Toxoplasmosis and Listeriosis
TOXOPLASMOSIS
Toxoplasmosis is caused by the parasite Tbxoplasma gondii. If the mother is infected by this organism during pregnancy it may be transmitted to the foetus.
The most common way to acquire the parasite is by eating undercooked meat, or by contact with cat faeces. Pregnant women should be advised to ensure that meat is properly cooked and that gloves are worn when working in the garden or cleaning cat-litter trays. Fruit and vegetables should be washed thoroughly and hands should always be carefully cleaned after handling raw food.
About 10 per cent of'infected babies present with severe problems at birth or shortly afterwards. Complications include neurological damage, cerebral calcification, hydrocephalus or chorioretinitis. The remaining 80-90 per cent of babies tend to develop evidence of toxoplasma infection months, or even years, later. There may be bilateral visual loss due to chorioretinitis and a systemic infection with hepatosplenomegaly can also occur.
LISTERIOSIS
Listeriosis is a bacterial infection caused by LisLeria monocytogenes and infection during pregnancy is associated with miscarriage, stillbirth and infection in the baby.
Listeriosis is acquired from unpasteurised milk, ripened soft cheeses made from unpasteurised milk, and pate, all of which should be avoided in pregnancy. An unusual property of L monocytogenes is that it can multiply at low temperatures, which can therefore occur in some refrigerators.
Pregnant women should also be advised to avoid some uncooked foods, such as raw cabbage, cooked foods that are inadequately reheated and undercooked foods, which all carry the risk of listeria infection. To avoid infection, food should be thoroughly heated because L monocytogenes is killed by heating to yo°C for about two minutes.
The diagnosis is made by the clinical picture, blood cultures and serology. If suspected, listeriosis can be treated with amoxicillin or erythromycin. Severe identified cases may need intravenous antibiotics, including gentamicin.
ALCOHOL *
About 40 per cent of women who drink alcohol continue to do so during pregnancy. Fortunately, most drink only small amounts.
Foetal alcohol syndrome consists of foetal growth restriction, neurological abnormalities and characteristic facial deformities. This is a rare event and in women who consume more than 18 units of alcohol per day throughout their pregnancy, it is seen in approximately 30 per cent of births.
Alcohol consumption of more than 15 units per week is associated with a reduction in birthweight. The recommendation Tom the Royal College of Obstetricians and Gynaecologists is that alcohol consumption should be limited to fewer than seven units per week, with no more than one unit of alcohol per day.
FREQUENTLY ASKED QUESTIONS
Sexual activity
"here is no evidence to suggest that sexual activity is harmful 'uririg pregnancy, provided there is no discomfort. Changes in echnique and position may be necessary to avoid this, but even in late pregnancy there should be no worrying consequences.
Exercise during pregnancy
Many women are keen on sport and if they play to a high standard, may want to continue during their pregnancy. There is no evidence that moderate exercise in pregnancy is detrimental to the outcome. For most women, it is beneficial to continue with appropriate exercise. Exceptions to this advice would include contact sports and high-impact sporting activity. Horse-riding is
POTENTIAL RISKS
• Toxoplasmosis caught by the mother may be transmitted to the foetus.
• About 10 per cent of toxoplasmosis-infected foetuses present with severe problems at the time of birth or shortly after.
• Listeria is acquired from unpasteurised milk, ripened soft cheeses and pate.
• Foetal alcohol syndrome is seen in about 30 per cent of babies born to women who drink more than 18 units of alcohol a day.
not recommended and pregnant women should be advised to avoid scuba diving because the physiological effects of changes in oxygen tension, nitrogen solubility and hydrostatic pressure at depth are not clearly understood.
Air travel in pregnancy
There is no evidence that air travel is detrimental to pregnancy. Long-haul travel is known to be associated with an increased risk of DVT, but whether this risk is greater in pregnancy is not known. General advice to avoid alcohol and to keep well hydrated during the flight is important and women should be encouraged to move around as much as possible. Correctly fitted compression stockings may also reduce the risk.
Most airlines will allow women to travel up to 36 weeks of pregnancy, although many operators require a doctor's letter to confirm that there are no additional risk factors for women who are more than 28 weeks pregnant.
Pregnancies beyond 40 weeks
Most women (82 per cent) will deliver by 42 weeks. Pregnancies extending beyond this are associated with increased perinatal morbidity and mortality. The NICE guideline recommends that all women should be offered labour induction after 41 weeks.
A vaginal examination to sweep the membranes at 41 weeks has been shown to reduce the need for formal induction of labour and is not associated with any adverse neonatal outcomes. If a woman chooses not to be induced, intensive foetal surveillance should be undertaken.
Elective caesarean section
Caesarean section rates continue to rise and increasing numbers of women request this, despite the absence of a medical indication. Although an elective caesarean section is safe, when compared with vaginal birth, the rate of complications is higher and they are often more serious. There is also increasing evidence that a caesarean section in the first pregnancy has a negative effect on outcomes of future pregnancies, with increased rates of stillbirth, infertility and placental problems. It should be made clear to women thinking of choosing a caesarean that it is not the easy option.
VACCINATIONS AND INFECTIONS
Live vaccines, such as MMR, BCG and yellow fever, are contraindicated in pregnancy. Yellow fever is fatal in 50 per cent of cases, so travel to endemic countries should be avoided. If the patient must travel, vaccination may be considered after 24 weeks of pregnancy, when the risk/benefit ratio tips in favour of doing so. In general, killed or inactivated vaccines and toxoids are safe in pregnancy. Oral polio vaccine is also safe.
If a pregnant woman is travelling to a malaria-endemic region, she should be advised to take the usual precautions to minimise exposure and the antimalarial drugs chloroquine and proguanil can be prescribed for travel to areas where malaria strains are not resistant. Malaria is extremely serious, with a maternal mortality rate as high as 10 per cent.
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MIMS WOMEN'S HEALTH VOL1, NO 2, 2006 41 |
