YES mold has been tied to MS, specifically a couple species found in water-affected buildings, incl. the common "black mold".
The Seattle area has the highest rate of MS in the nation and surprise surprise, why do you think that is? I will tell you why. Most of our buildings here have a problem with black mold, especially older ones or ones built without appropriate thought to the climate. The house I spent birth through age 10 in had black mold in the closets, windows, behind dressers, and I'm sure all through the walls. It was a cinderblock house which is basically a form of cement that wicks water up and holds it in dampness of the walls. There were many suburbs outside of seattle built of cinder block houses as post-WWII houses for returning GIs and the new suburban lifestyle. However, this material couldn't have been more poorly chosen for the damp pacific NW climate. It is extremely difficult to keep a cinder block house from becoming a toxic black mold factory in this climate. It's difficult enough even with 2 and 3 story wood houses with airspace between floor and ground (floors raised above ground level or with basements) in sunny locations with woodstoves to dry out the air and materials, much less ranch style cinder block houses built flat on the (wet) ground in shady areas with non-drying electric or gas heat, etc.
The other area in the world with extremely high MS is Scotland. The environment of Scotland and Seattle are extremely similar in many ways: they are on almost the same latitude, they are both maritime climates with average temperatures between 40's-60's farenheit with 100% humidity. Both places rarely get strong heat or clear strong sun of enough UV rays heat and drying to dry out moldy houses, cars, etc and dry out or kill spores in the air, nor does either place get much of a hard freeze to arrest mold growth and dry out air. in both places, most of the year conditions are perfect for rampant proliferation of mold growth. The southern equivalent of the same latitude and problem is that MS is seen in New Zealand which also has a large number of people of celtic descent (seattle is also largely white, although not particularly celtic, more Scandinavian however there is also a Scandinavian connection with MS, and Scotland is largely Scandinavian in its DNA due to Viking contact and settlement. Scandinavian culture and American culture influenced by it is to drink a lot of milk and there is a milk-MS connection as well).
The reason that areas that are damp enough to have mold problems but in a warmer area i.e. New Orleans don't have the rate of MS that Seattle, Scotland, and New Zealand have, is because the sun is what creates vitamin D in the human body, with sufficient D we have strong immune systems able to better ward off effects of mold etc but with deficiencies in D the immune system does not work as well. there is a known correlation between vitamin D deficiency and MS, and also mold exposure and MS, both of which relate to lack of sun and a cool cloudy damp climate. we know that damp, cool climates (by the sea usually) have higher MS. also, I suspect that the strains of mold that grow in a cool range of temperatures average 50* f are different than those that grow in warm temperatures of average 80* f. BUT there are a couple more things involved - feeding babies and children animal milk, first as formula and later in the diet, either/or or both, can trigger latent MS genes which is why MS is seen in damp cool moldy climates where also the babies and children are fed animal milk formula or in childhood in the mistaken assumption that it helps build bones (the opposite is true - check the Harvard nurse's study. Harvard removed dairy from its food pyramid due to results of this study). There are societies where the climate conditions would indicate high MS but without the immune disruption of the animal milk trigger their rates seem to be less. however with the spread of bottle feeding and dairy use in japan the rate of MS is rising and their climate in many areas is unfortunately prime MS territory (damp oceanic cool temperate climate average temp 50* f). the Hep B shot also raises risk of MS many times, areas that vaccinate with this shot are more likely to see MS rates be high especially if they have the climate risk and the dairy risk in addition.
there are a couple hot weather areas that have fairly high MS including Sardinia and Palestine, however, in the case of Sardinia it is suspected to be genetic due to a gene prevalent in the small gene pool on island, and in the case of Palestine, it is suspected to be possibly caused by an STD spread by polygamy and practice of mix and match marriage/divorce (epidemiologists look at some areas of the world with MS and say that it reads like an STD by all indicators). Palestine also has high dairy consumption (goat and camel more than cow) and one of the world's highest birthrates, which indicates bottle feeding of infants.
Every state in the US and every country I would think has laws on the books about mold in rental housing, and there are federal laws about housing and building safety, toxic mold, sick building syndrome etc. Look up the housing authority website of your local area, or your local area's tenants union. look up your state's laws about toxic mold, black mold, or sick building syndrome. a landlord cannot legally rent a building with toxic mold in it. a professional mold remediation or environmental toxicity company needs to come out and do an assessment of the situation. they will probably do a free assessment and write up a report and remediation plan and cost quote, this report of findings and estimate of what is necessary to remediate it can be used in court. if they find mold in amounts and species known to be toxic to health, the landlord is required to put you up in an alternate residence while the remedication work is done, which can include ripping out wall board, insulation, floors etc down to the studs, cleaning, proofing against mold with anti mold agents, and re-insulating and putting walls back together. however, the chemicals used to prevent mold can be toxic in and of themselves. however, one of them is now being used as an MS drug, tecfidera. The ingredient used in tecfidera is also used to protect wood furniture made in china from molding while being shipped on freighter ships to the US, and also has been proven to prevent mold in bread. so this anti mold substance is also being used as a medication in the body to counteract and prevent effects of toxic mold in the body as it also protects other organic things against mold damage.
if you are noticing MS symptoms in a moldy house, you already knew what you felt and the research is all there that proves toxic mold i.e. mycotoxin effects on both neurology and immune system and connection to MS. GET OUT NOW and turn your landlord to the law in for moldy house rental. there may be a law firm in your area that specializes in these cases. talk to your tenants union. I would call a mold remediation specialist and see if they will come out and do a free assessment, get their assessment in writing, find a lawyer who will take the case without payment from you i.e. pay on winning the case (if there are other residents, get them in on the case as well), and then turn your landlord in to the housing authority with a toxic mold property rental case to get them to do the remediation. inside the bathroom walls tends to be some of the worst but it can be anywhere in the residence, and what you see is only the tip of the iceberg, even if you see little, the inside walls and under the floors can be infested. black mold on window seams is common. single pane windows that sweat tend to gather mold at the window seams and prevent the inside of the house air from being able to dry out due to window condensation. window replacement may be necessary to fight mold in the house and many cheap scheisty landlords don't want to do it because it is expensive. however most landlords are living in the rich side of town and making money off renting properties in the poorer area of town so they are not hurting for $ and don't feel bad for making them do their job, they are not allowed to profit off making people sick.
I had a landlord who would make half assed gestures at maintenance but there was water damage all through house that continued to happen, water dripping down inside walls (place had a flat roof that was leaking somewhere - who builds a flat roof in seattle? where puddles will stand on it almost all the time, recipe for roof leakage, etc.) and it contributed to my onset of MS, however I think in my case it was more that my formative years of immune system being established were in severely mold toxic damp cinderblock house with black mold and even small fungi growing out of walls behind dressers, in closets, etc. The data shows that when people live in a cool damp cloudy rainy climate in childhood the higher MS risk effect follows them even if they move to a warmer climate later, and this is partly because it is before age 15 that our immune system develops and is established in childhood and if altered by mold toxicity in that time it can lead to autoimmunity later in life (autoimmunity is one of the effects of toxic mold exposure).
Every state in the nation has laws against renting or selling property with mold in it due to the health effects and the owner or renter of the property is liable for mold remediation. look up the laws in your area and get AWAY from that exposure ASAP it's not worth MS the rest of your life.