In the years before vaccines were available to protect people from measles (rubella, rubeola), mumps (infectious parotitis) and chickenpox (varicella), epidemics of these diseases happened every three or four years. Children were routinely exposed within the family, or even in the neighborhood, to provide lifelong immunity to the next epidemic. Mortality among healthy children was rare enough that parents were not concerned about deliberately exposing their children. So rare was a person who escaped exposure that it is even today generally assumed that adults born before vaccines were used are already immune.

I was until recently one of those individuals who had not been exposed to chickenpox. My work doesn't involve contact with children, so I did not think that, in my mid-60s, I could possibly be at risk. A little more knowledge about these not-so-benign viral infections could have saved me a bout of serious illness and possible disfigurement of my face.

Measles and chickenpox are cited by the Merck Manual as the most contagious of all infectious diseases. The manual's list of viral infections includes measles (rubeola), rubella (German measles), chickenpox (varicella) and mumps. Most hospitals use isolation and negative air pressure to prevent any escape of the airborne viral droplets from the patients with chickenpox or measles—serious precautions similar to those used in cases of pulmonary tuberculosis and the Ebola-Marburg virus. Nonimmune persons are not allowed to enter the rooms of patients with chickenpox or measles. On the other hand, simple respiratory precautions (wearing facemasks) are used for patients with mumps or rubella. However, these diseases are still considered highly contagious.

Several problems exist for the person who thinks, as I did, that safety lies in not being in contact with children due to an adult-centered lifestyle or in avoiding being near a child who appears to be ill.

First, airborne diseases do not need physical contact and, to make matters worse, infected secretions from the mouth, nose and hands can easily be transmitted by fomites: these are inert objects handled by many people, such as doorknobs, computer keyboards at the library, money and shopping carts. (Important defenses include using a paper towel to open public bathroom doors, and always washing your hands before you eat anything, anywhere, anytime.)

Another problem is that transmissibility can begin at two to three days before the spots or rash appears. Also, early symptoms can be subtle: the fever is slight, there may be a mild headache, or the child may seem only tired. Even in adults, the early signs of chickenpox (before vesicles develop) can be mistaken for the effects of insect bites or stings.

For the senior who is not immune to one or more of these viral diseases, the risks of complications, more severe illness or death can be high. The following are complications and sequelae mentioned in Current Pediatric Diagnosis & Treatment., edited by William W. Hay Jr. et. al.

Rubella can cause arthritis in the knees and small joints and, in a small percentage of cases, can result in permanent arthritis. Encephalitis is rare but possible. (Note that rubella or German measles is a serious risk to pregnancy in the first trimester in a nonimmune woman; the child is likely to be aborted, stillborn or severely damaged.)

Mumps inflames the testes in about 30 percent of males; only about one-third of these testes will atrophy, and sterility is rare. One-sided nerve deafness, usually transient, can become permanent in less than 0.1 percent of cases. Myocarditis and facial paralysis are also rare but possible.

Measles (rubeola) can result in dangerous respiratory complications like pneumonia, especially for seniors. Liver-function problems have been detected in almost 50 percent of young adults, and reactivation or progression of tuberculosis is a risk.

Chickenpox is likely to promote a secondary bacterial infection with staphylococci or a fatal pneumonia in older patients. With more severe disease, scarring or disfigurement is possible. Varicella, as many senior sufferers know, is associated with herpes zoster (shingles). It's one of the best arguments I know for immunization in adults who have not had chickenpox. Zoster is very painful prior to eruption; the rash usually appears on the head and neck, but can involve the cornea. The resulting vesicles are tightly grouped and contagious before crusting. (Note also that chickenpox and shingles are a moderate risk to pregnancy of up to 20 weeks in a nonimmune woman.)

Seniors need to evaluate with their health-care provider the risks of remaining nonimmune and weigh those against the risks of exposure to an illness that could be severe or fatal. Is the vaccine safe for you and worth the expense? Meanwhile, I await for six months the outcome that may result in some facial scarring. If I had a chance to do it again, I would pay for the vaccine.