QUESTION: Have you anything on sandfly fever, which I understand is prevalent in the Mideast? - P.Y.N.

ANSWER: The Mideast has illnesses that are alien to our environment, and sandfly fever is one of them.Sandfly fever is a viral infection spread by that insect. It comes on suddenly and with very high temperatures, as high as 104 F (40 C). Along with the fever, there may be headache and muscle ache, nausea and vomiting. The symptoms usually last two to four days, but recuperation can take much longer. There is no medicine to treat or prevent sandfly fever.

The same insect is responsible for the skin problem leishmaniasis (Baghdad boil). The fly injects the leishmania germ into the skin. In two to eight weeks, a red nodule appears at the site. If untreated, the nodule turns into a large skin ulcer. There is medicine for this infection.

Schistosomiasis is another illness endemic to that part of the globe. The liver and urinary tract are prime targets, but this too can be treated with medicine. The infection is from a marine parasite carried by snails.

Certainly, the military medical establishment is aware of and has encountered such ailments, to which most personnel have not been exposed, as have most of the native population.

QUESTION: Please discuss for me sideroblastic anemia. - B.N.

ANSWER: Sideroblasts are parents of deformed red blood cells. They appear in the bone marrow, the blood-cell manufacturing site.

Specifically, they are characterized by abnormal rings of iron specks. Hence the name (sidero-iron; blast-bud).

Actually, sideroblastic anemia is a group of disorders with a variety of causes and the same result, production of defective red blood cells. That, by definition, is what anemia's all about. The disparate causes of sideroblastic anemia range from alcohol abuse to certain cancers. Many times, the cause cannot be pinpointed.

I assume you are interested in treatments. The B vitamins (folic acid and pyridoxine) are used to treat some sideroblastic anemias, and sometimes blood transfusion is needed to bring the red-cell count up to snuff.

QUESTION: This is not a major problem. In fact, everything is fine - blood pressure, cholesterol and the rest. I am not on any medicine. I am 72. I have some ankle swelling. My doctor says it's nothing to be concerned about. I've thought of asking another doctor, but I hesitate. This one has always done right by me, and I don't want him to think I question him. This may not be important enough to answer, but thanks anyway. - M.O.

ANSWER: You've heard that people with heart failure often have ankle swelling, and you probably read about that here. But given your excellent health and health care, you don't have to leap to that conclusion.

Ankles swell from some pretty banal causes in people your age. Standing overlong can do it. So can constricting garments. This won't apply to you, but some women may experience such swelling at the time of their monthly periods, when more fluid is being retained.

I'll bet you can get rid of the swelling by cutting back on salt and elevating your legs from time to time during the day and at night, also by adjusting any constricting undergarments.

Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.