What causes herpes, and how can you treat it? - Christine Johnston — Transcript

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1. 0:06In the 1st century CE,
2. 0:08Roman emperor Tiberius made an unprecedented decision:
3. 0:12banning kissing at all public events.
4. 0:16This move was aimed at thwarting a puzzling outbreak,
5. 0:20which many historians believe was an epidemic of oral herpes.
6. 0:26Fast forward to today,
7. 0:27and more than half the population is infected with herpes simplex virus,
8. 0:32though as many as 90% of those infected don't actually know they have it.
9. 0:39The term “herpesvirus” refers to a whole family of viruses.
10. 0:44But what we typically call the condition of herpes
11. 0:47is caused by two viruses in particular:
12. 0:50herpes simplex 1 and 2, or HSV-1 and HSV-2.
13. 0:57While similar, they tend to infect different parts of the body.
14. 1:02HSV-1 is typically associated with oral herpes,
15. 1:06which causes cold sores on the mouth.
16. 1:09Genital herpes can be caused by either virus,
17. 1:12though it’s more often caused by HSV-2.
18. 1:16Other body parts, such as fingers and eyes,
19. 1:19can also be infected by either virus.
20. 1:23Regardless of location or type,
21. 1:25HSV enters the body through microscopic breaks in the skin or mucous membranes,
22. 1:32like the mouth and genitals.
23. 1:35Once inside,
24. 1:37viral proteins hijack the cellular machinery to replicate and spread.
25. 1:43For many people, this initial infection won’t result in any symptoms.
26. 1:48But for others, the virus causes enough damage
27. 1:51that fluid-filled blisters develop and rupture,
28. 1:55causing painful lesions.
29. 1:57With more severe initial infections,
30. 2:00the virus can enter the bloodstream
31. 2:02and lead to fevers, muscle aches, and headaches.
32. 2:05This viral onslaught alerts the immune system,
33. 2:09which gets to work attempting to eliminate the HSV virus,
34. 2:13just as it would when faced with other common viral pathogens.
35. 2:17But what makes HSV particularly difficult to clear
36. 2:21is that some virus hides itself away,
37. 2:25evading detection by the immune system.
38. 2:28You see, in addition to penetrating skin and mucosal cells,
39. 2:32HSV also infiltrates nearby nerve cells in the skin.
40. 2:38They then travel along the stretch of axons
41. 2:41until they reach nerve clusters called ganglia.
42. 2:45HSV-1 thrives in the trigeminal ganglia, located in the skull,
43. 2:52and HSV-2 prefers the sacral ganglia near the base of the spinal cord.
44. 2:58Here, the virus goes dormant, turning off its replication machinery,
45. 3:02which helps it avoid attacks from the immune system.
46. 3:06It doesn't cause any damage or disease symptoms,
47. 3:09but it doesn't disappear either.
48. 3:11While living in the ganglia, the virus can reawaken periodically,
49. 3:16often triggered by sickness or stress,
50. 3:19though the cause isn’t always clear.
51. 3:22No matter the reason, the virus travels back down along the nerve,
52. 3:27which may cause itching or tingling, often the first symptom of recurrence.
53. 3:33Once back at the surface, the virus begins to replicate,
54. 3:36potentially causing a new bout of symptoms.
55. 3:39The frequency of these recurrences can vary and happen as often as monthly,
56. 3:45or as infrequently as every few years.
57. 3:49And when the infection is active and shedding from the skin or mucosa,
58. 3:53it's possible to spread to others via direct contact.
59. 3:58Yet since most infections are asymptomatic or only cause mild flare-ups,
60. 4:03many people don’t know they have HSV.
61. 4:07And herpes is surprisingly difficult to diagnose.
62. 4:11Blood tests aren’t normally recommended as they’re often inaccurate
63. 4:15and can’t reliably distinguish between a genital or oral HSV-1 infection.
64. 4:22If you do have symptoms,
65. 4:23the best way to get a clear diagnosis is to see a health care provider
66. 4:28when a lesion is present.
67. 4:31Aside from the pain caused by sores during a flare-up,
68. 4:34for most people, herpes doesn’t lead to serious health problems.
69. 4:38And there are treatments to improve symptoms:
70. 4:41antiviral medications work by mimicking a component of viral DNA
71. 4:46and inhibiting viral replication.
72. 4:49These medications can also reduce the risk of transmission,
73. 4:53in the case of HSV-2, by about 50%.
74. 4:57Over time, symptoms and shedding usually decline
75. 5:00as the body produces immunity against the virus.
76. 5:04Though, there is always some risk of flare-ups and transmission.
77. 5:09That’s why for decades,
78. 5:11scientists have searched for treatments that can prevent or cure herpes.
79. 5:16But the virus's unique ability to establish silent infections
80. 5:20and evade the immune system has made progress difficult.
81. 5:24Still, there’s hope.
82. 5:26Breakthroughs in emerging technologies like gene editing and novel vaccines
83. 5:31show promise in the fight against this stealthy virus.