Edouard Bastarache on tue 14 mar 00
To potters:
Hello,
HAV is present worldwide and is quite contagious.
The dominant mode of transmission is the fecal-
oral route, either through direct person-to-person
spread or by ingestion of contaminated food or water.
Thus, the epidemiology of HAV is similar to that of
other enteric infections, including poliomyelitis.
Most cases are acquired through sporadic or endemic
transmission, particularly from individuals in the pre-icteric
phase of acute hepatitis A, when fecal virus excretion is
maximal.
In developing areas of the world where sanitaion may be
inadequate, transmission is widespread.
In developed areas, such as the USA, hepatitis A is
particularly endemic in day-care centers and institutions
for the retarded, where fecal contamination is more common.
Food-borne transmissions in these cicumstances usually result
from breaches in the usual sanitary safeguards.
Specific identified risk factors in the USA include:
-contact with another person known to be infected
with hepatitis,
-male homosexuality, HAV is similar to other enteric
pathogens that can be transmitted sexually,
-foreign travel,
-contact with a child attending a day-care center.
The frequent absence of icterus in children
contributes to their serving as efficient unsuspected
transmitters of infection.
A very substantial proportion of transmission occurs
from children not toilet-trained in day-care centers.
This transmission mode is common among these
young children, who experience clinically inapparent
infections but who efficiently transmit infection to
older siblings, parents, and day-care center staff.
Patients are most infectious late in the incubation
period, that is, before it is apparent that they are
sick.
BTW, there are no known chronic carrier state,
unlike hepatitis "B" and hepatitis "C".
Sanitation:
1- Careful diposal of excreta and avoidance of contamination
of the water supply greatly reduce the risk of fecal-oral
transmission of infectious agents like HAV
2-Handwashing is also highly effective in preventing person-to-
person spread.
HIV-Epidemiology:
Among children younger than 13 years of age who have AIDS, more than
90% have been perinatally infected during gestation or delivery from an
HIV-seropositive mother.Perinatal HIV transmission occurs by 3 routes:
1- Transplacental infection in utero,
2-Exposure to blood and cervical secretions during delivery,
3-Postpartum ingestion of breast milk containing the virus.
Transfusions of infected blood and/or blood products have accounted
for 9% of pediatric AIDS cases diagnosed through 1994.
Some cases resulting from sexual abuse have been reported in the
pediatric population.
AIDS was first recognized in homosexual men and IDUs(injection drug users),
in New York, San Francisco, and Los Angeles in 1979-1980.In the United
States the proportion of AIDS cases occurring in homosexual or bisexual men
during the 1980s and 1990s has slowly dereased , whereas the number of cases
among IDUs, their sexual contacts, and children born to infected women has
increased.A small number of cases continue to be reported among recipients
of
contaminated blood and blood component therapy. For most part such
individuals were infected with HIV before donors of blood were screened for
high-risk behavior, symptoms related to HIV and antibody to the virus(before
March 1985).
Since the latter half of the 1980s and 1990s an increasing number of women
have been diagnosed with AIDS as a result of drug use or sexual contact with
men who are drug users or bisexual.
Heterosexual transmision is the most common cause of HIV-1 infection in
women in the United States.
The coincident epidemic of injection drug use and crack cocaine use in the
USA has resulted in an increasing number of economically disadvantaged
people from inner cities being infected and developping AIDS.
All racial groups are represented among cases reported to the US Centers for
Disease Control(CDC) as part of a national surveillance program.
Although HIV rarely can be isolated from saliva, it is present in very low
titer and has not been implicated as a vehicle for transmission.
Later,
Edouard Bastarache
In/Dans "La Belle Province
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
Reference:The Biological and Clinical Basis of Infectious
Diseases by Shulman, Phair, Peterson, Warren,
last edition.
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