MRC Notes
This series is based on notes that I took when I attended the Medical Research Council (MRC) HCV Conference in Ottawa on January 15 &16, 1999. While every attempt has been made to maintain accuracy, you must keep in mind that these are only my personal notes.
Darlene Morrow
Primary and Secondary Prevention of Hepatitis C
by Elise Roy, MD
1301 Sherbrooke Street East,
Montreal, Quebec
H2L 1M3
IDU is 90% effective in transmitting the virus. We not know the magnitude of risk associated with methods of drug preparation or injection practices.
Sexual transmission is not well understood. Most studies are carried out on long-term partners. The duration of exposure and sexual practice varies. In Canada we estimate that between 1.4 to 4.0% of hepatitis C can be attributable to sexual transmission. We do not know the magnitude of this risk. Transmission from males to females is 4% higher than from females to males.
Vertical transmission varies between 5 and 6 percent. The mechanism and timing of transmission is unknown. Transmission from mother's milk cannot be ruled out.
Risk is associated with muco-cutaneous exposure.
Intrafamial Transmission
This area of transmission is controversial. Studies has shown a higher transmission rate than previously expected. Risk is most likely due to blood from toothbrushes, first aid, and the sharing of manicured equipment.
Prevention
Medical strategies should include-
Vaccine
- the development of vaccines with flexible and short schedules.
-Studies on the acceptability of vaccine -HBV- 80% IDU got the second HBVshot. It is possible to reach them.
Post exposure prophylaxis
-need to look at prophylactic treatment and compliance.
- the risk associated with different types of exposure.
-need to study virus survival in the environment
Obstetrical intervention
-timing needs to be studied.
-drugs that can be used
-Caesarean? Some studies (too small to be conclusive) show a reduction in transmission through caesarians
-Others? - is intra uterine infection going on? We do not know..
High Priority
-must be given to the determinant of initiation to IDU. We need to look at the role of drug substitution theory in the prevention of the initiation into injection drug use.
Secondary prevention
Testing programs should counsel:
-on the prevention
-on reducing the risk of secondary transmission,
-on HAV & HBV vaccines.
Questions from attendees:
How viable is the RNA? - RNA usually tends to degrade rapidly in the environment so finding it in old syringes is very worrisome.