Friday, May 23, 2008

What are co-infections and why are they important?

It turns out that our friend Ixodes, the deer tick, carries other germs which it can transmit to us, not just Borrelia, Lyme. These other tick borne germs are referred to as co-infections. Evidence of these co-infections can be significant in one of two ways. It adds supporting evidence to the Lyme diagnosis; or the co-infections themselves may be complicating the disease, making you sick or sicker, perhaps the reason why you are not getting better when Lyme alone is treated. In the usual sense the term, co-infection is reserved for other germs carried by the tick vector. Your doctor may look for evidence of other infections which are not tick borne. Although they are not strictly c0-infections, they may be other chronic infections which act in concert along with the tick borne germs, as if things weren't already bad enough. Some writers speak of Lyme as the "gateway" germ. It lowers your body's immune defenses to the point that previously contained organisms now gain the ability to cause illness. This of course is conjectural. The primary co-infections are: Ehrlychiois, which comes in two varieties. It is a small bacteria, will a gram negative cell wall (bacteria are divided based on two different cell wall types, the gram negative nomenclature indicates that the cell wall does not take up the gram stain). These germs live inside the vacuoles inside the cytoplasm of cells(they are only intracellular). Infection is usually mild and found incidentally when patients are tested for Lyme; however, Ehrlychia chaffensis, also called HME (Human Monocytic Ehrlychiosis) has rarely reported to be fatal. Lyme is generally not considered a fatal disease. Although many "Lyme docs" would dispute this assertion. HME can cause symptoms which mimic those of Lyme disease. It typically has more fever and headache. It may have more atypical symptoms, including nausea, vomiting, diarrhea as well as cough. It also can cause confusion. Fulminating infection with shock has been reported. HGE, Human Monocytic Ehrlychiosis is also caused Anaplasmosis. They names are annoying and redundant, sorry about that. It is very similar to HME. The kicker is that many labs only test for HME, so your doctor must specify a test for HGE as well. I use Labcorp a lot. They give me antibody levels for HME, which I find more accurate, but tend to give me PCR testing, which looks for the DNA form HGE which I find less reliable. This is one test where Quest labs does a better job. Both are treated with Doxycycline, which is convenient since this is a good Lyme drug as well. If Doxy can not be used, Rifampin has been used second line. The best bet is to find a tetracycaline if possible. The duration of therapy of course is controversial. Standard texts suggest that only a short course of therapy is needed. I like to treat with Doxycyline 200mg twice daily for two months.

The second co-infection is Babesiois. This is more controversial. There may be many strains, but tests are available for B. microti and B. WA. Most doctors get an antibody test. Many infectious disease specialists insist the disease is not present unless it is seen in a blood smear or by PCR DNA/RNA testing. Lyme docs don't think is shows up this way once it is chronic. It infects red blood cell, but very few cells may be infected so microscopic screening of blood smears is inaccurate. The DNA test may be better. But it only works if you know what strain you are looking for. And again, in chronic infections if may be associated with false negative results. Babesia is not a bacteria. It is protozoan. A larger one cell organism of the kind frequently lumped in with the term parasite. It is malaria like, because it attacks red blood cells. Many experts believe the normal immune system is usually able to clear it without medicines. Some infections can be life threatening, but this is rare. It causes a lot of Lyme like symptoms. But it is more typically associated with a malaria like pattern. Patients tend to have recurrent fevers and chills, weakness and muscle pains which occur on a daily or frequent cycle. When low antibody titers are present in the absent of such symptoms, I may defer treatment, viewing this more a sign post of likey Lyme exposure. Many other doctors always treat it aggressively. The usual therapies are either quinine and clindamycin, which I avoid because it is toxic, or Mepron and Zithromax, which is effective, but very costly. Quinine frequenly causes hearing loss and clindamycin is associated with a high incidence of diarrhea. The dose of Mepron is 750mg twice daily and the dose of Zithromax is 600mg daily. The Zithromax is a good Lyme drug so you get two for the price of one. A three to six week course may suffice, although I find that many of my colleagues prescribe it for 2 to 4 months. All of this causes apoplexy to most infectious disease specialist, since they believe it should be treated for only a week or so. They also believe it should only be treated if there is a positve blood smear or PCR test. Oy vay.

The last co-infection is Bartonella. This surprisingly is the bacteria which causes cat scratch fever. The usual culprit is B. henselae. Cipro is commonly used. I find this a good Lyme drug, although most of colleagues seem unaware of this. Other drugs including Zithromax, Rifampin and Doxycycine are also reported to work. So it seems that any treamtment for Lyme is likely to cover this pathogen. I do not find it often. It may be associated with more brain symptoms and it probably is fairly easy to irradicate in most patients. A month of Cipro, 250mg to 500mg twice daily for 30 days should dispatch this germ. In my next piece I will discuss germs which are not co-infections but may complicate the scenario.

2 comments:

Starlings Preschool said...

Thought I would revisit this post.
Is your take on coinfections still the same ?
I was interested to see that 3-6 weeks to 2-4 months of babesia treatment seems to be the norm. I don't know of anyone who has eradicated babesia with either of those lengths of treatment (with Mepron and Zith). Are we missing something? My LLMD says WA-1 requires a MINIMUM of 10 months of treatment as it has a different genome than microti and is more virulent. Are you finding this to be true?

Clyde Bowers said...

So I guess Rocky Mountain Spotted Fever and other rickettsia that are transmitted by ticks simply do not exist? Anaplasma? There are only 3 coinfections? Your ignorance of tickborne pathogens is astounding doc. You should call your offshore medical school in the Caribbean and ask for a refund. You are lyme illiterate.