Pertussis (Whooping Cough) and Diphtheria

If you’d ever heard an infant with pertussis (whooping cough) it isn’t something you’d quickly forget. Infants are at particularly high risk for complications from pertussis, with the highest percentage of severe complications occurring in children less than six months of age.

• Pertussis is extremely contagious and passed person to person through the air in droplets.
• Immunity wears off. Getting pertussis either from natural exposure or from a vaccine does not provide lifelong immunity. Adolescents and adults need boosters. Make sure those around your baby have gotten theirs.
• Infants are at the greatest risk for pertussis because they are not protected until they have received at least 3 doses of the vaccine. Sadly, 83% of deaths from pertussis occur in babies under 3 months.

Pertussis is a very contagious disease caused by the Bordetella pertussis bacterium. These bacteria make us sick by producing toxins which paralyze the cilia (tiny hairlike extensions) in the respiratory tract and cause inflammation.

Initially a person with pertussis may have only mild symptoms, runny nose, sneezing, fever and a mild cough, much like a cold. In adults, those may be the only symptoms of pertussis. Symptoms usually develop within 7–10 days after being exposed, but sometimes as long as 6 weeks after exposure. –CDC

As the disease progresses the cough becomes much more severe with bouts of coughing followed by a “whooping” sound as the person tries to inhale.

Treatment for pertussis is generally limited to supportive care. Antibiotics are sometimes given to reduce the transmission of the Bordetella pertussis bacteria from an infected person’s secretions. But in general, antibiotics are not likely to affect the course of the illness unless given early on. A person with pertussis can be sick for months.

The most common and fatal complication of pertussis is bacterial pneumonia. Other complications include seizures, ear infections, dehydration and rib fractures (primarily in the elderly) from coughing.

Pertussis Cycles

Pertussis has a natural tendency to cycle every 3–5 years, with higher numbers of reported cases during some years and in various states. For example, in 2011 there were 18,719 cases of pertussis in the US; in 2012 there were 41,880 cases (the highest number since 1955). There were 18 related deaths, of which 13 were infants under 3 months of age. (Link to pdf provisional pertussis surveillance report). But in 2010 there were about 27,000 cases reported in the US. Nine thousand of those cases were in California, and 10 infants in CA alone died that year. The pattern of epidemics is still not completely understood.

Pertussis is often underreported because it varies in its severity across all age groups. It is also often underdiagnosed or misdiagnosed. It is estimated that in most years, between 600,000 to 900,000 cases occur in adolescents and adults. –CHOP

Diphtheria is a very contagious and potentially life threatening bacterial infection that affects the throat and nose. It is spread by coughing or sneezing. Due to routine vaccination diphtheria is now a rare disease in the US. However, it remains a common disease in some countries. For example, in Russia, where vaccination rates have decreased, there has been a significant increase in the number of cases. Diphtheria is especially dangerous for children under 5 years of age and adults older than 40.

Pertussis vaccines are the most effective tool to prevent pertussis, but no vaccine is 100% effective. That doesn’t mean the vaccine doesn’t work. It just doesn’t work 100% of time. That’s why we need high levels of vaccination in a community to prevent the disease from spreading. If pertussis is circulating in the community, there is a chance that a fully vaccinated person can catch this very contagious disease. Infection is usually less severe in those that have been vaccinated. If you or your child develops a cold that includes a severe cough or a cough that lasts for a long time, it may be pertussis.

Diphtheria, tetanus and pertussis are 3 separate bacterial diseases that the DTaP and Tdap vaccines protect against. These vaccines contain inactivated forms of the toxin produced by the bacteria. The Td vaccine protects against diphtheria and tetanus only.

Who gets which, when and how much is a little complicated. We think the Children’s Hospital of Philadelphia (CHOP) has done a nice job explaining the differences. The following information comes from that source.

DTaP: The DTaP vaccine is given to infants and young children in a series of 5 shots, at 2 months, 4 months, 6 months, 15 to 18 months and again at 4 to 6 years of age.

Tdap: The Tdap vaccine contains lesser quantities of diphtheria and pertussis proteins than the DTaP. The Tdap vaccine is recommended for most people 11 years and older who have not previously received it.

• Adults who are going to be around infants, including those who are 65 and older.
• Those 65 and older who have not had Tdap previously.
• Pregnant womenshould get one dose of Tdap vaccine between 27 and 36 weeks’ gestation during each pregnancy.
• Children ages 7–10 who aren’t fully vaccinated or never vaccinated against pertussis should get a single dose of the Tdap vaccine.
• Teens 13–18 who haven’t gotten the Tdap vaccine yet should get a dose, followed by a booster of tetanus and diphtheria (Td) every 10 years.

Td: The Td vaccine is the one people commonly think of when they think of getting their tetanus booster. Previously it was recommended that adults receive this vaccine every 10 years. It is likely that the Td version will eventually be replaced with Tdap for the 10-year booster doses; however, this has not happened yet as studies are being completed to make sure this is both safe and effective. –CHOP

Mild Problems (Common)

• Fever (up to about 1 child in 4)
• Redness or swelling where the shot was given (up to about 1 child in 4)
• Soreness or tenderness where the shot was given (up to about 1 child in 4)
• Fussiness (up to about 1 child in 3)
• Tiredness or poor appetite (up to about 1 child in 10)
• Vomiting (up to about 1 child in 50)

These problems occur more often after the 4th and 5th doses of the DTaP series than after earlier doses.

Moderate Problems (Uncommon)

• Seizure (jerking or staring) (about 1 child out of 14,000)
• Nonstop crying for 3 hours or more (up to about 1 child out of 1,000)
• High fever over 105°F (about 1 child out of 16,000)

Severe Problems (Very Rare)

Serious allergic reaction (less than 1 out of a million doses). Other severe problems have been reported after DTaP vaccine, including: long-term seizures, coma and permanent brain damage. These are so rare it is hard to tell if they are caused by the vaccine.

• Pain (about 3 in 4 adolescents and 2 in 3 adults)
• Redness or swelling at the injection site (about 1 in 5)
• Mild fever of at least 100.4°F (up to about 1 in 25 adolescents and 1 in 100 adults)
• Headache (about 4 in 10 adolescents and 3 in 10 adults)
• Tiredness (about 1 in 3 adolescents and 1 in 4 adults)
• Nausea, vomiting, diarrhea, stomach ache (up to 1 in 4 adolescents and 1 in 10 adults)
• Chills, body aches, sore joints, rash, swollen glands (uncommon)

In the mid-1990s the whole cell pertussis vaccine (DTP) which was very effective but also had both mild side effects (fever, vomiting, and soreness at injection site) and severe side effects (inconsolable crying, and seizures related to fevers) was dropped from routine use in the US. No evidence has shown that the seizures caused any long-term damage, but they were frightening and thus motivated scientists to develop a better vaccine: the acellular pertussis vaccine.

“Whole cell” means just that: It used the complete Bordetella pertussis inactivated bacteria. Unfortunately, the newer acellular pertussis (aP) vaccine, which uses only parts of the pertussis bacteria, offers less protection and wears off quicker than the previously used whole cell vaccine (DTP). So, a bit of efficacy (the ability to produce a desired or intended result) was traded for increased safety. The acellular vaccine which has been used since 1996 is the best protection we have until a better vaccine is developed.

“In general, DTaP vaccines are 80–90% effective. Among kids who get all 5 doses of DTaP on schedule, effectiveness is very high within the year following the 5th dose… There is a modest decrease in effectiveness in each following year.” –CDC

So why bother? The current vaccine isn’t perfect, but it is safe, and it does help to prevent pertussis infections not only in children and adults but also in those who can’t be vaccinated. More people vaccinated means improved community immunity making it harder for the disease to spread. Also, immunization reduces the risk of getting pertussis and makes the illness less severe in those who do get it.

The benefits of the pertussis vaccine do not outweigh the risks.

You might hear this when people use outdated information referring to the old whole cell vaccine, but the current vaccine is safe.

Unfortunately, we have a countrywide example of what happens when people stop getting vaccinated. In 1975 the Japanese discontinued use of the whole cell pertussis vaccine (DTP) due to its high rate of side effects. (This is the vaccine that is no longer in use.) The previous year, in 1974, nearly 80% of Japanese children were vaccinated for pertussis. That year only 393 cases of pertussis (no related deaths) were reported in the entire country. After the vaccine was discontinued, cases rose dramatically. By 1976 only 10% of infants were getting vaccinated. In 1979 Japan suffered a major pertussis epidemic, with more than 13,000 cases of whooping cough and 41 deaths. –CDC

Risk of disease versus the risk of the vaccine? Ultimately, pertussis can and does kill, especially babies. No death has ever been connected to the vaccine. In addition about half of the cases of pertussis in infants under 1 year of age result in hospitalization. This is another example showing the cost of not getting a vaccine is not $0, as was recently stated by an Ashland author.

Herd immunity and cocooning will protect my children.

Well, yes and no. Herd or community immunity, is when enough people in a population are immune to a disease through vaccination or prior illness that the disease has difficulty spreading. This is how we protect individuals who are not vaccinated (such as newborns and those who have medical contraindications to vaccines). However, since pertussis spreads very easily and vaccine protection decreases over time, we can’t rely solely on herd immunity to protect everyone. This doesn’t mean community immunity doesn’t work, it just means we can’t rely on it 100%. The following explains why.

1. “Adult vaccination is an important part of community protection. However, fewer than 10% of adults have gotten their Tdap booster dose, so we can’t yet measure how well herd immunity could work for pertussis.” –CDC
2. Sometimes vaccinated people are exposed and get pertussis anyway. As stated above, the vaccine is only 80–90% effective. However, it’s important to remember that vaccinated people who get pertussis usually have milder symptoms, a shorter illness and are less likely to spread the disease to other people.
3. The safety and effectiveness of vaccines is constantly being studied. We now know from the last few pertussis epidemics in 2010 and 2012 that it was children aged 10–11 years that had the highest incidence of disease. This tells epidemiologists and vaccine researchers that the immunity provided by the vaccine wears off quicker than was previously thought. That was the tradeoff for having a vaccine with fewer severe side effects. However, changing the recommended immunization schedule is a difficult process and more research is required. We wouldn’t want to see changes to the schedule be made on a whim.

That being said, vaccines still provide the best protection against pertussis.

Pertussis can be treated effectively with antibiotics.

Antibiotics only help to prevent pertussis transmission; they don’t necessarily reduce the symptoms, such as the cough. Antibiotics may be used to treat bacterial pneumonia which is a common complication of pertussis.

DTaP vaccine causes sudden infant death syndrome (SIDS)

This confusion arose because a moderate proportion of children who die of SIDS have recently been vaccinated with DTaP. At first glance it seems like there could be a causal connection. But…

“If you consider that most SIDS deaths occur during the age range when 3 shots of DTaP are given, you would expect DTaP shots to precede a fair number of SIDS deaths simply by chance. In fact, when a number of well-controlled studies were conducted during the 1980s, the investigators found, nearly unanimously, that the number of SIDS deaths temporally associated with DTP vaccination was within the range expected to occur by chance. In other words, the SIDS deaths would have occurred even if no vaccinations had been given. In several of the studies, children who had recently gotten a DTaP shot were less likely to get SIDS. The Institute of Medicine reported that “all controlled studies that have compared immunized versus nonimmunized children have found either no association . . . or a decreased risk . . . of SIDS among immunized children” and concluded that “the evidence does not indicate a causal relation between [DTaP] vaccine and SIDS.” –CDC

This same sort of coincidence has fueled the MMR vaccine and autism debate. The developmental symptoms of autism become apparent at the same time the MMR is routinely given.

When someone has pertussis you will know it by their cough.

Many people with pertussis such as older children and adults may only have a mild but persistent cough. They may not make that classic whooping sound. This is especially true if there is a past history of whooping cough or the person is fully immunized for their age.

Why is the focus on protecting infants from pertussis?

Infants are those most at risk for getting and suffering severe complications from pertussis. We can protect infants until they’re old enough to receive vaccines using two tactics.

First, is to vaccinate pregnant women with Tdap during each pregnancy (at 27 through 36 weeks). Mothers who are vaccinated in pregnancy build antibodies that are transferred to the newborn. They can provide the infant some protection against pertussis before the baby can start getting their DTaP vaccines at 2 months old. Vaccinating moms also makes it less likely that they will transmit pertussis to their infants.

The second tactic is often referred to as “cocooning.” This is a strategy of protecting infants from pertussis by vaccinating those in close contact with them. This includes parents, siblings, grandparents (including those 65 years and older), other family members, babysitters, etc. They should get the age-appropriate vaccine (DTaP or Tdap) at least 2 weeks before coming into close contact with the infant. Cocooning works best in conjunction with maternal vaccination to provide maximum protection to the infant.

Effective cocooning is very difficult to achieve.

AAP: The Red Book

CDC

Children’s Hospital of Philadelphia

History of Vaccines

Deville JG, Cherry JD, Christenson PD, et al. Frequency of unrecognized Bordetella pertussis infections in adults. Clin Infect Dis. 1995;21(3):639-642.

Edwards KM. Overview of pertussis: focus on epidemiology, sources of infection, and long term protection after infant vaccination. Pediatr Infect Dis J. 2005;24(6):S104-S108.

Jardine A, Conaty SJ, Lowbridge C, Staff M, Vally H. Who gives pertussis to infants? Source of infection for laboratory confirmed cases less than 12 months of age during an epidemic, Sydney, 2009. Commun Dis Intell. 2010;34(2):116-121.

Murphy TV, Slade BA, Broder KR, et al. Prevention of pertussis, tetanus, and diphtheria among pregnant and postpartum women and their infants: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2008;57(RR-4):1-50.

Wendelboe AM, Njamkepo E, Bourillon A, et al. Transmission of Bordetella pertussis to young infants. Pediatr Infect Dis J. 2007;26(4):293-299.