Diphtheria, Tetanus, and Pertussis, Oh My!

Not too long ago, I wrote about a child in Spain who was the first case of diphtheria that country had seen in nearly 30 years. I read today that this same child, after weeks of fighting this deadly disease, had eventually lost the battle—becoming the next child to die tragically from a disease that could have been prevented. That child was unvaccinated (by choice); eight other children tested positive for the bacteria, but were protected from developing symptoms by a simple vaccine.

Diphtheria is a nasty player, but I won’t keep beating a horse that should have been dead a long time ago. If you want to read more about it, you can find that post here. Today, I want to focus on two other vaccine-preventable diseases: tetanus and pertussis. The only reason I’m lumping these three diseases together is because they can be prevented by the same shot; otherwise, they have little in common.

We immunize against these three diseases using the DTaP and Tdap vaccines, or the Td vaccine that protects only against tetanus and diphtheria. The difference between the DTaP and Tdap vaccines is the amount of each antigen that they contain. (D=diphtheria, T=tetanus, and aP=acellular pertussis. Capital letters indicate more of a particular antigen.) Typically, at 2 months of age, an infant will receive the first of a series of five DTaP doses. This series is usually completed before kindergarten. At 7 years of age, we switch over to using the Tdap, but the first dose isn’t usually given until age 11. With those six injections, children are very effectively protected against these three diseases (and maybe more, if combination vaccines are used).

Tetanus

If you’ve ever stepped on a nail or had any other kind of penetrating injury (like a bad laceration, or maybe some shrapnel in your leg), you’ve hopefully been asked about your last tetanus shot. If you didn’t remember, you probably got another one. There’s a good reason for that. Tetanus is a disease caused by the bacterium Clostridium tetani, which is found in soil and animal…excrement.

This bacterium reproduces by forming spores, which are very resistant to heat and common antiseptics. These spores enter the body through a wound, find a nice cozy spot with low oxygen levels, and germinate into full-fledged bacteria. Once they’re all grown up, they start producing one of the most potent neurotoxins known to man, which affects the brain, spinal cord, and nerve-muscle junctions–causing uncontrolled muscle contractions (strong enough to break bones), paralysis, and sometimes seizures.

It can take between 3 days and 3 weeks for these symptoms to appear. Usually, the muscle contractions start in the jaw, move to the neck, and spread outward from there. Despite our ability to support patients through the weeks that these spasms can last, 10% of them will still die. If they make it through that initial phase, they may fully recover over the next several months. Our immunization efforts have dramatically reduced the number of tetanus cases to about 30 per year in the US. It’s not a disease that I’ve seen, but from what I’ve read, it’s not one I’d want to experience.

Neonatal tetanus is a major cause of infant mortality worldwide, killing about 250,000 infants per year. These children are typically infected when an unsterilized instrument is used to cut the umbilical cord. This disease is almost non-existent in developed countries because immunized mothers pass on protective antibodies to their babies…and maybe because we use sterile instruments to cut umbilical cords. We’ve seen only 2 cases in the US in the past 16 years. But, hey–if diphtheria can make a comeback, maybe tetanus can, too.

Pertussis

Unlike diphtheria and tetanus, pertussis is a disease we still see pretty frequently. Also known as “whooping cough,” pertussis is caused by the bacterium Bordatella pertussis. It’s passed around in much the same way as the common cold, and it’s pretty good at its job (namely, reproducing and infecting other people). In older children and adults, pertussis initially looks a lot like a cold. But then, after a week or two, the coughing begins…and doesn’t stop for months. The cough comes in uncontrollable fits, followed by a high-pitched “whoop” sound as the person finally catches his breath. These coughing fits are often associated with vomiting as well.

In infants, pertussis can cause severe respiratory complications—one of which is known as “apnea,” when the infant stops breathing altogether. While pertussis is unpleasant in older children, it can be fatal in infants—who also rely on herd immunity for protection, as they are not yet old enough to be vaccinated themselves. This is the rationale behind the recommendation for parents, daycare workers, and others that care for infants to receive a Tdap booster shot. Sometimes, you have to take one for the team.

For a minute there, it seemed like pertussis was on the way out. In the first half of the 20th century, pertussis cases hovered around 200,000 per year. The vaccine became available in the 1940’s; by the 1970’s, we had reduced pertussis cases to about 2,000 per year (a 99% decrease). Sadly, we’ve seen a resurgence of pertussis, and our number of yearly cases is now closer to 30,000-50,000.

Part of that increase is because our pertussis vaccine isn’t that great. We switched to a new pertussis vaccine in the 1980’s because the old one had a high rate of side effects. The newer vaccine contains only certain parts of the pertussis bacteria, and no actual cells (called an “acellular” vaccine). It was a trade-off. The incidence of adverse effects dropped significantly, but so did the vaccine’s effectiveness.

But, let’s be real–it’s not all the vaccine’s fault. The anti-vaccine movement has resulted in record-low immunization rates, as parents have decided for a variety of reasons not to immunize their children. Coupled with a relatively weak vaccine, declining immunization rates have resulted in a resurgence of pertussis. We’ve seen several recent outbreaks, usually in areas of high vaccine exemption rates (surprise!). And, in the past 6 months, two infants have died from this disease.

It was starting to look like pertussis wasn’t going away any time soon. But a recent bill in California (a state with a history of high vaccine exception rates, as well as a high rate of vaccine-preventable disease outbreaks) may change that trend. The bill, known as SB277, eliminates “religious” and “personal belief” exemptions for children who attend public or private schools. The bill has sparked a heated debate about personal liberty and religious freedom (although I’m unaware of any major religion that discourages vaccines). Despite vocal–and sometimes violent–protests, the bill has been passed by the California Senate and Assembly, needing only the governor’s signature to become law. SB277 would make California one of three states that doesn’t allow these exemptions, and it may pave the way for other states to pass similar bills.

I understand the opposition. Parents feel like they should have absolute freedom to choose which medical treatments their children receive. (Although, to be fair, SB277 does allow them to decline vaccines–just not to send unvaccinated children to schools.) There are a variety of reasons parents don’t want to immunize their children, some more misguided than others. But sometimes, choices affect more people than those who make them; in those cases, the personal liberty argument gets dicey. Legally, there’s pretty solid precedent that one’s personal liberties end where harm to others begins.

Honestly, I wish we didn’t need bills like this. I wish that parents would listen to the doctors who know about these diseases and how to prevent them. I wish parents would choose to protect their children, as well as other children who can’t be immunized. I wish that all of our vaccines were 100% effective and never caused any side effects. I wish a lot of things. But, when kids are dying from preventable diseases, it’s time to stop wishing and start doing something. Their parents agree.