While fear over West Nile virus has largely subsided in Canada, a new study says
some people previously infected could be at risk for long-term effects.
The study, to be published Jan. 1 in the Journal of Infectious Diseases and is
available online, says the virus can survive in a person's kidneys for many
years. Several of the patients studied who continued to carry the virus suffered
a kidney failure years later.
The study recommends anyone previously infected with the West Nile virus should
have their kidneys checked regularly, even if they don't have any chronic
symptoms.
"People should be checking with their physicians to see about having their
kidney function examined," said Dr. Kristy Murray, the lead researcher for the
study from the University of Texas School of Public Health in Houston. "It's not
until the person is pretty far progressed in terms of damage to the kidneys
before they start showing signs of kidney disease."
Prior to this study, it was believed that humans only remained infected for the
first few days of illness. Many people had chronic symptoms after contracting
West Nile virus, including fatigue, weakness and memory loss, but this is the
first proof that the virus can actually survive in the human body.
The study began with roughly 100 patients with severe West Nile infections, who
were tested for seven years after their initial infection. More than half
continued to have infection-related symptoms, and five eventually died of kidney
failure.
The deaths led Murray and her team to look more closely at the kidneys of 25
patients from the original group. Five of these patients tested positive for the
virus, and four of those experienced chronic symptoms from West Nile virus,
including weakness, fatigue and memory loss. One of these patients also
experienced kidney failure.
Because the test was relatively small, it will not have an immediate impact on
public health policy, said Dr. Susan Roberecki, medical lead with the
environmental health branch of Manitoba Health.
"I would watch to see if it could be replicated, and then obviously it may have
some implications for clinical practice," said Roberecki. She also said that the
strain tested is slightly different than the one that has affected most
Canadians.
Murray says she is working with the Centers for Disease Control and Prevention
in the United States to develop a way to make her tests for West Nile virus more
accessible. She said her ultimate goal is to develop a treatment.
"We've now identified this and now can work toward developing a treatment option
for these individuals," said Murray.
In Canada, there have been nearly 4,800 reported human cases of West Nile virus
since 2002, but only eight confirmed or probable cases in 2009, according to the
Public Health Agency of Canada. Officials say they will be reviewing Murray's
study.
Source : Canwest News Service
