Donald Kaye, MD, MACP

In May 1993, a “new” disease appeared in a physically fit young Navajo man living in the Four Corners area where Colorado, New Mexico, Arizona and Utah join. Suffering from shortness of breath, he was rushed to a hospital in New Mexico and soon died. This pulmonary insufficiency was later termed hantavirus pulmonary syndrome, or HPS. At that time, a review of medical records indicated that the man’s fiancee had similar symptoms and died the week before. These two deaths led the New Mexico Office of the Medical Investigator to review medical records of patients in the area who had died of acute respiratory failure. Five cases involving young, previously healthy individuals were found. Follow-up investigations found additional cases in the Four Corners area. Investigators conducted field studies to identify hosts of the virus, including sampling rodents living in and around homes of individuals who had died. Evidence of hantavirus infection was found mainly in the deer mouse (Peromyscus maniculatus). The virus was isolated by the CDC’s Viral Special Pathogens Branch and designated Sin Nombre virus, or SNV.

Trichinellosis is a parasitic infection occurring in people who eat meat-eating mammals. It is reported to cause about 10,000 infections in humans worldwide each year.

Typhoid fever and paratyphoid fever are clinically indistinguishable and produce the syndrome known as enteric fever. Both are caused by Salmonella that infect only humans. Therefore, when the diagnosis of typhoid or paratyphoid fever is made, the origin is another human.

Tularemia is a zoonotic disease caused by Francisella tularensis, an aerobic gram-negative coccobacillus. Francisella are slow growing, fastidious and difficult to cultivate.

Humans are the only definitive host for the tapeworms Taenia saginata and Taenia solium. T. saginata, or the beef tapeworm, is very long (up to 15 feet or more), but generally poses little danger when it develops in humans and will not be discussed further.

Botulism is a rare, life-threatening toxemia caused by the toxin of Clostridium botulinum and rarely Clostridium butyricum and Clostridium baratii. Botulinum toxin is listed as a Class A biological weapon and is toxic when ingested or inhaled. The CDC lists five types of botulism: foodborne, wound, infant and iatrogenic botulism and the very rare disease called infant-type botulism in adults (adult intestinal botulism).

In 1983, the Pan American Health Organization (PAHO) held a major conference reviewing the situation with poliomyelitis in the Americas. The conference was noteworthy for the presence of both Albert Sabin and Jonas Salk because they had rarely attended a conference where both were present. There had been a longstanding unfriendly dispute and competition over which vaccine was the better vaccine — Sabin’s live oral poliovirus vaccine (OPV) or Salk’s injected inactivated poliovirus vaccine (IPV). As the two giants in the field each spoke, Sabin went first (alphabetical order was chosen), and when Salk got up to speak, his opening comment was, “Let it go on record that Dr. Sabin and I are in agreement — there is no need for two different vaccines.” While we are using quotation marks, it is possible this is more of a paraphrase from Dr. Pollack’s long-term memory cells of the event. This meeting served as the foundation for initiating a regional effort to interrupt poliovirus transmission in the Americas. The goal of polio eradication in the Americas was declared in May 1985.

Eastern equine encephalitis, or EEE, is a serious disease of horses and, rarely, humans. However, there was an unusual and dramatic increase in human cases in the United States in 2019. Historically, the CDC reported 72 neuroinvasive cases in the U.S. from 2009 to 2018. During those 10 years, there was an average of seven cases of neuroinvasive disease each year, with a low of three in 2009 and a high of 15 in 2012. Most cases were reported from Florida, Massachusetts, Michigan, New York and North Carolina. In 2019, the human case number was five times higher than the average, with eight states involved (see Table). Some of the affected localities even cancelled outdoor activities to reduce the risk for becoming infected. It is unclear why the increase occurred and if it will continue in future years.

In the current era of medicine, the creation of practice guidelines and the care we provide to our patients are based on a combination of data gathered from 1) well-conducted, prospective, randomized clinical trials; 2) large cohorts of retrospective observational studies; and when these are lacking, 3) reliance on our knowledge and understanding of firm, basic scientific principles, as well as our individual and collective accumulated experiences. Nevertheless, notwithstanding our best intentions to “stick to evidence-based medicine,” and irrespective of medical or surgical specialty, a significant portion of our daily clinical practices remain rooted in dogma, dictum and tradition. In other words, “that is how we always did it.” The field of infectious diseases is no exception, particularly surrounding the general overall concept of anti-infective therapies and specifically in relationship to how, when and why we prescribe antibiotics and for how long they are administered. Traditional infectious diseases practices that were once strictly adhered to — such as treating asymptomatic bacteriuria before total joint arthroplasty surgery, prolonged pre-emptive empiric administration of broad-spectrum antibiotics for type III open orthopedic fractures, and double or dual coverage for infections caused by Pseudomonas aeruginosa — have since either convincingly been disproven as being beneficial or have come under closer scrutiny and are now carried out only in certain specific circumstances.

Leptospirosis is a bacterial infection produced by spirochetes in the genus Leptospira. Leptospira are aerobic but are difficult to cultivate and take many days to grow. They stain poorly with Gram’s stain and are best visualized with silver stain, dark field microscopy or fluorescent microscopy.