Two recent stories highlight the good and the bad when it comes to infectious disease prevention.
The good
Death rates for vaccine-preventable diseases are at an all-time low:
The study, by the Centers for Disease Control and Prevention in Atlanta, and published in The Journal of the American Medical Association (link), is the first time that the agency has searched historical records going back to 1900 to compile estimates of cases, hospitalizations and deaths for all the diseases children are routinely vaccinated against.
In nine of the diseases, rates of death or hospitalization declined more than 90 percent since vaccines against them were approved, and in the cases of smallpox, diphtheria and polio, by 100 percent.
In only four diseases -- hepatitis A and B, invasive pneumococcal diseases and varicella (the cause of chickenpox and shingles) -- did deaths and hospitalizations fall less than 90 percent. Those vaccines are all relatively new -- the one for chickenpox, for example, was adopted nationally only in 1995. Also, some diseases like hepatitis typically strike adults, who are less likely to be immunized.
(More after the jump...)
However, while this is good news, they caution in the paper that "...there is a predictable inverse relationship between the levels of vaccine-preventable diseases and safety concerns, with safety concerns likely to emerge as first-hand experience with vaccine-preventable diseases decreases." Therefore, there's still much work to be done, as recent pertussis outbreaks in Wisconsin and Ohio demonstrate.
But while the burden of vaccine-preventable diseases has dramatically decreased, those which we can't vaccinate against linger.
The bad
Rates of gonorrhea, chlamydia, and syphilis are still on the rise:
Chlamydia and gonorrhea are the two most common diseases among those doctors must report in the United States. And the 1,030,911 cases of chlamydia in 2006 are the highest ever recorded for any nationally reported disease in any year, the officials said in releasing their annual report on sexually transmitted diseases. They said that because of underreporting, a more accurate estimate is 2.8 million new chlamydia cases annually.
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From 1975 through 1997 the reported rate of gonorrhea dropped 74 percent, then plateaued, only to rise the last two years to 358,366 cases in 2006. The centers estimate that at least twice that number actually occurred.
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Syphilis cases dropped to their lowest ever total in 2000 soon after health officials had announced a national syphilis elimination program.
But cases have risen each year since then to 9,756 cases in 2006. Most cases have involved gay men, who account for about 65 percent of cases, and to a lesser extent women. Also, a small number of cases have occurred among newborns.
Some of this rise, they note, is likely due to better detection and additional screening, but the LA Times story on the same topic suggests that "insufficient public health funds," and "a resurgence of risky sexual behavior in some groups" (coupled, they suggest, with increasing use of methamphetamines as well) has also played a role in the increases. This rise was particularly evident in gay and bisexual men, which made up 64% of the new cases of syphilis in 2006. However, due to lack of funding, many public health departments have had to stop or curtail partner notification programs, and reduce testing in high-risk populations such as jails and detention centers. Public health simply isn't a political priority, unfortunately.
There is some hope. Unlike herpes or HIV, syphilis, gonorrhea and chlamydia are all bacterial diseases, and can be treated with antibiotics. However, all can be asymptomatic or cause only mild symptoms, meaning treatment may be delayed (and allowing those infected to pass the infection along to sexual partners). Long-term infection in women with chlamydia, for example, can also lead to pelvic inflammatory disease and even infertility; and of course, untreated syphilis can lead to all sorts of complications, and can also infect newborns during birth.
The reduction in mortality due to vaccination shows how far we've come, but the rise in preventable sexually-transmissible diseases reflects just how far we've yet to go.
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I don't think we can really implicate the two pertussis outbreaks to low vaccine rates. The news accounts you linked to only mentioned two high schools and one middle school. The Wisconsin report even states all the cases have a history of vaccination. It's well-known that the vaccine's protection is just about gone by the time a child hits middle school, so the affected population's vaccine rates are probably not an issue unless you're looking at their rates for the new Tdap vaccine. Frankly, I'm surprised neither news report mentioned the availability of the Tdap vaccine and suggesting to their readers to -- as the other drug commercials always state -- ask their doctor if Tdap is right for them.
With pertussis it isn't so much low rates (although that has played a role in some outbreaks in areas with low vaccination rates), but also waning immunity to the bacteria that occurs over time. I agree, these outbreaks aren't necessarily due to low vaccine coverage, but they highlight the fact that the bacterium is still out there in the community causing disease, so we need to be vigilant.
If I recall correctly, chlamydia lowers fertility. I wonder if it is possible to calculate how many fewer children are born in this country each year because of it?
Because syphilis, gonorrhea and chlamydia are all due to bacterial infections, do you believe because of the increase in antibiotic resistant bacterial strains, we could see this happening among STI's?