Hello dear readers and welcome to the it’s-almost-winter edition of our monthly letters column. The weather has changed, and so have your concerns, moving from the ticks and mosquitoes of summer, to colds and the dreaded flu. Speaking of which:

-- Many of you have asked whether it’s time for a flu shot, and the answer is an emphatic YES! After vaccination, it will take your body a few weeks to build up immunity. Considering all the travel and shopping and visiting the holidays bring -- much of it in crowded and under-ventilated spaces -- we need all the help we can get in staying healthy.

-- In a recent column about age-related insulin resistance, we cited research that links a decrease in a gut bacterium known as A. muciniphila, or Akk, to an increase in insulin resistance. A reader from Pennsylvania asked how levels of Akk in the gut can be restored. Unfortunately, as with many gut bacteria that have been revealed to play important roles in health and metabolism, we don’t yet have a way to affect specific populations. The best course at this time is to “eat for your gut.” That is, choose from a wide range of fresh fruits and vegetables, beans, grains, legumes, healthy fats and fermented foods to provide a diverse range of nutrients for the trillions of microscopic organisms that make our guts their homes.

-- We heard from a reader who has begun to struggle with leg cramps at night. “The outside muscles of my leg from the knee to the ankle abruptly harden for a few minutes while I am sleeping, which wakes me up several times during the night,” she wrote. “None of the meds I take list this as a side effect. What can I do?”

Nocturnal leg cramps, which become more common as we age, affect up to 60% of adults. They tend to be more common in women than men. For most people, the condition is occasional, but some experience leg cramps on a nightly basis.

Thank you for all of your letters, your kind words and, yes, the occasional criticism. We love hearing from you and are always working to make this column more useful. Just a reminder that while we can address the big picture on medical issues, news and conditions, we can’t offer a diagnosis or second opinion. For comments, tips or other suggestions, our mailbox is always open.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My wife does calligraphy, but she’s having trouble because her hands have started shaking. She’s worried it’s Parkinson’s disease. What else could be the cause?

Dear Reader: Uncontrolled shaking, trembling or quivering, which is known as a tremor, occurs as the result of sustained and involuntary muscle contractions in the affected area. A tremor can range from something so slight that the person barely notices, to more pronounced movement that interferes with daily activities. Although tremors mostly involve the hands, they can affect virtually any muscle in the body, including those in the head and neck, vocal cords, legs, feet, arms and torso. The movement may occur at irregular intervals with periods of stillness in between episodes, or it can be constant. And while the condition becomes more common as people enter their later years, it can occur at any age.

There are two major types of tremor -- resting and action. In resting tremor, which most often involves the hands and fingers, the affected body part shakes or trembles when the muscles are relaxed and at rest. An action tremor occurs when the muscles are engaged. This can happen during general movement, like when you pat a dog or pass a plate; while bracing a body part, such as holding out an arm; when engaging in a fine motor task, such as writing; or while zeroing in on a specific target, such as touching the tip of one’s nose.

Tremors can occur without a discernible cause; may be a symptom of a physical, medical or neurological condition; or can result from medical treatment. Many of us have experienced the shaky hands that can accompany fear, anxiety, anger, anticipation and exhaustion. Substances like caffeine, alcohol and nicotine can contribute to tremors. So can a range of drugs, both legal and illicit. Medications that may cause tremor include those used to manage asthma, certain antidepressants, some types of blood pressure drugs, thyroid medications, weight-loss medications, anti-inflammatory drugs and antivirals.

It’s true that tremor can be a symptom of a neurological disorder, including Parkinson’s disease. In your wife’s case, it is likely an action tremor because it occurs while she is writing. Parkinsonian tremor falls into the category of the resting tremor: A person with Parkinson’s disease will notice that their fingers or hands tremble while at rest, and that as soon as the muscles are engaged in activity, the tremor disappears. However, since any type of tremor can be a symptom of an underlying condition, it’s a good idea for your wife to speak about it with her family doctor.

Diagnosis entails a comprehensive physical and neurological exam, a detailed medical history, performance tests and certain laboratory tests. Imaging tests such as CT scans or MRI don’t diagnose tremor, but may be used to rule out other conditions. There is no cure for tremor at this time, but with medication and, in some cases, surgery, the condition often can be successfully managed.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Our son’s work as an engineer is taking him to Kampala, Uganda. He’s had to get all sorts of vaccinations, but his mother is concerned that Ebola wasn’t on the list. Is there a vaccine yet?

Dear Reader: After decades of research and testing, an injectable vaccine that targets the deadly Ebola virus in humans won approval from the European Union in late November. Known as Ervebo, the vaccine also meets standards of quality, safety and efficacy set forth by the World Health Organization. In the United States, the Food and Drug Administration has placed the vaccine under priority review, but it is not yet available here.

Ebola virus disease, or EVD, is a rare and often fatal illness that affects both humans and nonhuman primates. The family of viruses that cause EVD are found mainly in sub-Saharan Africa, but because the disease is highly contagious, the WHO considers it a potential global threat. The virus is originally transmitted to people from animals, including fruit bats, porcupines and nonhuman primates. It then spreads through direct contact with the blood or bodily fluids of someone who is sick with, or died from, EVD. The average fatality rate of the virus is 50%. There is no evidence of transmission of the Ebola virus by mosquitoes or other insects.

Symptoms can appear from two days to three weeks after infection. The disease typically begins with bodily aches and pains, often including a sore throat or severe headache, accompanied by a fever. Weakness, fatigue, intestinal pain and vomiting are also possible. Some patients experience hemorrhaging, bleeding or bruising, which gave the disease its original name of Ebola hemorrhagic fever.

Health care workers and others tending to patients with EVD, and laboratory workers dealing with the bodily fluids of an infected individual, are at highest risk of contracting the disease. The disease is also easily transferred to family and friends in close contact with someone who is sick, or even with the surfaces and materials the infected person contaminated.

There is no cure for EVD at this time. Since its discovery in 1976, the largest outbreak of EVD occurred from 2014 to 2016; more than 11,000 people died in Guinea, Liberia and Sierra Leone.

The new vaccine, which protects against the Zaire species of Ebola, had been in limited use on a “compassionate basis” during the most recent outbreak of the disease in the Democratic Republic of Congo. It has been reported to be more than 97% effective at preventing infection. Still, more than 3,000 cases have been reported, included several in Uganda.

Thanks to the recent bureaucratic green light, nations most at risk of an outbreak will soon begin to receive the vaccine for distribution. The pharmaceutical company Merck reports that it has donated more than 250,000 doses of the vaccine for use by the WHO. With the vaccine now fast-tracked by the FDA, manufacture of the drug is expected to begin in the fall of 2020.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)