ASLO is not a disease!

ASLO is not a disease!

A conversation with a patient went as follows:

“Doctor, that my ASLO no does not want to leave me. I have taken several injections of Bezathine Penicillin to no avail. Every time I come to the hospital, the lab tests always show that I have ASLO. I have been having this ASLO for a very long time.”

ASLO is not a disease. ASLO is a blood test used to detect the presence of certain bacteria. Now, let’s learn a few things about ASLO.


When one is exposed to harmful bacteria, one’s body produces antibodies that help to protect it against future infection by the same bacteria. These antibodies are most of the time specific to the bacteria against which they are produced and can be detected using blood tests.

The term ASLO is an abbreviation for Antistreptolysin O antibody test. It is a blood test carried out to detect the presence of antibodies in blood when the body is exposed to a bacterium known as group A streptococcus. These bacteria can cause throat and skin infections and if present in the body without treatment can lead to complications like rheumatic fever and glomerulonephritis, the latter of which is a serious disease of the kidneys.

Antibodies can be produced within one week to one month if one’s body is exposed to group A streptococci, and so can be detected in blood.

Why is the test ordered?

The ASLO titer test is usually ordered when complications caused by group A streptococcus infection such as rheumatic fever and glomerulonephritis are suspected in a patient. Rheumatic fever is a disease that commonly occurs in children and is characterized by fever, joints pain, small painless nodules under the skin, jerky movements of the limbs, skin rash and sometimes the heart may be inflamed. Thus, ASLO titer test is ordered when recent streptococcus infection in the throat or skin is suspected as the cause of these complications when the bacteria can no longer be found in the throat or skin. The test can be ordered alone or with another test called anti-DNase B test.

What does the test result mean?

If the body is exposed to group A streptococci, antistreptolysin O antibodies are produced within a week to one month and will have the highest level at three to five weeks after exposure. They then begin to get reduced in the blood but may remain detectable several months after infection.

It is not just important for the ASLO test to be positive but for the titer to be known. If the test is positive with a titer above 200 in adults (above 100 in children) it means a recent streptococcus infection was the cause of a complication such as rheumatic fever or glomerulonephritis. If the titer is increasing after repeating the test in two weeks, it means the patient has a recent streptococcus infection. If the titer is below 200 (below 100 in children) it means there was streptococcal infection but not sufficient enough to cause complications. If the test is negative, it means there was no streptococcal infection. However, in medicine, research is constantly going on and your doctor is in the best place to interpret the results of your ASLO titer test.

Group A streptococcal infection can be treated with Benzathine penicillin injections or any other antibiotic that can take care of the bacteria. There are many of these antibiotics but your doctor is the only one that can prescribe them.

Infection with streptococci can be prevented by thoroughly washing the hands after coughing or sneezing and avoiding exposure to persons who are constantly coughing and sneezing. Such persons should be encouraged to see a doctor who can find out whether the infection is due to streptococci.