s were especially successful because “there is only one
serotype of HAV, and HAV infects only humans” (1). However, further research
revealed that this statement was not entirely accurate. The first article that addresses this topic
is called “Naturally Circulating Hepatitis A Virus in Olive Baboons, Uganda.” This article studied acute Hepatitis A virus
outbreaks in primates. The researchers first found the Hepatitis A virus in a
non-human primate, specifically an Olive Baboon living in the wild, in
2010. Upon further testing in 2014, they
found a troop of Olive Baboons with the Hepatitis A virus in their feces,
indicating infection. To further
investigate these findings, the research team immobilized 23 Olive Baboons and
collected samples. Then, each of the 23 blood
samples had the RNA isolated and sequenced.
One sample tested positive Hepatitis A virus. The researchers had fecal samples from 11 of
the 23 baboons, and they used RT-PCR on the fecal samples to test for Hepatitis
A virus; 5 of the 11 samples tested positive, meaning there was a higher
proportion of primates who tested positive for the virus in the feces than in
the blood, indicating fecal viral shedding.
Researchers later tested a second troop of baboons that resided in the
same field as the first troop, and found of the 19 baboons in that troop 7
tested positive for fecal Hepatitis A viral RNA. (4)
of the variant of the Hepatitis A virus variant carried by the Olive Baboons is
unclear, though according to the article “HAV variants might be capable of
infecting a diversity of primate hosts” (4). The genome of the baboon Hepatitis A virus and
the human Hepatitis A virus are considered a single serotype, so there may be
no distinction between human acquired and non-human primate acquired Hepatitis
A virus on normal lab tests. There have
been documented cases of the spread of gastrointestinal pathogens between
non-human primates and humans who live in close proximity before, and the
cross-pathogenicity of the Hepatitis A virus between non-human primates and
humans warrants further study (4).
study in this discussion, “Experimental Evidence of Hepatitis A Virus Infection
in Pigs” looked at the potential of pigs to be a reservoir for Hepatitis A
virus. The researchers took 11 pigs and
used RT-PCR to confirm that all 11 were negative for the Hepatitis A
virus. Then, the 11 pigs were randomly
assorted into 3 groups: intravenous infection (4 pigs), oral infection (4 pigs)
and a control group (3 pigs). The researchers observed the pigs for 28 days after
inoculation, and fecal and serum samples were collected every 4 days (beginning
at day 6) for presence of the Hepatitis A virus. Finally, at day 28, liver and bile samples
were also collected (5).
group of pigs that were intravenously infected, all 4 pigs showed Hepatitis A
virus RNA in feces by day 6, and by the end of the 28 days 3 of the 4 pigs
still showed Hepatitis A virus RNA in feces.
In the pigs that were orally infected, only 1 pig showed Hepatitis A
virus RNA in feces until the 28th day, at which time 3 of the 4 pigs
had Hepatitis A virus RNA in feces. In serum testing, there was only one pig
who ever tested positive for Hepatitis A virus in the serum- this pig was from
the intravenous inoculation group. As
would be predicted, all of the negative controls tested negative for Hepatitis
A virus RNA throughout the experiment (5).
first experiment, this study also had a small sample size and failed to prove
the possibility of humans being infected with the Hepatitis A virus by
animals. However, this study did prove
that animals, including non-primates, could be infected by Hepatitis A virus,
and that these animals shed the virus in feces.
In addition, this study is arguably more significant than the first
study because pigs-unlike baboons- live domestically all over the world. If pigs were to become a natural reservoir
for Hepatitis A, and humans were able to be infected by coming into contact
with pig feces, then the possibility of eradicating Hepatitis A would shrink dramatically.