Toxoplasmosis – Prevention in Pregnancy
Toxoplasmosis is a subject that instills fear in pregnant women and it’s also a question that comes up with patients who have contact with cats, so I wanted to give you my thoughts and help allay any concerns you might have.
In truth, Toxoplasmosis is a common infection usually acquired during childhood and adolescence, with up to 50 % of adults showing evidence of previous exposure in our climate and maybe 80% in the tropics. It is only when toxoplasmic infection occurs for the first time in pregnancy that there is potential for problems.
Cats get a bad name when it comes to toxoplasmosis because if infected themselves, then once in their lives they will excrete infective faeces for three weeks. They will never be infective again but the parasites themselves may remain infectious for up to a year, especially in warm, humid environments.
The feedback we receive is that pregnant women are concerned they have the potential to catch toxoplasmosis if handling material from exposed cat faeces. The bigger source of toxoplasmic infection is contaminated water, soil or unwashed vegetables or undercooked meat products.
The rate of maternal infection is quoted as between 1 and 8/1000 pregnancies and even if the mother has infection, the risk of transfer to baby is approximately half. So all in all, this is still a low chance of this presenting.
Symptoms of toxoplasmosis are vague and non-specific and include fevers, muscle aches and lymph glands enlarging – almost like glandular fever. Unfortunately, there is minimal evidence that any treatment is effective if baby does get toxoplasmosis. Prevention and being careful in pregnancy is always your best chance to decrease infection. I have used information from www.uptodate.com on the ways of decreasing risks:
PREVENTION — Prevention of toxoplasmosis is based upon avoidance of sources of infection. While access to reliable information on sources of infection is undoubtedly important, there is a lack of clear evidence that such information changes women’s behaviour during pregnancy. Evidence from case control studies of risk factors in Europe has identified the following principal sources of infection:
- Travel to less developed countries is a major risk factor, especially to South America, where more virulent parasite genotypes predominate.
- Women should avoid drinking unfiltered water in any setting.
- Avoid ingesting soil by observing strict hand hygiene after touching soil. Fruit and vegetables should be washed before eating.
- Raw or undercooked meat is an important source of infection. Cutting boards, knives, and the sink and counters should be washed after food preparation. Avoid mucous membrane contact when handling uncooked meat. Women should also avoid tasting meat while cooking.
- Meat should be cooked to 152ºF (66ºC) or higher, or frozen for 24 hours in a household freezer (at less than -12ºC), both of which are lethal to tachyzoites and bradyzoites. Meat farmed in strict indoor conditions is less likely to be contaminated than outdoor reared meat. There is weak evidence that meat that has been smoked or cured in brine is not safe. The risk of infection is likely to be increased when cured products involve meat from more than one animal and limited drying and curing, as in some local production methods.
- There is some evidence that shellfish can be infected with toxoplasma cysts.
- Owning a cat is only weakly associated with acute infection. This is probably because cats only excrete oocysts for three weeks of their life, and people are just as likely to be exposed to oocysts excreted by someone else’s cat. Nevertheless, it seems sensible for pregnant women with cats to ask someone else to change the litter box daily (fresh cat faeces are not infectious).
- Hand washing is the single most important measure to reduce transmission of microorganisms from one site to another on the same patient. Therefore, hand-washing is important after activities such as preparing food or gardening.
The best simple advice “prepare today, cook today and eat today” will make all your food questions easy.