A US doctor working in Kenya assumed he had (almost) seen it all when it came to the causes of anaemia.

But, as he found out, every day is a school day.

“Before today, I felt pretty confident that I had encountered most causes of anaemia until this was pulled from the upper oesophagus of a three-year-old,” Dr Jason Brotherton tweeted, accompanied by a juicy image of a 6.5cm-long leech.

It looked as if the patient had “been feeding it for a while”, he said, adding that their haemoglobin was an extremely low 30g/L (normal: 110g/L or higher).