit to the Hong Kong Special Administrative Region in China, Japan, Kuwait, Malaysia, Oman, Qatar, Singapore, Bahrain and the United Arab Emirates. The contaminated cantaloupe also may have been shipped to Seychelles.
More than 30 samples of melons from the grower’s farm collected through the supply chain all the way to retailers tested positive for Listeria monocytogenes.
“Additional testing found Listeria. monocytogenes in the packing area (of the grower’s operation),” according to the report from the World Health Organization (WHO). “All Listeria monocytogenes samples had the same genetic sequence as the human cases.”
“It is believed that the cause of the outbreak was a combination of environmental conditions and weather contaminating the surface of the fruit, with low levels of the bacteria persisting after the washing process.”
The Australian grower recalled the cantaloupe on Feb. 27. Illnesses in Australia began in January, with the most recent report April 6.
Symptoms of Listeria infection include fever, muscle aches, nausea and diarrhea. In high-risk groups the pathogen can cause serious infections leading to complications including meningitis, blood poisoning and death. High risk groups include pregnant women, newborns, children younger than 5, adults older than 65 and anyone with impaired immune systems, including cancer patients, diabetics and HIV/AIDS patients. It can also cause stillbirths.
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