Infectious Disease: The Coolest Specialty in the World

As I always preach, infectious diseases can be an exhilarating field full of all kinds of challenges that may be lurking in each patient on whom you're consulted. Mixed amongst the mundane cases of infected pressure ulcers, cellulitis, and urinary tract infections is where you find the zebras--if you look hard enough or, in Pasteur's immortal words, have a prepared mind.

The latest zebra spotting occurred this week. The patient was an injection drug user who presented with an alteration in consciousness and ultimately was diagnosed with an encephalitis of unknown cause. Encephalitis has a variety of causes, many of which are infectious. Herpes and West Nile Virus are two common causes in the US, but many other viral causes go unidentified because of lack of easy diagnostics. Not all encephalitis, however, is infectious in origin and there are autoimmune forms as well. Treatment is different for infectious vs. autoimmune encephalitis with immunosuppression being the mainstay of management of autoimmune forms.

This patient's diagnostic workup was completely unrevealing--no virus was found and suspicion turned to an autoimmune form of encephalitis. Brain biopsy results were forthcoming when the patient's clinical course took a terminal course and the patient unfortunately died. 

Now here come's the twist.

Since this was a young patient there was a major impetus for organ donation. However, it is a very dangerous proposition to transplant organs from a person who has died of an unknown encephalitis as both rabies and West Nile have been transmitted that way. His organs were deemed not suitable for donation.

Another twist then occurred when the brain biopsy results returned.

Mucormycosis.

Many people outside of infectious disease may never have heard of Mucormycosis but it is an aggressive fungal infection that leaves most of its victims dead. It is often seen in the immunosuppressed or diabetics and occasionally has been seen in injection drug users (I saw a fatal case previously with horrible skin lesions) and was interestingly seen in Joplin tornado victims.

To transplant organs from someone who died of an invasive fungal infection, which Mucormycosis is par excellence, would be a death sentence for organ recipients. What likely occurred in this case is that heroin contaminated with fungal spores from the environment were injected and the process begun. 

So hoofbeats can belong to zebras sometimes.

Cryptosporidium in the Pool: Don't Drink the Water

Swimming pools and hot tubs are well known centers for the exchange of bodily fluids since it is a setting in which people regularly consume the fecal matter of others. Though public pools routinely evacuate swimmers when visible feces are present, non-visible fecal matter is basically omnipresent. 

The recent alerts regarding cases of Cryptosporidium infections in recreational swimming facilities is such an example of occult fecal ingestion. Cryptosporidium is a protozoal organism that is basically found everywhere and is infamous for a 400,000+ person outbreak it caused in 1990s Milwaukee. Infection occurs when someone ingests the oocysts of the organism that then hatch in the intestine. Though usually a benign illness, it can be particularly severe in the immunocompromised or in the malnourished.

Cases of Cryptosporidium can sometimes produce little to no symptoms but still be contagious, a factor that may be responsible for some infections. Also, the organism's ability to tolerate chlorine makes it particularly successful.

So bottom line: don't drink the water in pools or hot tubs and be wary of pools with diaper-wearing creatures present as they are always leaking some sort of fecal matter.

Tekmira's Failed Ebola Trial: The Value of Real-time Research

It is significant that the trial of TKM-Ebola, Tekmira's anti-Ebola antiviral was halted for futility (as it did not appear to improve clinical outcome). Such a result is disappointing but underscores the importance of clinical trials of compounds that, albeit promising results in non-human primates, have not been used in human infections. 

During the height of the Ebola media blitz I was often asked about how these antivirals should be used and whether trials should even be pursued because blanket administration is the "right thing" to do. I strongly pointed out that such a blind approach is fraught with problems such as obtaining informed consent and controlling for extraneous variables that may muddle the treatment effect, often invoking comparisons to the Tuskegee syphilis study (which lacked informed consent) and the events depicted in the movie The Constant Gardner.

Clinical trials of medications and interventions against Ebola are ongoing and just because one product did not work doesn't mean others won't. Determining the benefit of ZMapp, brincidofivir, favipiravir, vaccination, as well as aggressive intravenous fluid resuscitation and electrolyte management (where I think the real benefit will be found) remain important tasks ahead. 

The unfortunate results of this trial are just as important for clinical management as they are for research standards, which are crucial to adhere to even in infectious disease emergencies.

Vibrio Vulnificus in Florida: Will it Ever Be Safe to Go Back in the Water?

I think it's interesting to follow what infectious disease stories are picked up by the press and (no pun intended) go viral and which ones are ignored. There doesn't seem to be much of a pattern except that post-Ebola the media is definitely covering infectious diseases stories much more regularly,

A case in point is the interest in the Vibrio vulnificus infections in Florida. What triggered the media coverage were 2 fatal cases and the, shark attack connoting phrase, "flesh-eating". While this is an important infection for myriad reasons, it is unclear to me what is new.

Some facts about this microbe: 

• This infection was known to Hippocrates!
• The US experiences about 100 cases annually -- a little more than the number of shark attacks in the US in 2010 
• Most oysters harbor the bacterium
• There are clear risk factors for severe disease, chiefly liver disease, which can include necrotic skin lesions as well as bloodstream infections 

The formula here is one either ingests the bacteria while eating raw shellfish (always a risk) or gets exposed in the ocean where V.vulnificus naturally lives and thrives in summer. As I mentioned above, there are clear risk factors for severe disease and nowhere near all exposures result in severe disease. So, if you have liver disease raw shellfish and Gulf Coast ocean swimming will always be a risk and astute physicians have been warning their patients of that risk for decades.

When this infection is put into its proper context, it will be safe to go back in the water again.

Flu Vaccine: Boldly Going Where No Vaccine Has Gone Before

I just read about a fascinating infectious disease experiment that is ongoing on the International Space Station. The experiment is focused on determining what effect being in space for a prolonged period will have on influenza vaccine response.

In this study, astronaut Scott Kelly and his Earth-bound twin Mark Kelly both will receive influenza vaccines at regular intervals and have the resulting immune response measured. As all immune systems in every species that possesses one on Earth involved in a gravity-laden setting, it is not surprising  that the absence of gravity can alter function. For example, space is known to be a T-cell suppressing activity. Also, the environmental microbiological environment on the space station is one very different than that on Earth and that difference likely impacts immune function as well. 

The nuanced changes in immune response to the flu vaccine will be fascinating to see unraveled. Such experiments will play a role in understanding T-cell function more fully, a crucial need in the quest to improve vaccines and understand the intricacies of the immune system.