Strongyloides stercoralis (Parasitic Roundworm)- A Threadworm


Strongyloides stercoralis is a parasitic roundworm that belongs to the phylum Nematoda and the order Rhabditida. It is commonly known as threadworm because of its slender and thread-like appearance. It is one of the smallest nematodes that infect humans, measuring about 2.5 mm in length and 0.05 mm in width.

Strongyloides stercoralis causes a disease called strongyloidiasis, which is characterized by chronic intestinal infection that can persist for decades without symptoms. However, in some cases, especially in immunocompromised individuals, the infection can become severe and life-threatening, leading to hyperinfection syndrome or disseminated strongyloidiasis.

Strongyloides stercoralis has a complex life cycle that involves both free-living and parasitic stages. The free-living stage occurs in the soil, where the worm can reproduce sexually or asexually. The parasitic stage occurs in the human host, where only female worms are found embedded in the mucosa of the small intestine. The female worms produce eggs by parthenogenesis, which hatch into rhabditiform larvae that are either excreted in the feces or undergo autoinfection.

The main mode of transmission of Strongyloides stercoralis is through skin penetration by the infective filariform larvae that are present in the contaminated soil or water. The larvae can also be transmitted by organ transplantation, transplacental or transmammary routes, or zoonotic infection from dogs or nonhuman primates.

Strongyloides stercoralis is a global health problem that affects more than 600 million people worldwide, mainly in tropical and subtropical regions, but also in temperate areas. It is associated with poverty, poor sanitation, and agricultural activity. It is also endemic in some parts of the United States and Europe, especially among immigrants, refugees, travelers, and military veterans who have lived in endemic regions.

Strongyloidiasis is a neglected tropical disease that requires more attention and research to improve its diagnosis, treatment, and prevention. It is often underdiagnosed because of its low sensitivity of stool microscopy and its nonspecific clinical manifestations. It is also often undertreated because of its potential for relapse and reinfection due to autoinfection. It is also often overlooked because of its low awareness among health professionals and the general public.

Therefore, it is important to increase the knowledge and understanding of Strongyloides stercoralis as a threadworm that can cause serious health consequences if left untreated.