People with a genital herpes simplex virus type 1 (HSV-1) infection, which usually causes cold sores, often shed the virus in the first few months after infection, increasing the risk that they can spread the virus to sexual partners during this time. .
But the rate of elimination declines during the first year, researchers at the University of Washington (UW) School of Medicine in Seattle have found.
In the past, HSV-1 was mainly associated with blisters and sores on the lips often called cold sores, or cold sores, and herpes simplex virus type 2 (HSV-2), a closely related virus , was primarily responsible for the genitals. herpes But this has changed in recent decades, and today HSV-1 is the leading cause of new genital herpes infections in many parts of the world.
In recent decades, fewer people have been infected with HSV-1 during childhood, making them susceptible to infection when they become sexually active.
Most genital herpes infections are acquired without symptoms. But when symptoms do occur, they can include often painful genital blisters and sores, fever, chills, fatigue, muscle aches and other flu-like symptoms. Infections can also cause emotional distress, as patients may feel the social stigma associated with the infection and worry about passing the virus on to their sexual partners and, if they give birth, to their newborn.
In the new study, Johnston and colleagues sought to better understand the course of genital HSV-1 infections and how the immune system responds. Although it is known that HSV-1 appears to cause less frequent genital symptoms than HSV-2, this was the first study to comprehensively examine oral and genital shedding of HSV-1 using the reaction test in highly sensitive polymerase chain reaction (PCR).
They enrolled 82 men and women who had been diagnosed with their first episode of genital HSV-1 infection. Fifty-four (66%) were women and 28 (34%) were men. Their ages ranged from 16 to 64, with an average age of 26. Antibody studies indicated that about half of the participants had been infected with HSV-1 before.
To detect shedding, participants swabbed their mouths and genitals daily for 30 days, at two and 11 months after their first episode of genital HSV-1. Swabs were tested for the presence of HSV-1. Blood samples were also collected at various times during the study to analyze the participants’ immune response to the infection. Enrollees took an antiviral medication to treat their initial episode, but agreed not to take virus-suppressing treatments during the periods when samples were collected.
The number of days participants cleared the virus varied. Some participants did not shed any virus, but shedding was relatively common at two months, with participants shedding HSV-1 on 12% of days. At 11 months, however, the rate had dropped to 7% of days. In most cases, the participants had no symptoms even though they were clearing the virus.
Participants who missed at least 10% of days at 11 months had another 30 swab days two years after their initial genital infection. In this group, the spillage rate had dropped even further, to 1.3% of days. Although the sample size was small, the rates are considerably lower than those seen with HSV-2, in which clearance occurs on about 34% of days in the first year and remains on 17 % of days at 10 years. Along with shedding, recurrences were infrequent, with an average of one recurrence during the first year of infection.
“I think patients can feel some reassurance that with genital HSV-1 infection, you’re likely to have less stool and have a lower risk of transmitting the virus than with HSV-2 infection,” Johnston said.
Analysis of the viruses sampled and the participant’s immune response to infection did not explain why clearance rates differed between participants. But the stool was more common among those for whom it was a newly acquired infection.
Patients who lack antibodies to HSV-1 and -2 when they are diagnosed with their first case of genital herpes should be warned to expect more frequent shedding, Johnston said, and may be candidates for a suppressive antiviral therapy during the first year of infection.
And while neonatal herpes is rare, it can be devastating, she added. The finding that stool is common in the first few months after infection underscores the importance of identifying pregnant people at high risk of acquiring HSV-1 so that preventive measures can be taken to avoid infection.
This work was supported by the National Institutes of Health (75N93019C00063, R01 AI132392, R21 AI130676, T32 GM 102057-5), the National Institute of Allergy and Infectious Diseases (P01 AI030731), and The Pennsylvania State University (P01 AI030731). .
The JAMA article is titled Viral shedding 1 year after first episode of HSV-1 infection.