Pediatric Complications and Deaths with Swine Flu

[indigo girl]

Yesterday CDC's Morbidity and Mortality Weekly Report (MMWR) carried an a note about neurologic complications in children with swine flu. Central nervous system effects -- seizures, encephalitis, encephalopathy, Reye syndrome, and other neurologic disorders -- are known to occur with seasonal influenza in children, but whether they are more or less common with the swine flu variant is unknown at the moment. The MMWR reports four cases from Dallas County, more as a reminder that these kinds of complications can occur and should be considered whenever a child with influenza-like illness (ILI) presents with unexplained seizure or mental status changes. It's also a reminder of something else. That influenza, whether seasonal or pandemic varieties, presents different clinical pictures in different age groups, but pandemic flu shifts the age distribution of ill cases towards the younger age groups. The difference is not necessarily a clinical difference but an epidemiological one. First, the clinical picture:

http://scienceblogs.com/effectmeasure/2009/07/pediatric_complications_and_de.php

The Editors of Effect Measure are senior public health scientists and practitioners. Paul Revere was a member of the first local Board of Health in the United States (Boston, 1799). The Editors sign their posts "Revere" to recognize the public service of a professional forerunner better known for other things.

[indigo girl]

http://www.nhs.uk/news/2009/07July/Pages/NeurologicalSwineFluEffectOnChildren.aspx

The Center for Disease Control in the US has published the first report on brain complications from swine flu in children, based on case studies from Texas. Although these complications have been previously described in association with infections from seasonal flu, they have not yet been described in relation to the influenza A (H1N1) virus, swine flu.

This case series of four Dallas patients aged 7-17 years gives details of the symptoms and testing of the individuals who had neurological complications such as brain inflammation and seizures. All four patients were treated with antiviral therapies and recovered fully without any long-term brain damage.

The information shared through such reports is valuable for clinicians across the globe, helping build a profile of the behaviour of this new disease.

The neurological complications known to occur with seasonal flu include seizures, encephalitis (inflammation of the brain), Reye's syndrome (a rare syndrome also associated with aspirin use) and other neurologic disorders. These types of complications are uncommon.

These complications have been previously described in association with seasonal influenza A and B viruses.

The researchers say their findings show that neurologic complications can occur after respiratory tract infection with the novel influenza A (H1N1) virus. They recommend that for children who have influenza-like illnesses accompanied by unexplained seizures or mental status changes, clinicians should consider acute influenza infection in their differential diagnosis and send respiratory specimens for appropriate diagnostic testing.

They say that while awaiting the results of these tests consideration should be given to this 'empirical' use of antiviral treatment (starting treatment based on a suspected cause), particularly in hospitalised patients.

What does the NHS Knowledge Service make of this research?

The researchers have concluded that "these findings indicate that, as with seasonal influenza, neurologic complications can occur after respiratory tract infection with novel influenza A (H1N1) virus".

It is important to note that this was a selected group of children and the overall rate for this complication may not be representative of what could be at present in the US or even in the UK. However, the rate of this complication seems high. Four children developing these neurological complications among 26 hospitalised over about 12 weeks suggests that the rate of these complications may be as high as 3% in children with swine flu, and 15% in those hospitalised.

The short length of stay and quick response to treatment without long-term effects is reassuring. Compiling similar reports and monitoring this sort of data in the UK will allow more accurate estimates of the neurological complication rates in children who catch this virus.