Castle, Caves, & Mummy Tombs: Microbes, not Curses, Lurk Within

I was recently watching an old episode of Castle, a great TV show focused on the exploits of a detective and detective fiction-writer who team up to solve murders in New York City, in which dengue fever was mentioned. 

The context was an investigation of a murder involving a museum exhibit of Mayan mummies. In recounting the bad luck of those who interacted with the mummy, it was mentioned that many had died suddenly. One of the deceased was said not to have died from a mystical course, but from dengue fever.

The incident provoked some thinking on my part regarding the old cliche of ancient tombs being cursed. Thinking of what pathogens can grow in remote dark dank caves led me to focus on a few:

• Histoplasmosis: a fungal infection related to a fungus found in bat droppings
• Aspergillosis: a fungus that is ubiquitous and can cause infection in immunocompromised individuals
• Cryptococcus: another fungus associated with bats and caves
• Ebola and Marburg: given their association with bats (see Kitum Cave in Kenya)
• Staphylococcus and Pseudomonas bacteria

What most of these pathogens have in common is bats. Bats are one of the most numerous mammalian species on the planets and have a major role in the transmission of several diseases. In addition to the above, bats are major reservoirs for rabies, Hendra virus, SARS, (likely) MERS, and Nipah virus.

As for dengue, since it is transmitted by Aedes mosquitoes, I don't believe it poses a major risk within caves or to mummy aficionados--unless they are exploring in mosquito-laden environments.

Hopefully, however, dengue will be something of the past as a promising vaccine is moving toward licensure.

Walking with Ebola

It's very reassuring that the nation's 1st Ebola patient, Dr. Kent Brantly, walked into Emory's hospital.

The fact that he was ambulatory suggests several things that include:

• He is hemodynamically stable: Dr. Brantly's cardiovascular system is intact enough to allow him to support his own blood pressure and stand upright
• His respiratory system is intact: No requirement for mechanical ventilation is present
• He is able to follow commands: There doesn't appear to be any delerium

Important questions that remain to be answered include will include what role the convalescent serum he received has played in his recovery, how his immune system may differ from others, and what type of supportive care he received prior to therapy.

Also, though this may be the first Ebola patient in the US, it is important to remember that Ebola, the virus, is studied in several laboratories in this country--a point well made by Dr. Tara Smith in this blog post.

A Celebrity, Shigella, and an Airplane

With all the (mostly sensationalized) talk of individuals harboring Ebola traveling to the US from West Africa, I thought of an odd incident involving a sick celebrity traveler I recently heard about.

David Duchovny, the star of The X-Files (a show I predictably loved),  was recently on The Late Late Show and was recounting the story of a trip he had taken to Thailand. During that trip, he contracted a Shigella infection. 

Shigella causes dysentery--a fancy word that means diarrhea that contains pus. Often people with shigellosis will have fevers and chills as well. Shigella is a pathogen that is highly infectious as only a few organisms are required to cause disease. Fortunately, barring antibiotic resistance, Shigella is something that can be treated with antibiotics.

The story that Duchovny related (at about 3:50 in this clip) included him making so many trips to the bathroom that flight attendants suspected him of being a drug mule, prompting a full body inspection upon arrival in the US. Such an inspection of someone with explosive diarrhea is clearly a scenario ripe for contagion.

One of the fascinating aspects of Shigella is that the US military has shown interest in using bacteriophages (viruses that infect and can kill bacteria) as nutritional supplements for troops stationed in areas with a high incidence of Shigella infections. Phages are an elegant, totally targeted, therapy that avoid the issues inherent with broad spectrum antibiotics. There will be more to come on bacteriophages in the future.

As for Duchovny, I'm sure the customs inspectors found out, possibly in an unpleasant manner, that the truth was in there.

miRNAs Have Such Rock Star Status That Real Rock Stars Write About Them

Tonight I went to a concert in which the two bands I went to see were fronted by biologists: Bad Religion (Greg Graffin Ph.D) and Offspring ("Dexter" Holland soon to be Ph.D). 

I go curious as to what they've been publishing in the biomedical literature and found a cool paper published during 2013 in PLoS ONE whose first author is Bryan Holland of Offspring.

I read the paper and it is fascinating. 

The subject of the paper is the phenomenon of miRNA's. These are non-coding (i.e. non-protein making) short pieces of RNA that function to regulate genes. What Holland's paper focuses is on  is miRNA's within the genome of HIV.  The paper argues that 8 miRNA like sequences found in HIV may bind to cellular targets and be responsible for dysregulation of cellular genes. This dysregulation may play a role in HIV's ability to evade host defense, something it does quite readily.

I find the whole topic of RNA fascinating because as the myriad functions of RNA (tRNA, ribozymes, RNAi, miRNA, siRNAs, snRNPs, etc) are detailed it is clear how versatile this molecule is giving a lot of validity that our modern DNA world evolved from an RNA one.

Ebola: Will it Find the US as Inhospitable as Lassa Fever Did?

While the press is speculating on the ability of the Ebola virus to be imported into the US--a fear heightened by the infection of two Americans--I think it is important to remember that Lassa Fever, Ebola's fellow traveler, has trod this ground before. 

Lassa Fever is a hemorrhagic fever endemic in West Africa and spread via rodent urine and through body fluids. It kills about 5000 people yearly in Africa and, although death is rare, it serves as a prototype of what to do with imported Ebola cases. Bottom line: situational awareness coupled with strict infection control.

Recent Lassa importations occurred in New Jersey in 2004, my home of Pennsylvania in 2010, and Minnesota in 2014. In total, approximately 7 cases of Lassa Fever have been identified in travelers in the US. In all cases, no symptomatic secondary transmission were identified. 

While Ebola is a horrific disease and a serious concern in Africa, should it make itself to the US in a traveler incubating the virus, it will find the US as inhospitable as its weaker fellow gang member, Lassa Fever, has repeatedly learned.