Epidemiology, pathogenesis, diagnosis and dental relevance HIV Flashcards
what infection occurred in individuals before HIV was known?
Pneumocystis pneumonia
Oct 1980-June 1981, LA
what individuals did Pneumocystis pneumonia infect?
young, active homosexual men
all had previous or current CMV and oral mucosal candidosis
what rare cancer was seen in 41 homosexuals?
Kaposi’s sarcoma
what was associated with Kaposi’s sarcoma and Pneumocystis pneumonia?
massive decrease in T cells
what are T cells important in?
immune system protection for infections and cancers
what are the 2 main groups of T cells
Killer
Helper
what do killer T cells do
circulate the body, scan for abnormal cells and destroy
what do helper T cells do
messengers, imitate activity other immune cell and generate antibodies
Kaposi’s sarcoma
Previously rare - associated with elderly (immunocompromised) and generally non-aggressive
The most frequent opportunistic tumour observed in 20% of patients with AIDS (mostly homosexuals).
Now associated with a human herpes virus
what was the first mode of transmission of the virus identified?
sexual transmission
what other groups were affected by the virus?
groups typically associated with immunosuppression
- women (associated with injecting drug use or sexual contact with men who had AIDS)
- Haitians residing in the US (all young and denied homosexual activity)
- Heterosexual men with haemophilia – all received factor VIII
groups of people affected spread beyond MSM
when was the name AIDS acquired and what does it stand for?
1982
Acquired Immunodeficiency Syndrome
what is the causative agent of AIDS
Human Immunodeficiency virus (1984)
what is AIDS
is a syndrome or range of symptoms, that may develop in time in a person with HIV
when was the first test for HIV-1 approved?
1985 in America
what was the first HIV-1 test like
Very sensitive but high false positive rate (low specificity)
- Give a wrong diagnosis to someone and no way of confirming either way
what was the first HIV-1 test used for
- routine diagnosis
- screening blood donations
Screening tests were augmented with confirmatory tests allowing expansion of testing to wider populations for diagnostic purposes
when was testing and ‘clear’ status of US blood banks
April 1985, clear by July
6-month period before blood testing in UK
- Unclear why
(Logistics? One company licensed to produce test – not sufficient capacity to assess all countries)
what is the confirmatory test for HIV
ELISA positive results all checked again – disregard false positives so give correct diagnosis
what was a process that helped build a stigma around HIV
Pre-test counselling:
- knew what test was for and consequences of those tests
mistakes by the UK surrounding HIV/AIDS stigma
late action
Iceberg advert (shock and shame) – shock people into changing their behaviour
- Hindsight wrong thing to do. Made a lasting stigma
- Now Hope for adverts
- National HIV Testing Week starts Saturday 16 November
- There is no shame in knowing your status
what is the new style of HIV care
Test and Treat approach
- Due to very good drugs, prevent them from suffering from opportunistic infections
Know most infections come from an unaware host – reduce their infectivity by testing and treating – reduce spread
More positive view
how is HIV transmitted (5)
- Unprotected sex
- Drug addicts
- Blood transfusion
- Pregnancy
- Non-sterile instruments
how is HIV not transmitted (5)
- Touching
- Through food
- Kissing
- Insect bites
- In the pool
what is HIV PrEP
Anticipatory treatment
- Available on NHS in Scotland since July 2017 for HIV negative individuals who are at risk (consistent high risk sexual encounters)
Take daily, build up protective levels in build steam, HIV cannot take hold when exposed
where did HIV come from
Xenosis – derived from animals, jump to humans (e.g. avian flu)
- From chimp, via ingestion and/or blood exposure
1970s move from Congo to Haiti, then America, then Global
1980s peak
what is the global impact of HIV/AIDS
37.9 million people living with HIV globally, 21% don’t know their status
what is happening to the number of new HIV diagnoses
decreasing in most part
- 8 million people newly infected in 2017 globally
- 26% decrease in number of new infections across the global population since 2010
New infections still increasing for some places
Battle not won concern
- Women more new infections than males now (social context – vulnerable to sexual violence)
what is happening in relation to number dying compared to number living with HIV infection
Less dying of infection but more living with infection
- As the number of people receiving treatment in increasing
HIV WHO targets for 2020
90% aware of infectious state
90% on HIV treatment
90% have undetectable viral levels
how is Scotland doing in HIV levels
300-250 new transmissions a year
- 91% aware of status,
- 87% (less) on treatment (not all getting specialist care – 96%),
- nearly 100% (97%) virally supressed
(low enough level in blood very unlikely to pass on infection)
Deaths in Scotland
- 40-50 per year
how many main viruses are there of HIV
2
what type of virus is HIV
small retrovirus
structure of HIV
Main structural (core) protein p24 encases - P9 and P7 - Single stranded RNA - Reverse transcriptase Then there’s matrix protein p17
With a lipid membrane envelope (host-derived) with host proteins and envelope glycoproteins (gp41, gp120)
- Since lipid virus hard to survive out with host
2 glycoporteins: important in replication, facilitate entry into body’s CD4 cell
Once in release Viral RNA, enzymes of virus convert into DNA and then inserted into body’s DNA
what are the glycoporteins role in HIV virus
important in replication, facilitate entry into body’s CD4 cell
how does being a lipid virus impact on how HIV can live
hard to survive out with hosts
how does HIV replicate in host
Body replicating CD4 cells replicate virus
- Small infection causes billions of infected virus cells in small time span
what type of HIV causes pandemics
HIV 1 causes pandemic
- Multiple strains
3 groups: major, new and other
- New and other in West Africa
- Main seen distributed globally
how many groups of HIV 1 are there
3 groups: major, new and other
- New and other in West Africa
- Main seen distributed globally
5 key stages in HIV life cycle
- HIV releases genetic material into CD4 cell
- Reverse transcriptase copies RNA – DNA
- Viral DNA inserted in cell DNA
- Many copies of the viral RNA and proteins made
- New viral particles assemble and bud from cell
Small minority of T4 cells are infected
virus half life of HIV
5.7 hours
how many HIV virons per ml of blood
100 - 10 million
course of HIV disease
Start of infection: huge number of virus circulating in body
- Asymptomatic period (if do flu like)
- Non-specific, unaware
Then between 2-15 years (variable) extended period, virus multiplies in body and body can no longer keep on top of it CD4 drops and virus in circulation increases
- No therapy = death
AIDS definition
the presence of one of 25 conditions indicative of severe immunosuppression or HIV infection in an individual with a CD4+ cell count of <200 cells per cubic mm of blood
therefore, is end point of long-established infection (continuous, progressive or pathogenic)
clinical features of AIDS
Lymphadenopathy and fever
- Insidious onset
- May be accompanied by weight loss and malaise
Opportunistic Infections
- Pneumocystis carinii pneumonia
- Cerebral toxoplasmosis
- Cryptococcal meningitis
- Candidosis
- Herpes virus infections
- Diarrhoeal disease
Malignancies
- Kaposi’s Sarcoma
- Non-Hodgkins lymphoma
Wasting
- Common in Africa
AIDS-related dementia
- Disease in cognitive and/or motor function
4 alternative tests for HIV/AIDS
Rapid tests
Oral fluid tests
Dried blood spot (DBS)
- easy to obtain – good for research
At home kits (2014) - sampling and testing
- All positive results must be confirmed
Big change from 80s with pre-test counselling
improved diagnosing of HIV infection
Antibody tests:
- sensitive but only pick up 6-12 weeks post infection (many misses
2nd generation assays, 3rd – closer
Viral antigen detection better than antibodies (2 weeks and detects virus)
PCR (1-2 weeks)
dental relevance of HIV
HIV infected individuals have poorer oral health and greater dental care needs than the general population
BUT Experience high levels of HIV-related stigma and discrimination when attending dental services
- double-gloving, end of day appointments etc
Standard Infection Control Procedures mean no risk
Need HIV positive to come into practice – oral lesions they have can cause pain and affect mental health
3 groups of oral lesions related to HIV
Group 1
- Key
- Lesions strongly associated with HIV infection
- Candidosis, Hairy Leukoplakia, Kaposi’s sarcoma, Non-Hodgkin’s lymphoma, Periodontal disease
Group 2
- Lesions less commonly associated with HIV infection
Group 3
- Lesions seen in HIV infection
HIV screening in dental setting
Key prevention strategy is to improve the availability and access to HIV screening
Early diagnosis improves health outcomes and provides opportunities to prevent further transmission events
Several key HIV indicator that are encountered by the dental professional
Rapid point of care HIV tests could be used to offer chairside HIV screening to patient during dental appointments
Individuals advised recommended to get diagnosis if present dental
infection control in the dental setting
Both patients and dental professionals can be exposed to pathogens
Contact with blood, oral and respiratory secretions and contaminated equipment occurs
Proper procedures can prevent transmission of infections to patients and dental professionals
(Follow controls = no risk
All are exposed to pathogens)
what is a famous case that causes fear in the general public in failure of infection control procedures
the Florida Dentist
- First incident of clinical transmission of HIV
- Investigation strongly suggests that five patients (patients A, B, C, E, and G) became infected with HIV while receiving care from a dentist with AIDS
- Numerous patient notifications exercises associated with the dental setting – no further cases of transmission since
what is regularly monitored in health care workers?
viral load
what is the duty of candor legislation
requires health care professionals to notify patients if they have been put at risk of infection
what is important to remember about needletstick injuries
they are common
hard to acquire infection (prevalence and risk of transmission in population)
risk is further reduced by
- source on cART with undetectable viral load
- follow up and management with PEP
Risk of transmission reduced when undetectable viral load – means HIV untransmissible
how is risk of infection by needle stick injury further reduced
- source on cART with undetectable viral load
- follow up and management with PEP
Risk of transmission reduced when undetectable viral load – means HIV untransmissible
dental professionals should
- possess adequate knowledge about HIV infection and the significance of oral lesions associated with HIV which may help identify those who would benefit from HIV testing
- provide HIV patients with oral healthcare of the highest standards. A focus on routine and preventative care will maintain and improve the quality of life for patients with HIV
- Infection control measures should be strictly followed
- Dental professionals have a legislative duty to report all sharps injuries and seek appropriate follow up and management as per local policies.
