Third trimester Listeria

What is listeriosis?

Listeriosis is an illness thats caused when you come into contact with bacteria called listeria. You usually get it by eating food contaminated by listeria, but you can also catch it by handling infected soil, water, or animal poo [FSA 2016, OTIS 2016].

When youre pregnant, youre more susceptible to getting listeriosis. This is because changes in your immune system mean that your defences against the infection are lower than usual [NHS 2015a]. Listeriosis is almost 20 times more likely to affect pregnant women than other healthy adults [Okike et al. 2013, NHS 2015a].

Listeriosis is still a rare condition, though. There are fewer than 200 cases in the UK each year [PHE 2014, 2016, Scottish Government nd], and up to 30 of these are pregnant women [PHE 2014]. Although rare, its vital to recognise and treat listeriosis because it can seriously affect your unborn baby.

Will listeriosis harm my baby?

Listeriosis can be very dangerous for your baby [Awofisayo et al. 2015, Okike et al. 2013, NHS 2015a]. The infection may be passed on to your baby either in the womb [uterus] or during birth [Caserta 2015].

Recognising the infection and treating it quickly with antibiotics can help protect your baby [Okike et al. 2013, NHS 2015a, OTIS 2016,].
However, without treatment, listeriosis can sometimes lead to:

• miscarriage
• premature birth
• a baby being stillborn [Caserta 2015, Okike et al. 2013, OTIS 2016]

If your baby is exposed to listeria in the womb or during the birth, he may become dangerously ill after hes born, with pneumonia, meningitis, or neonatal sepsis [Caserta 2015, Okike et al. 2013]. Usually, the babys infection becomes obvious soon after birth, but sometimes the symptoms take a few weeks to appear [Caserta 2015, Okike et al. 2013, OTIS 2016].

How will I know if I have listeriosis?

Its easy to confuse listeriosis with flu because the symptoms are usually mild [NHS 2015a].

You may have:

• a fever
• muscle aches
• chills
• nausea or vomiting
• diarrhoea [NHS 2015a]

The symptoms may appear up to 10 weeks after youve been exposed to the bacteria [NHS 2015a]. To be on the safe side, see your doctor any time you have a fever and chills during pregnancy [NHS 2015a].

Very rarely the infection spreads to your blood or nervous system and becomes severe [Kourtis et al. 2014, NHS 2015]. In this case the fever, muscle pains and chills will be worse, and you may develop a severe headache, stiff neck, confusion, shakiness, or fits [convulsions] [NHS 2015].

However, about one in three pregnant women dont have any symptoms at all [Okike et al. 2013]. Its possible that the first you know about being infected is when you have a serious pregnancy complication, or if your baby becomes ill after the birth [Kourtis et al. 2014].

How can I prevent listeriosis?

The best thing is to steer clear of the foods that could cause listeriosis. Eating food contaminated with listeria is the most common cause of infection [NHS 2015].

Youre most likely to contract listeria in the third trimester when your immunity is lowest [Okike et al. 2013, Kourtis et al. 2014], so its best to take care with food right up until the end of your pregnancy.

When youre pregnant, the NHS advises you to avoid foods that are more likely to harbour the listeria bug, including:

• unpasteurised milk
• mould-ripened soft cheeses, such as camembert or brie, and soft blue-veined cheeses, such as Danish blue or gorgonzola
• pâté of any sort, including vegetable pate
• under-cooked foods, such as ready meals [NHS 2015a, NICE 2008]

Its safe to have any pasteurised or UHT milk and yoghurts, including probiotic yoghurts [NHS 2017]. Hard and soft pasteurised cheeses, such as cheddar, cottage cheese, or processed cheese are also fine to eat [NHS 2017]. The same goes for hard blue-veined cheese, such as stilton [NHS 2015a, 2017]. Also, take extra care when youre handling food at home:

• Wash your hands before and after preparing meals.
• Wash cooking utensils, chopping boards and surfaces thoroughly after preparing food.
• Keep raw and ready-to-eat foods separate in the fridge, so keep uncooked meats below ready-to-eat foods so that juices from the meat cannot drip onto cooked food.
• Peel or wash raw vegetables, fruit, or salads thoroughly before eating them.
• Always cook and reheat foods thoroughly, according to the instructions, until they are piping hot. [NHS 2015]

Unlike mould, you cant usually see when listeria has grown on your food as it attaches to surfaces as a slime-like layer [FSA 2016]. Listeria can survive freezing and, unlike other bacteria, can continue to grow very slowly at low temperatures, such as in your fridge [FSA 2016].

Most outbreaks of listeriosis are associated with chilled, ready-to-eat foods that may have been stored for too long or at the wrong temperature [FSA 2016].

Foods that are considered safe to eat in pregnancy but that have most commonly been linked with listeriosis include:

• smoked fish and cooked shellfish
• cooked meats, poultry, and cured meats
• pre-packed sandwiches, prepared salads, and some cut fruits, including melon
  [FSA 2016]

For chilled ready-to-eat foods, its particularly important to:

• Check that your fridge is set at the manufacturers recommended temperature, usually 5 degrees C or below.
• Eat the food by the use-by date so the bacteria dont have time to grow to dangerous levels.
• Follow instructions on the packaging, such as how soon to use food once opened [FSA nd, NHS 2015].

Its also possible to catch listeriosis from sheep, cows, and goats around the time they give birth[DEFRA et al. 2015, NHS 2015b]. If you work on a farm or visit farms with your children, stay away from sheep, cows, and goats, and avoid touching clothes or equipment used while handling farm animals [DEFRA et al. 2015]. This is especially important during the lambing season, which is usually from January to April [NHS 2015b].

If you or your partner are involved in farming, its vital to protect yourself and your baby from listeria and other potential infections, such as toxoplasmosis. You can learn more from Public Health England or the Scottish government.

How can listeriosis be treated?

If you have any flu-like symptoms, especially if you think youve eaten something that could have infected you with the listeria bug, speak to your GP straight away.

If your GP suspects listeriosis, she will arrange for you to have a blood test [NHS 2015]. If the results show an infection, the doctor will recommend a course of antibiotics to protect you and your baby [Caserta 2015, Okike et al. 2013]. You may also have extra ultrasound scans to check on your babys health [NHS 2015a, OTIS 2016]. Its reassuring to know that prompt treatment with antibiotics is usually very successful.

Worried about something youve eaten? Find out whats not safe to eat in pregnancy.