Nervous System- Infection & Inflammation I
Question No. 21. The Answer is: (E) Strongyloides stercoralis.
Discussion: Strongyloides stercoralis is a small nematode that is most commonly found in the tropics but can also be found world wide. The parasite infects human by penetrating the skin and also possibly through fecal oral contamination. The invading infective larvae are highly motile. They would move into the lymphatics to reach the vein and eventually into the alveoli. They would then move up the airways to the glottis and enter the small intestine through the esophagus and stomach. From there, the larvae will mature and lay eggs. After hatching, rhabditiform larvae are produced. The larvae can be excreted through the feces but can also re-enter the host (autoinfection). The invading larvae can also carry bacteria into the blood to cause bacteremia and sepsis. The clinical manifestations are mainly that of the gastrointestinal tract and the skin. An overwhelming larval infection (hyperinfection syndrome) can occur in patients with severe immunosuppression and such infection can involve every organ. The complication is fatal if therapy is not instituted in a timely manner. However, it is often difficult to be diagnosed. As the cycle of autoinfection can persist up to 40 years, hyperinfection syndrome in an immune compromised host that has left the endemic area for a prolonged period of time can be difficult to be diagnosed. Under normal circumstances, the CNS is not involved. However, involvement of the CNS may be prominent in hyperinfection syndrome.
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