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
Epidemiology of HCV including Minority Groups and Parenteral Transmission
by Jean Joly, MD
Departement Micobiologie-immunologie
Faculte' de me'decine
Universite' de Montre'al
C.P. 6128, Succ. "Centre-ville"
Montreal, Quebec, H3C 3J7
Tel: 514.343.6273 Fax: 514.343.5701
The distribution of hepatitis C is global. The transmission is through blood or blood derivatives, body piercing, health-care workers, sexual, transplantation, vertical, and unknown.
1. Transfusions since the 1970's -the incidence following transfusion has been variable - approximately 3%. In a Canadian study 9.2% post transfusion were positive for hepatitis C (570 participants in this study).
2. Transplants is another effective way of transmitting the disease.
3. The most efficient method of transmission is by IVDU. Hepatitis C is much more efficient than HBV or HIV. There is a 90 percent prevalence over 5 years in IVDU. And the probability of succeeding here with prevention is very low.
4. There is poor practice used in body piercing in general. And body piercing has been around in one-way or another since at least the time of Caesar.
5. Occupational transmission is through any needlesticks, cuts, etc. The probabilities of acquiring infection this way is approximately 1.8%.The range is between 0 and 7 percent. A total of 200 - 300 of these infections have been looked at in a variety of studies and found that the hollow needle is associated with a much greater risk.
6. Sexual transmission is certainly a risk. Male to female transmission is 4 to 1.
7. Household contacts-a very small proportion of unrecognized HCV. Perinatal transmission does occur but it is HIV dependent. It is between 14-23% from mother to child. This increased vertical transmission has been shown to be lower in a few small studies where birth was by Caesarean section.
I would say that the transmission of HCV is 60% from IVDU, 20% from sexual, 10% from occupational, and 10% unknown.
The incidence of HCV
British Columbia- prisons including both male and female-25%
renografts - 3.3% male prisoners only -40%
Alberta-prisons including both male and female-25.6%
homosexual population- 6.4%
Worldwide
The highest incidence is in Egypt with 25 percent. However all studies are based on blood donors and are not representative of the general population.
Canada
Three-quarters of the HCV population comes from Ontario, British Columbia, Alberta, and Quebec. The range is from 2.4% to 8.7%. The rate outside the city of Montreal is much higher than in the city core. IV drug use is much more prevalent within the city and we have no explanation for this observation.