Abstract
BackgroundThe convergent distribution of the Human Immunodeficiency Virus (HIV) and helminth infections has led to the suggestion that infection with helminths exacerbates the HIV epidemic in developing countries. In South Africa, it is estimated that 57% of the population lives in poverty and carries the highest burden of both HIV and helmith infections, however, the disease interactions are under-researched.MethodsWe employed both coproscopy and Ascaris lumbricoides-specific serum IgE to increase diagnostic sensitivity and to distinguish between different helminth infection phenotypes and their effects on immune responses in HIV co-infected individuals. Coproscopy was done by formol ether and Kato Katz methods. HIV positive and negative adults were stratified according to the presence or absence of A. lumbricoides and/or Trichuris trichuria eggs with or without elevated Ascaris IgE. Lymphocyte subsets were phenotyped by flow cytometry. Viral loads, serum total IgE and eosinophils were also analysed. Lymphocyte activation markers (CCR5, HLA-DR, CD25, CD38 and CD71) were determined. Non parametric statistics were used to describe differences in the variables between the subgroups.ResultsHelminth prevalence ranged between 40%-60%. Four distinct subgroups of were identified, and this included egg positive/high Ascaris-specific IgE (egg+IgEhi), egg positive/low IgE (egg+IgElo), egg negative/high IgE (egg-IgEhi) and egg negative/low IgE (egg-IgElo) individuals. The egg+IgEhi subgroup displayed lymphocytopenia, eosinophilia, (low CD4+ counts in HIV- group), high viral load (in HIV+ group), and an activated lymphocyte profile. High Ascaris IgE subgroups (egg+IgEhi and egg-IgEhi) had eosinophilia, highest viral loads, and lower CD4+ counts in the HIV- group). Egg excretion and low IgE (egg+IgElo) status demonstrated a modified Th2 immune profile with a relatively competent response to HIV.ConclusionsPeople with both helminth egg excretion and high Ascaris-IgE levels had dysregulated immune cells, high viral loads with more immune activation. A modified Th2 helminth response in individuals with egg positive stools and low Ascaris IgE showed a better HIV related immune profile. Future research on helminth-HIV co-infection should include parasite-specific IgE measurements in addition to coproscopy to delineate the different response phenotypes. Helminth infection affects the immune response to HIV in some individuals with high IgE and egg excretion in stool.
Highlights
The convergent distribution of the Human Immunodeficiency Virus (HIV) and helminth infections has led to the suggestion that infection with helminths exacerbates the HIV epidemic in developing countries
The convergent distribution of the Human Immunodeficiency Virus (HIV) and helminth infections has been widely associated with the notion that persistent infection with helminths exacerbates the HIV epidemic in developing countries [1]
In this study the combined use of coproscopy and serology improved the diagnosis of helminthiasis, and facilitated the distinction of four phenotypically different infection profiles: (i) stool egg positive and high IgE, (ii) the stool egg positive and low IgE, (iii) the stool egg negative and high IgE and (iv) the egg negative, IgE low subgroups
Summary
The convergent distribution of the Human Immunodeficiency Virus (HIV) and helminth infections has led to the suggestion that infection with helminths exacerbates the HIV epidemic in developing countries. In South Africa, it is estimated that 57% of the population lives in poverty and carries the highest burden of both HIV and helmith infections, the disease interactions are under-researched. A major challenge in studies of co-infection with intestinal parasites is accurate laboratory diagnosis of the helminth infection, in adults. In such studies, proper classification of helminth infection status is critical to avoid misinterpretation of results. Stool egg detection has been supplemented with serum Ascaris lumbricoides -specific IgE measurement. Four distinct subgroups, based on the presence or absence of stool eggs with or without elevated serum Ascaris-specific IgE were delineated. This paper reports the lymphocyte profiles including eosinophil counts, viral loads and the activation status in the defined subgroups
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