Zika Resource Center

Zika Resource Center

September 01, 2017
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Zika virus infection lowers sperm count in men

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Zika virus infection may reduce fertility among infected men and can be transmitted through semen even after clinical remission, according to findings recently published in The Lancet Infectious Diseases.

“Zika virus has been isolated from numerous human fluids and identified in human semen and vaginal secretions,” Guillaume Joguet, MD, of the Centre Caribéen de Médecine de la Reproduction, and colleagues wrote. “The localization of Zika virus in the human genital tract and its consequences are not yet known. Understanding the localization of Zika virus within the male genital tract, its dynamics and shedding in semen, is of paramount importance to prevent sexual transmission.”

The researchers carried out a prospective observational study of 15 men who were treated for Zika virus infection at Pointe-à-Pitre University Hospital in Guadaloupe, French Caribbean — the site of a Zika virus outbreak that occurred between April and November of 2016. The researchers collected blood, urine and semen samples at days 7, 11, 20, 30, 60, 90 and 120 after the onset of symptoms. Joguet and colleagues assessed semen characteristics, including sperm count, sperm motility, vitality and morphology. They also evaluated concentrations of reproductive hormones such as testosterone, inhibin, follicle-stimulating hormone and luteinizing hormone. The researchers isolated motile sperm cells from semen on days 7, 11 and 20. Follow-up was 120 days, except for one patient who withdrew on day 30. Four patients gave additional samples on day 150, and two patients gave additional samples on day 180.

The patients’ mean age was 35 years. Joguet and colleagues reported that total sperm count fell from a median of 119 x 106 spermatozoa on day 7 to 45.2 x 106 at day 30 and 70 x 106 at day 60. Inhibin levels rose steadily, increasing from 93.5 pg/mL on day 7 to 150 pg/mL on day 120, at which point the sperm count had recovered, the researchers reported.

Zika virus RNA was present in the motile sperm of three of 14 patients on day 7, four of 15 at day 11 and four of 15 at day 20, Joguet and colleagues wrote.

Of all bodily fluids, the one that tested positive most frequently for Zika virus was whole blood (n = 62 of 92 samples). Three patients were still positive at day 120.

“These findings suggest a direct effect of viral infection on the testes or epididymis with impairment of sperm development, in agreement with findings in animal models,” Luisa Barzon, MD, Enrico Lavezzo, PhD, and Giorgio Palu, PhD, from the department of molecular medicine at the University of Padova, Italy, wrote in an accompanying editorial. “Notwithstanding the major recent advances in our knowledge of Zika virus biology and diseases, achieved especially with in vitro and animal studies, several questions on the effect of Zika virus infection on human health remain open. Studies such as that of Joguet and colleagues, although with the limitations of a small patient population and absence of a control group, provide novel and valuable baseline information that warrant further research on the consequences of Zika virus infection on human reproduction.” – by Andy Polhamus

Disclosures: Barzon, Lavezzo, Palu and the researchers report no relevant financial disclosures.

Total sperm count fell from day 7 to day 30 in Zika-infected men.