Blood borne Infections Flashcards
Define HIV: what is it? What are the main species?
HIV: Human Immunodeficiency Virus - Type of retrovirus which causes HIV infection and overtime AIDS if left untreated. -> No cure but can be controlled through treatment.
2 Distinct Species of HIV:
HIV1 & HIV2
Tell me about the epidemiology of HIV (Worldwide & UK)
33 Million people world wide affected by HIV
In 2014 an estimated 103,700 people with HIV in the UK.
Name some ways in which HIV can be transmitted.
- Exposure to certain bodily fluids (blood, pre-seminal fluid, rectal fluid, vaginal fluid, breast milk)
1. Sexually - Anal sex is the highest risk behaviour followed by vaginal sex. Oral sex RARELY leads to HIV transmission (lol)
- Vertical transmission: Mother to child - can occur during intrauterine life, delivery or breast feeding.
In untreated women - rate of transmission is 30% which can be reduced to <1% with intervention. - Injecting drug users: HIV can live on a used needle for up to 42 days. Sharing needles = high risk behaviour.
- Transfusion of blood products & organs i.e tissue transplants. (Rare in UK due to testing and other regulations)
Pathophysiology of HIV
- In HIV there is a loss of CD4+ T-cells and impaired cell immunity.
Clinically HIV infection undergoes 3 phases.
- Acute seroconversion.
- usually within a few weeks of initial infection and marks the period of time during which HIV antibodies develop and become detectable.
- People are extremely infectious at this stage. (Occurs in 50% of people) - Asymptomatic HIV infection
- Can last a few years to decades.
- May be asymptomatic or have a few symptoms
- If left untreated –> steady decline in CD4+ T-cells - AIDS - Final stage
- Does not occur in all patients with HIV
To be diagnosed with AIDs there be either opportunistic infections or CD4+ T-cell count is <200 cells/mm^3
There are a number of AIDS defining conditions which include:
- Kaposi Sarcoma
- Candidiasis of bronchi/trachea/lungs etc.
What is the normal range of CD4+ T-cell levels?
500-1500 cells/mm^3
Which factors need to be addressed in clinical assessment (history)? (HIV)
- risk assessment
- evidence of past seroconversion
- system enquiry
- sexual health
- PMHx
- FHx
- Sexual Hx
- Any partners or children
- Transmission risk in current job
- Use of drugs (i.e needle sharing)
How do you diagnose HIV?
Blood culture - ELISA or PCR.
Treatment of HIV?
HAART, NRTI, NNRTI, Protease inhibitors, Integrease inhibitors
Prevention of HIV?
good sexual practice, treatment of pregnant mothers, PPE.
What is the clinical presentation of HIV?
- Related to degree of immunosuppression
- Measured by monitoring Cd4+ count
- Disease progressive related to viral load. Increased viral load = faster disease progression.
–> Seroconversion phase often flu-like symptoms:
Indicator conditions
Resp: TB, HIV-associated pneumonia, histoplasmosis
Dermatalogical: Kaposi sarcoma
Opthal: CMV retinitis
Who to test for HIV?
National guidelines: All adults registering in GP practices in areas where prevalence is greater than 2 per 1,000 population.
Leading cause of death for HIV patients?
Tuberculosis
How many types of Hepatitis are there?
5 Types: A B C D E
Which types of hepatitis transferred by faecal oral route
A and E
Which types of Hepatitis can be transferred by blood or sex?
B, C and D
Which types of Hepatitis can be transferred vertically?
B and D
What is Hepatitis A?
Symptoms:
- Jaundice
- Abdominal pain & distension
- Dark urine
- Light coloured stool
- Vomiting
- Fatigue
Caused by Hepatitis A Virus (HAV)
Pathogenesis:
Spreads via person to person contact or by food/water contaminated by faeces from an infected person.
Travel in GI tract and invades mucosal epithelia and replicates and spreads. Reaches liver and infects hepatocytes –> stimulates immune response & hepatocytes are killed.
Diagnosed by: IgM detection.
Treatment: Supportive Care
Prevention:
Two vaccines available.
Two dose vaccine - recommended for those travelling to high risk areas & IV drug users.
Immunoglobulin can provide short-term immunity.
Basic hygiene can reduce incidence
What is hepatitis B?
Can be acute or chronic. Acute < 6 months, chronic >6 months.
Symptoms:
- Jaundice
- Dark urine
- Fever
- Joint pain
- Loss of appetite
- Nausea & vomiting
- Weakness and fatigue
Caused by: Hepatits B Virus (HBV) - has a DNA genome that is replicated via an RNA intermediate
Pathogenesis:
Virus is spread via contact with bodily fluids. Virus enters bloodstream & targets hepatocytes of the liver. The host immune response causes both hepatocellular damage and viral clearance. Acute infection <6 months
Chronic infection lasts >6 months. it lingers because your immune system can’t fight off the infection.
Diagnosed by: Serology.
Also see Ground Glass hepatocytes in chronic Hep B liver biopsy.
Treatment: Acute may require no treatment.
Anti-HBV immunoglobulin is effective soon after exposure or neonatally to children of HBsAg-positive mothers.
Chronic: - Antivirals - Interferon injections - Liver transplant - Three FDA approved drugs I. interferon alpha 2b II. Hepsera III. Lamivudine
Complications:
Hep D infection; liver cirrhosis; liver failure; cancer.
Prevent: Vaccine - given over 6 month period and offers protection to 95% of individuals - SUBUNIT.
What is Hepatitis C?
Symptoms:
Typically asymptomatic and live normal lives.
Symptoms may be mild and flu like: nausea, fatigue, loss of appetite etc
Most people do not have jaundice - although can sometimes occur along with dark urine.
Caused by: Hepatitis C Virus (HCV) - envelope RNA virus that lacks proof reading ability as it replicates – results in many genetic strains within the same patient
–> Major problem in developing an adaptive immune response and hence vaccine.
6 distinct genomes. Genotype 1 is most common.
Pathogenesis:
Spread primarily through contact with infected blood. (Less commonly via sexual contact, snorting drugs and childbirth).
The virus replicates in the hepatocytes of the liver. The host immune response causes both hepatocellular damage and reduces viral load. Many patients infected can develop cirrhosis - some may also develop hepatocellular carcinoma.
Acute - Short term illness occurs within first 6 months after exposure. For most people acute leads to Chronic
Chronic - Long term illness occurs when HCV remains. Can last a life time and lead to serious liver problems.
Diagnosed by: Serology
Treatment: Anti-viral medications, Liver transplant, vaccine against HAV and HBV.
Prevent:
No vaccine. Prevention only through reduction of risk of exposure
Those affected should not drink alcohol –> accelerates liver damage.
What is HBsAg?
Hepatitis B surface antigen
- A protein on the surface of Hep B V it can be detected in high levels in serum during chronic or acute Hep B infection
- Presence indicates person is infectious
HBsAg - is antigen used when making Hep B vaccine.
What is Anti-HBs (HBsAb)
Hep B surface antibody
- Generally interpreted as conferring immunity or recovery.
Develops in patients successfully vaccinated.
What is Anti-HBc (HBcAb)?
Total hep B core antibody
- Appears at onset of symptoms in acute hep b infection and persists for life.
- Presence indicates previous or on-going HBV infection in un-defined timeframe
What is IgM Anti-HBc (IgM HBcAb)?
IgM antibody to Hep B core antigen
- positivity indicates recent HBV infection
- Presence indicates ACUTE infection (<6months)
What is HBeAg?
Hep B e Antigen
- Usually expressed when Hep B is replicating at high level
- Occurs in acute level of infection & disappears when Antibodies are produced against it.
- Indicates high level of infectivity.
What is Anti-HBe (HBeAb)?
Hep B e Antibody
- Usually indicates HBV replication is lowered. (Not always the case however)
What is Infective Endocarditis?
Symptoms:
- Fever
- Chills
- Night sweats
- Headaches
- SOB
- Cough
- Heart Murmurs
- Fatigue
- Muscle & joint pain
Caused by: Multiple usually streptococci or staphylococci
Pathogenesis:
Bacteria in bloodstream multiply and spread across endocardium –> which becomes inflamed causing damage to heart valves.
If heart valves damage –> bacteria can take root and bypass normal immune response to infection.
small clumps of bacteria can develop at site of infection –> risk these clumps break off and block blood supply to organs –> organ failure or stroke.
Diagnosed by: ESR and CRP - test for inflammation
- ECG
Treatment: Antibiotics or surgery to fix valves.
Prevention:
Good dental hygiene
