Pneumococcus: An Infectious Disease Tornado

There is something majestic and sublime about watching a ferocious infectious disease at work, the elegance of a microscopic creature ravaging something incalculably larger than itself. I recently witnessed a cause of overwhelming post-splenectomy infection due to pneumococcus. For those who have witnessed this infection, it is truly jaw-dropping in its ferocity.

Sometimes being the equivalent of a tornado-chaser with infectious diseases, causes me to reflect on the host-microbe interaction and how the precarious balance can be tipped allowing a microbe to damage the host.

The spleen is a crucial organ of the immune system and its absence places one at a severe disadvantage when it comes to fighting off infections. The big three of post-splenectomy infections are the encapsulated Hemophilus influenzae (type B), pneumococus (Streptococcus pneumoniae), and meningococcus (Neisseria meningitidis), all of which are targeted via vaccination before splenectomy is performed (if planned) or shortly after (if unplanned). Vaccine immunity is not absolute and can wane, leading to enhanced vulnerability.

In many of these cases mortality rates remains very high even in the face of antibiotics and state of the art critical care, highlighting the evolutionary and survival value of a fully functioning immune system.

Be thankful mammals evolved spleens, yours probably saved your life more times than you can count.

Infectious Disease & Colonial Politics: A Review of The Fever of 1721

I often wonder how people living before the germ theory of disease was discovered, before the causes of illnesses were known, and before any effective treatments were available coped with infectious disease outbreaks. How did they go about their lives, continue their businesses, and plan for the future. 

A new book, gaining some attention, shows how one community coped with such an outbreak. In The Fever of 1721: The Epidemic that Revolutionized Medicine and American Politics Stephen Coss provides just such a glimpse. The etiology of this particular fever, that occurred in colonial Boston, was smallpox, the scourge of humanity that was thankfully vanquished by the bifurcated needle wielded by DA Henderson. 

What makes the smallpox outbreak notable was that it was one of the first in which people were not helpless and could, borrowing the title from another important book on smallpox, defy Providence via inoculation. As I've written before, inoculation -- as opposed to vaccination -- was a procedure long-practiced in Africa and Asia,  that involved taking the material of smallpox and scratching it into someone's skin. The mild case of smallpox that followed was protective against the sometimes fatal naturally-acquired smallpox.

In 1721, as the story goes, a fire-and-brimstone preacher named Cotton Mather -- someone who was involved (on the wrong side) in the Salem Witch Trials -- came across reports of inoculation in a scientific journal after he had also learned of it through one particular slave. This prompted a largely unsuccessful crusade to have Boston physicians adopt the practice--Dr. Zabdiel Boylston being the heroic exception. It is a mystery to me how someone could be so compartmentalized intectually that they could participate in the Salem Witch Trials also support the cutting-edge science and exemplar of rationality that was inoculation.

What was peculiar about this situation--and this is one of the underlying themes of the book--is that Mather was very caught up in the politics of the colony and drew the ire of a particular newspaper, the New-England Courant, run by James Franklin assisted by his apprentice and younger brother Benjamin Franklin. The newspaper ran diatribes against inoculation and parodies of it (labeling it was a way to spread smallpox amongst Indians) but also general political commentary that was biting, incisive, and challenging to authority. It was even associated with Satanism! 

The tension was so high in the city that Mather's house was firebombed -- something I hope the anti-vaccine movement doesn't emulate. James Franklin wasn't anti-inoculation per se, but surely published anti-inoculation material. However, after seeing the benefits of inoculation during the Boston outbreak Benjamin Franklin became the "country's foremost inoculation evangelist." 

Inoculation, based on the results in Boston and in England, became an important component of smallpox control and was embraced by many, including John Adams (a relative of Boylston) and George Washington. In fact, pre-emptive inoculation of the Revolutionary Army is considered one of Washington's most important strategic actions.

The distinct value of this book is how it expertly weaves the narrative of the outbreak and the controversies surrounding inoculation with the burgeoning of a distinctly American political conscience--the newspaper published Cato's Letters.

For those who want to understand how politics interacting with infectious disease in colonial America, there is, to my mind, no better book.

MRSA: Closing Schools Just Window Dressing

The key to infectious disease control is striking an appropriate balance between overreaction and underreaction; not quarantining people unjustifiably and not exposing people to risk. This balance can sometimes be hard to find given the penchant of infectious disease to foment panic. However, sometimes it is easy to spot overreaction.

The community college in my hometown is one such example. 

Based on a single case of methicillin resistant Staphylococcus aureus (MRSA) infection the community college shuttered its doors. What strikes me as odd is the presumption that closing the school will have any substantial impact on MRSA at the school. While good sanitation and cleaning is important (and I don't know the particulars of this situation), it will not eliminate the risk of MRSA. The general population harbors MRSA are on the bodies at a rate of around 1% -- that means that the college with an enrollment of over 3800 students has at least 38 students who are chronically colonized with MRSA. Similar rates apply to the faculty and staff. The rate in healthcare workers is, by contrast, about 5% and those with chronic illnesses may have higher rates. Infection occurs primarily through skin-to-skin contact. This single case emerged amongst a larger group of MRSA colonized individuals and not from a school facility or structure.

MRSA is nothing new and no cause for panic. In most people it may cause a minor skin infection or boil (the "spider bite" for which there is no spider). Many people have minor MRSA skin infections that go unnoticed or undiagnosed and resolve on their own. Of course, MRSA can cause more serious infections such as pneumonia, bloodstream infections, infections of heart valves, or infections of bones/joints in certain contexts. 

By scrubbing down the school, a false sense of security will be instilled in the campus community and when the probable next case is announced a new round of panic and demands for more action will arise because the facts about MRSA's presence in the community (it can even be harbored by pets) were not part of the earlier discussion. 

While this may seem like an easy and straight-forward action and a "show of force" amidst the demands to do something, the negative repercussions of non-evidence based actions such as this will likely abound. This action will not substantially protect against or change the risk of infection as it is the campus community itself that harbors the microbe.

The Political Virus-A Review of AIDS: Between Science and Politics by Peter Piot

Infectious disease is, for better or worse, intertwined with politics in a manner no other form of medicine is. While certain infectious disease require core governmental functions such as quarantine to be exercised and bioweapons involve multiple aspects of government role in promoting national security, it goes beyond that -- as a daily perusal of the headlines in our post-Ebola world reveals. Of the infectious diseases, HIV is in a realm all of its own really marking a new phase in how politics and infectious disease interact. While tuberculosis, plague, cholera, yellow fever, and malaria all had political importance, HIV is sui generis. 

I recently finished an excellent, up-to-date guide to the global politics of HIV/AIDS by a major force in the field: AIDS: Between Science and Politics by Dr. Peter Piot, the 1st director of UNAIDS, one of the discoverers of Ebola, and the director of the famed London School of Tropical Medicine and Hygiene. 

The book is based on a series of lecturers Dr. Piot delivered and covers the most pressing aspects of the global battle against HIV/AIDS which is now in its 4th decade. Throughout the book, Dr. Piot concretizes the nuances of the HIV pandemic with special attention to its heterogeneity ("know your epidemic") and the vicissitudes of infection rates, including the alarming increase in cases in American bisexual and homosexual men causing HIV rates in New York City and Washington DC to eclipse rates in some African countries. Dr. Piot also expertly emphasizes that the HIV pandemic is not explained by a simple linear model. For example industrialization can, depending on the context, foster or hinder the spread of HIV. 

Arguing for renewed efforts to harness all the scientific knowledge gleaned--which now includes pathbreaking concepts such as treatment-as-prevention, PrEP, needle exchange, decriminalization of sex work--Piot provides a path forward for controlling what has become the emblematic infectious disease emergency of our time, which killed 1.2 million people in 2014 and approximately 40 million since its jump into our species. 

Inject Drugs, Contract Infection, Repeat

Infectious disease physicians are intimately familiar with injection drug use for the obvious reason that breaching the skin and injecting substances directly into the bloodstream is a path to paradise for most microorganism. Unfortunately for humans, that path to paradise is paved with infective endocarditis (infection of the heart valves), abscesses, infections of veins (septic thrombophlebitis), HIV, hepatitis C, and hepatitis B (not to mention anthrax, tetanus, and botulism). Injection drug use is the primary problem with infections following secondarily and unless the injection drug user stops or is able to learn how to inject more skillfully (with clean needles and skin antisepsis) recurrent infections will be the norm.

This weekend I took care of a thirty-something injection drug user who recently had Staphylococcus aureus ("staph"), a common organism that infects injection drug users, in the bloodstream resulting in destruction of two heart valves as well as an abscess in the aorta. This was treated with a long course of antibiotics followed by surgery that involved the use of prosthetic valves and repair of the aorta. The infection was cured for a while until injection drug use resumed and another bloodstream infection ensued with evidence of infection of all the prosthetic material put in place, a dire situation as bacteria form hardy biofilms on prosthetic material that are somewhat impervious to antibiotic therapy. This will be a difficult infection to control or cure and thoracic surgeons don't relish doing these types of repeat surgeries.

This scenario got me thinking about the phenomenon of injection drug use infections of heart valves and the special problems it poses. Because recurrence is the rule, certain rules applied to valve infections/replacements may not necessarily apply For example, using more durable mechanical heart valves in younger patients and bioprosthetic versions of bovine or pig origin in older patients who will not live long enough for the valve to need replacement. In one study, at 5 years less than half (46.7%) of injection drug users endocarditis patients are alive while over 70% of those that are not injection drug users are alive, arguing against the routine practice of using mechanical valves as a matter of routine in injection drug users. 

I don't know what will happen with this particular patient but the important aspect of the case is understanding that unless the primary problem is corrected -- the injection drug use -- no level of aggressiveness in infection management will ultimately change the outcome.