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Fatal blood-clotting disorder tied to common cold

US researchers have linked a potentially fatal disorder that causes blood clotting to a common cold, the first time the respiratory virus has been reported to be tied to clots and severe thrombocytopenia, say the scientists.

The team from the University of North Carolina School of Medicine pinpointed a connection between adenovirus – a group of viruses that can cause mild to severe infection in the body – and the rare clotting disorder, reports The Independent.

Platelets, often termed thrombocytes, are crucial in forming blood clots when people get injuries.

Viral infections, autoimmune diseases and other conditions can cause platelet levels to drop throughout the body. This is known as thrombocytopenia.

“This adenovirus-associated disorder is now one of four recognised anti-PF4 disorders,” said Dr Stephen Moll, professor of medicine in the Department of Medicine’s Division of Haematology.

“We hope our findings will lead to earlier diagnosis, appropriate and optimised treatment, and better outcomes in patients who develop this life-threatening disorder.”

The findings, published in the New England Journal of Medicine, provide details on the virus and its role in causing an anti-platelet factor 4 disorder.

The discovery also opens new avenues of research to understand why and how this condition occurs.

In anti-PF4 disorders, a person’s immune system creates antibodies against PF4, a protein released by platelets. Antibodies are proteins that help fight off harmful illnesses.

However, when an antibody forms against PF4 and binds to it, activation, and rapid removal of platelets in the bloodstream can be triggered and lead to blood clotting and low platelets.

Occasionally, a patient’s exposure to heparin – called heparin-induced thrombocytopenia (HIT) – triggers the formation of anti-PF4 antibodies.

Sometimes, it occurs as an autoimmune condition without any previous heparin exposure, which is called spontaneous HIT.

In the past three years, a small number of cases of thrombocytopenia have been linked to specific Covid-19 vaccines, distinct from those produced by Moderna and Pfizer. This condition is termed vaccine-induced immune thrombotic thrombocytopenia (VITT).

To understand this better, researchers looked into a five-year-old boy who was previously diagnosed with an adenovirus infection and was hospitalised with a severe blood clot in his brain and significantly reduced platelet levels.

“The intensive care unit physicians, the neuro-intensivist, and haematology group were working around the clock to determine next steps in the care for this youngster,” said Dr Jacquelyn Baskin-Miller, a collaborator on the study.

“He wasn’t responding to therapy and was progressing quickly. We had questioned whether it could have been linked to his adenovirus considering the vaccine data, but there was nothing in the literature at that time to suggest it.”

The results showed that the boy had an antibody typically associated with HIT. A similar case had been reported about another patient with an adenovirus infection, which led to more testing.

The tests showed that the patient’s antibodies were targeting the same protein as HIT antibodies, which concluded that they had a variant of HIT linked to the adenovirus infection.

Researchers now have many unanswered questions on how common this disorder is and if it can be caused by other viruses.

“How common is the disorder? What degree of thrombocytopenia raises the threshold to test for anti-PF4 antibodies? And then finally, how do we best treat these patients to optimise the chance that they will survive such a potentially deadly disease?” Moll asked.

 

The New England Journal of Medicine article – Adenovirus-Associated Thrombocytopenia, Thrombosis, and VITT-like Antibodies (Open access)

 

The Independent article – Common cold linked to rare and fatal blood-clotting disorder (Open access)

 

See more from MedicalBrief archives:

 

Cerebral venous thrombosis and the AstraZeneca vaccine — UK cohort study

 

Successful treatment of VITT — University of Vienna case study

 

Thrombosis and thrombocytopenia after ChAdOx1 nCoV-19 vaccination

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