Although the available evidence cannot exclude with certainty contaminated polio vaccines as the source of the AIDS pandemic, the balance of evidence argues against it—contaminated vaccines do not appear to have been responsible for what is shaping up to be one of the worst pandemics in human history. Does this conclusion mean that we do not need to worry about vaccines as a source of emerging disease? No. Vaccine contamination has already shown its ability to cause outbreaks of nasty viral diseases. As the United States was playing catch-up during its first year in World War II, a yellow fever vaccination program inadvertently infected over a quarter million soldiers with the hepatitis B virus. Fifty thousand became sick, but they got a lucky break. Apparently, when the hepatitis B virus infected people through this vaccine, it generated a fantastically low number of carriers and thus almost no chronic hepatitis and no liver cancer. Otherwise the vaccination might have caused around ten thousand deaths among the soldiers, and perhaps many more as the virus continued to spread through their contacts.Now, more than a half century later, vaccine researchers are still nervously watching a contaminant of polio vaccines: simian virus 40 (SV40), the virus that lent credibility to the polio vaccine hypothesis for the origin of AIDS. SV40 naturally infects the monkey cells in which the polio vaccine viruses were grown. Safety experts knew it was there but were not particularly concerned about it because it was not known to be harmful to humans. Their level of concern changed in the early 1960s when experimental studies showed that the virus could cause lung and brain cancer in hamsters. The virus was expunged from the vaccines by the mid-1960s, but that was too late for those of us who were vaccinated between 1955 and 1963. In the United States “those of us” make up about one third of the population. No one knows yet just how bad SV40 is. We are now the experimental hamsters being studied to obtain the answer. We do know that SV40 is found in most cases of a rare, dangerous lung cancer called mesothelioma, which has been increasing in the United States, Britain, and Europe since the use of SV40-contaminated vaccines. This is the same kind of lung cancer that SV40 causes in hamsters. The virus sabotages the same defenses against cancer that are sabotaged by papillomaviruses: p53 and a protein known as retinoblastoma suppressor. The emerging consensus is that SV40 is not just an innocent bystander but is causing the human mesotheliomas in concert with asbestos. SV40 is also found in human brain tumors. Whether it causes brain tumors is still being debated, but its activity in these cells is not comforting: as in the mesotheliomas, SV40 was found in human brain tumors bound to the cells’ tumor-suppressing proteins.The role of SV40 in human cancer will become more apparent as the experiment on the human hamsters continues. The most recent studies indicate that those who received the vaccine are about twice as likely to develop mesothelioma; the risk of the particular brain tumor most associated with SV40 appears to be increased by about one third in vaccine recipients.If SV40 does not get transmitted from person to person, then the cancer caused by SV40 contamination of polio vaccines can be viewed as another it-could-have-been-worse lesson imparted by the vaccine practices of the twentieth century. But the potential for transmission of SV40 between people is unclear. It has been recovered from children and HIV-infected patients who were born after SV40 had been purged from polio vaccines. The source of these SV40 infections is unknown, but if the virus is transmissible from person to person, our lesson may be just beginning. Concern is heightened because SV40 is a polyomavirus, a kind of virus that includes two other members, called JC and BK, which are full-fledged human pathogens. Most people are infected, for example, with JC polyomavirus, which resides in the brain and other organs. The scope of its effects are not yet clear, but it has recently been linked to colon cancer.Though vaccine contamination is frightening, in the long run it will probably turn out to be preventable, as soon as the people responsible for vaccine safety know what infectious contaminants to look for. This goal could be reached in time to benefit our grandchildren or great-grandchildren. In the meantime, we can expect that molecular techniques for identifying unwanted hitchhikers will provide incremental advances toward this goal.*41\225\2*


The teacher has called and says Lisa is daydreaming in school. You have noticed some episodes of “daydreaming” at the dinner table. Does she have absence seizures? Does she have atypical absence seizures? Does she have complex partial seizures or is she daydreaming?The questions your physician will want to ask you about Lisa are:• “How frequently is she having these episodes?” Daydreaming would occur infrequently and be situational. Absence seizures may occur many times a day. Complex partial seizures rarely occur more than several times a day or a week.• “How do these episodes begin?” While most seizures have an abrupt onset, occasionally complex partial seizures begin slowly and a warning precedes them. Daydreaming usually does not start abruptly.• “Can you interrupt these episodes?” Daydreaming can easily be interrupted by calling Lisa’s name or by physically touching her. Seizures, on the other hand, cannot be interrupted.• “How long does the episode last?” Daydreaming can go on until something else catches a child’s attention. Absence seizures rarely last more than fifteen seconds. Complex partial seizures may last up to several minutes.• “What does the child do during the episode?” While daydreaming or during absence seizures, the child is likely to stare into space. During complex partial seizures, the child is likely to smack her lips, pick at her clothes, or display other automatisms.• “What is the child like when she ‘comes back?’” The child who is daydreaming or having an absence seizure immediately is alert. The child with a complex partial seizure is usually confused for seconds or minutes.• “Does the child remember what was said during the episode?” While daydreaming, the child may be aware of what is happening but not pay attention. During a seizure, the child is not fully aware of what is happening around her.• “Do the spells occur only at special times?” If they happen only, say, in math or geography class, the child is likely to be daydreaming. If they occur at random times or whenever the child is tired, they are more likely to be seizures.With these careful observations, you and your physician can usually differentiate the type of episode.*73\208\8*


lthough lung cancer rates have dropped among white males during the past decade, the rate among white females and black males and females has begun to slow, but still continues to be a pervasive threat. Lung cancer caused an estimated 164,000 deaths in 2000. Since 1987, more women died from lung cancer than from breast cancer, which for over 40 years had been the major cause of cancer deaths in women. Today, lung cancer continues to be the leading cancer killer for both men and women. As smoking rates have declined over the past 30 years, however, we have seen significant declines in male lung cancer. But these rates are not dropping as quickly among women. Another cause for concern is that although adult smoking rates have declined, tobacco use among youth is again on the rise.Symptoms of lung cancer include a persistent cough, blood-streaked sputum, chest pain, and recurrent attacks of pneumonia or bronchitis. Treatment depends on the type and stage of the cancer. Surgery, radiation therapy, and chemotherapy are all treatment options. If the cancer is localized, surgery is usually the treatment of choice. If the cancer has spread, surgery is used in combination with radiation and chemotherapy. Unfortunately, despite advances in medical technology, survival rates for lung cancer have improved only slightly over the past decade. Just 13 percent of lung cancer patients live five or more years after diagnosis. These rates improve to 47 percent with early detection, but only 15 percent of lung cancers are discovered in their early stages of development.
Prevention Smokers, especially those who have smoked for over 20 years, and people who have been exposed to certain industrial substances such as arsenic and asbestos or to radiation from occupational, medical, or environmental sources are at the highest risk for lung cancer. The American Cancer Society estimated that in 2000, over 430,000 cancer deaths were caused by tobacco use and an additional 20,000 cancer deaths were related to alcohol use, frequently in combination with tobacco use. Exposure to sidestream cigarette smoke, known as environmental tobacco smoke or ETS, increases the risk for nonsmokers. Some researchers have theorized that as many as 90 percent of all lung cancers could be avoided if people did not smoke. Substantial improvements in overall prognosis have been noted in smokers who quit at the first signs of precancerous cellular changes and allowed their bronchial linings to return to normal.*14/277/5*