Updated April 22, 2015.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
Well it depends on what kind of mold.
Mold is all around us - and usually this isn't a problem. There are many types of molds. There are thousands, maybe even over a million, species of mold.
There are however types of mold that cause us problems. One particular type of mold - aspergillus - causes problems for people around the world.
Some reactions are allergic; some are invasive infections, especially in those with weak immune systems.
There are different species of aspergillus that live in different environments and can be associated with different effects in people. These environments vary from mildew and damp walls to bread and peanuts. Most are not harmed by aspergillus. It is frequently present without causing any problems. Also not everything about aspergillus is bad. It's the mold that used in fermentation to create Sake. It's also used to produce citric acid.
When Aspergillus is a Problem:
Who is at risk for getting sick from mold?
Those who have weak immune systems
Those who have allergies
Building reconstruction, especially when in a hospital, has led to outbreaks, by spreading the mold in the air. Rising rates of bone marrow transplants, organ transplants have led to more infections in the immunocompromised. Improvements in care of cystic fibrosis patients making the disease a chronic disease among adults has also led to more cases.
Allergic bronchopulmonary aspergillosis (ABPA) is a type of asthmatic lung reaction caused by aspergillus.
Its thought to be the cause of about 2.5% of adult asthma cases. It can lead to asthma in adults who had not had asthma as children unlike most with asthma. The disease is particularly a problem for those with Cystic Fibrosis.
Symptoms: wheezing, shortness of breath, cough, rarely: fever. This occurs in those who have not had wheezing before.
Allergic Asperillus sinusitis can cause a chronic sinus infection. These infections do not usually spread if there are no immune system (or anatomical) issues.
Symptoms: nasal stuffiness, headache, sinus pain, reduce sense of smell, runny nose.
Aspergillomas are fungus balls. These are literally clumps of fungus that tend to form in holes - particularly in the lungs. Those who have had lung damage - such as from Tuberculosis, Chronic Obstructive Pulmonary Disease (COPD, emphysema), and sarcoid. These can persist for long periods of time without changing.
Most cases do not require treatment. Many are found through a Chest X-Ray or imaging for another reason.
Symptoms: rarely: coughing up blood, coughing, shortness of breath - particularly in someone with a known lung problem.
Chronic Pulmonary Aspergillosis can also lead to aspergillosis in other forms, whether in a cavity in the lung, nodules in the lungs, pulmonary fibrosis and scarring, as well as other pulmonary infections. This is particularly a problem for those with damaged lungs or weak immune systems.
Symptoms: problems breathing, coughing, fever, and severe illness
Invasive Aspergillus is largely a disease of those with particular defects in their immune systems or are taking immunosuppresives (even steroids). Aspergillus can spread from the lungs to other organs through the blood. This can be a very severe illness in those who are already quite ill. It can even lead to meningitis in rare cases. There are also occasions where medical procedures or devices can introduce aspgerillus, such as a case of meningitis in the setting of contaminated steroid injections for back pain.
Doctors often provide prophylaxis for avoiding such infections in those undergoing organ or bone marrow (stem cell) transplants.
Aspergillus flavus and Aspergillus parasiticus produces alfatoxin which is a cancer-causing toxin contaminating grains and peanuts. This toxin particularly affects the liver. This has led to outbreaks in countries where there is little ability to monitor levels. The US Federal Drug Administration has set maximum levels that such food products as well as animal feeds may contain.
Can mold spread from person to person?
No. Fortunately. The disease is usually breathed in through the sinuses or lungs.
Is there treatment?
Yes. There are drugs that under the careful watch of infectious disease specialists may treat the infection. Treatment of fungus balls may not be needed. Those with allergic symptoms may need both treatment with antifungal drugs and steroids to reduce symptoms.