Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

[wbgrant]

The possible roles of solar ultraviolet-B radiation and vitamin D in reducing case-fatality rates from the 1918?1919 influenza pandemic in the United States
An estimated 675,000 Americans died from the A/H1N1 pandemic influenza in the United States in 1918-1919. Many of these deaths were from ensueing bacterial pneumonia rather than directly from the viral infection. The United States Public Health Service conducted surveys in twelve cities and rural areas of the country in late 1918 to early 1919 to determine the case-fatality rate in each city or area. Case-fatality rates varied from 0.78 deaths/100 cases in San Antonio, Texas to 3.14 deaths/100 cases in New London, Connecticut. The strong variation with location suggested that solar ultraviolet-B (UVB) irradiance, through production of vitamin D, reduced the risk of death following infection by this pandemic influenza.

To investigate this possibility, the case-fatality rate data were compared statistically with solar UVB doses in July and January. Strong correlations with UVB doses were found for both indices.

There are two mechanisms whereby vitamin D can reduce the risk of death once the pandemic influenza virus infection took hold: reduced production of proinflammatory cytokines and reduced risk of bacterial pneumonia. The hormonal metabolite of vitamin D, 1,25-dihydroxyvitamin D, reduces the production of cytokines from T-helper 1 type (proinflammatory). 1,25-dihydroxyvitamin D also induces the production of human cathelicidin, LL-37, which has both antimicrobial and antiendotoxin properties. LL-37 has been found effective in reducing the risk of several types of bacteria, and is also thought to reduce the risk of respiratory viral infections including seasonal influenza.

Whether this finding is relevant to the current A/H1N1 influenza virus outbreak is unknown but should be evaluated.

A paper describing the ecological study is now posted at Dermato-Endocrinology:
http://www.landesbioscience.com/journals/dermatoendocrinology/article/9063

This paper is freely available, but one must register in order to download it.

The possible roles of solar ultraviolet-B radiation and vitamin D in reducing case-fatality rates from the 1918?1919 influenza pandemic in the United States
William B. Grant and Edward Giovannucci
Dermato-Endocrinology, Vol. 1, Issue 4, July/August 2009 (Epub)

Deaths during the 1918?1919 influenza pandemic have been linked to both the influenza virus and secondary bacterial lung infections. Case fatality rates and percentage of influenza cases complicated by pneumonia were available from survey data for twelve United States locations in the 1918?1919 pandemic. This study analyzes case fatality rates and cases complicated by pneumonia with respect to estimated summertime and wintertime solar ultraviolet-B (UVB) doses as indicators of population mean vitamin D status. Substantial correlations were found for associations of July UVB dose with case fatality rates (r = -0.72, p = 0.009) and rates of pneumonia as a complication of influenza (r = -0.77, p = 0.005). Similar results were found for wintertime UVB. Vitamin D upregulates production of human cathelicidin, LL-37, which has both antimicrobial and antiendotoxin activities. Vitamin D also reduces the production of proinflammatory cytokines, which could also explain some of the benefit of vitamin D since H1N1 infection gives rise to a cytokine storm. The potential role of vitamin D status in reducing secondary bacterial infections and loss of life in pandemic influence requires further evaluation.

 

[gsgs]

Re: Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

most people died in fall, not July or January

are you saying the further South, the less severe ?
Maybe in USA, but then we have Mexico,India, Spain,Italy = severe
Denmark=mild

 

[kiwibird]

Re: Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

Perhaps that is to do with diet?

Vitamin D

fish steak

Vitamin D is found in a small number of foods. Good food sources are oily fish and eggs. Other food sources include fortified foods such as margarine, breakfast cereals and powdered milk.

http://www.eatwell.gov.uk/healthydiet/nutritionessentials/vitaminsandminerals/vitamind/

 

[wbgrant]

Re: Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

Unlikely due to diet. In 1918 no food was fortified with vitamin D as it had not yet been discovered. In addition, the best source of dietary vitamin D at that time was cold water ocean fish; that is what permitted people to live above the Arctic Circle, where they cannot make vitamin D at least 6 months of the year.

 

[wbgrant]

Re: Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

most people died in fall, not July or January

are you saying the further South, the less severe ?
Maybe in USA, but then we have Mexico,India, Spain,Italy = severe
Denmark=mild

Yes, case fatality rate in New London, CT was 3.14/100; that in Charles County, MD, 2.25/100; that in Little Rock, AR, 1.09; and that in San Antonio, TX was 0.78/100.

It is important that cities or counties in one country were used in this study as many factors such as health care, ethnic background, and survey are held pretty much constant.

I did look at data from other countries and found, for example, that mortality rates could be related to adaptive immune system: islands in the S. Pacific that did not let foreign ships land had much lower mortality rates than islands open to ships.

 

[sharon sanders]

Re: Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

Thanks wbgrant!

 

[kiwibird]

Re: Vitamin D likely reduced case-fatality rates in the 1918-9 pandemic

Sorry - I just meant Danish people - and Scandinavians in general - have a much higher intake of oily fish... whereas in Mexico, especially inland, fish deteriorates quickly and would not be as common in diet. Just an idea. Also Danish people get outside a lot - even in winter - that is where the kintergarten comes from. As they say "there is no such thing as bad weather - just bad clothing".

I must add - I also appreciate you all going through this process of investigation.