Trypanosomiasis: Diagnosis, IgM in cerebrospinal fluid

Antibodies should if possible be detected in the cerebrospinal fluid (technically difficult). Determining the IgM content in the cerebrospinal fluid can be very difficult or even impossible to carry out in endemic areas and under field conditions. An experimental latex agglutination test for detection of IgM was developed at the Institute of Tropical Medicine, Antwerp, Belgium. Blood-CSF barrier dysfunction is usually absent or mild and occurs in very advanced late-stage disease. It is possible to calculate and plot diagrams of the quotients CSF/serum concentration for IgG, IgA and IgM (demonstration of intrathecal production of antibodies). Especially intrathecal IgM production will be present in late-stage sleeping disease (occurs in 98% of people with leukocyte counts higher than 20/µl). Similar patterns do occasionally occur in Lyme neuroborreliosis, neurosyphilis, mumps meningoencephalitis and in non-Hodgkin lymphoma involving the central nervous system.

Usefulness of the lumbar puncture:

A lumbar puncture is important :

• sometimes in order to make a diagnosis

• in order to determine the stage (main purpose)

• in order to monitor therapy.

In the 2nd stage the cerebrospinal fluid is characterised by:

• white blood cell count (WBC) > 5 per mm^3, (normally <3)

• protein > 45 mg%, (normally 15-45 mg%)

• IgM increase, (difficult to carry out; Latex IgM)

• Sometimes trypanosomes and/or Mott cells

In African trypanosomiasis, the cerebrospinal fluid can contain numerous lymphocytes. Some of them will have developed into plasma cells containing cytoplasmic vacuoles filled with accumulated immunoglobulines. These cells are also known as morula cells or Mott cells.

Control lumbar punctures should be carried out for late stage West African trypanosomiasis every 6 months for 2 to 3 years after diagnosis and therapy. In East African trypanosomiasis they should be carried out more frequently (every 3 months, certainly in the first year). Good follow-up is essential. Recurrence often presents as a deterioration in results obtained with the cerebrospinal fluid (increased lymphocyte count). Parasitological proof of recurrence is often lacking. Immediately after treatment the lymphocyte count in the cerebrospinal fluid increases (so-called "cerebrospinal fluid storm"). This should not be regarded as a recurrence. There is no permanent protective immunity. Reinfection can occur.

Category: Medicine Notes