How can Strongyloides Kill Someone ?

2009-10-20T23:44:00.000-07:00

Q: Richard Trudgen: 16th of Oct 2009

So how can Strongyloides kill somebody? This is the question I am being asked.

A: Professor Rick Speare

It is a good question. People with strongyloidiasis die from disturbances to their physiology and microscopic anatomy.

Main causes of death seem to be:
1. Sepsis - pneumonia, septicemia, meningitis, peritonitis. These seem to be the most common fatal infections. In most cases bacteria commonly found in the gut are the cause. These have probably been taken into the body by autoinfective larvae. Infection occurs in at least in 50% of fatal cases.

2. Severe inflammation in gut associated with autoinfective larvae, probably bacteria and the host's response to these and the adult parasites. This results in diarrhoea, vomiting, hemorrhage in some cases and finally gut paralysis (paralytic ileus). Gastrointestinal inflammation occurs in all fatal cases.

3. Inflammation in a range of organs due to autoinfective larvae migrating through them and the host responding to larval passage and also to death of larvae. When counts of parasites have been done on fatal cases, there are usually 1000s of adult worms in the gut and tens of thousands of autoinfective larvae in tissues. Hence, in fatal cases there are typically inflammatory microscopic granulomas found in lung, brain, liver, kidneys, skin, and a range of organs. The granulomas are often associated with local hemorrhage in the tissues, particularly in the lungs. Occurs in most fatal cases.

4. From these various processes there is often a severe disturbance in electrolyte balance and vascular volume and this is probably what kills people, delivers the cup de grace. However if the lung is severely damaged, people die from hypoxia and respiratory failure, not just electrolyte abnormalities.

Remember, however, that these events are typically superimposed on an individual that has a poorly functioning immune system. So inflammation can occur, but antibody and/or T cell production is often markedly depressed and there is little impact on the parasite.

People without immunodeficiencey or immunosuppression can develop hyperinfection, but it is rare. Hyperinfection rarely happens quickly. The chronic progression to hyperinfection highlights that the underlying immune problems are largely to blame for increasing the fatality rate of strongyloidiasis. There is always a build up of increasing worsening of symptoms, which sometimes takes weeks or months. In most fatal cases there are typically a number of opportunities to diagnose and treat strongyloidiasis before it becomes severe. Death rate with hyperinfection is high, even with treatment. Diagnose and treat early is the rule!

Hope this helps

Rick Speare
PS Here is an interesting case report (scowden-1978.pdf) that talks about the lesions seen in several fatal cases. It is an old paper; hence it has the scope to present findings in detail. But read it with its date of publication in mind.

ARDS

How can Strongyloides Kill Someone ?