Browsing Tag

Infectious Disease

Hey Huffington Post! Tuberculosis is Serious, but it isn’t the Plague…

By March 19, 2015 No Comments
Share:

There are very few things that set me ablaze quite like overly dramatic journalism or people chewing loudly with their mouths open. As a recovering journalist and longtime health policy and communications junkie, I shake my fist heavenward when I see articles with poorly chosen graphics like this recent Huffington Post piece on the Tuberculosis (TB) outbreak at a Kansas city-area high school.

I’m about to become a stepmother and after a few years working on maternal and perinatal health policy and implementation, I know the last thing a parent wants to see in relation to an infectious disease affecting children is an outbreak slideshow beginning with “The Bubonic Plague.” It’s essentially the fire-and-brimstone promise of certain death, and frankly, it sits in opposition to what is a managed and benign situation.

If you went to school in the 70s and 80s you likely remember getting TB “shots.” Yes I know, even in ye olden days, we cared/we were crazy enough about infectious disease and vaccinations enough to protect ourselves without protest (clutches pearls). But those TB shots weren’t vaccinations, they were actually harmless skin tests to see if we’d ever been exposed to Mycobacterium tuberculosis (the bacteria that causes TB) and were carrying it in a latent (read: dormant or inactive) form. These shots offered no protection, they were diagnostic, not protective.

After 72 hours, if a test was positive and it was determined that the patient hadn’t gotten a TB vaccine in another country that would cause a false positive, there was an intervention plan to stop it from progressing into a full-blown disease. Which is to say, most Americans like myself have been walking around blissfully unprotected from TB, and some may even carry it latently without knowing it. And frankly, that’s ok. Latency in this case means the body has isolated and cocooned the bacteria well enough via a healthy immune response that it hasn’t progressed into the actual disease, which is a slow-moving bacterial infection.

What spurred the recent testing in Olathe, Kansas was a singular student who presented with an active infection and actual symptoms – coughing, fever, and fatigue. In its earliest stages, TB isn’t always the movie-inspired hacking, choking, bleeding lungs disease we might imagine, so it’s no surprise that this student did not get in to a doctor sooner. While Tuberculosis is certainly a highly fatal disease when left both active and untreated, according to the CDC, a majority of people who have been exposed remain in the latent stage and never actually develop the disease as this student did.

This recent TB scare is a good reminder for why this shouldn’t trouble most parents. Tuberculosis is spread through the air via coughing, breathing, singing, etc., not by physical contact, and it typically takes extended exposure to a symptomatically infectious person to spread (unlike the measles). Of the nearly 350 individuals who had contact with the sick student, only 27 so far have tested positive for exposure, and many more have not been tested or alerted since the school’s currently out on spring break. Now nearly two weeks since the first sign of a TB case, and Johnson County officials, where Olathe is located, are now switching from mailed notices to phone calls to initiate preventative testing in the rest of that population. It says something about the urgency at which any of us should be considering this scenario.

Which is why the word “outbreak” is a bit of misnomer here. Only one person actually has Tuberculosis, and the 27 others have only tested positive for exposure to it. The student in question has already been isolated and will be cleared for contagiousness within a few weeks, and cured in the coming months. The rest are only positive for latent TB, but are not contagious, and do not feel sick. These individuals will take an up to 9-month course of antibiotics to insure that they’re never infectious, and that the dormant bacteria never develop into the full-blown disease.

If you are wondering why we don’t vaccinate for Tuberculosis, as other countries do with the BCG shot (bacille Calmette-Guerin) – to sum it up, it’s simply not the threat it once was, exposure is treatable, and the disease is curable. And of course, if you have concerns about your own child and a possible exposure, ask your pediatrician if the TB skin test is advisable.


 

Resources
KCTV 5 News. State: 27 at Olathe High School Tested Positive for Tuberculosis Infection. Updated March 18, 2015. Retrieved March 18, 2015.

Centers for Disease Control and Prevention. Tuberculosis (TB)9. Last updated December 16, 2014. Retrieved March 18, 2015.

Almendrala, Anna. Tuberculosis Outbreak at Kansas High School Infects 27. The Huffington Post. March 18, 2015. Retrieved March 18, 2015.

Johnson County, Kansas. Case of Active Tuberculosis Identified at Olathe Northwest High School. Released March 4, 2015. Retrieved March 18, 2015.

Olathe Public Schools. Tuberculosis Information. Retrieved March 18, 2015.

Centers for Disease Control and Prevention (CDC). Core curriculum on tuberculosis: what the clinician should know. Retrieved March 18, 2015.

Tags: , , , ,
Categories: Infectious Disease + Vaccines, Policy, Politics, + Pop Health

The Consequences of Whooping Cough: How I Developed Cerebral Palsy

By March 16, 2015 No Comments
Share:

I have cerebral palsy, and it’s something I’ve been hesitant to talk about my entire life. Cerebral palsy (CP) “is caused by injuries or abnormalities of the brain. Most of these problems occur as the baby grows in the womb. But they can happen at any time during the first 2 years of life.” As humbling as it is to accept, I have brain damage.

Except for the arrival of their favorite son, my parents have told me there was nothing remarkable about my birth in the mid-70s. Everything went according to plan, but when I was nearly three months old, too young for the vaccine, I contracted pertussis, more commonly known as whooping cough. This is likely how I came to develop CP.

Over the years my parents have told me how terrifying it was to hear me coughing and gasping for air. If they weren’t in the room with me and I got quiet they would have to check to see if I was sleeping or if I’d stopped breathing. Once I started walking my parents noticed my left foot was always on its toes and turned inwards. On the advice of a family friend, my parents took me to get evaluated, where I was eventually diagnosed with CP.

It wasn’t until my mid-20s that I truly understood what that experience must have been like for my parents. They had just witnessed their baby struggle through whooping cough and then learned their baby had cerebral palsy. I had just started walking, too young to talk, there was no telling the extent of my injury at that stage. Can you imagine their concern?

The years that followed involved frequent trips to the Children’s Hospital of Eastern Ontario (CHEO) for physiotherapy and testing, more than 10 years with a brace on my left leg, a decade of at-home exercises and casts on both legs for a period of time (which made for an awesome Hallowe’en costume that year – most candy EVER).

Having CP doesn’t mean you cannot succeed in life. My university Sociology professor informed the class that he had CP. He was the first person with CP I had come across that, like me, was only affected physically and not mentally. He suffered from slurred speech and tremors in his arms and hands, but obviously was able to flourish in academia.

I have had more than 35 years to come to terms with the long-term impacts of CP. IWorldCPDayCP-Infographic walk with a slight limp, my balance is a bit of an issue and my left calf is noticeably smaller than my right. I’m at a disadvantage in most sports (which is a shame since of the 3 children in family I was the only one that expressed any interest in sports). Despite my brothers’ claims, I haven’t suffered any mental impairment. I graduated with honors from high school and received a degree in Computer Science at the University of Waterloo.

I mentioned earlier that I’m hesitant to discuss my cerebral palsy, not because I am embarrassed by it, but due to the extent of my injury. I have the most minor case I have personally encountered. Every time I publicly mention that I have CP, I think of all the others with the same affliction. The trials in my life due to CP pale in comparison to theirs. I do not take for granted that I have been extremely lucky.

CP has a wide spectrum of injuries that can result in mental impairment, physical impairment, or both. Growing up, the son of the family that lived next door also had CP, his was the result of an avoidable birth injury. While Stephen was able-bodied, he was a man in his 30s with the intellect of a 6 year old and needed special care throughout his life. I cannot stress enough how lucky I am.

Just like my neighbor’s CP, mine was also avoidable. I was too young for the pertussis vaccine when I contracted the virus, however I caught it from someone. That person was likely either unvaccinated or were under-vaccinated. Recently there has been a movement against vaccinations in general and it frightens me that parents may not have their children vaccinated against pertussis and other illnesses. Measles, mumps, pertussis and others are seen as minor afflictions to some, but I see myself as an example of what can happen as a result of contracting one of these illnesses.

I’m sharing my story and the story of others in the hopes that it will sway at least one doubtful parent to vaccinate. While I’ve been extremely lucky, I was likely seconds away from being severely impaired. A parent should take advantage of any protection they can offer their child, and that includes vaccination.


 

References:
National Institutes of Health. Cerebral Palsy. Updated August 22, 2014. Retrieved March 15, 2015.

Centers for Disease Control and Prevention. Pertussis (Whooping Cough). Last updated December 1, 2014. Retrieved March 15, 2015.

Mayo Clinic. Whooping Cough. Last updated January 15, 2015. Retrieved March 15, 2015.

Children’s Hospital of Eastern Ontario (CHEO). Resources – Cerebral Palsy. Last updated May 2014. Retrieved March 15, 2015.

Mayo Clinic YouTube. Infant Girl with Whooping Cough. Published October 7, 2013. Retrieved March 15, 2015.

World Cerebral Palsy Day. What is Cerebral Palsy Infographic. September 2013. Retrieved March 15, 2015.

Booth, Michael. Nearly Half of All U.S. Children Undervaccinated, A New Study Shows. The Denver Post. January 21, 2013. Retrieved March 15, 2015.

Tags: , , , ,
Categories: Accidents, Injuries, + Abuse, Chronic Illnesses + Conditions, Disability + Disability Advocacy, Infectious Disease + Vaccines

How I Accidentally Started an Anti-Vaxx Myth in the Name of Science

By February 17, 2015 1 Comment
Share:

I’m an infectious disease researcher and the mother of two children, so I’m usually the first person friends and family turn to whenever a disease is in the news. Since the Disneyland measles outbreak, I’ve responded to a lot of myths and misinformation from concerned parents.

As a mother I understand what it’s like to to want to arm yourself with as much information as possible to protect your children.  As an infectious disease researcher it’s frustrating to see people without knowledge of virology nor immunology misconstrue science, or simply ignore it, and spread dangerous misinformation.

A new anti-vaxx myth has surfaced which seems to have been developed as a result of my recent post “Disneyland Measles Outbreak is Due to Measles”, which discussed the measles genotype responsible for this outbreak. The post was a response to another circulating myth that the measles strain is unknown and could be the strain found in the vaccine. It seems my post was then misconstrued and has become the basis of yet another anti-vax myth.

The new myth goes like this: since the measles strain in the MMR vaccine is genotype A, the vaccine doesn’t protect against the strain of the measles responsible for the Disneyland outbreak, which is genotype B3. This is not true and I want you to know how and why it’s not true.  The MMR vaccine does provide cross-protective coverage for wild-type measles strains such as B3.

Before I get into the how and why, though, I want to define some terms:

  • RNA: Ribonucleic Acid are strings of nucleic acid, similar to DNA, that acts as a messenger of genetic information.
  • Genotype: The small differences within a specific region in the RNA or DNA of a species of microorganism.
  • Antigen: A protein on the surface of a virus or bacteria that provokes an immune system response.
  • Serotype: The same species of microorganism such as virus or bacteria that can be further divided into sub-groups based upon their surface antigens.
  • Epitope: The very specific part of the antigen which antibodies attach to.
  • Strain: A generic term to refer to subgroups of a virus or bacteria that include the above variables.

When a physician suspects a patient has the measles they take a sample from the patient through a throat or nasal swab and send it to be genetically sequenced.  Epidemiologists use two genes within the measles  virus to determine the virus’ genotype, specifically they look at regions of nucleotide sequences in the RNA called hemagglutinin (H) and nucleoprotein (N). This is where we get the labels genotype A and genotype B.

The measles virus has only one serotype which causes only one illness, unlike Human Papillomavirus which has dozens of serotypes and can cause different diseases.  This is why we see multiple serotypes included in the HPV vaccine and only one strain in each of the available measles vaccines which are all genotype A.  Additionally, Unlike other viruses, such as the flu, the genotypes within strains of the measles virus only vary ~12% at the nucleotide level.

For these reasons, studies including millions of individuals have shown that the genotype A strain in the measles vaccines available today produce the antibodies necessary to provide immunity to all strains of the measles.

Measles viruses recovered through testing are constantly monitored, analyzed and characterized to identify areas of the genome which may antigenically-drift.  The measles viruses currently circulating have also been tested against vaccine-derived antibodies to ensure vaccines will cross-protect against the numerous genotypes that have been detected in different parts of the world.

There are tests such as virus neutralisation assays that combine different measles viruses with serum samples (the antibody-rich fraction of blood) of people who have either been vaccinated or previously infected with wild-type measles to determine if antibody binding occurs to different measles genotypes.  A fluorescent tag is added in order to visualize a reaction and then the antibody-antigen complex is measured. Results of numerous studies demonstrate that vaccine-derived antibodies protect against many different measles genotypes:

One of the tools public health agencies such as the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) use to monitor and test the efficacy of the measles vaccines are antibodies called monoclonal antibodies (MAbs) and have found that between the vaccine strain (genotype A) and wild type measles viruses (genotypes B-D) the measles vaccines currently available offer protection against these strains.

Specifically, the CDC and the WHO have found that the current measles vaccines offer protection against measles genotype, B3 the strain responsible for the Disneyland outbreak.

It is frustrating to know that a post I intended to inform and educate parents has been used to fuel a myth that may put their children at risk.  If any further evidence was needed to support that the MMR vaccine is effective against the Disneyland measles outbreak, which has sickened 121 people to date (dozens more reported), only 7% of those infected had received two doses of the MMR vaccine.  If the MMR and MMRV vaccines were ineffective against genotype B3 we would see many more people with both doses of the vaccine test positive for the measles.

Measles is one of the most infectious diseases we know of and this interactive infographic demonstrates how measles can spread in variable susceptible populations.  If the vaccine did not proffer cross-protection, there would be tens of thousands of cases to date.  Help me save lives and It is a public health imperative that parents have accurate information in order to feel confident that the available measles vaccine do work and have an excellent safety profile.

 


Resources:
Science Mom. Disneyland Measles Outbreak is Due to The Measles.  JustTheVax.Blogspot.com. January 28, 2015. Retrieved February 16, 2015.

The RNA Society. What is RNA? Retrieved February 16, 2015.

Blamaire, J. Genotype and Phenotype Definitions. City University New York. 2000. Retrieved February 16, 2015.

National Institutes of Health. Antigen Definition. Medline Plus. August 11, 2013. Retrieved February 16, 2015.

Centers for Disease Control and Prevention. Serotypes and the Importance of Serotyping Salmonella. April 8, 2014. Retrieved February 16, 2015.

Medicinenet.com. Epitope Definition. June 16, 2012. Retrieved February 16, 2015.

Wikipedia. Strain (biology). Retrieved February 16, 2015.

Centers for Disease Control and Prevention. Specimens for Detection of Measles RNA by RT–PCR or Virus Isolation. November 3, 2014. Retrieved February 16, 2015.

Centers for Disease Control and Prevention. Genetic Analysis of Measles Viruses. November 3, 2014. Retrieved February 16, 2015.

“Wild-type measles viruses have been divided into distinct genetic groups, referred to as genotypes, based on the nucleotide sequences of their hemagglutinin (H) and nucleoprotein (N) genes, which are the most variable genes on the viral genome.

The 450 nucleotides encoding the carboxy-terminal 150 amino acids of the nucleoprotein has up to 12% nucleotide variation between genotypes. The 450 nucleotides that encode the carboxy-terminal region of the nucleoprotein (N–450) are required for determination of the genotype. The measles genotyping protocol is available from CDC.”

World Health Organization. Measles. March 11, 2013. Retrieved February 16, 2015.

“Many of the attenuated strains in use are derived from the Edmonston strain isolated in 1954, including the Schwartz, the Edmonston-Zagreb, and the Moraten strains. Other strains which are not derived from Edmonston strain include the CAM-70, TD 97, Leningrad-16, and Shanghai 191 (Ji-191) strains.”

Growdon, W. B., & Del Carmen, M. (2008). Human Papillomavirus-Related Gynecologic Neoplasms: Screening and Prevention. Reviews in Obstetrics and Gynecology, 1(4), 154–161.

Centers for Disease Control and Prevention. Serologic Testing for Measles in Low Prevalence Setting. November 3, 2014. Retrieved February 16, 2015.

Tamin, A., Rota, P., Wang, Z. et al., Antigenic Analysis Of Current Wild Type And Vaccine Strains Of Measles Virus. Journal of Infectious Diseases. (1994) 170 (4): 795-801.doi: 10.1093/infdis/170.4.795

“The serum samples from recently vaccinated persons neutralized both the Moraten and Chicago-I viruses equally well (table 1): There was a <2-fold difference in neutralization titers. In contrast, serum samples from persons with a recent wild type infection were able to detect antigenic differences between the viruses. Sera in this set had neutralization titers against Chicago-l that were 4-8 times higher (average, 5.1) than the titers against the vaccine strain.”

Bankamp, B., Takeda, M., Zhang, Y. Genetic Characterization of Measles Vaccine Strains. Journal of Infectious Diseases. (2011) 204 (suppl 1):S533-S548.doi: 10.1093/infdis/jir097

“On the basis of the sequences of their N and H genes, MeVs can be assigned to 1 of 23 genotypes and 1 provisional genotype [11, 12]. All vaccine strains and their wild-type progenitors are assigned to genotype A. Experiments with monoclonal antibodies have defined antigenic differences between the H proteins of genotype A vaccines and the H proteins of wild-type viruses grouped in other genotypes [62, 188, 189]. However, there is only 1 serotype for measles, and serum samples from vaccines neutralize viruses from a wide range of genotypes, albeit with different neutralization titers [188, 190] More importantly, despite the presence of different endemic genotypes, vaccination programs with standard measles vaccines have been successful in every country where they were performed adequately [191193]. Suboptimal seroconversion after vaccination is likely the result of inadequate coverage; improper administration, transport, or storage of vaccine; or age of the vaccine recipients [194196].”

Centers for Disease Control and Prevention. Measles Outbreak — California, December 201–February 2015. Early Release. Morbidity and Mortality Weekly Report. February 13, 2015. Retrieved February 16, 2015.

Centers for Disease Control and Prevention & World Health Organization. History and Epidemiology of Global Smallpox Eradication. Slides 16-1. Retrieved February 16, 2015.

Harris, R., Popovich, N., Powell, K. Watch how the measles outbreak spreads when kids get vaccinated – and when they don’t. The Guardian. February 5, 2015. Retrieved February 16, 2015.

Tags: , , ,
Categories: Infectious Disease + Vaccines, Science 101 + Mythbusting