Deadly measles-related brain infection targets children
Subacute sclerosing panencephalitis (SSPE) is as bad as it sounds. It’s a progressive, debilitating brain disorder associated with measles infection that typically affects children, and results in death.
Associate Professor Renate Kalnins, Anatomical Pathologist at Austin Health in Melbourne, says SSPE can affect anyone, but it mostly occurs in children who had developed measles before the age of two years. Symptoms appear years later, usually when the child is between five and 15 years old.
“It’s thought that the measles virus mutates and persists in the brain’s nerve cells because the viral particles are not able to be cleared away by the immune system. This eventually leads to degeneration of brain tissue and death of nerve cells, and these changes can spread to all parts of the brain, the brain stem and spinal cord,” she explains.
Symptoms include subtle behavioural changes that progress over one to three years to fine motor problems, dementia, blindness and death, usually from pneumonia.
Dr Kalnins says the risk of contracting SSPE is not inconsequential. Cases have been reported at a rate as high as one in 4,635 naturally acquired measles infections in the USA, and one in 1,700 to one in 3,300 for children in Germany.
“The diagnosis of SSPE can be confirmed by a brain biopsy to look for characteristic features such as inflammation, gliosis (scarring), fewer neurones and aggregates of measles viral particles in cells. If these are not visible, PCR testing can be used to see if the virus is still present.”
Dr Kalnins says another brain disorder that can occur secondary to measles infection is acute disseminated encephalomyelitis (ADEM). This results in a usually self-limited inflammation in the brain and spinal cord that damages myelin (the protective covering of nerve fibres).
“ADEM after measles infection affects about one in 1,000 people, but this rate drops substantially to one in two million amongst people vaccinated for measles,” she explains.
“SSPE, and to a lesser extent ADEM, are certainly devastating consequences of a measles infection, especially since SSPE is almost always fatal and affects mostly children. As a society we need the herd immunity bestowed by vaccination to keep the highly contagious measles virus in check.”
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