CMV and Toxoplasmosis in Pregnancy

Two infections, one thing in common

Cytomegalovirus and toxoplasmosis are grouped together here because they share the feature that matters most: neither is part of NHS antenatal screening, and both are usually silent in the mother while capable of affecting the baby. That combination is why prevention advice carries so much weight.

The NHS describes CMV as "a common virus that's usually harmless. Sometimes it causes problems in babies and people with a weakened immune system", and notes that it "does not usually cause any symptoms and most people do not realise they have it". Where symptoms occur they are flu-like: "a high temperature, aching muscles, tiredness, a skin rash, feeling sick, a sore throat, swollen glands", usually settling "without treatment within about 3 weeks".

Toxoplasmosis is similar. The NHS notes that it "is not usually serious and normally gets better on its own", but "can cause serious problems if you get it while you're pregnant".

Cytomegalovirus: where it comes from

CMV is passed on through body fluids, and in practice the main source for pregnant women is young children. Toddlers in nursery shed the virus in saliva and urine for months without being ill, and the transmission route is a child's dribble on your face, a shared spoon, or a nappy change followed by touching your own mouth or eyes.

The practical measures follow directly from that. Do not share food, cutlery, cups or dummies with young children. Avoid kissing toddlers on the mouth — kiss the top of the head or the cheek. Wash your hands thoroughly after changing nappies, wiping noses and handling toys. None of this is glamorous advice, and it is the only advice there is, because there is no vaccine and no screening programme.

If CMV is passed to the baby, the result is congenital CMV. The NHS explains: "When a baby is born with a CMV infection, it's known as congenital CMV. Most babies with congenital CMV do not have any symptoms. But congenital CMV can sometimes cause problems, including a rash, yellowing of the skin and the whites of the eyes (jaundice), a low birth weight, a smaller head than usual (microcephaly), seizures (fits)."

Hearing loss is the most common long-term consequence of congenital CMV, and it may not be present at birth, which is why babies with congenital CMV have ongoing hearing surveillance. If you develop flu-like symptoms in pregnancy, the NHS advice is to see a GP: "The GP may arrange tests to find out if you've been infected with CMV."

Toxoplasmosis: where it comes from

The NHS is specific about the sources: "The parasite that causes toxoplasmosis can be found in the poo of infected cats, and in undercooked meat. You can also catch it from soil that's been contaminated by cat poo."

UKHSA's guidance adds a finding from a case-control study in England and Wales: "A strong association between beef and infection was seen, which remained after adjustment for potential confounders. These findings emphasize the need to ensure food is thoroughly cooked and handled hygienically, especially for those in vulnerable groups." It also records that "around 350 cases of toxoplasmosis are diagnosed in England and Wales each year", which puts the risk in perspective.

The prevention measures the NHS lists include wearing gloves while gardening and washing hands thoroughly afterwards, washing hands before preparing food and eating, and washing hands, knives and chopping boards thoroughly after handling raw meat. Cook meat thoroughly, wash fruit and vegetables, avoid unpasteurised goat's milk, and if you have a cat, have someone else change the litter tray daily where possible — or use gloves and wash your hands afterwards.

There is one exposure people forget. UKHSA notes that "there's a small risk during the lambing season of toxoplasmosis infection passing from sheep to humans. The T. gondii parasite is sometimes found in the afterbirth and on newborn lambs after an infected sheep has given birth." Lambing is a known risk to pregnant women and should be avoided.

You do not have to rehome the cat

This is the single most common misunderstanding in pregnancy. The risk is from faeces that have been sitting long enough for the parasite to become infectious, and from soil contaminated by them — not from stroking a cat, or from a cat living in your house. Indoor cats fed on commercial food are very unlikely to be shedding the parasite at all.

Litter tray hygiene, gloves for gardening and handwashing cover the realistic routes. Giving the cat away does not.

What happens if infection is suspected

For toxoplasmosis, the NHS advises asking for an urgent GP appointment or NHS 111 help if "you're pregnant or have a weakened immune system, and have any symptoms of toxoplasmosis", adding that if you are pregnant "you can also call your midwife for advice".

Diagnosis is by blood test. The NHS explains that "if you're pregnant and you test positive for toxoplasmosis, the GP can refer you for more tests to see if your baby has been infected. This is very rare." Treatment exists: "you'll usually be given medicines, including antibiotics, if you are pregnant", and newborn babies with toxoplasmosis "are also treated with antibiotics and sometimes other medicines".

For CMV, treatment options in pregnancy are more limited and are managed by fetal medicine specialists. Where infection is confirmed, monitoring usually involves detailed ultrasound looking for changes in the baby's brain, growth and abdomen, alongside specialist counselling.

Why there is no screening programme

Neither infection appears in the NHS antenatal screening schedule set out under NICE guideline NG201, and neither is among the conditions the 20-week scan screens for. Screening programmes are only introduced where testing everyone leads to better outcomes than not doing so, and for both of these the case has not been made in the UK — largely because a positive result in the mother does not reliably tell you whether the baby is affected, and because the interventions available are limited.

That places the emphasis firmly on prevention, and on reporting symptoms rather than waiting for a test nobody is going to offer. If you develop an unexplained fever, swollen glands or a flu-like illness in pregnancy, mention it rather than assuming it is nothing.