Why Does HIV Infection Not Lead to Disseminated Strongyloidiasis?

Abstract

We investigated the hypothesis that host immunosuppression due to advancing human immunodeficiency virus (HIV) disease favors the direct development of infective larvae of Strongyloides stercoralis, which may facilitate hyperinfection and, hence, disseminated strongyloidiasis. To do this, we sought correlations between the immune status of the subjects and the development of S. stercoralis infections. Among 35 adults, there were significant negative rank correlations between CD4+ cell counts and the proportions of free-living male and female worms. Thus, in individuals with preserved immune function, direct development of S. stercoralis is favored, whereas, in individuals with lesser immune function, indirect development is relatively more common. These results may explain the notable absence of disseminated strongyloidiasis in advanced HIV disease. Because disseminated infection requires the direct development of infective larvae in the gut, the observed favoring of indirect development in individuals immunosuppressed by advancing HIV disease is not consistent with the promotion of disseminated infection.

Strongyloidiasis – the most neglected of the neglected tropical diseases?

“…23 In many parts of the world strongyloidiasis occurs together with HIV/AIDS, but co-infection has not been found to be associated with higher S. stercoralis prevalence or the development of hyperinfections. 24 However, S. stercoralis hyperinfection has been described in AIDS patients as part of the immune reconstitution syndrome after starting highly active antiretroviral therapy. 25 In a study in Tanzania involving HIV-infected pregnant women, S. stercoralis infection was associated with a higher risk of low birth weight, which is the single most important factor for high infant mortality.…”

Strongyloides stercoralis infection in the immunocompromised host

“…A recent study postulates that lower CD4 + counts may favor indirect rather than direct development of Strongyloides larvae based on the proportion of free-living adult and infective larvae in stools of coinfected patients [31]. Whether immune reconstitution syndrome occurs after the antiretroviral therapy initiation in Strongyloides-infected patients remains unclear, although case reports have raised this issue [32].…”

Strongyloidiasis-Related Deaths in the United States, 1991–2006

“…Another study in London, United Kingdom, that examined the ratio of CD4 cells counts and strongyloidiasis incidence (n = 34) concluded that persons immunosuppressed by advancing HIV disease are not at increased risk for disseminated Strongyloides infection. 18 A study of seven HIV cases in Brazil co-infected with Strongyloides infection reported that the relationship identified may be more related to steroid treatment of HIV patients than the disease. 25 Sexual transmission of Strongyloides has also been reported in other studies 23 and may be another explanation for the apparent association with HIV and predominance of men found in our study.…”

“…9 Additionally, studies during this time also indicated that immunosuppressive illnesses such as hematologic malignancies may increase strongyloidiasis severity, which later studies have elaborated on. 10 Since the 1960s, severe strongyloidiasis has been associated with a variety of immunosuppressive health conditions and/or health conditions that may require corticosteroid treatments, which include asthma, 11 arthritis, 12 lupus, 13 inflammatory bowel disease (IBD), 14 hypogammaglobulinemia, 15 chronic obstructive pulmonary disease, 16 sarcoidosis, 17 acquired immunodeficiency syndrome/human immunodeficiency virus (HIV), [18][19][20][21][22][23][24][25] and organ transplants. 26,27 Many of these findings have been summarized by Genta.…”