You bowel me over

This digitally colourised scanning electron micrograph depicts a Giardia lamblia protozoan caught in a late stage of cell division, producing a heart shape.

People catch the disease if they eat or drink contaminated water and food or come in contact with faeces and infected people or animals.

The parasite sets up shop in the gastrointestinal tract. Some people don’t show any symptoms, even though they can still pass the parasite on, and others end up with gastroenteritis, with symptoms such as stomach cramps, bloating, excessive gas and wind, and watery smelly diarrhoea.

Happy Valentine’s Day!