Potential Sexual Transmission of Zika Virus

Didier Musso; Claudine Roche; Emilie Robin; Tuxuan Nhan; Anita Teissier; Van-Mai Cao-Lormeau


Emerging Infectious Diseases. 2015;21(2):359-361. 

In This Article


The ZIKV natural transmission cycle involves mosquitoes, especially Aedes spp.,[7] but perinatal transmission[8] and potential risk for transfusion-transmitted ZIKV infections has also been demonstrated.[9] Moreover, ZIKV transmission by sexual intercourse has been suggested by Foy et al.,[10] who described a patient who was infected with ZIKV in southeastern Senegal in 2008. After returning to his home in Colorado, United States, he experienced common symptoms of ZIKV infection and symptoms of prostatitis. Four days later, he observed signs of hematospermia, and on the same day, his wife had symptoms of ZIKV infection. Because the wife of the patient had not traveled out of the United States during the previous year and had sexual intercourse with him 1 day after he returned home, transmission by semen was suggested. ZIKV infection of the patient and his wife was confirmed by serologic testing, but the presence of ZIKV in the semen of the patient was not investigated.

Infectious organisms, especially sexually transmitted microorganisms including viruses (human papillomavirus or herpes simplex virus), are known to be etiologic agents of hematospermia.[11] To our knowledge, before the report of Foy et al.[10] and this study, arbovirus infections in humans had not been reported to be associated with hematospermia, and no arboviruses had been isolated from human semen.

We detected a high ZIKV RNA load and replicative ZIKV in semen samples, but ZIKV remained undetectable by rRT-PCR in the blood sample collected at the same time. These results suggest that viral replication may have occurred in the genital tract, but we do not know when this replication started and how long it lasted. The fact that the patient had no common symptoms of ZIKV acute infection concomitantly to hematospermia suggests that the viremic phase occurred upstream, probably during the first or second episode of mild fever, headache, and arthralgia.

The detection of ZIKV in both urine and semen is consistent with the results obtained in a study of effects of Japanese encephalitis virus, another flavivirus, on boars. The virus was isolated from urine and semen of experimentally infected animals, and viremia developed in female boars that artificially inseminated with the infectious semen.[12]

Flaviviruses have also been detected in urine of persons infected with West Nile virus (WNV). WNV RNA was detected in urine for a longer time and with higher RNA load than in plasma.[13] WNV antigens were detected in renal tubular epithelial cells, vascular endothelial cells, and macrophages of kidneys from infected hamsters,[14] suggesting that persistent shedding of WNV in urine was caused by viral replication in renal tissue. Dengue virus (DENV) RNA and DENV nonstructural protein 1 antigen were also detected in urine samples for a longer time than in blood, but infectious DENV has not been isolated in culture. Hirayama et al. concluded that the detection of DENV by rRT-PCR was useful to confirm DENV infections after the viremic phase.[6] Also, yellow fever virus RNA was isolated from the urine of vaccinated persons,[15] and Saint Louis encephalitis viral antigens, but not infective virus, have been detected in urine samples from infected patients.[10]

Our findings support the hypothesis that ZIKV can be transmitted by sexual intercourse. Furthermore, the observation that ZIKV RNA was detectable in urine after viremia clearance in blood suggests that, as found for DENV and WNV infections, urine samples can yield evidence of ZIKV for late diagnosis, but more investigation is needed.

Dr. Musso is a medical doctor and director of the Diagnosis Medical Laboratory and the Unit of Emerging Infectious Diseases of the Institut Louis Malardé, Papeete, Tahiti, French Polynesia. His research programs target endemic infectious diseases, especially arbovirus infections, leptospirosis, tuberculosis, and lymphatic filariasis.