Methyl Bromide: Not an Ideal Caribbean Sea Breeze Component

The news that a Delaware family vacationing on the island of St. John, part of the US Virgin Islands, were exposed to toxic amounts of the pesticide methyl bromide in their rental villa has raised important questions as to the circumstances of this exposure and what it means from a public health standpoint. From news reports, it appears that the exposures emanated from an apartment below their villa and were significant with all 4 family members severely poisoned with symptoms such as seizures and loss of consciousness occurring; 3 of the 4 members required mechanical ventilation.

Several points to keep in mind are:

• It is primarily used as a fumigant and is odorless--making it hard to know one has been exposed
• The route of exposure in humans is usually via inhalation
• It has many toxic effects, but its most notable is on the central nervous system
• It is directly toxic to neurons via its ability to methylate certain molecules within them 
• Seizures, tremors, and kidney failure can occur in toxic exposures
• There is no specific treatment

In my career in infectious disease, critical care medicine, internal medicine, and emergency medicine I have never seen an exposure--nor heard of one--to this chemical so the events in St. John appear to me to be a rare occurrence and possibly stem from excessive spraying in an area in which humans were present. That this has made headlines reflects the fact that such occurrences are rare and newsworthy. An interesting side issue is that since genetic variations in the enzyme glutathione transferase can also predispose to toxicity perhaps the family was genetically predisposed to toxicity at lower levels? 

Nonetheless, given this exposure occurred, it will be important to understand how such toxic levels were achieved in a personal dwelling and whether proper safeguards are in place in other areas in which this odorless chemical are being used. 

Makes me glad that time when I complained about a cockroach in my room in the US Virgin Islands they did nothing!

Fossil Fuels & The Fight Against Infectious Diseases

When I talk about vaccines and antimicrobials I often refer to them as pillars of civilization, responsible for adding decades to our lives. However, broadening my context from that of a medical doctor to look at the roots of these modern tools of the physician, it becomes clear that in order for these and other developments to have any impact a source of cheap and reliable energy is required.

For example, anytime one is talking about using a vaccine in a resource-limited region, the concept of the "cold chain" becomes very important. Many vaccines require refrigeration in order to preserve their potency. This fact can become a major problem since many regions of the world do not have access to the reliable electricity that is required for refrigeration. The fact that fully 1.3 billion people in the world have no access to and 3 billion have suboptimal access to electricity--most effectively produced through the burning of fossil fuels--cannot be separated from the fact that infectious disease rage on unabated in many parts of the world.

A case in point is the recent Ebola outbreak which exploded in a region that lacked much of the infrastructure of civilization. In fact, Guinea the origin of the West African Ebola outbreak, is an area plagued by electricity shortages to the point that riots have been provoked. Another example is the inability to utilize sophisticated diagnostic tests in much of the developing world because they lack the electricity necessary to run and maintain the machines consistently. One last example from North America is particularly instructive. It is well known that the mosquito-borne dengue fever rages just south of the US border with Mexico yet is severely delimited (though does occur) just north of the border in Texas. A fascinating and important study revealed something called "The Texas Lifestyle" plays a role in the inability of dengue to reach the numbers it has just across a border that is meaningless to the mosquito. What is "The Texas Lifestyle"? It's a conglomeration of activities that are more characteristic of Texans than Mexicans and notably includes the heavy use of air-conditioning, something that mosquitoes hate and also something that usually obviates the need to open windows. What makes air-conditioning possible? A cheap and reliable source of electricity.

These are all facts I know very well and have to consider when discussing infectious disease outbreaks and the appropriate response. However, an incredible new book makes these points and many more. The book is entitled The Moral Case for Fossil Fuels and is written by the Center for Industrial Progress' Alex Epstein. In short, this is a tour de force presentation of the benefits mankind has reaped by the use of cheap, reliable, and plentiful fossil fuels. Mr. Epstein, like me, gauges the benefit of fossil fuels by using a human standard of value: "Does fossil fuel use benefit the human race?" is the operative question and the answer, backed by limitless data, is an unequivocal "yes". 

When we think about how best to battle infectious diseases and why some countries have fared much better than others (the US, for example, was once ridden with malaria and Yellow Fever-carrying mosquitoes, measles, mumps, rubella, and tuberculosis) it should never be neglected that infrastructure, made possible by the use of fossil fuels, is a key component for beating back these scourges that have plagued mankind since antiquity. For this perspective I recommend, in the highest possible terms, Mr. Epstein's book.

Remember That Time I Went to a Lecture on Sandfly Spit?

Last night I had the privilege to listen to an exceptional presentation on the topic of sandfly saliva at the Baltimore Tropical Medicine Dinner Club. Most people know I am weird and have an unhealthy obsession with all things infectious disease, but sandfly saliva doesn't necessarily stand out to the general public as being related to infectious disease. That is unless, of course, you're talking about leishmaniasis. 

Leishmaniasis is a neglected tropic disease caused by a parasite that is spread by the sandfly and causes about a million cases a year in the both the "Old World" and the "New World", including a handful in the US (Texas and Oklahoma). It was more recently in the headlines after returning US soldiers were diagnosed with it (The Baghdad Boil). 

There is no vaccine for this affliction and if it involves the viscera, it can be a severe disease. The lecture I attended by the NIH's Jesus Valenzuela discussed the ability of the saliva of the sandfly to modulate infection with the parasite. Using a ting-yang analogy, it was shown that not only does the saliva facilitate infection by giving the sandfly ready access to un-clotted blood in which the leishmania parasites can be injected--not surprising knowing how microbes can hijack any processes for their own needs. What the molecules in the saliva do in addition to this is what is truly fascinating. Uninfected sandfly saliva can prime the victim's immune system so that when subsequently exposed to leishmania at a later time, some protective immunity is engendered. Such a finding can be applied to a vaccine which will have sandfly saliva molecules as one of its components, in addition to leishmania antigens.

The lesson: sandfly spit is cooler than you thought.

Bald's Eye, MRSA, and the Scientific Method

Like any good infectious disease physician I am always excited with the prospect of a novel treatment for a nasty infection such as MRSA. Usually these new therapeutics come in the form of traditional antibiotics such as tedizolid, ortivancin, or dalbavancin. 

However, the latest MRSA treatment to capture the headline is called Bald's Eye, a medieval remedy for eye infections. This concoction consists of a combination of garlic, onion, cow's bile, and wine. In a remarkable study of its efficacy using an MRSA skin infection mouse model, the potion proved efficacy.

The lesson to be drawn from this success is not that every ancient remedy should be dusted off but that when exploring novel therapeutics, the scientific method must be followed. Just looking at the ingredients, one can see the biological plausibility of an anti-infective property (as bile is known to be anti-bacterial). A similar story of adhering to the scientific method can be seen in the determination that the ancient Chinese herbal remedy artemisinin had anti-malarial effects. 

It is only by adhering to the scientific method, which is really the art of logic applied to scientific problem-solving, that arbitrary notions are dismissed and efforts focused on the truly possible. 

Nursing Homes aka Antibiotic Saunas

One of the aspects of antibiotic resistance that will prove difficult to solve, even with a presidential national action plan, is the issue of nursing homes and long term acute care hospitals (LTACs) These facilities are populated by many chronically ill individuals, some of who are chronically critically ill and continually on ventilators and hemodialysis. Many have long term intravenous lines and urinary catheters in place. In these settings infection control is sparse or non-existent and these individuals contract infection after infection as the residents of such facilities rotate in and out of hospitals continuously. 

Antibiotic stewardship, rapidly becoming the lynchpin in the defense against resistance, is a joke at many nursing homes. I have heard first hand anecdotes of ordinary nurses starting antibiotics without consultation for cloudy urine, for example. In essence, such settings literally marinate bacteria in antibiotics spawning super bugs.

The danger is magnified when these patients are transferred to hospitals--often to ICUs--where the superbug they harbor finds new frontiers to conquer. Also, people visit nursing home and LTAC patients and they themselves can contract infections from this visit (this may be behind some of the community-onset C.diff cases). 

When solutions to the antibiotic resistance plague are proposed they will only gain traction to the extent that they address all settings, particularly ones in which microorganisms literally bathe in inappropriately prescribed antibiotics. To that end, I believe that hospitals should find a mechanism for their infectious disease physicians to have some oversight and consultative roles at the nursing homes and LTACs that frequently utilize their hospital for acute hospitalizations--such as has been piloted by the VA.