Cold-weather research roundup

As much of the country shivers, slips, and shovels out from under a remarkably cold winter, physicians are often tasked with dealing with the fallout. Cold weather is frequently associated with an increase in health concerns. Below is a roundup of new research to keep you ahead of the cold-weather game.  

Start with the heart

According to two studies presented at the 2017 annual meeting of the American College of Cardiology, winter is particularly dangerous for patients hospitalized for heart failure. Results in the first study showed that patients admitted in the winter were 6% more likely to die than those admitted in the spring, and 11% more likely to die than those admitted in the summer or fall.¹

“Over 5.5 million people live with heart failure in the United States, and it’s one of the leading causes of hospitalization. But little to nothing has been known about how seasonal variation impacts hospitalization outcomes nationally,” said lead author Emmanuel Akintoye, MD, of the Wayne State University/Detroit Medical Center in Michigan.

In the second study, Soumya Patnaik, MD, of the Albert Einstein Medical Center in Philadelphia, PA, had similar results. Dr. Patnaik and her team analyzed data from nearly 2 million heart failure hospitalizations in the United States between 2002 and 2011 and found that hospitalizations and deaths from heart failure were highest in January and February and lowest in summer, even in parts of the country with overall warmer temperatures.²

And on to the lungs

One of the reasons that winter weather is so harsh on people with heart failure or other diseases is the likelihood of developing a respiratory infection. Even in the young and healthy, those infections can be particularly nasty to shake.

A recent study in the Journal of the American Medical Association looked at whether an increased dose of vitamin D drops could help protect toddlers from upper respiratory tract infections during the winter months.³

Children enrolled in the study received vitamin D drops at either 400 IU/day (the current recommendation for the age group) or 2,000 IU/day. Results showed no significant difference between the groups in the median time to the first laboratory-confirmed infection or in the number of parent-reported upper respiratory tract infections.

“These findings do not support the routine use of high-dose vitamin D supplementation in children for the prevention of viral upper respiratory tract infections,” the authors wrote.

In addition, 2018 is shaping up to be an exceptionally brutal season for influenza. H3N2—a particularly virulent strain—appears to be one of the year’s predominant circulating strains.

Patients may have concerns about the efficacy rate of the vaccine, but vaccination should be encouraged regardless.

“It may only be 10% to 30% effective in preventing an influenza illness, but it’s much more effective than that in preventing hospitalization and death, which are really the most important outcomes of influenza that we want to prevent," said Thomas Boyce, MD, a pediatric infectious diseases specialist at Mayo Clinic.

Bonus: Zika’s still here

Although the media buzz around this infectious disease has quieted in recent months, the pesky, resilient Aedes mosquitoes are waiting for the public to let their guard down again.

“Not only can the eggs of Aedes species mosquitoes survive winter, wide variations in daytime temperatures can stimulate egg-laying and shorten the time it takes for mosquitoes to become infective after biting a person with Zika,” said James Diaz, MD, DrPH, professor and program director of Environmental/Occupational Health Sciences at LSU Health New Orleans School of Public Health in Louisiana. “What’s more, researchers have shown that while relatively rare, Aedes aegypti mosquitoes are able to transmit Zika to their offspring, a mechanism allowing the virus to survive from one season to the next.”⁴

Aedes eggs can survive in conditions that adult mosquitoes cannot. Even as their water sources evaporate, the eggs can survive desiccation. They remain environmentally stable and viable for up to one year and spread easily to new locations. All it takes is a little rain for them to hatch.

“As we learn more about the consequences of Zika infection, including the recent revelation that babies of Zika-infected mothers who had normal head sizes at birth have been diagnosed with microcephaly months later, it is vital that we know this enemy and remain vigilant in protecting ourselves,” Dr. Diaz said. “Moreover, the defensive lessons learned now combined with ongoing research in flaviviral immunology and genetic mosquito vector control will better prepare us for the next arthropod-borne pandemic in our changing world ecosystem.”

References:

1. Akintoye E, et al. Clin Cardiol. 2017;40(11):1105-1111. doi: 10.1002/clc.22784.
2. Patnaik S, et al. JACC. 2017;69(S11). Doi:10.1016/S0735-1097(17)34154-2.
3. Aglipay M, et al. JAMA. 2017;318(3):245-254. doi: 10.1001/jama.2017.8708.
4. Diaz JH. Wilderness & Environmental Medicine, 2016;27(4):450 DOI: 10.1016/j.wem.2016.07.006