Modulation of circulating cytokine production in alcoholic patients infected with Strongyloides stercoralis

Immunodominant Molecules for the Immunodiagnosis of Strongyloides stercoralis Infection

This study aimed to identify immunodominant molecules with potential for S. stercoralis infection immunodiagnosis. Serum samples were tested by an IgG-ELISA using Strongyloides venezuelensis soluble (AgS) and membrane (AgM) antigens, and its protein fractions (<100 and >100 kDa). Proteins were tested by one- and two-dimensional (2D) gel immunoblotting. The ELISA results showed sensitivities, ranging from 82.3 to 85.3 %, while specificities ranged from 60.0 to 93.3 %. Cross-reactivities were observed with sera from individuals infected with other helminths. Immunoreactive protein bands were revealed by Western blotting using both antigens, and a band with molecular weight around 140 kDa of AgS showed 100 % sensitivity and specificity, without cross-reactivity. The 2D immunoblotting revealed 7 spots in the 140 kDa protein with the S. stercoralis pool of serums. The pre-selection of Strongyloides immunodominant proteins that are highly specific and free from cross-reactions is essential for the production of recombinant antigens for the immunodiagnosis of strongyloidiasis.

Strongyloidiasis

Strongyloidiasis is a neglected tropical disease caused primarily by the roundworm Strongyloides stercoralis. Strongyloidiasis is most prevalent in Southeast Asia and the Western Pacific. Although cases have been documented worldwide, global prevalence is largely unknown due to limited surveillance. Infection of the definitive human host occurs via direct skin penetration of the infective filariform larvae. Parasitic females reside in the small intestine and reproduce via parthenogenesis, where eggs hatch inside the host before rhabditiform larvae are excreted in faeces to begin the single generation free-living life cycle. Rhabditiform larvae can also develop directly into infectious filariform larvae in the gut and cause autoinfection. Although many are asymptomatic, infected individuals may report a range of non-specific gastrointestinal, respiratory or skin symptoms. Autoinfection may cause hyperinfection and disseminated strongyloidiasis in immunocompromised individuals, which is often fatal. Diagnosis requires direct examination of larvae in clinical specimens, positive serology or nucleic acid detection. However, there is a lack of standardization of techniques for all diagnostic types. Ivermectin is the treatment of choice. Control and elimination of strongyloidiasis will require a multifaceted, integrated approach, including highly sensitive and standardized diagnostics, active surveillance, health information, education and communication strategies, improved water, sanitation and hygiene, access to efficacious treatment, vaccine development and better integration and acknowledgement in current helminth control programmes.