Eurosurveillance: `Possible' Sexual Transmission Of Zika, Italy - 2014

#11,062

Now that better testing is available for Zika virus infection it is possible to go back and re-analyse older samples stored from previously undiagnosed patients that exhibited Zika-like symptoms.

Today, the Journal Eurosurveillance looks at just such an occurrence from 2014, where a man returned to Italy from Thailand, developed a fever and rash - and was hospitalized.

Based on suggestive but inconclusive lab results, clinical signs, and travel history - he was initially diagnosed with Dengue. Nineteen days after his return, his girl friend developed similar symptoms, despite not having left the country. 

Test results on her were inconclusive as well.  

Stored serum samples from both patients were re-analysed in 2016 using newly developed Plaque reduction neutralisation tests (PRNTs), and both showed positive results for ZIKV neutralising antibodies.

Eurosurveillance, Volume 21, Issue 8, 25 February 2016

Rapid communication

An autochthonous case of Zika due to possible sexual transmission, Florence, Italy, 2014

G Venturi ¹ , L Zammarchi ^{2 3} , C Fortuna ¹ , ME Remoli ¹ , E Benedetti ¹ , C Fiorentini ¹ , M Trotta ³ , C Rizzo ⁴ , A Mantella ² , G Rezza ¹ , A Bartoloni ^{2 3}

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Received:16 February 2016; Accepted:25 February 2016

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We report a case of Zika virus infection imported in Florence, Italy ex-Thailand, leading to a secondary autochthonous case, probably through sexual transmission. The two cases occurred in May 2014 but were retrospectively diagnosed in 2016 on the basis of serological tests (plaque reduction neutralisation) performed on stored serum samples. Our report provides further evidence that sexual transmission of Zika virus is possible. 

(SNIP)

Because patient 2 had not travelled to tropical areas during the previous year and had unprotected sexual intercourse with patient 1 during a 20 day period between his return to Italy and her own onset of symptoms, transmission by semen was suggested. Exact dates of sexual intercourse could not be recalled by the patients, who reported several sexual contact events before patient 2’s symptom onset. Other transmission modalities (i.e. direct contact with other bodily fluids) are unlikely to play a role but may not be completely ruled out.

Transmission through local potentially competent vectors, Ae. albopictus, can likely be excluded considering that patient 1 came back to Italy outside the usual period of vector activity and vector control measures were implemented within eight days after his arrival to Italy, possibly before the estimated extrinsic incubation period could be completed [1,24].          

(Continue . . .)

Although we don't know how common sexual transmission of Zika really is, in recent days we've seen reports that the CDC is investigating more than a dozen suspected cases in the United States (see CDC : Sexual Transmission Of Zika May Be More Common Than Previously Believed).


While mosquito transmission is undoubtedly the biggest threat, evidence now suggests that sexual transmission is more than just a theoretical concern, and so public health agencies are aggressively producing guidance on the subject, including:

WHO: Interim Guidance On Prevention of Potential Sexual Transmission Of Zika Virus

CDC Issues Updated Guidelines For Preventing Sexual Transmission Of Zika

UK PHE Warns On Potential Sexual Transmission Of Zika