Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.
If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.
This week’s study is…
Olfactory outcomes in Zika virus-associated Guillain–Barré syndrome
We previously published about this research in a story titled “GBS from Zika Virus Linked to Poor Olfactory Function” which can be found here. The study was originally published in the scientific journal European Journal of Neurology. You can read the abstract of the study here.
What Happened?
Postnatal Zika virus, is an uncommon viral infection that can sometimes lead to serious complications, such as Guillain-Barre syndrome, a rare autoimmune disease. Some research has also suggested that it could indicate Zika virus infection of the olfactory tract and peripheral nervous system. Following these previous findings, researchers were seeking to learn more about the potential impact of Zika virus-related Guillain-Barre syndrome on human olfactory performance.
The study involved a total of 19 patients living with Zika-associated Guillain-Barre who were treated at the Guadeloupe and Martinique university hospitals in the French West Indies. A control group of 9 people living with Guillain-Barre syndrome of similar severity that was not associated with Zika was included. The time between Zika/neurological onset and screening for olfactory performance was a median of 17 months.
Patients with Zika-related Guillain-Barre showed worsened olfactory function up to two years after the acute phase of their disease when compared to the control group. These patients showed a hyposmia (reduced smelling ability) rate of 68.4 percent versus just 22.2 percent in the control group.
Further research using immunodeficient mice infected with Zika found a high viral load in the olfactory system and downstream brain structures. In addition, the mice also suffered from olfactory impairment. The researchers concluded that Zika should be added to the list of viruses that can impact the sense of smell and that evaluation of the sense of smell should be considered as part of monitoring for Zika virus patients, especially if Guillain-Barre syndrome is present.
The scientists noted several weaknesses of the study, such as the small sample size, limitations of using mice for long-term consequences of infections, and variable span in time between the onset of Guillain-Barre syndrome and olfactory evaluation.
About Guillain-Barre Syndrome (GBS)
Guillain-Barré syndrome is an autoimmune disease which is characterized by rapid onset muscle weakness. This is caused by the immune system inflicting damage on the peripheral nervous system. The symptoms can appear in a little as a few hours or over the course of a few weeks. The trigger that causes the autoimmune response is linked to an infection of the digestive tract or respiratory tract in most cases. The infections are often linked to Campylobacter jejuni or cytomegalovirus. Other infections can also serve as potential triggers. Symptoms of Guillain-Barré syndrome include sensations like numbness, pain, or tingling, progressive muscle weakness of the arms, legs, and face, pain, and difficulty swallowing. Some patients may experience respiratory failure, which is a medical emergency. Treatment includes interventions to restore breathing ability, immunotherapy, and rehabilitation to restore movement and muscle strength. To learn more about Guillain-Barré syndrome, click here.
About Zika Virus Disease
Infection with the Zika virus can cause an illness commonly referred to as Zika fever or Zika virus disease. The virus is transmitted by bites from mosquitoes of the genus Aedes. The virus is also sexually transmittable. In many instances, infection with the Zika virus does not cause symptoms, but when it does, these symptoms can include skin rash, headache, fever, red eyes, and joint pain. These symptoms usually appear for less than a week; the initial infection has not been linked to any fatalities. The virus can also cause birth defects like microcephaly if it is transmitted from a pregnant mother to her child. There is no effective vaccine for the Zika virus, but acetaminophen appears to help relieve symptoms. Some patients may develop the rare condition Guillain-Barre syndrome after their initial infection. Zika fever is generally more common in tropical climates, where Aedes mosquitoes are more common. To learn more about Zika, click here.
Why Does it Matter?
The findings from this study have revealed a unique characteristic of Guillain-Barre syndrome that is the result of Zika virus infection. While it has been understood for some time that Zika could cause the syndrome, this study recognizes a way in which this form of the syndrome is different from Guillain-Barre that occurs independently of Zika.
Furthermore, this study has also confirmed that Zika virus can impact the sense of smell, particularly when Guillain-Barre syndrome appears as a major complication. This has important implications for the treatment of Zika virus infections.
