I recently had the opportunity to discuss a case of chronic gastrointestinal parasite infection whilst on holiday in Canada and I thought I would share this with you. The case was a new mother with triplets who had recently passed a large (up to 1 metre) tapeworm. She had a degree of malnutrition as a result of this chronic infection which was being made worse due to the fact that she was currently nursing.
Sorry, I should have mentioned, the case is a 400kg brown bear called Lucy with 3 cubs under the age of 1 year, who currently is eating her way through vast quantities of raw salmon to fatten up for hibernation (or more correctly denning) over winter. Bears like her are regularly seen with long tape worms hanging from their backsides or in their scat. This probably explains why you rarely see wildlife pictures of a bear’s behind!
Essentially Lucy’s problem is her diet of raw salmon. Tapeworms of all types (and in all species) are acquired through the ingestion of eggs, either from eating faecal material or inadequately cooked meat (see diagram for life-cycle).
Essentially Lucy’s problem is her diet of raw salmon. Tapeworms of all types (and in all species) are acquired through the ingestion of eggs, either from eating faecal material or inadequately cooked meat (see diagram for life-cycle).
Click for larger image
Tapeworm infections can occur anywhere in the world, including in the United Kingdom. They are not specifically infections of developing countries although they are more common when basic hygiene measures have been neglected and where there is a risk of exposure to inadequately cooked or raw meat.
There are lots of different types of tapeworm; the most common of those seen in humans are listed below with the type of meat they are acquired from.
• Taenia saginata – beef – up to 10m in length
• Taenia solium – pork – up to 3m in length
• Diphyllobothrium latum – fish – up to 10m in
length
• Hymenolepis nana – human faeces – only 40mm
All of these organisms can cause chronic infections which only come to light because the patient is either shown to be anaemic and has an eosinophilia (due to blood loss and failure to absorb vitamin B12 because the tapeworm absorbs this), or they actually pass a worm in their stool... not a pleasant experience I suspect.
In order to diagnose these infections unless of course a worm has actually been seen (please send them in...Microbiologists like to see them!) the microbiology laboratory examines the patient’s stool looking for evidence of worm eggs. Usually three separate samples would be examined before the laboratory releases a negative result because the worm eggs can be very hard to find and identify.
The treatment in humans is relatively straight forward. A single dose of PO Praziquantel 5-10mg/kg is enough to treat most tapeworm infections. H. nana is slightly more difficult to treat and requires 25mg/kg of PO Praziquantel with a second dose given 1 week later (I don’t know why this is the case, do leave a comment if you know). In H. nana a stool sample should be retested 3 weeks after the second dose.
In bears, intervention is less easy, but treatment is actually similar, PO or subcutaneous Praziquantel 5mg/kg! It is thought wild bears may expel adult egg-laying worms prior to denning as they have fewer tapeworms in spring compared to autumn. However when they start eating raw salmon again, high tapeworm levels return. Put simply bears have chronic infections and there really isn’t much that can be done about that.
There are lots of different types of tapeworm; the most common of those seen in humans are listed below with the type of meat they are acquired from.
• Taenia saginata – beef – up to 10m in length
• Taenia solium – pork – up to 3m in length
• Diphyllobothrium latum – fish – up to 10m in
length
• Hymenolepis nana – human faeces – only 40mm
All of these organisms can cause chronic infections which only come to light because the patient is either shown to be anaemic and has an eosinophilia (due to blood loss and failure to absorb vitamin B12 because the tapeworm absorbs this), or they actually pass a worm in their stool... not a pleasant experience I suspect.
In order to diagnose these infections unless of course a worm has actually been seen (please send them in...Microbiologists like to see them!) the microbiology laboratory examines the patient’s stool looking for evidence of worm eggs. Usually three separate samples would be examined before the laboratory releases a negative result because the worm eggs can be very hard to find and identify.
The treatment in humans is relatively straight forward. A single dose of PO Praziquantel 5-10mg/kg is enough to treat most tapeworm infections. H. nana is slightly more difficult to treat and requires 25mg/kg of PO Praziquantel with a second dose given 1 week later (I don’t know why this is the case, do leave a comment if you know). In H. nana a stool sample should be retested 3 weeks after the second dose.
In bears, intervention is less easy, but treatment is actually similar, PO or subcutaneous Praziquantel 5mg/kg! It is thought wild bears may expel adult egg-laying worms prior to denning as they have fewer tapeworms in spring compared to autumn. However when they start eating raw salmon again, high tapeworm levels return. Put simply bears have chronic infections and there really isn’t much that can be done about that.
So in answer to the original question “does a bear poo in the woods” I can now say with some certainty, “no, they poo anywhere they want... woods, rivers, roads and even campsites!” After all, who is going to tell a 400kg bear that they can’t...?
P.S. I strongly recommend Bella Coola in British Columbia for Bear viewing.
P.S. I strongly recommend Bella Coola in British Columbia for Bear viewing.
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