Working to End HIV

Could HIV soon follow in the footsteps of smallpox and polio?  On The Pump Handle, Sara Gorman says that recent research has “allowed political figures such as Secretary of State Hillary Clinton to proclaim that the phenomenon of a generation without HIV/AIDS is within reach.”  But no vaccine has proven effective at curtailing HIV infection, and a new prophylactic called Truvada could select for drug-resistant versions of the virus.  On ERV, Abbie Smith explains that researchers have traced the origin of HIV to a single population of chimpanzees in West-Central Africa, thanks to “3108 samples of monkey poop.”  Chimps elsewhere carry similar loads of immunodeficiency virus, but their variants are not fit to infect humans.  Until we can stop HIV, can we slow it down without further enhancing its fitness?

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All Arms on Deck

On The Pump Handle, Anthony Robbins discusses his tenure at NIOSH, the World Health Organization’s drive to vaccinate people around the world, and the fallout of the CIA’s decision to use a vaccination program as a subterfuge for spying operations in Pakistan.  Robbins writes, “WHO had hoped to complete global polio elimination by 2005, but local armed conflicts and rejection by religious fundamentalists slowed polio campaigns in Nigeria and in Pakistan.”  Now, the CIA’s actions have likely exacerbated distrust of vaccines, which festers abroad as well as at home.  Robbins writes that no vaccine is fully effective, but herd immunity can protect weak responders.  Yet when some people refuse vaccines, herd immunity starts to fall apart.  Robbins concludes, “This is why vaccination is a community decision based on weighing costs and benefits, not an individual decision.”  Meanwhile, Orac deconstructs the fall and rise of pertussis infections in America.

Genetic Mutability

We’ve all heard of bird and swine flu, but bats, which comprise “about a fifth of all known mammalian species,” also carry a diverse host of viruses. By swabbing the rectums of little yellow-shouldered bats, researchers in Guatemala discovered a new influenza virus that defies easy classification. Flu viruses are described by two key genes—hence the name ‘H1N1.’ Tara C. Smith writes “The novel bat virus was a completely new H type—type 17 (provisional, they note, pending further analyses). The NA gene was also highly divergent.” Smith continues “the authors did do some molecular work suggesting that these novel bat viruses could combine with human viruses and form a functional recombinant virus.” It’s only a matter of time. Meanwhile Abbie Smith explains why some individuals won’t develop immunity from a vaccine. She writes “Measles needs a protein on the surface of your cells in order to successfully mediate infection: CD46.” The virus must interact with this protein to infect a cell, but antibodies generated by a vaccine get in the way. Looking at the CD46 gene, researchers found that “children who had mutations at the right spot, in a particular flavor, seemed to respond better than others. But if a child had a mutation at the right spot, but not a mutation of the right flavor, they didnt respond as well.” Luckily, herd immunity can protect non-responders—as long as everyone else gets vaccinated too.

Vaccine Varieties

On The Pump Handle, Liz Borkowski examines the ethical dilemma of testing the anthrax vaccine in children. If a widespread attack were to occur, we would want to know the safety and efficacy of the vaccine beforehand. But is an attack likely enough to warrant testing the vaccine on children? On ERV, Abbie Smith explains how vaccines are made: “Sometimes we use dead viruses. Sometimes we use crippled viruses. Sometimes we dont need to use whole viruses at all—little chunks of the virus are fine. Sometimes we just need chunks of the virus, but we keep them dressed up in hollow membranes.” Sometimes none of these approaches work (against diseases such as HIV, TB, and malaria). However a new vaccine against malaria may prevent about half of infections. Other vaccines can be nearly 100% effective. Such is the case with the HPV vaccine, which the CDC is now recommending for boys as well as girls. The vaccine protects against several variants of human papillomavirus, which can cause changes in a cell’s DNA that lead to cancer. In fact, from 2001 to 2004, HPV caused 71.7% of oral cancers. Finally, on Respectful insolence, Orac considers the efficacy of the flu vaccine, which reduces the infection rate from 2.7 out of 100 adults to 1.2 out of 100. Orac writes, “our current generation of vaccines are far from perfect, but they do pretty well and, given how safe they are, currently represent the best defense we have against influenza.”

Good Health for Haiti

Vaccines are a tried and true mechanism for controlling disease, but they are not always a magic bullet. Researchers who study the spread of cholera in Haiti recently modeled what would happen if 150,000 vaccines were administered in Port-au-Prince. They concluded “the benefits would have been negligible.” Liz Borkowski writes, “this intervention’s small effectiveness is due partly to the slow pace at which full immunity builds up and to the likelihood that many vaccine recipients would’ve already built up natural immunity.” A better way to control a water-borne disease like cholera is to nip it in the bud, as John Snow did in 1858. In Haiti, this means providing clean water, sanitation, and hygiene education. Mike the Mad Biologist clarifies, “The simple reason we don’t have shigellosis or cholera outbreaks in the U.S. is that we don’t have to drink our own shit.” He concludes, “Like I said, let’s build some sewers.”