Health officials with the Haliburton, Kawartha, Pine Ridge District Health Unit (HKPR) continues their investigation into a cluster of six cases of an unusual skin infection that appears to be associated with handling raw shrimp in the Campbellford area.
Preliminary lab reports suggest the infections are caused by the slow growing bacterium, Mycobacterium marinum.
The HKPR District Health Unit has investigated five of six cases of the infection with people from the Campbellford area, and all seem to be associated with handling shrimp grown at a local shrimp farm.
Health officials did not name the shrimp farm in question.
The Health Unit is working with the shrimp farmer and local grocery store that sells the shrimp to provide information to customers to ensure they wear waterproof gloves when handling the raw shrimp and wash their hands thoroughly with soap and water.
“The shrimp farmer has been extremely co-operative during this investigation and is working closely with the Health Unit to determine what, if any, steps can be taken to eliminate this naturally occurring bacterium from the shrimp and to provide public education materials on safe practices to use when handling the raw shrimp,” says Anne Marie Holt, Director, Communicable Disease Control, Epidemiology and Evaluation, for the HKPR District Health Unit.
Human infection with Mycobacterium marinum was first recognized a pathogen of aquarium fish about nine decades ago.
It survives in both fresh and salt water in most parts of the world. It was once responsible for outbreaks of skin infection in swimming pools prior to the stricter pool disinfection we have now. M. marinum doesn’t survive in a well chlorinated swimming pool.
Today, exposure to aquariums is by far the most common risk factor for acquiring this infection. Certain other recreational activities are rarely implicated such as skin diving and boating activities. Occupational exposure is seen in oyster workers and marine animal handlers.
Human infection is typically associated with trauma, like cuts and abrasions from fish spines or crustaceans. The injury may be quite trivial and typically is confined to the arms and hands.
Mycobacterium marinum is a bacterium that doesn’t grow well at body temperature. This may explain why infections are localized to the extremities where body temperature is cooler.
The infection makes take a few months to manifest. The lesions may appear as groups of small papules or a nodule (granuloma). About half of those infected feel pain and it rarely goes systemic. It is more common in adults than children.
Dissemination in immunosuppressed people have been reported, again usually acquired from home aquariums.
How can you prevent infection with Mycobacterium marinum?
• Use rubber or plastic gloves when handling fish or cleaning aquariums.
• Stay out of fresh or salt water when you have open cuts or sores.
• If you are cleaning fish, wear heavy leather gloves to avoid cuts from sharp spines.
• Make sure your swimming pool is properly chlorinated and maintained.
• Special care should be taken if you have a depressed immune system.
Anyone who may have developed red, painful sores on their hands and arms after handling raw shrimp is asked to contact the HKPR District Health Unit and their health care provider for assessment and treatment. The Health Unit is also working with neighboring health units in this investigation.