DEAR DR. DONOHUE: I would greatly appreciate it if you would discuss the fungal disease histoplasmosis. My son is being treated for it. From what I’ve heard, a cure takes a long time. His breathing is difficult, and he had to have a calcified lymph node removed. It was adjacent to his right lung. – M.C.

ANSWER: If you mention histoplasmosis to most people, you’re likely to get a “huh?” However, more than 50 million Americans have been infected with it, and half a million are newly infected yearly. Histoplasma is a fungus found in soil enriched with bird or bat droppings. When such soil is disrupted in excavation, construction or cultivation, fungal spores (immature fungi) are spewed into the air and people nearby inhale them into their lungs. Histoplasma also can be found in chicken coops, old buildings and caves.

In the United States, the Mississippi River Valley and the Ohio River Valley are places where this fungus thrives and where the majority of infections takes place.

Most people’s encounter with histoplasmosis is a silent one. They never get ill. About 5 percent develop symptoms consistent with lung infections. They come down with a cough, shortness of breath, fever, chills, sweats and chest pain. Quiet often, the symptoms are so mild that a person brushes them off. A few, however, have severe symptoms that require hospitalization.

Acute, severe infections of histoplasmosis call for intravenous antifungal medicines for one to two weeks, followed by oral medicine for three months. For infections of longer duration, intravenous treatment is followed by oral medicine for a year. Most infections yield to treatment, and the lungs recover.

Calcified chest lymph nodes are a common consequence of this infection. Large ones can bore into the breathing tubes and cause trouble. Removal of those nodes prevents that from happening.

DEAR DR. DONOHUE: I have a 16-year-old grandson who has been diagnosed with glaucoma in both eyes. No medicines have been prescribed. All we were told is to have his pressure checked every three months. We were not told what will have to be done if the pressure rises.

I have never heard of anyone so young having this condition. Any information you can give would be a godsend. – K.M.

ANSWER: The central issue in glaucoma is a change in the optic nerve. The doctor can see the nerve when he looks in the eye with a handheld, lighted scope. An increase in eye pressure is often what causes those changes, but not always. The “pressure” spoken of is not blood pressure. It’s fluid pressure. The front of the eye is filled with a fluid that is constantly produced and constantly drained. If production exceeds drainage or if there is a block of the drainage, then eye pressure rises and presses on the optic nerve.

I’ll bet your grandson’s pressure was on the high side but not so high as to damage the optic nerve. If it does rise, then he’ll be treated with medicines that lower it, usually in the form of eyedrops or with a procedure to unblock the eye’s drainage channel. That’s often done with a laser beam.

Glaucoma mostly occurs after age 50. However, it can come on in the first three years of life, and it’s called infantile glaucoma. It also can develop between the ages of 3 and 30, and then it’s called juvenile glaucoma.

DEAR DR. DONOHUE: I have a son who is an alcoholic and attends AA. He is having trouble with alcohol cravings. I read of a drug called Campral that helps recovering alcoholics overcome those cravings. What do you know about this drug? – F.Z.

ANSWER: Campral (acamprosate) was approved by the Food and Drug Administration in 2004 to decrease the unpleasant withdrawal symptoms that often appear when habitual alcohol use is stopped. Some of those symptoms are insomnia, restlessness and anxiety. They make the abstainer want to take a drink. Campral minimizes those symptoms. It’s a useful adjunct to stay sober.

DEAR DR. DONOHUE: I am writing for a friend who has been afflicted with a very bad case of hiccups, which is making his life miserable. He has been to many doctors, but not one can give him a cure. He is 65 and does not drink. He has given up hope of ever getting over this disease. – V.D.

ANSWER: I take it you mean your friend has been hiccupping for a long time. Hiccups are spasms of the diaphragm – the broad, horizontal muscle that separates abdomen from chest and that is the principal breathing muscle. Hiccups lasting more than 48 hours are “persistent,” and those lasting for a month are “intractable.” They are in a different class from hiccups that are bothersome but short-lived. Readers have provided me with a slew of remedies for those.

A doctor has to examine your friend for serious causes of long-lasting hiccups – things like abdominal tumors, brain tumors, kidney failure and irritants of the phrenic nerve, the nerve that innervates the diaphragm.

Sometimes a doctor can put an end to chronic hiccups by introducing a thin, rubber tube into the nose and down into the throat to stimulate it. Chlorpromazine, baclofen and carbamazepine are a few of the medicines used to terminate a prolonged spell of hiccups. Blocking or even crushing the phrenic nerve, the nerve to the diaphragm, is another technique to end this unpleasant experience.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.