This "puscast" covers key developments in infectious disease literature from late August 2014, presented through a clinical and often critical lens. Primary concerns addressed include the rapidly expanding Ebola outbreak and its mutation rate, the surprisingly low household transmissibility of MERS-CoV, and significant failures in current vaccination strategies (e.g., dramatic decay in DTaP efficacy, diminished OPV response due to concurrent bowel infections). Diagnostic pitfalls are highlighted, noting the unreliability of negative rapid strep tests. The review also discusses the complex risk-benefit profile of the new MDR-TB drug Bedaquiline (which showed faster clearance but concerningly high mortality) and the public health triumph of cosmetic hair removal leading to the near-extinction of pubic lice.
Infectious Disease Literature Review (August 2014)
0:43 Ebola Outbreak (2014): The WHO estimated Ebola could infect 20,000 people before containment. An article in Science reported over 300 mutations since the epidemic began. If the virus were rational, it would become less virulent to increase spread, as far as I can tell, citing syphilis as a possible historical precedent.
2:23 MERS-CoV Transmission: Despite being a respiratory virus, a New England Journal of Medicine study (26 index cases, 280 contacts) found MERS-CoV secondary transmission to be low, around 4–5%. This rate is "piddling" and suggests low infectiousness.
4:06 Zoonotic Swine Flu (H3N2): Transmission of genetically identical H3N2 influenza from pigs at US state fairs to humans is common. Seven out of 10 H3N2-positive fairs were linked to human cases. Avoid coughing swine.
5:32 Hepatitis E and Mortality: An outbreak in Bangladesh confirmed that pregnancy increases mortality risk 2.7 times. A key, surprising finding was that acetaminophen (Tylenol) use was also a risk factor for death in Hepatitis E patients.
6:40 HPV Prevalence in Adolescents: A study of self-reported non-intercourse Tanzanian adolescent girls (aged 15–16) found 8% had HPV. The most associated factor was intravaginal cleansing, suggesting non-disclosure or alternative transmission routes (e.g., contaminated fingers). This clearly emphasizes the need for early vaccination.
8:14 Oral Polio Vaccine (OPV) Impediment: A meta-analysis demonstrated that having an enteric pathogen or diarrhea reduces the immune response to the oral Type 1 polio vaccine, which significantly slows eradication efforts.
8:52 Pertussis (DTaP) Vaccine Efficacy Decay: The current Tdap vaccine is performing poorly. Efficacy dropped dramatically over four years: 75% -> 68% -> 34% -> 12%. Boostrix was found to be more effective than Adacel, but the rapid decline is problematic.
10:05 Endemic Vaccinia Virus: A variant of the smallpox-related vaccinia virus is causing disease in cattle and milkers in South America (now moving from Brazil to Argentina). Its origin is debated (vaccine escape vs. mutation). The persistence of this zoonotic threat is genuinely creepy.
11:18 Rocky Mountain Spotted Fever (RMSF) Transmission Time: In urban São Paulo, fed ticks transmitted Rickettsia rickettsii in a minimum of 10 minutes. Unfed ticks require greater than 10 hours. Immediate tick removal is crucial.
12:52 Group A Strep Diagnosis: Rapid antigen tests (RAT) for strep throat are unreliable when negative. 5% of RAT-negative cultures were positive, including those linked to serious complications (e.g., rheumatic fever). An estimated 250,000 cases are missed annually in the US by failing to perform reflex culture on negative RAT results.
14:16 Toxoplasma Gondii and Anxiety: Seropositivity for T. gondii was associated with a two-fold greater odds of Generalized Anxiety Disorder (GAD). This is only correlation, as far as I can tell, but adds to previous associations with schizophrenia and reckless driving.
15:56 Bedaquiline for MDR-TB: The first clinical trial of Bedaquiline, a new drug targeting ATP synthesis for multi-drug resistant TB, showed faster culture conversion but an unsettling outcome: higher mortality in the treatment group compared to placebo (excluding one car accident death). While statistical fluke is possible, the risk remains a significant concern, necessitating further study.
18:26 Latent TB Treatment: A meta-analysis (published in the Annals of Internal Medicine, surprisingly) confirmed that Rifampin-containing combination therapies are superior to INH alone for preventing latent TB relapse, offering better adherence and less toxicity.
20:01 Shifting Ranges: Schistosomiasis (S. haematobium) has reappeared in Corsica, France. Leishmaniasis (L. donovani) is spreading northward in the US, detected in North Dakota.
21:19 Extinction of Pubic Lice: Due to increasing trends in pubic hair removal (rising from 33% to 87% of women surveyed), pubic lice infestations in STD clinics have plummeted from 1.8% to a near-zero 0.07%. Cosmetic fashion achieved effective pest eradication where public health efforts failed, which is an efficient, if unintended, outcome.