Strongyloides stercoralis: parasitological, immunological and pathological observations in immunosuppressed dogs

Abstract

Four specific pathogen-free, two to three-month-old, laboratory-raised beagles were infected with Strongyloides stercoralis and monitored by thrice-weekly faecal examinations. Larvae were not detected in the faeces after the 11th week. During the 14th week, daily oral prednisolone (2.2 mg/kg) was given. This led to weak recrudescence of the infection. During the 21st week, the daily dose of prednisolone was doubled and thereafter two of the four dogs developed severe hyperinfective strongyloidiasis with their adult worm populations markedly exceeding the number of larvae inoculated, as did one dog which remained asymptomatic. One dog died during the 15th week, i.e., before there was time for a marked increase in the parasite population. Three of the four dogs provided evidence of disseminated infection with adult worms occurring in ectopic sites. Parasite-specific cellular and humoral immune responses were monitored weekly. All dogs developed a significant rise in specific IgM titres lasting until the fifth week. From the fourth week, all dogs had detectable parasite-specific IgG antibody levels that persisted throughout the experiment in spite of the immunosuppression. Strongyloides-induced lymphocytic responses in vitro were demonstrated in three dogs from the second to the fifth week of infection, but returned to pre-infection levels thereafter. All animals were necropsied. Relevant pathological lesions were found in the small intestine, the colon and the lungs. Larvae were seen in such ectopic sites as mesenteric nodes and prostate. The observations provide further evidence that canine S. stercoralis infections can be manipulated to reproduce with great fidelity the parasitological and clinico-pathological events occurring in human disseminated strongyloidiasis.

The value of an immunoenzymatic test (enzyme-linked immunosorbent assay) for the diagnosis of strongyloidiasis in patients immunosuppressed by hematologic malignancies.

“…The production of IgG was detectable only after the sixth week of infection. 34 In conclusion, the immunoenzymatic test seems to be a good screening assay in ruling out strongyloidiasis in patients with hematologic malignancies, in the view of the poor compliance of patients to repeated stool tests. Nevertheless, positive results must be viewed in the context of clinical symptoms because of the high rate of false positive results.…”

Intestinal parasitic infections in HIV/AIDS patients: epidemiological, nutritional and immunological aspects

“…Studies have connected serious or disseminated intestinal parasitic infections to immunosuppression, including AIDS, although several aspects remain obscure (12,26,(32)(33)(34)(35)(36)(37). This study aimed to better clarify the participation of intestinal parasites and their correlation with Various studies have associated intestinal parasites with education levels.…”

Strongyloides stercoralis hyperinfection associated with human T cell lymphotropic virus type-1 infection in Peru.

“…Carriage by Strongyloides larvae of enterobacteria from the colon often produces sepsis 2,7 or meningitis. The results of several studies have documented an association of disseminated Strongyloides infection with malignant tumors, severe malnutrition, 8,9 corticosteroid therapy, 10,11 and renal transplantation. 12,13 Some reports have described a significant association between human T cell lymphotropic virus type-1 (HTLV-1) infection and the carriage of S. stercoralis larvae in the stools of both Japanese and Jamaican patients 14,15 This virus is endemic in Peru and has been associated with high risk sexual behavior, 16 Japanese origin, 17 and Quechua ethnicity.…”

“…Over the last 30 years, a substantial number of patients were diagnosed at the Cayetano Heredia Hospital in Lima, Peru with Strongyloides hyperinfection syndrome who were apparently normal hosts without any of the classical predisposing immunosuppressive conditions listed above. [9][10][11][12][13] Because Strongyloides and HTLV-1 coexist in Peru, this study was conducted to determine if HTLV-1 is associated with Strongyloides infections.…”