What is the difference between Human Papillomavirus (HPV) type 1 and Human Papillomavirus (HPV) type 2?

Differences Between HPV Type 1 and HPV Type 2

HPV type 1 and HPV type 2 are distinct low-risk HPV types that primarily cause benign skin lesions (common warts), while the high-risk types like HPV 16 and 18 are responsible for most HPV-related cancers.

Key Differences

Clinical Manifestations

• HPV type 1: Primarily causes common warts (verruca vulgaris) on the hands and feet, particularly plantar warts on the soles of feet
• HPV type 2: Typically causes common warts on the hands and fingers

Oncogenic Potential

• Both HPV 1 and HPV 2 are considered low-risk types that rarely cause cancer
• Unlike high-risk types (HPV 16,18,31,33, etc.) which are associated with cervical, anal, vulvar, vaginal, penile, and oropharyngeal cancers 1

Transmission

• Both are transmitted through direct skin-to-skin contact
• Unlike genital HPV types which are primarily sexually transmitted 2

HPV Classification Context

Low-Risk vs High-Risk Types

• Low-risk types (including HPV 1 and 2):

  • Cause benign lesions like common warts
  • Rarely associated with malignancy
  • HPV 6 and 11 are other low-risk types that cause genital warts 2

• High-risk types (HPV 16,18, etc.):

  • Cause approximately 99% of cervical cancers 1
  • HPV 16 accounts for 50-60% of invasive squamous cell carcinomas
  • HPV 18 accounts for an additional 10-15% of cervical cancers 1
  • Associated with other anogenital and oropharyngeal cancers 2

Clinical Relevance

Disease Burden

• HPV 1 and 2 cause common cutaneous warts that are generally benign and self-limiting
• These differ significantly from the high-risk HPV types that cause approximately 70% of cervical cancers (types 16 and 18) 2
• HPV-related cancers represent approximately 4% of all cancers worldwide 3

Prevention and Management

• Common warts caused by HPV 1 and 2 can be treated with:

  • Cryotherapy with liquid nitrogen
  • Topical treatments like salicylic acid
  • Surgical removal in persistent cases 2

• For high-risk HPV types, prevention strategies include:

  • HPV vaccination (targeting HPV types 16,18 and others depending on vaccine) 2
  • Regular cervical cancer screening 1

Common Pitfalls and Misconceptions

1. Confusing with genital HPV types: HPV 1 and 2 are not the same as the genital HPV types that cause cervical cancer or genital warts

2. Vaccination misconception: Current HPV vaccines (Gardasil, Cervarix) target high-risk types like HPV 16 and 18, not HPV 1 or 2 2

3. Testing confusion: Standard HPV tests used in cervical cancer screening detect high-risk HPV types, not HPV 1 or 2 2

4. Treatment approach: Treatment for common warts (HPV 1 and 2) differs from management of genital HPV infections or cervical abnormalities

Summary

HPV types 1 and 2 are non-oncogenic types that cause common cutaneous warts, primarily affecting the hands and feet. They are transmitted through direct skin contact and are not associated with genital infections or cancer development, unlike the high-risk HPV types 16 and 18 that are responsible for most HPV-related cancers.