This is a parasite that usually causes about 3000 cases of illness per year in the USA, Michigan currently has reported about 2900 (the confusion about “Michigan outbreak” is because Michigan is the first that caught an uptick in cases and has been very proactive about trying to trace them). Last official update from Massachusetts was 18 cases here centered in Greater Boston. The CDC recommends NOT assuming there are no sources of the parasite in your state even if no cases have been reported.

It isn’t an unknown illness but it is an unusual quantity of cases, and the fact that they haven’t been able to pin down the source after weeks of tracking is what makes it particularly concerning this year (harder to contain).

NOT THE CRABS WE EXPECTED BUT STILL SOME CRABS WE DESERVE!!!

This was a fun mend. I like how the sashiko pattern looks like a bandage.

Our bodies, generally speaking, are pretty good at recognizing self and differentiating that from non-self. When our immune systems detects cells or components made by our body, it shouldn't react. When it detect foreign, potentially harmful substances, our white blood cells can respond in a variety of ways. One type of white blood cell, called B cells, produce antibodies.

Usually, we think of antibodies when we talk about diseases and vaccinations, but there are several types of antibodies which get produced in different kinds of reactions. In all cases, antibodies are proteins that recognize and bind with specific substances, known as antigens. That means each antibody has a target, like a specific protein or sugar, that it matches with like a lock with a key. The process of binding together is called agglutination and sometimes lots of antigen-antibody complexes get clumped together. Agglutination often acts as a signal for other cells to come respond to the threat, although it can sometimes neutralize targets directly.

Note: antigen =/= allergen! Allergens are a type of antigen that cause an allergic response

We can imagine with disease, once the body recognizes a foreign microbe through infection or vaccination, it can produce antibodies that target some part of the virus/bacteria/etc, like a protein structure on the microbe's surface. The antibodies bind to their targets and often work as huge flags to the immune system that there is a foreign material that needs to be destroyed. Many blood transfusion reactions work in a similar way. Our red blood cells have many antigens, mostly proteins on or in the cell membrane. A, B, and D (the +/-) are examples of antigens, but there are a ton more. Our bodies are familiar with the antigens we produce and can react when exposed to foreign ones. When someone receives blood with antigens they don't make themselves, they may have an immune response as their body recognizes and attacks the foreign cells.

This image shows how agglutination can happen with 2 types of antibodies. They bind to red blood cells and can cause them to stick to each other. "Complement activation" refers to proteins involved in increasing immune system response to destroy and clear cells from the body

These types of antibody-mediated transfusion reactions can be acute and occur minutes to hours after the start of the transfusion, or they can be delayed days or weeks after. The antibodies signal for the immune system to destroy the foreign donor red blood cells, which is called hemolysis. The breakdown of cells can cause mild to severe side effects and complications as the pieces of red blood cells flood the body. It also ruins the intent of the transfusion itself, since the destroyed blood can't help fix the original blood problem.

Note: As a term, "blood transfusion reactions" can refer to a variety of reactions, including immune-mediated (hemolytic, non-hemolytic febrile, allergic reaction, and TRALI) and non-immune (infection, TACO) responses. Blood bank testing is mostly focused on preventing immune-mediated hemolytic reactions

Now, antibodies can be weird. People produce them in different amounts and strengths, they can be affected by age or illness, and our bodies remember how to produce them for different periods of time. Not everyone who is exposed to blood with foreign antigens produces antibodies against it or will have the same response. There are also a lot of different blood antigens; some can cause stronger or longer antibody response.

Many transfusion-related antigens also only cause reactions after repeat exposure. Much like vaccines or allergies, the first exposure primes the immune system, showing it what the foreign substance looks like. Then, the next time that substance appears, the immune system can respond faster and harder than it did before. Most antibodies in transfusions, including the one that targets D (the +/- of your blood type) antigen, work like this.

This means people may be exposed to new blood antigens during a transfusion, transplant, or through pregnancy (including ectopic and aborted pregnancies), and not have a significant response. But during a following exposure, their body then produces lots of antibodies against the antigen it has seen before and produce a reaction. People who receive multiple blood transfusions are at a much higher risk of repeat exposure to antigens they don't make.

The exception to this is ABO mismatching. A and B antibodies are naturally occurring, meaning that our bodies can produce them without having ever been exposed to other blood before. This means that we can have a large antibody response on first exposure to an incorrect type. Different countries and transfusion centers have different testing procedures and requirements, but ABO typing is given priority because of its ability to cause immediate, severe reactions.

Remember, people make antibodies against what they don't already have themselves. Those with type-A blood will not make A antibodies, but they can make B antibodies. Type-B blood can make A antibodies, but not B. Type-AB have both antigens, so they don't make antibodies for either.

But there are over 40 blood group systems that can produce different antigens, with varying degrees of clinical significance. Most people have never been exposed to foreign antigens before and/or don't make any antibodies that would cause hemolytic transfusion reactions, so testing every person for every antigen would be a waste of time and resources.

Generally, blood testing before a transfusion has two components: a type test to identify the presence of 3 antigens and a screening test for relevant antibodies.

For most people, there is a very low risk of having an antibody-mediated transfusion reaction because it requires prior exposure to mismatched blood and the production of antibodies. A majority of people have never had a transfusion/transplant before and most people have never had a pregnancy that produces significant antibodies. Because of this, many hospitals can now do electronic crossmatches depending on their individual policies.

@cantankerouscatfish yes!!! Here are some better, less blurry close ups of the fellow. They're like the shrimps of the air....... pretending to be a bird...

Our bodies, generally speaking, are pretty good at recognizing self and differentiating that from non-self. When our immune systems detects cells or components made by our body, it shouldn't react. When it detect foreign, potentially harmful substances, our white blood cells can respond in a variety of ways. One type of white blood cell, called B cells, produce antibodies.

Usually, we think of antibodies when we talk about diseases and vaccinations, but there are several types of antibodies which get produced in different kinds of reactions. In all cases, antibodies are proteins that recognize and bind with specific substances, known as antigens. That means each antibody has a target, like a specific protein or sugar, that it matches with like a lock with a key. The process of binding together is called agglutination and sometimes lots of antigen-antibody complexes get clumped together. Agglutination often acts as a signal for other cells to come respond to the threat, although it can sometimes neutralize targets directly.

Note: antigen =/= allergen! Allergens are a type of antigen that cause an allergic response

We can imagine with disease, once the body recognizes a foreign microbe through infection or vaccination, it can produce antibodies that target some part of the virus/bacteria/etc, like a protein structure on the microbe's surface. The antibodies bind to their targets and often work as huge flags to the immune system that there is a foreign material that needs to be destroyed. Many blood transfusion reactions work in a similar way. Our red blood cells have many antigens, mostly proteins on or in the cell membrane. A, B, and D (the +/-) are examples of antigens, but there are a ton more. Our bodies are familiar with the antigens we produce and can react when exposed to foreign ones. When someone receives blood with antigens they don't make themselves, they may have an immune response as their body recognizes and attacks the foreign cells.

This image shows how agglutination can happen with 2 types of antibodies. They bind to red blood cells and can cause them to stick to each other. "Complement activation" refers to proteins involved in increasing immune system response to destroy and clear cells from the body

These types of antibody-mediated transfusion reactions can be acute and occur minutes to hours after the start of the transfusion, or they can be delayed days or weeks after. The antibodies signal for the immune system to destroy the foreign donor red blood cells, which is called hemolysis. The breakdown of cells can cause mild to severe side effects and complications as the pieces of red blood cells flood the body. It also ruins the intent of the transfusion itself, since the destroyed blood can't help fix the original blood problem.

Note: As a term, "blood transfusion reactions" can refer to a variety of reactions, including immune-mediated (hemolytic, non-hemolytic febrile, allergic reaction, and TRALI) and non-immune (infection, TACO) responses. Blood bank testing is mostly focused on preventing immune-mediated hemolytic reactions

Now, antibodies can be weird. People produce them in different amounts and strengths, they can be affected by age or illness, and our bodies remember how to produce them for different periods of time. Not everyone who is exposed to blood with foreign antigens produces antibodies against it or will have the same response. There are also a lot of different blood antigens; some can cause stronger or longer antibody response.

Many transfusion-related antigens also only cause reactions after repeat exposure. Much like vaccines or allergies, the first exposure primes the immune system, showing it what the foreign substance looks like. Then, the next time that substance appears, the immune system can respond faster and harder than it did before. Most antibodies in transfusions, including the one that targets D (the +/- of your blood type) antigen, work like this.

This means people may be exposed to new blood antigens during a transfusion, transplant, or through pregnancy (including ectopic and aborted pregnancies), and not have a significant response. But during a following exposure, their body then produces lots of antibodies against the antigen it has seen before and produce a reaction. People who receive multiple blood transfusions are at a much higher risk of repeat exposure to antigens they don't make.

The exception to this is ABO mismatching. A and B antibodies are naturally occurring, meaning that our bodies can produce them without having ever been exposed to other blood before. This means that we can have a large antibody response on first exposure to an incorrect type. Different countries and transfusion centers have different testing procedures and requirements, but ABO typing is given priority because of its ability to cause immediate, severe reactions.

Remember, people make antibodies against what they don't already have themselves. Those with type-A blood will not make A antibodies, but they can make B antibodies. Type-B blood can make A antibodies, but not B. Type-AB have both antigens, so they don't make antibodies for either.

But there are over 40 blood group systems that can produce different antigens, with varying degrees of clinical significance. Most people have never been exposed to foreign antigens before and/or don't make any antibodies that would cause hemolytic transfusion reactions, so testing every person for every antigen would be a waste of time and resources.

Generally, blood testing before a transfusion has two components: a type test to identify the presence of 3 antigens and a screening test for relevant antibodies.

Everyone carries two copies of the gene that decide their ABO blood system. You inherit one copy from each of your parents. You can inherit either an A, a B, or a null option, o, that produces neither A nor B antigens.

This means basically that your red blood cells have a one type of sugar molecule on its membrane or a different type of sugar molecule. O results in a no sugar attached.

But because there are two copies, you can have mixes of A, B, and o genes. Type A and B are codominant, which means if they both get inherited, both antigens get expressed/produced and you have type AB blood. However, A and B both dominate over o.

Imagine, in the image above, the A molecule had some empty spaces instead of sugar molecules. It would still have a lot of A that wins out and makes the molecule get seen as A blood. That means inheriting A and o genes (Ao) looks and tests similarly to blood with two (AA) copies. The same is true for Bo testing as B blood.

The way people have type-O blood is by inheriting two copies of the null gene. No sugars get added, only empty spots. (I like to use lowercase "o" to help remember that it's quiet)

When we want to predict the genetic likelihood of what children can inherit from their parents, we can use a Punnett square.

In this instance, we know the what copies each parent carries. Type AB people have one A copy and one B, but they can only pass one of them down to their offspring. Type O blood only occurs with two null oo copies. They must pass down an o copy, there isn't any option.

Now we can create possible options for how those gene copies are distributed to children. We fill out our square by adding the parents genotypes, AB and oo, to the outside edges of the square. Then we create the different combinations by adding each parent option to the squares below or beside them.

This shows that an AB parent has a 50% chance of giving their child an A gene, and a 50% chance of giving them a B gene. A type O parent has a 100% chance of giving their kid an o gene.

2/4 of our squares resulted in Ao genotypes. The other half had Bo genotypes. As we see above, Ao results in A blood and Bo results in B blood. So the child has a 50% chance of being type A and 50% chance of being type B. No type O because one parent has no o gene copy to give.

Now, there are 4 reasons I can think of where the situation you've described occurs and there's probably more

1. Someone is misremembering their blood type. This happens quite a lot. Thats why we test people's blood type regardless of what they say.

2. One of the tests was wrong. Tests can be impacted by internal factors like pan-agglutination (where everything tests as positive) or lack of antibody/antigen production resulting in weak reactions, and external factors like poor testing methods and lack of skill in interpreting results. Many of these issues cause test discrepancies that should be resolved by the hospital, but they do happen.

3. Rare genetic inheritance patterns. Sometimes due to the way genes physically get inherited or rare blood antigens, type AB and O parents could produce an O child, or someone who types as O. I don't really do that sort of science.

Our bodies, generally speaking, are pretty good at recognizing self and differentiating that from non-self. When our immune systems detects cells or components made by our body, it shouldn't react. When it detects foreign, potentially harmful substances, our white blood cells can respond in a variety of ways. One type of white blood cell, called B cells, produce antibodies.

Usually, we think of antibodies when we talk about diseases and vaccinations, but there are several types of antibodies which get produced in different kinds of reactions. In all cases, antibodies are proteins that recognize and bind with specific substances, known as antigens. That means each antibody has a target, like a specific protein or sugar, that it matches with like a lock with a key. The process of binding together is called agglutination and sometimes lots of antigen-antibody complexes get clumped together. Agglutination often acts as a signal for other cells to come respond to the threat, although it can sometimes neutralize targets directly.

Note: antigen =/= allergen! Allergens are a type of antigen that cause an allergic response

We can imagine with disease, once the body recognizes a foreign microbe through infection or vaccination, it can produce antibodies that target some part of the virus/bacteria/etc, like a protein structure on the microbe's surface. The antibodies bind to their targets and often work as huge flags to the immune system that there is a foreign material that needs to be destroyed.

Many blood transfusion reactions work in a similar way. Our red blood cells have many antigens, mostly proteins on or in the cell membrane. A, B, and D (the +/-) are examples of antigens, but there are a ton more. Our bodies are familiar with the antigens we produce and can react when exposed to foreign ones. When someone receives blood with antigens they don't make themselves, they may have an immune response as their body recognizes and attacks the foreign cells.

This image shows how agglutination can happen with 2 types of antibodies. They bind to red blood cells and can cause them to stick to each other. "Complement activation" refers to proteins involved in increasing immune system response to destroy and clear cells from the body

These types of antibody-mediated transfusion reactions can be acute and occur minutes to hours after the start of the transfusion, or they can be delayed days or weeks after. The antibodies signal for the immune system to destroy the foreign donor red blood cells, which is called hemolysis. The breakdown of cells can cause mild to severe side effects and complications as the pieces of red blood cells flood the body. It also ruins the intent of the transfusion itself, since the destroyed blood can't help fix the original blood problem.

Note: As a term, "blood transfusion reactions" can refer to a variety of reactions, including immune-mediated (hemolytic, non-hemolytic febrile, allergic reaction, and TRALI) and non-immune (infection, TACO) responses. Blood bank testing is mostly focused on preventing immune-mediated hemolytic reactions

Now, antibodies can be weird. People produce them in different amounts and strengths, they can be affected by age or illness, and our bodies remember how to produce them for different periods of time. Not everyone who is exposed to blood with foreign antigens produces antibodies against it or will have the same response. There are also a lot of different blood antigens; some can cause stronger or longer antibody response.

Many transfusion-related antigens also only cause reactions after repeat exposure. Much like vaccines or allergies, the first exposure primes the immune system, showing it what the foreign substance looks like. Then, the next time that substance appears, the immune system can respond faster and harder than it did before. Most antibodies in transfusions, including the one that targets D (the +/- of your blood type) antigen, work like this.

This means people may be exposed to new blood antigens during a transfusion, transplant, or through pregnancy (including ectopic and aborted pregnancies), and not have a significant response. But during a following exposure, their body then produces lots of antibodies against the antigen it has seen before and causes a reaction. People who receive multiple blood transfusions are at a much higher risk of repeat exposure to antigens they don't make.

The exception to this is ABO mismatching. A and B antibodies are naturally occurring, meaning that our bodies can produce them without having ever been exposed to other blood before. This means that we can have a large antibody response on first exposure to an incorrect type. Different countries and transfusion centers have different testing procedures and requirements, but ABO typing is given priority because of its ability to cause immediate, severe reactions.

Remember, people make antibodies against what they don't already have themselves. Those with type-A blood have A antigens, so they will not make A antibodies, but they can make B antibodies. Type-B blood can make A antibodies, but not B. Type-AB have both antigens, so they don't make antibodies for either.