Tuesday, 4 October 2011

The unholy trio of the sandpit - Toxoplasmosis, Meliodosis and Silicosis

Sandpits and digging patches are a constant source of misinformation and over-hyped paranoia. In the past years I have been asked about the risks of toxoplasmosis and melioidosis and silicosis. I have heard numerous complaints about how children playing in pits and patches get “dirty”???, how difficult it is to place a sand pit cover on a sandpit, and my personal favourite, that the sand found in sandpits is carcinogenic.




Part 1 - Toxoplasmosis
Summary
1) Toxoplasmosis is caused by exposure/ingestion of undercooked, contaminated meat (humans and animals).   Cats who are fed undercooked, contaminated meat may carry the parasite in their system.

2) Humans may accidentally swallow the parasite through contact with cat faeces by touching or ingesting anything that has come into contact with cat faeces that contain Toxoplasma (e.g., not washing hands after gardening/play or eating soil/sand that have come in contact with the parasite)

3) Cats who have been fed only canned or dried commercial food or well-cooked table food are not susceptible to contracting and spreading the parasite. Cats only carry Toxoplasma in their faeces for a few weeks following infection with the parasite. The infection will go away on its own.

4) “While the parasite is found throughout the world, more than 60 million people in the United States may be infected with the Toxoplasma parasite. Of those who are infected, very few have symptoms because a healthy person's immune system usually keeps the parasite from causing illness. However, pregnant women and individuals who have compromised immune systems should be cautious; for them, a Toxoplasma infection could cause serious health problems. 


A Toxoplasma infection occurs by: 
· Eating undercooked, contaminated meat (especially pork, lamb, and venison)

· Accidental ingestion of undercooked, contaminated meat after handling it and not washing hands thoroughly
 (Toxoplasma cannot be absorbed through intact skin)

· Eating food that was contaminated by knives, utensils, cutting boards and other foods that have had contact 
with raw, contaminated meat

· Drinking water contaminated with Toxoplasma gondii

· Accidentally swallowing the parasite through contact with cat faeces that contain Toxoplasma. This might 
happen by: 
1) cleaning a cat's litter box when the cat has shed Toxoplasma in its faeces 
2) touching or ingesting anything that has come into contact with cat faeces that contain Toxoplasma
3) accidentally ingesting contaminated soil (e.g., not washing hands after gardening or eating unwashed fruits 
or vegetables from a garden)

· Mother-to-child (congenital) transmission.

How can I prevent toxoplasmosis?
There are several general sanitation and food safety steps you can take to reduce your chances of becoming infected with Toxoplasma gondii.
· Cook food to safe temperatures. A food thermometer should be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked. USDA recommends the following for meat preparation

· For Whole Cuts of Meat (excluding poultry) Cook to at least 145° F (63° C) as measured with a food 
thermometer placed in the thickest part of the meat, then allow the meat to rest* for three minutes before carving or consuming

· For Ground Meat (excluding poultry) Cook to at least 160° F (71° C); ground meats do not require a 
rest time[i]

· For All Poultry (whole cuts and ground) Cook to at least 165° F (74° C), and for whole poultry allow the 
meat to rest* for three minutes before carving or consuming

· Freeze meat for several days at sub-zero (0° F) temperatures before cooking to greatly reduce chance of 
infection

· Peel or wash fruits and vegetables thoroughly before eating.
· Wash cutting boards, dishes, counters, utensils, and hands with hot soapy water after contact with raw meat, poultry, seafood, or unwashed fruits or vegetables

· Wear gloves when gardening and during any contact with soil or sand because it might be contaminated with 
cat faeces that contain Toxoplasma. Wash hands with soap and warm water after gardening or contact with soil or sand

· Teach children the importance of washing hands to prevent infection and keep your outdoor 
sandboxes covered


If I am at risk, can I keep my cat?
Yes, you may keep your cat if you are a person at risk for a severe infection (e.g., you have a weakened immune system or are pregnant); however, there are several safety precautions to avoid being exposed to Toxoplasma gondii:
· Ensure the cat litter box is changed daily. The Toxoplasma parasite does not become infectious until 1 to 5 days after it is shed in a cat's faeces

· If you are pregnant or immunocompromised:
1. Avoid changing cat litter if possible. If no one else can perform the task, wear disposable gloves and wash your hands with soap and warm water afterwards.
2. Keep cats indoors.
3. Do not adopt or handle stray cats, especially kittens. Do not get a new cat while you are pregnant

· Feed cats only canned or dried commercial food or well-cooked table food, not raw or undercooked m
eats

· Keep your outdoor sandboxes covered.

Once infected with Toxoplasma is my cat always able to spread the infection to me?

No, cats only spread Toxoplasma in their faeces for a few weeks following infection with the parasite. Like humans, cats rarely have symptoms when first infected, so most people do not know if their cat has been infected. The infection will go away on its own therefore it does not help to have your cat or your cat's faeces tested for Toxoplasma.

[i] According to USDA, "A 'rest time' is the amount of time the product remains at the final temperature, after it has been removed from a grill, oven, or other heat source. During the three minutes after meat is removed from the heat source, its temperature remains constant or continues to rise, which destroys pathogens." 
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