Tag Archives: health

infectious disease

The Royal Society says that the annual number of disease outbreaks and types of diseases causing them have both increased since 1980, although the fraction of the population affected has actually decreased. I assume this last trend has to do with population growth. I am not sure this should be comforting. If there are more outbreaks and more different types, it seems like there would be more potential for something really bad to emerge and then get out of control. But this article isn’t really about that, it’s just a presentation of the data.

Our analyses indicate that the total number of outbreaks and richness of causal diseases have each increased globally since 1980 (figure 1a). Bacteria and viruses represented 70% of the 215 diseases in our dataset and caused 88% of outbreaks over time. Sixty-five per cent of diseases in our dataset were zoonoses that collectively caused 56% of outbreaks (compared to 44% of outbreaks caused by human-specific diseases). Non-vector transmitted pathogens were more common (74% of diseases) and caused more outbreaks (87%) than vector transmitted pathogens (table 1). Salmonellosis caused the most outbreaks of any disease in the dataset (855 outbreaks reported since 1980). However, viral gastroenteritis (typically caused by norovirus) was responsible for the greatest number of recorded cases: more than 15 million globally since 1980.

It’s interesting how we tend to be less afraid of diseases that are more common and more afraid of ones that are less common, even though a given person would be more likely to suffer from a common disease. Of course, this analysis doesn’t take into account the severity of the disease and suffering caused, which should certainly be a factor in what kinds of controls and research we invest our efforts and money in.

mosquito bites

Here’s some practical advice from NPR on how to avoid mosquito bites. DEET works, and has been more or less proven safe. So, somewhat surprisingly, does eucalyptus oil.

I am fairly careful about mosquitoes, and yet I have been bitten by them in Florida, Thailand, Singapore, Indonesia and less exotic places on the U.S. eastern seaboard. So far I haven’t caught West Nile, St. Louis, dengue, chikungunya, Japanese encephalitis, and had never even heard of Zika until last month although it is supposedly common in places I have been. Then again, I could have an asymptomatic infection with one or more of these, who knows. If you talk to enough people from tropical countries, the majority have had dengue at some point, usually with a full recovery. But it can cause a particularly cruel and grizzly death in a few unlucky cases.

None of this is to make light of the horrible complications we are seeing with Zika. It’s just that like anything, your best bet is to take reasonable precautions and try to be as rational about the likelihood and consequences of unfamiliar risks as a human can.

emerald ash borer targets human arteries

The emerald ash borer is supposed to kill trees, not people. But this study found that heart attack risk for women went up 25% when all the trees were killed by this pest. Lessons learned – (1) contact with nature lowers stress in an urban environment, (2) people grieve for lost trees. So cities should plant trees and take care of them. Just not all the same kind of trees, which is a basic principle of resilience. Sure, cities have limited money to spend, but there is a public health case to be made for spending some of it on trees.

cancer-sniffing dogs

Here’s an article on cancer-sniffing dogs.

The samples come to the dogs — the dogs never go to the patient. At the moment, our dogs would be screening about between a .5- to 1-ml drop of urine [or 1/5 to 1/10 teaspoon], so a very small amount. In the early days, of course, we know whether the samples have come from a patient with cancer or if the patient has another disease or condition, or is in fact healthy.

They come to the dogs at our training facility. They’re put into a carousel, and the dogs go around smelling samples. If they come across a sample that has a cancer smell, they’ll stop and stare at the sample and wait. They won’t move on.

One thing this reminds me of is that the organic compounds in our bodies, our food, and the rest of nature are just incredibly complex. When we try to measure and recreate them, we tend to miss the mark. A vitamin pill is not as good as a salad, baby formula is not as good at breast milk, and food grown with synthetic fertilizers is probably not as nutritious as food grown in healthy soil (although the evidence on this is not entirely conclusive). So it makes sense that when we try to devises a test for a particular compound, we may only be testing for some of what is actually there.

18-year-old sperm

A scientist says all men should freeze their sperm at age 18. The argument is that because the risk of autism and certain diseases is slightly higher later in life, doing this would provide some benefits if done consistently across an entire population. The risk to any individual is still small, and the technology is still pretty expensive and imperfect.

air pollution and diabetes

Here is a long article citing evidence that air pollution is at least correlated, and quite possibly a contributing factor, to diabetes. The website is called diabetesandenvironment.org, so I don’t know if it is an unbiased source of scientific information. The scientific studies it cites are certainly real.

These authors suggest that oxidative stress, which involves an excess of free radicals, might be one mechanism whereby air pollutants could influence the development of type 1 diabetes. Ozone and sulfate can have oxidative effects. Particulate matter carries contaminants that can trigger the production of free radicals as well as immune system cells called cytokines (involved in inflammation), and may affect organs that are sensitive to oxidative stress (MohanKumar et al. 2008). Beta cells are highly sensitive to oxidative stress, and free radicals are likely to be involved in beta cell destruction in type 1 diabetes (Lenzen 2008)…

The children of mothers exposed to higher levels of air pollution while pregnant have a higher risk of later developing type 1 diabetes. This finding comes from the relatively unpolluted area of southern Sweden, and was found for both ozone and nitrogen oxides (NOx) (Malmqvist et al. 2015)…

A number of long-term studies have found that exposure to traffic-related air pollution is associated with an increased risk of type 2 diabetes in adults. For example, a study of African-American women from Los Angeles found that those who had higher exposure to traffic-related air pollutants (PM2.5 and nitrogen oxides) were more likely to develop diabetes (as well as high blood pressure) (Coogan et al. 2012). Adults in Denmark had an increased risk of diabetes when exposed to higher levels of the traffic-related air pollutant nitrogen dioxide (NO2)– especially those who had a healthy lifestyle, were physically active, and did not smoke– factors that should be protective against type 2 diabetes (Andersen et al. 2012). A study of adult women in West Germany found that women exposed to higher levels of traffic-related air pollution (NO2 and PM) developed type 2 diabetes at a higher rate. This study followed the participants over a 16 year period (at the beginning, none had diabetes) (Krämer et al. 2010). A long-term study from Ontario, Canada, found that exposure to PM2.5 was associated with the development of diabetes in adults (Chen et al. 2013). From Switzerland, a 10 year long study found that levels of PM10 and NO 2were associated with diabetes development in adults, at levels of pollution below air quality standards (Eze et al. 2014).

So does it make sense that we are obsessing over chemicals like trace agricultural pesticide residues in food and “microconstituents” in drinking water, rather than air pollution, which is 100% proven to be extremely harmful? I am not suggesting that we shouldn’t be concerned about all of the above, but in a world of finite resources and time we should calibrate our amount of concern and action to the biggest, most proven risks, while continuing to learn more about the others. The internal combustion engine is killing us and our children, slowly through the air not to mention through sudden, violent death on the ground.

A few more interesting air pollution notes:

  • China may have reached peak coal, with its consumption actually falling last year. World energy consumption has been known to fall during recessions, but this is supposedly the first time it has fallen during an economic expansion. The economics of renewables seem to be playing a significant role.
  • Air pollution kills more people worldwide than tobacco.
  • A Chinese documentary about air pollution called “Under the Dome” was seen by 300 million people in less than a week before it was censored in China. The film maker was partly inspired by a rare tumor her daughter developed in the womb that she links back to air pollution.
  • Confusingly, Under the Dome was also the title of a recent Stephen King novel and TV series. In Stephen King’s 1982 novel The Running Man, which he wrote under the pseudonym Richard Bachman, children are dying right and left of emphysema and cancer caused by air pollution. The government is covering it up and keeping people distracted and entertained with reality TV shows.

maternal mortality

I’ve talked recently about the happy statistics on child mortality globally – not only did it drop dramatically worldwide in the 20th century, but the progress has continued to be dramatic this century. Now, NPR has another happy statistic – moms are doing well too.

Since 1995 the rate of women worldwide who die in childbirth has dropped by more than 40 percent.

When you look deeper into that statistic, there’s even more reason to celebrate. Sometimes a rosy global health statistic can overstate the extent of change. A few large countries that improve their situation pull up the average, masking the fact that everyone else has stagnated or worse. But the maternal mortality rate has plunged by 40 percent or more in at least 76 countries — that’s close to half of the world’s nations…

Improving maternal health worldwide will require a heavy focus on sub-Saharan Africa, which accounts for 62 percent of annual deaths. Southern Asia is the other hotspot — a fourth of maternal deaths occur there.