My sister and her husband have genital herpes. Their four children suffer with recurring bouts of hand-foot-and-mouth disease. In the past 18 months, they have had three outbreaks, two of which were so severe that one of her children had to be hospitalized due to the ulcerations down to his lungs. I find it strange that this occurs so much within this family. Then I found a reference on a website that said HFM can be caused not only by the coxsackie virus, but also by the herpes simplex virus. Could this be the cause of my sister's unfortunate events?

Eve

We've had quite a few questions regarding hand-foot-and-mouth disease (HFM) in the past few months. I am not sure if this is because there have been more cases than usual this year, but I have personally seen more this year than ever before. In fact, as I mentioned in an earlier column, my son recently had this infection.

HFM disease is caused by any of a few enteroviruses, usually coxsackievirus A16. Another virus, enterovirus 71, has caused some serious outbreaks of the disease, including an epidemic in Taiwan that had fatalities due to pulmonary (lung) involvement. However, except in the very rare severe cases, people recover completely from HFM. The body eliminates the virus and develops immunity against future reinfection by the same strain. It is possible that an individual could have a second episode of HFM, caused by a different enterovirus -- say, by enterovirus 71 after a previous infection with coxsackie A16 -- but this would be very unusual.

Herpes viruses, in contrast, are not eliminated from the body, and recurrences are the rule. I searched the entire Medline database (a database of medical journal articles that is maintained by the National Library of Medicine) from 1966 to the present and could not find a documented classic case of HFM caused by a herpes virus. So what could be happening in the case of your sister's family? Some people who have immune system defects have chronic and recurrent enteroviral infections. But these chronic infections typically affect the nervous system, so I would not expect such people to have recurrences of blisters and sores in the mouth and throat. It also would be rare for any HFM infection to progress all the way to the lungs.

One possibility is that your sister's children have had recurrent herpes infections, and not HFM at all. In primary herpes infection -- the initial infection -- the mouth ulcers (sores) can look somewhat like those seen in HFM. In these cases, the child can appear quite ill, with many ulcers in the mouth and on the face. Sores on the hands and feet are not common in herpes infections, but they can occur. Recurrent infections with herpes are not typically severe, however. Such outbreaks may involve a few blisters and ulcers around the mouth and, less commonly, inside the mouth. While someone with herpes can develop recurrent sores on the fingers or hands, such lesions are uncommon -- and, in any case, I would not expect them to occur in the mouth and on the hands at the same time.

Something is a bit unusual about the cases you describe. It is rare for any recurrent infection to involve four children in the same family. I would like to see the kids' proposed diagnosis of HFM confirmed or ruled out by a medical laboratory. Both herpes and enteroviruses can be identified in a culture grown from a swabbing of the lesion. Perhaps the children do not have HFM or herpes, but some other condition, such as human papillomavirus (HPV) infection. HPV infection can lead to a condition called recurrent respiratory papillomatosis, which causes progressive lesions in the mouth, throat and airways. These lesions look like warts, not like the blisters and sores of herpes or HFM. I suggest that your sister's children see a specialist who can prove the diagnosis.