Chapter 3 HIV Transmission Flashcards
How is HIV infection transmitted
Sexual intercourse
HIV infected blood that passes directly from an infected person to the body of another person.
From mother to baby during pregnancy, child birth or breastfeeding.
What is needed for a person to become infected with HIV
Virus must find way into person blood stream and must be able to embed itself.
Likely to occur is there are sufficient quantities of virus in the person in semen vaginal fluid etc.
Virus able to enter bloodstream
Virus is in bloodstream long enough to take hold.
What are the contributing factors influencing spread of HIV
Gender: more likely that women will be infected than men. Fact that semen stays in woman’s body for a period of time. Vagina has a large surface area of mucosa exposed to secretion during sex.
Age: younger people like those in their reproductive years are most vulnerable. These ones may engage in sex early due to low self esteem, pessimism peer pressure,sexual coercion and money.
What factors make woman vulnerable
Genital tract aren’t fully mature
They don’t have copious vaginal secretion
Vaginal mucosa lacerates easily.
After menopause the thinning and increasing dryness of the mucosal walls.
Tearing or bleeding of genital anal area.
List some other STIs
Genital ulcers are particularly vulnerable to HIV.
Sypilis
Chancroid
Herpes
Discharge
Gonorrhoea
Chlamydia
Trichomoniasis
What role does socioeconomic and cultural conditions play in the transmission of HIV
#High unemployment levels force people to move and leave families causing new sexual networks # tradition sometimes denies woman authority over their bodies #extreme poverty forces women to sell sexual services. #those in poor communities don't have access to health care. #lack of information and support services. #alcohol abuse. #
What factors play in the acquisition of HIV
Frequency of sex Multiple sex partners Condom use Immunological status Presence of other STIs Trauma during sex like bleeding
Define viral load
The amount of viral RNA detectable in the blood of an infected person. The quantitative PCR technique is used to count the HI virus particles or viral load in blood of HIV+ person.
When is an HIV+ person most infectious
HIV+ people are considered most infectious soon after becoming infected with virus during seroconversion and during final phase of aids when severe symptoms appear.
When is the greatest risk of HIV infections from blood transfusion
Occurs in the infectivity window period which is the period between a person being infected with HIV and a lab test detecting and confirming presence of antibodies or virus particles.
Give examples of HIV antibody test
First gen tests
Enzyme immune assays with 45 day window period.
PCR procedure
Nucleic acid testing with window period of 12days
How is HIV transmitted through needle sharing
When needles are shared drug users usually inject directly into their blood stream and draws up blood which remains the syringe and next user will then inject that blood into their body.
What quantity of infected blood need to be present for HIV transmission
The risk of HIV infection is directly proportional to the concentration of HIV in the blood.
The higher the concentration of HIV in blood the lower the quantity required to transmit the virus.
How long can HIV survive outside the body
As soon as HIV is no longer inside body fluid or when exposed to oxygen heat and dryness in atmosphere it dies. It can survive outside body for many hours if it remains in some or other body fluid.
HIV can survive and remain infectious up to 24hours in body fluid outside of body.
How does a mother infect her baby
Via the placenta during pregnancy
Through blood contamination during labour or
breastfeeding
How does breast feeding affect a baby with HIV+mother
It affects baby’s risk for HIV infection. Best time span to breastfeed is 6 months.
Best that mother’s on ARVs breastfeed until 6mnths mother should then continue with breastfeeding for another 6 months with complimentary foods. When baby 12 months old breastfeeding can be stopped.
What are the 3 main categories of HIV prevention
Behavioural interventions include efforts to change people’s behaviour to make sexual and drug using behaviour safer.
Condom use
One partner
Abstaince
Biomedical interventions involve development and use of biological or medical tools to prevent HIV infections HIV testing Circumcision ART PMTCT Microbicide Vaccine
Structural interventions focus on social political economic and physical environment of individual that can impact vulnerability to HIV.
Physical environment
Social political and economic structure
What is PEP and nPEP
PEP= post exposure prophylaxis is short term antiretroviral treatment taken after exposure to HIV
nPEP= non occupational post exposure where uninfected person receives ART after sex with HIV infected person.
What is a vaccine
Is a harmless substance that creates an immune response similar to infection which is used to build immunity or resistance to a later real infection.
In other words it teaches body to recognise and defend against future infection by bacteria and viruses that cause disease.
Which 2 processes does vaccines aim to copy
Humoral response
Is response where immune system produces antibodies that recognise specific pathogen in blood and neutralise it’s activity before it can infect body cells
Cellular response
Is response where white blood cells like CD4 T cells CD8 T cells are formed after pathogens have infected some body cells.
