AIDS: Back to School

Aliases: acquired immunodeficiency syndrome, AIDS

The 20th century was a veritable hit parade of medical breakthroughs: antibiotics were discovered in 1928, the polio vaccine was developed in 1952, and a suite of other vaccines were created that saved us from once life-threatening illnesses, such as rubella and tetanus. To top things off, smallpox was declared officially eradicated in 1980 (see my October post for more on smallpox). We were feeling a bit smug. That didn’t last long. In 1981, AIDS was identified. Over the last thirty-three years, the AIDS epidemic has taught us a great deal about disease, but it’s most important lesson may be that, despite our growing knowledge, there is still much to learn.

The initial outbreak of AIDS was terrifying, in part because we didn’t know what we were seeing. It was difficult to identify AIDS as a single unique disease, because people who develop AIDS don’t die from it. That seems impossible, but AIDS only weakens the body’s defenses, leaving patients vulnerable to infections that hit them while they’re down, taking advantage of their ravaged immune systems. Consequently, patients died of a range of other illnesses, which made linking the deaths more challenging. AIDS also appeared to come out of nowhere, because patients can seemingly remain healthy for over a decade after contracting the disease (see the Consequence section below). Unraveling the biology of AIDS has given us a crash course in the importance of retroviruses (rapidly evolving RNA viruses; HIV-1 evolves about one million times faster than mammalian DNA) and zoonotic diseases (diseases that emerge from non-human animal reservoirs; AIDS came from non-human primates)2.

AIDS has also delivered a brutal lesson in humility. Despite our best efforts, HIV (the virus that causes AIDS) has infected 60 million people and killed more than 25 million worldwide since it’s discovery2. In 2012, there were approximately 2.3 million new HIV cases and 35.3 million people were infected. The majority of these were in sub-Saharan Africa, where HIV afflicts 1 out of every 20 adults. Perhaps more than any other illness, AIDS has illustrated the importance of information. In the US alone, there are about 50,000 new HIV infections each year and about 1.1 million people are living with the virus- a shocking 16% of which do not know they have it1.

aids
Knowledge is power.

Cause: AIDS is caused by the human immunodeficiency virus (HIV), which is transmitted person-to-person through contact between the mucous membranes or damaged tissue of a healthy person and the bodily fluids (blood, semen, pre-seminal fluid, breast milk, and rectal and vaginal fluids) of an ill person. This most commonly occurs during sex; anal and vaginal sex are the highest risk behaviors for the spread of HIV. Sharing injection drug syringes is also high-risk. HIV is not spread by saliva, tears or sweat, and does not survive long outside the body, so it is not spread by environmental contamination. Unfortunately injury can be added to injury; there are multiple strains of HIV, and it is possible to be infected by more than one, resulting in a superinfection1.

Consequence: Most people do not immediately experience symptoms from an HIV infection; in fact, symptoms may not emerge for over a decade. Early symptoms sometimes occur 2 to 4 weeks after infection, and resemble the flu. This is the first stage of infection, called acute infection. The second stage, chronic HIV infection, is asymptomatic (symptomless), and may last several decades if the person is receiving treatment. Although they are not overtly ill, the HIV is still active, just reproducing at low levels. The third and final stage of an HIV infection is AIDS, when the patient’s CD4 cells (white blood cells that are a critical piece of the immune system) drop from the normal 500-1600 cells per cubic millimeter of blood to 200 cells/mm3, indicating that the immune system is badly damaged. Once this occurs, infections and infection-related cancers, collectively referred to as opportunistic illnesses, will afflict the ill person. Patients typically live 3 years after an AIDS diagnosis1.

Cure: Antiretroviral therapy (ART), a cocktail of antiretroviral drugs (medicine targeting retroviruses), is used to treat HIV. Although patients should be treated for related opportunistic illnesses, there is no treatment for AIDS. Despite the amazing medical advances since the discovery of HIV, 15,500 people died of AIDS in the US in 20101. The best defense truly is a good offense, and the best cure for AIDS remains good prevention. Use condoms (see my February post for more information). Get tested (but wait 6 weeks after the possible exposure, otherwise an infection may go undetected); it’s easy, relatively painless, and in most cases very cheap or free.

To find the testing center closest to you confidentially, text KNOWIT (566948) to or call 1-800-CDC-INFO (1-800-232-4636).

References

  1. HIV/AIDS. Centers for Disease Control and Prevention. 28 July 2014. Web. 16 September 2014. http://www.cdc.gov/hiv/basics/transmission.html
  1. Sharp, PM, & BH Hahn. (2011). Origins of HIV and AIDS Pandemic. Cold Spring Harbor Perspectives in Medicine.

Image source: The Stigma Project, http://www.thestigmaproject.org

Vaccination and Education: Ready for School

I’m not going to play games: I am pro-vaccine. This post is not meant to persuade anyone skeptical of vaccines to suddenly support their use (although it will enumerate some of the great things about vaccines), but rather to explore the relationship between vaccines and education, this month’s theme. However, I fully expect that my bias in favor of vaccination will pervade the following paragraphs. Consider yourself duly warned.

Vaccination and schools

There is a direct connection between vaccination and education. Vaccination helps make education in its modern incarnation possible; it contributes to the social and economic stability that our educational system requires to function. Globally, vaccines prevent an estimated 6 million deaths per year1, and untold incidences of disease. Vaccines accomplish this feat not only by protecting the vaccinated, but also through something called (unflatteringly, it must be said) herd immunity or herd protection.

vaccination
That’s us, ya’ll.

Herd protection works by insulating the unvaccinated with the vaccinated. If enough people who are immune surround a person who is vulnerable, the likelihood of disease transmission will plummet. Vaccination benefits the population at large, immunized and not, and is a foundational concept in public health (organized efforts to prevent disease, promote health, and prolong life). In the western world, there are now more than 10 vaccines recommended for infants2. By immunizing as many people as possible, as early as possible, public health initiatives are literally creating a human shield for the unprotected. This added level of safety is one reason we can house thousands of students in one building without regular epidemics.

Vaccines not only keep students well and in class, they grant more people access to education. Vaccination reduces social inequality by improving the health of the populations most affected by disease, those in poverty. Increasing vaccinations also reduces gender disparities. Decreasing child mortality leads to a decrease in birth rates, and when women have fewer children they are more likely to pursue education1.

The economic impact of vaccines is nothing to sneeze at either. Worldwide, vaccines save the equivalent of tens of billions of dollars (US) per year1. That’s billions, with a b, that can be reallocated to other governmental initiatives, like… education.

Vaccination and disease education

The controversy surrounding childhood vaccination is a great example of a strange dichotomy in the way we educate ourselves about disease. A paper published in The Lancet (Wakefield et al. 1998), a premier medical journal, was a critical catalyst for the anti-vaccine movement. The article was hotly debated and eventually retracted. But despite its inaccuracy, its central argument for a connection between autism and the MMR (measles, mumps, and rubella) vaccine has endured.

This approach tacitly acknowledges that medicine is a science. However, it stops short of embracing what that really means. Science demands both evidence and open-mindedness. Science isn’t one paper, it is a dialogue between debating parties. The same (il)logic has fueled the rise of web-based self-diagnosis. Let me be clear, knowledge is power, and I think educating yourself is great, but searching the internet is not a surrogate for talking to a doctor. It remains an excruciating and infuriating reality of illness that there are often no simple answers or ready solutions on hand.

Our ignorance about the human body can come as a real kick in the teeth when you’re sick, when you’re scared and in pain, and more than anything you just want to know what’s wrong with you and how to fix it. I’m as sorry as anyone (everyone, I’d imagine) that that’s true, but here we are. We have a choice when we encounter disease: we can either cherry-pick information or we can join an on-going scientific conversation. There is satisfaction in certainty, regardless of its accuracy, but I like to think it’s not nearly as gratifying as rejecting the assurance of blame in favor of knowledge.

References

1. Andre, FE, R Booy, HL Bock, J Clemens, SK Datta, TJ John, BW Lee, S Lolekha, H Peltola, TA Ruff, M Santosham, and HJ Schmitt. (2008). Bulletin of the World Health Organization 86(2):81-160.

2. Rappuoli, R. (2011). Twenty-first century vaccines. Philosophical Transactions of the Royal Society B 366:2756-2758.

Image credit: By Manokaran M (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons