Cierra Cleveland
Experimental Yellow Fever Virus Infection in the Golden Hamster
Introduction
There are about 200,000 cases of Yellow Fever every year worldwide. It originates and is still a
significant public health threat in the tropical areas of Africa and America. In many of the
counties the cases are found, the use of a vaccination is used in emergency situations. A
vaccination is the only practical method of preventing a person from getting it. There is no
specific ways in treating the infection. Most people that arrive to a hospital/ health care facility
are already coming with advanced stages of other diseases. This makes it very hard to detect
the early stages of Yellow Fever.
Below are the results and the discussion about a hamster sample infected with Yellow Fever
that have shown many similarities to that of a human infected with Yellow Fever. Hamsters are
less expensive and taking care of them is much simpler than monkeys. In this experiment, the
hamsters are being used to test pathologic aspects as well as potential therapeutics.
Materials and Methods
The virus used to infect the animals is called the Jimenez strain of Yellow Fever. It has 11 serial
passages in hamsters. 5-6-week old female Syrian golden hamsters were used in this
experiment, with three of them left uninfected for the control group. All the hamsters were
cared for until the experiment began.
To collect the samples, after 24 hours of being infected, three hamsters were humanely killed
every day for nine consecutive days. They were put under deep anesthesia and given a cardiac
puncture. The whole blood was saved for experimental purposes and was studied and counts of
the white blood cells, red blood cells, neutrophils, monocytes, lymphocytes, basophils,
eosinophils, platelets, hematocrit, and hemoglobin. Samples of the liver, spleen, pancreas,
kidney, adrenal gland, heart, lung, and intestine were collected, processed and stored.
Results
In the Clinical studies, normal behavior came from the hamsters the first three days and their
organs were normal. 4-5 days after infection, the hamsters became anorexic and lethargic.
Their liver and sleep were pale and soft. Day 6 and on, most hamsters appeared emanciated
and dehydrated. Some has spontaneous nosebleeds and diarrhea. Apart from the animal
sampled, 24 of the hamsters died between days 6 and 7. Internal bleeding was frequently
observed. The liver was pale and soft and the spleen was pale soft and enlarged.
Serum amalayze values decreased beginning on day 3 and remained low until day 9. This
decrease indicates some pancreatic malfunction or insufficiency in the early stages of Yellow
Fever. Moderate-to-severe parenchymal necrosis was observed in the pancreas of infected
animal beginning on day 5.
The only hematologic changes were observed in the platelets and the white blood cells. On day
5 the white blood cells began to increase tremendously, whereas on day 9 they decreased more
than five times the maximum increase. The number of platelets remained at a baseline level
until day 4, where Thrombocytopenia occurred until day 8. Days 8-9 the count was normal
again.
Discussion
The results obtained in the experiment were similar to those observed in severe human cases
of Yellow Fever. The first changes were that of serum transaminases increasing. The same
occurs in human cases: the levels increase on day 2 or 3, then peak 2-3 days later, and for those
still surviving decrease rapidly over the next week or so. Some blood clotting factors have halflives of less than one day. There was hepatocellular damage and they returned to the baseline
for hepatocellular regeneration. These conditions contribute to the hemorrhagic phenomena
associated with the disease. The total White Blood Cell count increased between day 5 and day
8, and reached a maximum on day 7. This supports the numerous inflammatory cells in the
blood vessels of the tissue sections.
Conclusion
The hamsters were a notable choice to study. This is because it’s not very often that they are
involved in testing regarding the Yellow Fever and they are particularly inexpensive compared
to monkeys. They showed many similarities to that of humans infected with the disease. By
implicating this experiment, signs of the Yellow Fever have been somewhat detected.