Tests for Infectious Diseases

Amyotrophic lateral sclerosis (ALS) is a severe progressive neurodegenerative disorder associated with the loss of motor neurons, which transmit signals from the brain to the voluntary muscles to contract. Without these, muscles begin to weaken, leading to a progressive loss of control over movement, speaking, eating, and breathing.

There is no single test to diagnose ALS, and it can be a time-consuming process. Several other conditions can show similar symptoms to ALS, such as some infectious diseases, and these must be ruled out before a diagnosis is confirmed.

What infectious diseases are tested for?

Certain infectious diseases can cause ALS-like symptoms. It is essential to differentiate these from ALS, because they need to be managed in very different ways. In some cases, ALS-like symptoms caused by infectious diseases can be reversed.

Human immunodeficiency virus (HIV) can cause fasciculations (twitching), muscle cramps, and muscle weakness similar to ALS. Examples of this have been published in the journal Neurology. In two case studies, published in 2001 and 2002, ALS-like symptoms were reversed following treatment with anti-retroviral therapy.

Human T-cell leukemia virus (HTLV) can also mimic ALS as it can cause gait problems and unexplained falls.

Polio is a virus that can cause a loss of muscle control and paralysis in its severe form and muscle weakness in its non-paralytic form. Furthermore, it is possible for patients who have recovered from a previous polio infection to show ALS-like symptoms many years later. This is referred to as post-polio syndrome, and may be due to damage originally caused by the infection.

The West Nile virus will mostly cause no or minor symptoms. However, in some rare cases, patients can experience more severe symptoms, including muscle twitches, partial paralysis, or muscle weakness, similar to ALS.

There has also been a case study of Lyme disease mimicking the symptoms of ALS, published in the International Journal of Neuroscience. Treatment with doxycycline reversed the symptoms.

What tests are carried out?

Normally, infectious diseases can be diagnosed through a blood test, where a blood sample is drawn from the patient and sent to a laboratory for testing.

Polio may be diagnosed by testing samples taken from the throat, stools, or the cerebrospinal fluid, the fluid that surrounds the brain and spinal cord. The sample is checked for the presence of particular proteins that indicate infection. These could be antibodies or immune proteins that specifically target the infection in the blood.

If a diagnosis of HTLV is inconclusive, the genetic material in certain types of blood cells may be tested to see if the viral DNA is present.

What do the results mean?

If the results of infectious disease tests come back positive, this does not definitively rule out ALS. However, it can change what treatment the patient receives. The patient may still have to undergo additional diagnostic tests.


ALS News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.