Tag: typhoid fever

Which Vaccines Don’t Prevent the Spread of a Disease?

As most folks know, Dr. Bob Sears has been put on probation by the California Medical Board.

Most vaccines don't prevent the spread of diseases?
Most vaccines don’t prevent the spread of disease???

Surprisingly, that hasn’t kept him from posting dangerous misinformation about vaccines, including his latest idea that “most vaccines don’t prevent the spread of a disease.”

Which Vaccines Don’t Prevent the Spread of a Disease?

If vaccines don’t prevent the spread of disease, then how did we eradicate, eliminate, and control so many diseases?

Dr. Bob Sears actually reassured parents that measles wasn't deadly in developed countries, neglecting to mention the dozens of people who have died in outbreaks in Europe - another well-nourished population with lower vaccination rates than the U.S.
At least seven people have died in Italy with measles over the last few years. That’s not so good for Italy.

When was the last time you saw someone with small pox, rubella, diphtheria, or polio, for example?

It is true that vaccines don’t prevent the spread of some infections though.

There is tetanus, for example, but guess what?

Tetanus isn’t contagious.

Any others?

Well, unlike most other vaccines, the meningococcal B vaccines are not thought to decrease nasal carriage of the meningococcal B bacteria. So if you are vaccinated and an asymptomatic carrier of the bacteria, you could theoretically spread it to someone else, as could someone who is unvaccinated.

Still, the MenB vaccines can protect you from getting actual meningococcal B disease, and if you don’t have meningococcemia or meningococcal meningitis, you won’t expose and spread it to someone else. That’s why the MenB vaccines are especially useful in outbreak situations.

Any others? After all, Dr. Bob did say that “most vaccines don’t prevent the spread of a disease.”

Vaccines That Don’t Prevent the Spread of a Disease

There are a few other examples of vaccines that don’t prevent the spread of a disease.

“I also warn them not to share their fears with their neighbors, because if too many people avoid the MMR, we’ll likely see the diseases increase significantly.”

Dr. Bob Sears in The Vaccine Book

Of course, any vaccine that is delayed or skipped won’t work to prevent the spread of a disease.

Just like they are seeing measles outbreaks and deaths now, because of low vaccination rates, in Ukraine there were 17,387 cases of diphtheria and 646 deaths from 1992 to 1997. Also high, were cases of measles (over 23,000 cases in 1993) and pertussis (almost 7,000 cases in 1993).

And because of waning immunity, vaccines don’t do as good a job of preventing the spread of pertussis and mumps as we would like. Still, that’s only when the vaccines don’t work, and even then, as Dr. Bob says, they do work to reduce the severity of symptoms.  During recent mumps outbreaks, the rates of complications are far below historical levels. The same is true for pertussis.

Have you ever seen or heard an unvaccinated child with pertussis? It is truly heartbreaking, especially when you realize how easily it could be prevented.

We typically see the same thing with flu. Even when the flu vaccine isn’t a good match or isn’t as effective as we would like, it still has a lot of benefits, including reducing your risk of dying.

“IPV induces very low levels of immunity in the intestine. As a result, when a person immunized with IPV is infected with wild poliovirus, the virus can still multiply inside the intestines and be shed in the faeces, risking continued circulation.”

Inactivated poliovirus vaccine

Does the fact that IPV, the inactivated polio vaccine, can sometimes lead to infections and shedding mean that it doesn’t prevent infections?

Of course not!

“IPV triggers an excellent protective immune response in most people.”

Inactivated poliovirus vaccine

Most people vaccinated with IPV will be immune, won’t get wild polio, and so won’t be able to get anyone else sick.

Vaccines reduce disease by direct protection of vaccinees and by indirect protection of nonimmune persons. Indirect protection depends on a reduction in infection transmission, and hence on protection (immunity) against infection, not just against disease. If a vaccine were to protect only against disease, and not at all against infection, then it would have no influence on infection transmission in the community and there would be no indirect protection (vaccination of one person would have no influence on any others in the community). It would be possible to reduce disease with such a vaccine but not to eradicate the infection.

Plotkin’s Vaccines

But because IPV doesn’t provide indirect protection, we still use OPV in parts of the world where polio is more of a problem.

Vaccines work. Even the few that don’t prevent the spread of infections, still help to reduce disease.

What’s the Difference Between Infections and Disease?

Wait, is there a difference between infection and disease?

Yes there is, something that Dr. Bob, who actually wrote a book about vaccines, seems to have overlooked.

An infection is simply the presence of a virus, bacteria, or other organism in your body.

A disease, on the other hand, is a virus or bacteria in your body causing signs and symptoms.

All vaccines work to prevent disease, or at least they do when you actually get vaccinated.

A very few don’t prevent infections and the spread of infections, but that is not a good reason to skip or delay your child’s vaccines. In fact, it is one of the reasons why it is important to have high vaccination rates! Even natural infections don’t always keep you from becoming asymptomatic carriers that can infected others. Many people who have natural typhoid (remember Typhoid Mary?) and hepatitis B infections go on to become chronic carriers without any symptoms, but still able to infect others.

If you understand that a few vaccines don’t prevent the spread of infections, then you should understand that you can’t hide in the herd and expect to be protected, even though most folks around you are vaccinated.

What to Know About Vaccines and the Spread of Disease

Despite what Dr. Bob says, almost all vaccines work to prevent the spread of disease and infections, at least they do when you get your kids vaccinated.

More on Vaccines and the Spread of Disease

Typhus vs Typhoid Fever

Typhus and typhoid have both been in the news recently.

  • Texas officials issue alert about typhus threat
  • Typhoid: Two children die‚ 60 ill after drinking from contaminated stream in South Africa

Should you start panicking?

Of course not.

Even before they knew which bacteria actually caused typhus and typhoid fevers, they knew they were different diseases.
Even before they knew which bacteria actually caused typhus and typhoid fevers, they knew they were different diseases.

While neither is usually a threat to most people in developed countries, instead of panicking, get educated and learn how you can prevent these still common infections.

Typhus Fever

Epidemic typhus fever is spread by human body lice (not head lice!) that are infected with the Rickettsia prowazekii bacteria.

Symptoms of typhus fever can include the sudden onset of:

  • fever
  • muscle aches (myalgias)
  • headache
  • chills
  • not feeling well (malaise)
  • cough

Some patients develop a characteristic rash made up of small red spots (macules) that start on the upper trunk. It then spreads to the rest of the body, but spares the face, palms, and soles. The rash can eventually become petechial.

Untreated, the fever may last up to two weeks, followed by a slow recovery of two to three months for all of the other symptoms. Typhus fever can be fatal.

Fortunately, treatment is available – the antibiotic doxycycline.

How do you prevent epidemic typhus fever? You avoid body lice. And avoid flying squirrels, which can be infected with Rickettsia prowazekii bacteria.

Is typhus fever vaccine-preventable? No, although a typhus vaccine was once available, it was discontinued in 1979.

Keep in mind that in addition to epidemic typhus, which is now very rare, typhus can also be spread by fleas (murine typhus) and chiggers (scrub typhus).

Murine or endemic typhus is common in tropical and subtropical climates, where it is spread by rats and fleas. In the United States, it is mainly found in California, Hawaii, and Texas, where it has also been associated with cat fleas found on cats and opossums.

Scrub typhus is associated with chiggers in rural areas of Southeast Asia, Indonesia, China, Japan, India, and northern Australia.

Typhoid Fever

Although typhus and typhoid some very similar, there are some big differences between these two diseases.

What are they?

Unlike typhus, typhoid fever is:

  • caused by the Salmonella typhi bacteria
  • spread by ingesting contaminated food and water
  • characteristic by symptoms that include a gradual onset of fever, with stomach aches, headache, loss of appetite, and sometimes a rash.
  • still vaccine preventable – in fact, there are two typhoid vaccine, one oral and the other a shot

Fortunately, typhoid fever can be treated with antibiotics, although it is sometimes multi-drug resistant and some people become chronic carriers, even with treatment (Typhoid Mary).

While adventurous and fun, eating street vendor food is probably a good way to get typhoid fever.
While adventurous and fun, eating street vendor food is probably a good way to get typhoid fever. Photo by Sam Sherratt (CC BY-SA 2.0)

That it can still be treated is a good thing, because unlike epidemic typhus, typhoid fever is still very much around.

The CDC estimates that there are about 5,700 cases of typhoid fever in the United States each year, mostly in travelers that leave the country.

Worldwide, there are about 21 million cases of typhoid fever and 222,000 typhoid-related deaths each year!

In addition to getting vaccinated, if traveling to the developing world, to avoid typhoid, you should avoid risky food and be sure to “Boil it, cook it, peel it, or forget it.”

What to Know About Typhus and Typhoid Fever

Typhus and typhoid fevers are two very different diseases that can both be avoided with good hygiene practices.

More on Typhus and Typhoid Fever