IPC - Module 4 Flashcards
Examples of Diseases that can be transmitted via blood
1) Hepatitis B (HBV)
2) Hepatitis C (HCV)
3) HIV
If you are not wearing gloves, the approximate risk of infection following a poke (needle stick) with a needle contaminated with blood from an infectious patient is:
HIV – 0.3%
HCV – 3.0%
HBV – up to 30.0% for non-immune health care worker
If you are wearing gloves, your risk in reduced by 50% (i.e. It would be for HIV 0.15%, HCV 1.5%, HBV 15.0%)
Antigen =
Antigen = virus = bad news (infectious)
Antibody =
Antibody = immunity = good news
Exception: For HIV, the presence of antibody does not mean “good news”, as although antibodies are developed, the virus will not be destroyed because it is hiding inside cells of the cellular immune system. Ultimately, the cells will be destroyed, the immune system compromised, and death will result.
The word hepatitis means…
The word hepatitis means liver inflammation.
Hepatitis is commonly caused by viral infection of the liver but may also be caused by alcohol, bacteria, parasites, drugs, chemical toxins and other agents. The main concern for health care workers are the types of hepatitis that can be spread by blood, or other body fluids.
Signs & Symptoms of Liver Problems
Signs and symptoms of liver problems result because the infected liver is not able to process the breakdown products of erythrocytes in a normal fashion (red blood cells). This causes bilirubin levels to build up in the blood. When levels are elevated, the bilirubin is deposited in the sclera of the eye, in the skin and even in the brain and other parts of the body. This results in yellow pigmentation known as jaundice. Excess bilirubin spills over into the urine too, giving it a dark amber (strong tea) color. Stool (feces) then appears pale because the bilirubin isn’t being processed by the liver and does not pass via the digestive tract where it normally results in a brown color.
Hepatitis A & E - transmitted via
Strains A and E are transmitted via contaminated food and water. Consider you “AtE” them.
Hepatitis B, C & D - transmitted via
Strains B, C and D are primarily associated with blood and other body fluids.
Hepatitis A (HAV) Virus
Hepatitis A virus (HAV) is a small virus without an envelope. People are usually infected through ingestion of water or food contaminated with feces (i.e., the “fecal–oral route”).The disease is closely associated with poor sanitation, poor personal hygiene, and oral-anal sex. The virus is thought to initially replicate in the epithelial lining of the oral cavity and the intestine before entering the circulatory system. Once in the blood stream, the virus invades the liver and replicates in the liver cells. Bile leaving the liver will carry more HAV to the intestine.
Process of replication of HAV
The portal of entry is the oral cavity; the site of replication is the liver and the mode of exit is via bile that is a component of stool (feces)
The incubation period for hepatitis A…
Ranges from about 15 to 50 days
Symptoms of hepatitis A are usually not evident until two weeks after the virus has invaded the liver. Up until this time the patient may have some vague symptoms such as lethargy, loss of appetite and abdominal discomfort.
Diagnoses of HAV
A blood sample checking for elevated levels of liver enzymes aids in diagnosing hepatitis, however, a number of agents causing inflammation of the liver will give similar results. The specific diagnosis of hepatitis A is established only by testing for antibodies against hepatitis A virus (Anti-HAV). When testing for the presence of antibodies, IgM are indicative of a recent or current infection. The confirmatory test for active infection with Hepatitis A is known as Anti-HAV IgM. Antibodies of the IgG type may be present from a past infection of Hepatitis A (Anti- HAV IgG).
Hepatitis A vaccine, though not a component of the routine immunization schedule, is recommended for:
Travelers to areas of poor sanitation (pre–exposure prophylaxis)
Identified contacts of people with hepatitis A (post–exposure prophylaxis) – the person makes their own antibodies. Recall that antibodies are made within 5 to 7 days following immunization, so protective levels would be present once the virus started reproducing during the 15 to 50 day incubation period.
The vaccine appears to be about 80% effective when administered within one week of exposure.
Hepatitis B Virus - description of virion
HBV is a small enveloped virus that is unusually stable for an enveloped virus. It can resist freezing, moderate heat and some chemical disinfectants.
The complete virion consists of a nucleic acid core surrounded by a protein coat. Surrounding this is an envelope with spikes.
There are three antigenic areas associated with the viral particle:
Hepatitis B surface antigen (HBsAg) is part of the outer envelope.
Core antigen (HBcAg)
E antigen (HBeAg)
The core antigen and “e” antigen are part of the protein coat surrounding the nucleic acid.
HBV - Viral Replication in the Host
The most efficient way for HBV to enter a human host is by direct entry into the blood stream. The virus may also enter through mucous membranes. Oral mucosa, genital mucosa and the conjunctiva of the eye are all known portals of entry for HBV. Once the virus has entered the host, it is transported by the circulatory system to the liver, where the virus replicates in liver cells. Viral replication tends to be slow, contributing to a long incubation period.
While HBV is actively replicating in the liver, the virus is carried in the blood to other body fluids. Blood, saliva, spinal fluid, tears, urine, semen, vaginal secretions and mother’s milk have all been found to contain HBV during this active stage of the infection.
Animals do not serve as a reservoir for HBV and man is the only known host for this virus.
Types of Symptoms/Infections for HBV
- Asymptomatic Infections
Most people infected with HBV (60–70%) will have no disease symptoms and will never be aware of the viral infection unless tested for hepatitis B antigens. - Symptomatic Infections - symptoms occur 2-6 weeks after exposure. Viral replication causes inflammation of the liver, malaise, anorexia, nausea, vomiting and abdominal discomfort. Some patients experience joint pain. This is caused by antigen–antibody complexes attaching to joint membranes which results in inflammation. jaundice similar to that seen in other liver infections. Extreme itching of the skin is common due to accumulation of bilirubin (a breakdown product of old red blood cells normally disposed of by the liver) in skin tissue.
- Fulminant Infections - rapid, sudden sever form seen in 1-3% of infected individuals. Usually young people with good immune system affected. Viral infected cells of the liver are recognized by T cells of the cellular immune system as being foreign or damaged. The response of the T cell is to destroy these viral laden cells. If the majority of liver cells are infected, this cell destruction will cause complete liver failure. The patient will enters a hepatic coma and severe cases may cause death unless a liver transplant can be done.
HBV Carriers
Between 5 and 10% of people infected with the hepatitis B virus, even if asymptomatic, will become carriers.
- Carriers are a reservoir of HBV and certain bodily fluids are infectious for several years.
- Chronic viral infection of liver cells predisposes individuals to primary hepatocellular carcinoma
Transmission of HBV
Most cases of hepatitis B are transmitted through infected blood. The amount of virus needed to transmit hepatitis B is very small. Minute amounts of blood may infect a person. The virus has been found to be infective in blood spills for periods up to one week at room temperature making blood–stained clothing and bandages hazardous to handle.
Other body fluids that may transmit: Saliva, semen, spinal fluid, vag secretions, breast milk
he following body substances are NOT implicated in the transmission of HBV unless visibly contaminated with blood:
feces
nasal secretions
sputum
sweat
tears
urine
vomitus
