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Health

Weird cells in your semen? Don't panic, you might just have flu

By Jessica Hamzelou

30 June 2015

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I’m feeling a bit rough, you? (Image: De Agostini Picture Library/Getty)

Men: don’t worry but there are strange round cells floating in your semen. The question is why? The latest idea is that infections like flu are to blame, by disrupting sperm production.

When couples find it difficult to conceive, a man’s ejaculate is often under the microscope, literally. Beyond looking at the sperm cells themselves, clinicians often look for so-called “round cells”.

“They look like spermatozoa, without the tail,” says Gianpiero Palermo at Weill Cornell Medical College in New York. And that’s the usual assumption– although they are sometimes interpreted as white blood cells. A high number of white blood cells can indicate some kind of infection, and so men with lots of round cells in their ejaculate may be tested for sexually transmitted infections, says Palermo.

This isn’t the case in the UK, says Allan Pacey at the University of Sheffield, UK – but the cells are still a puzzle. “All we do in the UK is note their presence. What do they mean?”

Palermo and his colleagues analysed semen samples from 4800 men. A quarter of the mystery cells turned out to be white blood cells, but the other three-quarters had a half-set of chromosomes, like sperm cells.

But unlike normal sperm cells, these round cells also contained proteins normally made by sertoli cells that usually serve to nurture the growth of sperm.

Sloughed off in ejaculate

Together, the findings suggest that most of the round cells are in fact immature sperm that have been engulfed for some reason by sertoli cells and then sloughed off into the ejaculate, says Palermo, who presented the findings at the European Society of Human Reproduction and Embryology in Lisbon, Portugal, which ran between 14 and 17 June.

The team also noticed something else: that the number of round cells appeared to peak in the winter. In fact, the cell numbers correlated with the flu season in New York State, where the study took place.

Palermo reckons flu infections might temporarily disrupt the production of sperm, triggering the formation of the strange cells.

It is an idea that makes sense, says Pacey. “If an infection causes a systemic illness it can cause damage throughout the body,” he says.

The effect doesn’t seem to last – men who had lots of round cells during one analysis tended to have higher numbers of normal sperm in their second and third follow-up analyses.

The results suggest the cells are harmless, says Palermo. “We don’t need to worry about these cells, or treat them with antibiotics,” he says. “This should come as a relief for physicians.”

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