The Zika virus can be transmitted by a female mosquito to her eggs, eventually infecting her adult daughters, researchers reported on Monday.

But mother-daughter transmission happens so rarely among mosquitoes that it is probably not an important factor in the global Zika epidemic, according to the lead author of the study, published in The American Journal of Tropical Medicine and Hygiene.

Instead, this form of transmission is probably a survival mechanism, allowing the Zika virus to persist through winters and dry spells when adult mosquitoes die off, said the author, Dr. Robert B. Tesh, a pathologist at the University of Texas Medical Branch in Galveston.