Scientists detect replication-competent Oroporchi virus in travelers' semen, raising concerns about infection

New findings reveal the presence of replication-competent Oroporchi virus in semen, raising new questions about sexually transmitted disease risk and public health safety.

Research letter: Replicating Oropuche virus found in the semen of travelers returning from Cuba to Italy (2024). Image credit: CI Photos / Shutterstock

In a recent study published in the journal emerging infectious diseasesResearchers at the University of Brescia in Brescia, Italy, have discovered that the replicative Oropouchi virus (OROV), an arbovirus that causes influenza-like illness, can be found in the semen of travelers diagnosed with Oropouchi fever, which is transmitted by midges and mosquitoes. We investigated the existence of infectious diseases. , highlighting the potential risk of sexual transmission.

background

OROV is an emerging zoonotic arbovirus from the Simbu serogroup of the family Peribunyaviridae, genus Orthobunyavirus. Its natural hosts include nonhuman primates, some wild birds, and the blue-throated sloth. OROV is primarily transmitted by biting midges such as: Culicoides paraensis and pentagonal mosquito mosquito. Symptomatic Oropoch fever is a flu-like illness that can be self-limiting meningitis or meningoencephalitis (inflammation of the brain and its protective membranes). Although endemic in the Amazon region, as of September 2024, more than 9,852 confirmed cases of Oropouche have been reported in Brazil, Bolivia, Peru, Colombia, Cuba, and the Dominican Republic. Further research is needed to understand the impact of Oropouche, especially with regard to vertical transmission. and adverse pregnancy outcomes.

About research

In August 2024, a 42-year-old man from Italy was tested for acute febrile illness after returning from Cuba, where he had traveled from July 19th to 29th. He was symptomatic, experiencing a high fever, headache, and general malaise just before returning home. Recurrence occurred 4 days after onset. Clinical evaluation showed no meningeal irritation, rash, or lymphadenopathy (swollen lymph nodes).

Laboratory tests, including blood cultures and real-time reverse transcription-polymerase chain reaction (RT-PCR) specific for other arboviruses, yielded negative results. However, Oropoch fever was confirmed by two OROV-specific RT-PCRs, with positive results in serum, whole blood, and urine collected 4 days after onset. Blood and urine samples showed prolonged shedding of viral ribonucleic acid (RNA), whereas fresh semen samples revealed high OROV RNA levels. In particular, infectious OROVs were cultured from semen under biosafety level 3 conditions and their replication capacity was confirmed.

Research results

Examination of a 42-year-old man revealed significant clinical findings associated with OROV infection. On August 2, 2024, he was admitted to the Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Sacro Cuore Don Calabria Hospital with an acute febrile illness that began shortly after his return from Cuba. Initially, the patient complained of a high fever of 39.0°C, headache, and general malaise. The fever subsided after 2 days but recurred 4 days after onset, but neurological examination was unremarkable.

Laboratory tests showed that the white blood cell count was within normal limits and there were no signs of thrombocytopenia (low number of platelets in the blood). Blood cultures yielded negative results, and specific RT-PCR assays for dengue, chikungunya, and Zika viruses were also negative. However, Oroporchi fever was diagnosed by two OROV-specific RT-PCRs targeting small segments of the genome, confirming the presence of the virus in whole blood, serum, and urine samples taken on day 4 of onset. It was done. The patient showed clinical improvement and symptoms disappeared by day 10.

RT-PCR results on days 10, 16, and 32 after symptom onset showed persistent OROV RNA in whole blood and urine. Serum samples were positive for OROV RNA on day 10 but negative on day 16. viral load. Remarkably, fresh unfractionated semen samples collected on days 16, 32, and 58 had consistently higher viral RNA levels than those found in urine or whole blood. I showed it. Cycle threshold (Ct) values ​​for semen samples were 25.4 on day 16, 28.9 on day 32, and 34.1 on day 58, indicating ongoing progress. Virus shedding.

On day 16, infectious OROV was isolated from semen samples using cell culture techniques under biosafety level 3 conditions. This separation was confirmed by the observation of obvious cytopathic effects (CPE) and a significant increase in OROV RNA levels in the spent cell growth medium after 5 days. Although viral RNA shedding remained high in semen compared to urine and whole blood at day 32, its ability to replicate had ceased by this point.

conclusion

In summary, this study highlights the detection of replication-competent virus in patients returning to Italy from Cuba and the prolonged release of OROV RNA in multiple body fluids, especially semen. These findings raise serious concerns regarding the potential for sexual transmission of OROV. However, the study authors cautioned that the clinical relevance of these findings remains uncertain, as replication-competent virus can only be detected early in infection and more data are needed. The public health implications are particularly noteworthy in the context of sperm banks and assisted reproductive technologies. Further long-term studies are needed to establish how frequently infectious OROV is shed in semen and its potential risk in sexually transmitted infections.