A couple weekends ago, something of a firestorm erupted among skeptical bloggers. Namely, the news about parents sending pox-laden lollipops through the mail. It was covered by Mike the Mad Biologist, Emily Willingham, Reuben, Tara Smith, Orac and Phil Plait. Largely, the various bloggers, myself included, condemned the parents in the original story because they were knowingly sending infectious material in the mail.
Some folks in the comments of the various articles made the observation that every day, people lick envelopes, handle packages in perhaps less than sterile conditions and so, perhaps unwittingly, leave unintended presents for the recipients, not to mention the delivery personnel. How is that any different from what these parents have done?
First off, I will readily admit that what the parents were doing probably would not lead to anyone contracting chicken pox. Since the virus does not remain viable for very long at all in the environment, it would most likely be rendered harmless given the amount of time it takes the package to be mailed. Even if the pox package managed to reach its target quickly, fomites like lollipops and spit-soaked rags also are unlikely to cause an infection, as the virus is primarily spread via the respiratory system. The oral route is a bit rough on the bug, and it would likely be destroyed before it could actually cause an infection.
That caveat aside, there is still the issue of other viruses and bacteria that may have hitched a ride on the fomites. Other diseases, like Hepatitis A (PDF), have a certain predilection for getting into you via your mouth. In the case of Hep A, making matters worse is that under the age of 6 years, those infected with the virus are likely to show no symptoms at all. That means that some of these parents may not realize their child even has the disease at all, and so they do not take any manner of precautions to reduce the chances of sending anything other than the varicella virus.
But what about licking envelopes? Doesn't that carry the same risk?
Well, for the recipient, not really. It's unlikely that they are in the habit of sucking on envelopes. There may be some small, minute chance, of course, that touching your nose or mouth after handling the mail could introduce some pathogen into your body. However, with the package contents, the whole point is to suck on the lolli, rag or toy. The recipients are intentionally increasing their own odds (well, the odds of their child, since they're making the decision for someone other than themselves) getting sick from something in the package.
As for the mail carriers, it is a little more difficult to judge the danger. Although they are unlikely to come in contact with the contents of the package, there is a risk that the packaging will be damaged in some manner, thus exposing the carrier to whatever lies inside. That risk is generally not there with everyday mail; I don't know about you, but I don't think most people are in the habit of sending used suckers or damp rags in the mail. True, as with the recipients, there is some small risk, regardless of package contents, that there may be some sort of surface contamination that may cause an infection if the carrier touches their mouth or, something they are at a bit higher risk for, gets a paper cut.
So yes. Admittedly there is very likely the unwitting transfer of infectious agents on envelopes and boxes mailed around the world every day. Where the recent story differs from the every day handling of mail, though, is in intent. The parents know that they are putting infectious material in the mail. They intend that some other person will become infected with the disease they are sending. Furthermore, as evidence by posts on the Facebook group that started this whole brouhaha, they also know that it is against the law to do what they are doing, going so far as to recommend ways to skirt the law (e.g., don't put anything on the label or outside of the package indicating that there is infectious material inside).
When you get down to it, that element, intent, is what separates what people do each day from the criminal activities of this group of parents. In our every day lives, we take reasonable precautions to avoid transmitting diseases. One of those precautions is to avoid knowingly sending contaminated and infectious materials in the mail.