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Ehrlichia: confusing cousins, the blood supply, and the new kid on the block 05/04/2012

Posted by thetickthatbitme in Diagnosis, TBI Facts.
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Ehrlichia…I just met a girl named Ehrlichia…and suddenly the sound…

Nope. Doesn’t quite work.

Paul Ehrlich

Paul Ehrlich (1854-1915). Image via Wikipedia.

Ehrlichia is actually named after German microbiologist Paul Ehrlich (1854-1915), who won the Nobel Prize in 1908. Here are some things you actually need to know about Ehrlichia:

1. Ehrlichia is transmitted through the bites of lonestar ticks and deer ticks. If you’ve had another infection carried by these ticks (like Lyme Disease), your doctor should have had you tested for Ehrlichia (or maybe you’ll be asking him/her to test you after reading this post?).

2. Symptoms of Ehrlichiosis include: fever, headache, chills, malaise, muscle pain, nausea / vomiting / diarrhea, confusion, conjunctival injection (red eyes), and rash (in up to 60% of children, less than 30% of adults). When it goes untreated (or improperly treated), complications can include breathing problems, bleeding disorders, and death (1.8% of cases).

3. Ehrlichia is effectively treated with doxycycline in both adults and children. The CDC recommends a 7-14 day course.

4. Your doctor shouldn’t wait for your test results to come back before prescribing you doxycycline. If your doctor thinks you might have Ehrlichiosis, he/she might order a PCR, a blood smear, or an IFA (antibody test). These tests can take a few weeks to come back, and in that time, you could get very, very sick. In addition, a negative result on any of these three tests does not rule out the possibility of infection. Often, in the first 7-10 days you are infected, you will test negative. For more information about these tests, take a look at the Ehrlichiosis fact sheet.

5. Ehrlichia can be easily misdiagnosed as one of two other infections. It’s a rickettisial disease, which means it’s in the same family with A. phagocytophilum and Rocky Mountain Spotted Fever (RMSF). Sometimes the rash patients get with Ehrlichia looks a lot like the rash patients get with RMSF.

6. It may be possible to contract an Ehrlichia infection through a blood transfusion. The CDC has not been very vocal about it, but it’s on their website. Fun fact: “Ehrlichia chaffeensis has been shown to survive for more than a week in refrigerated blood.” If you’ve had an Ehrlichia infection, it’s probably not a good idea for you to be a blood or organ donor.

7. There’s a newly identified species of Ehrlichia in Wisconsin and Minnesota. It doesn’t have a fancy species name yet, so scientists refer to it as Ehrlichia Wisconsin HM543746 or Ehrlichia muris-like (EML). This one is carried by deer ticks. If you live in one of these states and your doctor is not so hip to the new infectious disease research, he or she may have told you that you didn’t need to be tested for Ehrlichia because “we don’t have that here.” (I hate it when doctors say that!)Hopefully there will be a commercially-available, species-specific test for this soon. For now, my guess is that physicians in Wisconsin and Minnesota who suspect Ehrlichia infection are ordering tests for E. chaffeensis and E. ewingii.

Got an Ehrlichia story you’d like to share? Shoot me an e-mail.

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Well, Babs, you’re trickier than I thought 05/01/2012

Posted by thetickthatbitme in Diagnosis, Peer-Reviewed, TBI Facts, Tick-Lit.
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Welcome to the second installment of Tick-Lit Tuesday, where I comb through PubMed so you don’t have to. Today’s topic: Babesia and Blood Transfusions. Now, I know I posted about Babesia in the blood supply just a few days ago, but an interesting study has since come to my attention (thanks, Dr. W), and the implications are a bit scary. Okay, get your popcorn and let’s begin.

The Issue:

blood donation

A blood donation pictogram. Image via Wikipedia.

It has been well-documented that the tick-borne protozoan parasite Babesia can be contracted through blood transfusions. Blood centers aren’t required to test donated blood for Babesia, but this may change in the future, as Babesia infections contracted through transfusions are on the rise. So if we were to test all donors for Babesia prior to donation, which tests should we rely on to detect this pesky parasite? Let’s look at the candidates.

IFA: IFA is an abbreviation for indirect fluorescent antibody test. This type of test can also be referred to as serologic (as in blood serum) testing. If you’ve had one of these tests for Babesia, it’s probably titled something like “WA1 IGG ANTIBODY IFA” (for B. duncani) or “BABESIA MICROTI ABS IGG/IGM” on your lab results. If you’ve had Babesia in the past and been treated for it, your antibody test might still read positive because your body is still making antibodies to the parasite. This is one of the reasons why most insurance companies refuse to pay for treatment for Babesia if your only positive test is the IFA. They think maybe you had a past infection that you got over, so you don’t need treatment. (The other reason they refuse to pay is that they’re jerks, to put it nicely.) I’ll talk more about why this is such a problem later in this post.

Babesia microti smear

A stained blood smear on which B. microti parasites are visible in red blood cells. (CDC Photo: DPDx). Via CDC.gov.

Smear: When we talk about a smear for Babesia, we mean a Giemsa-stained thin blood smear. This test involves looking at blood samples under a microscope to see if there are any parasites hanging around. The problem with this test is that Babesia can infect fewer than 1% of your circulating red blood cells, so it could take many, many smears before any Babesia show up under the microscope. For more information about that phenomenon, read this.

PCR: This stands for polymerase chain reaction. It’s basically a DNA test that tries to identify whether a gene associated with Babesia is present in the blood. PCR has been found to be “as sensitive and specific” as blood smears for Babesia (see this study), which is not saying much, considering the tendency of Babesia to go undetected with smears.

Hmmm, for whom shall I cast my ballot, the antibody test insurance companies don’t trust, the inaccurate smear, or the inaccurate PCR? Choices, choices…

Today’s question:

Can the donated blood of someone with a negative PCR and negative blood smear still be infected with Babesia and cause Babesia infection in transfusion recipients?

(Hint: This is a leading question.)

Let’s talk about a study published in the journal Transfusion in December of 2011 called “The third described case of transfusion-transmitted Babesia duncani.”

Here’s what happened:

In May 2008, a 59 year-old California resident (I’ll call him Cal) with sickle-cell disease had some red blood cell transfusions. Cal’s only risk factor for Babesia was the transfusions; he didn’t have any tick exposure. In September of 2008, Cal was diagnosed with a Babesia duncani (WA-1) infection. The parasites were visible on a blood smear, the indirect fluorescent antibody (IFA) test was positive, and the PCR was positive for the Babesia gene. This launched a transfusion investigation in which doctors tracked down 34 of the 38 blood donors whose blood could have infected Cal with Babesia. One donor, a 67-year-old California resident (who I’ll call Don) had a B. duncani titer of 1:4096 (on the IFA test). What does a titer of 1:4096 mean? Well, if the antibody test for B. duncani is negative, the titer will be < 1:256. That means that Don’s antibody test was positive.

What the article abstract doesn’t tell you, which the full article does, is that both Don’s PCR and blood smear were negative for Babesia. How did the researchers prove definitively that Don had Babesia in his blood? They injected the blood into Mongolian gerbils, and were later able to isolate the parasite from the gerbils. Conclusion: Even though Don showed no symptoms of Babesia and both his PCR and smear were negative, his donated blood caused Babesiosis in both Cal and the gerbils.

Here’s why the study’s findings are important:

1. Clearly, blood smears and PCRs are not good indicators of whether someone is infected with Babesia. Why insurance companies think these tests need to be positive before they’ll pay for treatment is a mystery to me. There are probably a lot of people out there who’ve had positive IFAs but negative smear and/or PCR who were then not treated for Babesia because either the doctor, the insurance company, or both said they didn’t have an infection.

2. As far as the blood donation goes, if we don’t start screening out donors with positive Babesia IFAs, we’re going to continue to contaminate the blood supply with Babesia. It should be as simple as that. Been bitten by a tick? No blood donation for you. Positive IFA? No blood donation for you.

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Parasites in the blood supply, and 7 other things you need to know about Babesia 04/27/2012

Posted by thetickthatbitme in TBI Facts.
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The fact sheet for Babesia is up today. Here are a few (disturbing) highlights:

1. Babesia is a parasite that attacks red blood cells. There are three ways Babesia spreads:  1) Through the bite of the blacklegged tick (or deer tick, Ixodes scapularis—the same tick that carries Lyme/B. burgdorferi); 2) Through blood transfusions with contaminated donated blood; 3) From mother to baby during pregnancy or childbirth.

tick nymph penny babesia

A nymphal stage Ixodes scapularis tick (approximately the size of a poppy seed) is shown here on the back of a penny. Credit: G. Hickling, University of Tennessee.

2. The tick that carries Babesia is most likely to infect humans when it’s in its nymphal stage. During this stage, the tick is about the size of a poppy seed. (Maybe this is one reason why Babesia cases are on the rise among older people–they probably have trouble spotting ticks that small!)

3. Many people who have a Babesia infection don’t show any symptoms. When they do show symptoms, they can include fever, chills, sweats, headache, body aches, loss of appetite, nausea, and fatigue. Some develop hemolytic anemia, which causes jaundice and dark urine.

4. Babesia can be deadly if it goes untreated. Here are some possible complications: low and unstable blood pressure; altered mental status; severe hemolytic anemia (hemolysis); very low platelet count (thrombocytopenia); disseminated intravascular coagulation (also known as “DIC” or consumptive coagulopathy), which can lead to blood clots and bleeding; and malfunction of vital organs (such as the kidneys, liver, lungs, and heart).

5. There are two main treatment options for Babesia: a combination of Mepron and Zithromax OR a combination of Clindamycin and Quinine. Children and women who are pregnant should probably not be treated with Mepron.To read more about treatment, go to the Babesia fact sheet.

6. Babesia is sometimes confused with Malaria because they look similar under a microscope and can have similar symptoms. To avoid confusion, doctors should order multiple types of tests for Babesia if patients show symptoms. To read more about available tests, see the fact sheet.

7. There are 4 identified species of Babesia that infect humans: Babesia microti, B. divergens, B. duncani (WA-1), and MO-1 (unnamed strain). Antibody tests for Babesia are species specific, so if you have B. microti and you are tested for B. duncani, the test will come back negative. This means that patients need to undergo multiple blood tests!

8. Even though Babesia infection is known to be transmitted through blood transfusion (As of Sept. 2011, the CDC has identified 159 cases, and at least 12 of those people have died.), donated blood is not tested for Babesia! Donors are asked to fill out a questionnaire asking whether they have Babesia (not whether they’ve had tick bites or Babesia-like symptoms). In other words, we are relying on patient self-reporting to screen the blood supply for this parasite! (Why they don’t screen out all people who’ve had tick bites is beyond me.) The CDC’s response as to whether they will implement testing of donated blood for Babesia in the future: Maybe. They say they are going to “Monitor reports of tick-borne infection to determine if the disease is spreading to other parts of the country and to identify emerging strains of Babesia that may cause human disease.” In other words, they’re going to wait to see how bad it gets before they do anything about the blood supply. Some organizations like the Rhode Island Blood Center have begun screening blood for Babesia using an experimental test, but this is not mandated by CDC policy.

This might prompt you to ask: What are my local health department, hospitals, and blood donation organizations doing about Babesia in the blood supply?

Have questions or  something to add about Babesia? Drop me a comment.

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