Human Papillomavirus Presentation PDF

HUMAN PAPILLOMAVIRUS A Presentation By Dr R.Venkatajothi, MSc., MPhil, PhD, FIAAM, FAVRS Lecturer, Department of Microbiology MCS School of Medicine The Copperbelt University Date: 20-11-2024 ...

HUMAN PAPILLOMAVIRUS A Presentation By Dr R.Venkatajothi, MSc., MPhil, PhD, FIAAM, FAVRS Lecturer, Department of Microbiology MCS School of Medicine The Copperbelt University Date: 20-11-2024  OBJECTIVES The objectives of this lecture are to  Discuss the morphology, classification, pathogenesis, clinical features, symptoms, risk factors, laboratory diagnosis, treatment and screening of the human papillomavirus.  INTRODUCTION  Human papillomaviruses (HPVs) belong to the Papillomaviridae family.  HPV is a common, sexually transmitted infection in humans worldwide. Almost 75% of all sexually active adults are likely to be infected with at least one HPV type.  HPV induces mostly benign papillomas. Some of the viruses are known to be oncogenic and others are non-oncogenic.  Nearly all cases of cervical cancer are caused by human papillomaviruses.  Cancer  Cancer is a severe health problem that continues to be a leading cause of death worldwide.  As per the WHO report, cancer is the second leading cause of death globally, accounting for an estimated 9.6 million deaths in 2018.  WHO estimates 12 million cancer deaths worldwide in 2030.  Many cancers can be cured if detected at an early stage and treated effectively.  Cervical cancer  Cervical cancer is the fourth most common cancer among women globally. Cervical cancer develops in a woman's cervix.  It’s the most successfully curable form of cancer when diagnosed in the early stages.  Cervical cancer affects all age groups of women, but the high risk age group is 25-49.  Cervical cancer was confirmed on the basis of a pap smear test and an HPV-DNA test. Continued…… Cervical cancer  Morphology of HPV  HPVs are double stranded DNA with a 52-60 nm diameter and are small, non-enveloped viruses. Structure of Human papillomavirus  Classification of HPV  There are over 100 types of HPV viruses; among them, about 30-40 types are sexually transmitted and are called “high-risk” viruses (genotypes 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73 and 82) that could lead to cervical cancer in women.  The remaining “low-risk” viruses could lead to other kinds of sexually transmitted diseases called genital warts in both men and women.  HPV types 16 and 18, which account for about 70% of cervical cancer in women.  Pathogenesis  Almost 75% of all sexually active adults are likely to be infected with at least one HPV type.  Cancer that develops in the ectocervix is called squamous cell carcinoma and around 80-90% of cervical cancer cases are of this type.  According to the Bethesda system (TBS) of classification, cervical cytology categorizes and organizes HPV associated lesions into low-grade squamous intraepithelial lesions (LSIL), high-grade squamous intraepithelial lesions (HSIL) and invasive cancer.  Atypical Squamous Cells of Undetermined Significance (ASCUS)  A Pap smear looks for abnormal cells; these abnormalities are due to either reactive change or a treatable, premalignant condition known as dysplasia.  Rarely, abnormal cells are encountered in screenings that are not easily classified as either reactive or premalignant, and their significance is therefore uncertain.  These cells are not of typical appearance and are called atypical squamous cells of undetermined significance (ASCUS).  Clinical features  Persistent infection with high-risk HPV types may lead to precursor lesions of the cervix, referred to as cervical intraepithelial neoplasia (CIN).  CIN is graded as CIN1 (mild), CIN2 (moderate), or CIN3 (severe) depending on the proportion of the thickness of the epithelium showing mature cells.  LSIL corresponds to the histologic diagnoses in CIN 1, whereas HSIL corresponds to CIN 2 and CIN 3. The Natural History of Preclinical abnormalities of the cervix Continued……  Symptoms  Symptoms generally do not appear until abnormal cervical cells become cancerous and invade nearby tissue.  The most common symptoms are abundant foul- smelling vaginal discharge, abnormal vaginal bleeding, back pain, pelvic pain and loss of appetite.  Some types of cervical cancer may not show any symptoms.  Risk factors  Cervical cancer is associated with many risk factors, including unprotected sexual intercourse, having multiple sexual partners or having sex with someone who has multiple sexual partners, being HIV positive, other STD coinfections, a family history of cervical cancer, smoking and poverty etc.  HIV/AIDS-positive women have shown a strong association with Human Papillomaviruses.  Prevalence of Cervical cancer in Zambia  Cervical cancer ranks as the first most frequent cancer among women in Zambia.  Zambia has the third-highest cervical cancer cases globally, with 65.5 cases per 100,000 women and 43.4 deaths per 100 000 women recorded. The peak age at diagnosis is between 40-49 years.  As per the WHO report, in 2018, Zambia began integrating cervical cancer screening into HIV treatment.  Laboratory diagnosis  HPV cannot be cultured in cell cultures.  Pap test: The pap smear test is widely used for the screening of cervical cancer in women.  It is a simple, cheap and reliable test. It can detect abnormal, pre-cancerous and cancerous cells in the cervix.  HPV-DNA Test: A laboratory test in which cells are scraped from the cervix to look for human papillomavirus DNA.  Continued……  For the general population of women, HPV-DNA detection is recommended as the primary screening method, starting at the age of 30 and with regular testing every 5-10 years.  For women living with HIV, WHO recommends HPV- DNA detection starting at the age of 25 years, with regular screening every 3-5 years.  Continued……  Other diagnostic methods:  Visual inspection with acetic acid  Visual inspection with Lugol's iodine (VILI)  Colonoscopy  Biopsy  Complete blood count (CBC).  Treatment and Screening  Treatment varies based on the stage of the cancer.  The stage of a cervical cancer refers to how much it has grown and whether the cancer has spread from its original location.  The standard treatments are surgery, radiation and chemotherapy. Side effects of chemotherapy and radiation treatment usually occur.  Vaccines have been developed to prevent certain HPV infections.  Continued……  Gardasil, Gardasil 9 and Cervarix: All three HPV vaccines protect against HPV types 16 and 18, which cause most HPV cancers.  Age group: HPV vaccination is recommended for ages 9-14.  Cervarix prevents infection with types 16 and 18, and Gardasil prevents infection with types 6, 11, 16, and 18.  However, these vaccines do not treat HPV infections and are recommended for those who have not been exposed to HPV infections.  Continued……  Cervical cancer can be prevented through screening programs, early detection and treatment for precancerous lesions.  The screening programs that should be conducted at regular intervals could effectively reduce both the mortality rate and the incidence rate of cervical cancer.  Effective screening involves the application of relatively simple, reliable and inexpensive tests to screen a large number of asymptomatic women.  Three vital approaches to saving lives from cervical cancer Education Secondary Primary Prevention: Prevention: Screening & Vaccination Treatment  LEARNING OUTCOMES At the end of the lecture, students should be able to:  Discuss the morphology, classification, pathogenesis, clinical features, symptoms, risk factors, laboratory diagnosis, treatment and screening of the human papillomavirus.  REFERENCE BOOKS  David Greenwood et al (2007), Medical Microbiology (7th edition). Churchill Livingstone Elsevier.  J. C. Pommerville (2004), Alcamo’s Fundamentals of Microbiology (7th Edition). Jones and Bartlett Publishers.  Mims et al, (2008) Medical Microbiology (4th Edition). Mosby Elsevier.  Patrick. R. Murray (2009), Medical Microbiology (6th Edition), Mosby Elsevier.