Dear Doctors: My wife read somewhere that when kids grow up with a do in the house, it can keep them from getting schizophrenia. I know that having a pet can help kids develop responsibility, but preventing mental illness seems like a stretch. Is this based on psychology -- or something else?

Dear Reader: Your wife is referring to the results of a study published several years ago that found a link between living with a dog in very early childhood and a reduced risk of developing schizophrenia later in life. As you can imagine, these findings generated quite a few headlines.

Schizophrenia is a mental illness that interferes with a person’s sense of reality. When left untreated, it is often disruptive and prevents someone from being able to participate fully in everyday life. The condition usually shows up between the ages of 16 and 30. Early symptoms often include visual and auditory hallucinations, disordered thought patterns, delusions and paranoia.

Although the causes of schizophrenia are not yet clear, both genetics and brain structure have been shown to play a role. More recently, researchers have begun to explore a potential link to the gut microbiome -- specifically, whether certain environmental exposures may influence brain development, and thus play a role in who develops a serious psychiatric illness and who doesn’t.

Childhood pets are an early source of exposure to a range of harmless microbes, as well as to potential allergens. We now are learning that, via the gut microbiome, such exposure may have a positive effect on some children’s immune systems. This made the researchers in this study curious about whether living with a cat or a dog during the first 12 years of life might have an effect on mental health. Specifically, they were seeking any correlations with a diagnosis of schizophrenia or bipolar disorder. The latter is a mental health condition marked by sudden and extreme shifts in mood, energy and concentration. Like schizophrenia, bipolar disorder often arises in adolescence and makes it difficult for the person to successfully manage the tasks of day-to-day life.

In this study, the researchers used health data from 396 adults diagnosed with schizophrenia and 381 adults diagnosed with bipolar disorder. They also included 594 adults with no mental health disorders to serve as the control group. The participants ranged in age from 18 to 65, were in good health and had no history of drug use. All were asked to detail their personal history with childhood pets.

When the researchers analyzed the data, they were surprised to find a statistically significant connection between the presence of a family dog in early childhood and a decrease in the risk of developing schizophrenia later in life. They did not find the same link in study participants with bipolar disorder or among those whose childhood pet was a cat. To understand the significance of this finding, further study is needed. But among the theories getting a closer look will be whether or not beneficial microorganisms in the microbiomes of dogs may have provided a measure of protection against schizophrenia later in life.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: My brother woke up to find a bat on his bed. He captured it in a bucket and took it to animal control, and it turned out to be rabid. Even though he didn’t touch the bat and his doctor couldn’t find any bite marks, he still had to get rabies shots. Why would that be?

Dear Reader: Bats are an important part of our ecosystem. They pollinate plants, disperse seeds, control bug populations and are a food source for hawks, falcons and owls. Unfortunately, they are also among the most frequently reported rabid animal in the United States, and they are the leading cause of rabies deaths in this country.

Rabies is a viral disease that affects the central nervous system. It is almost always fatal. The most common form of transmission is through direct contact with the saliva of a rabid animal. This can occur through skin broken by bite or a scratch, or secondhand contact with infected saliva via the mucous membranes in the victim’s eyes, nose or mouth.

Because bats have tiny teeth and claws, you can be scratched or bitten and not feel or see the point of entry. That makes it important to take close encounters with these flying mammals very seriously. Your brother did the right thing each step of the way. He captured the bat without contact and took it to his local health authorities for testing. And while it may seem an extreme precaution, he was wise to agree to the series of injections that are used in cases of rabies exposure.

Once someone has been infected with the rabies virus, there is a time lag before the visible signs of disease begin. This is because the virus first has to reach the brain. This incubation period can range from weeks to months after initial infection. The duration depends on the specific type of rabies virus involved, how far from the brain the exposure occurs and any immunity someone may have.

Early symptoms of rabies, which are often similar to the flu, include fever, headache and general discomfort and malaise. About one-fifth of those infected experience itching, tingling or paralysis of the limb that was bitten. The virus sets off inflammation in the brain, which causes cerebral dysfunction. Symptoms escalate from agitation, anxiety and confusion to insomnia, hallucinations, partial paralysis and coma. The cause of death may be seizures, blocked airways or widespread paralysis. There is no cure for rabies at this time. Once the clinical symptoms appear, treatment consists of supportive care. The disease is almost always fatal, with fewer than 20 documented cases of human survival.

The series of life-saving shots that your brother received is known as post-exposure prophylaxis, or PEP. They begin with a dose of human rabies immune globulin and also the rabies vaccine, administered on the day of exposure. Follow-up rabies vaccine is given again on the third, seventh and 14th days following exposure. The CDC recommends PEP to anyone with close contact or exposure to a rabid bat, whether or not a bite is known to have occurred.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: The new COVID-19 boosters are here, and I’m not sure if, or when, I need to get one. I had the two-shot Moderna series last winter. I had a mild case of COVID-19 this summer. When I got better, I got the booster. Do I still need to get another one? Am I the only one who is confused?

Dear Reader: You are not alone in wondering about the new boosters. The coronavirus landscape has undergone continual change, and it’s not a surprise there’s some confusion.

The modifications to advice about how and when to get a COVID-19 vaccine have been due, in part, to the steep learning curve we faced with this brand-new disease. And when it comes to the new boosters, the basic nature of viruses has played a big role. The good news is that our immune systems learn from each encounter with these pathogens. But because viruses continually mutate, they can stay one step ahead of our body’s defenses. When an altered version of an original virus becomes successful enough to spread widely, it’s known as a variant. And with the emergence of the omicron variant, the original coronavirus vaccine needed a tweak to be more effective.

At this time, more than 90% of new COVID-19 cases nationwide are being caused by infection with the omicron variant. It’s a great relief, then, that a new tool in the fight against the disease is now available. The reformulated boosters, known as a bivalent vaccine, include components of both the original virus strain that triggered the COVID-19 epidemic and the now-dominant omicron versions, BA.4 and BA.5. The result is broader protection against the coronavirus and its most widely seen variant. By staying up to date with the newest vaccine, you have improved protection against severe illness, hospitalization and death.

The FDA has authorized the bivalent formulations of the Moderna and Pfizer COVID-19 vaccines -- aka the omicron boosters -- for those who have completed their original two-dose vaccine series. The Pfizer version is available to individuals 12 years of age and older. The new Moderna booster is authorized for everyone 18 years of age and older. Each of these boosters is given as a single-dose shot.

This bivalent booster is recommended to everyone who is eligible, no matter how many previous boosters someone has had. However, there are some requirements when it comes to timing. The FDA set a wait period of at least eight weeks between the last dose of the original booster and getting a shot of the new omicron bivalent version. This is to optimize your immune response, and thus give more robust protection. There’s also a wait period for people who have recently had COVID-19. The FDA and the CDC recommend waiting at least 12 weeks after recovery from coronavirus infection to get the new booster. Again, this is to boost immune response.

And to those of you who have been asking, yes, you can get a flu vaccine and the new omicron booster at the same time.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)