Effect of co-infection with intestinal parasites on COVID-19 severity: A prospective observational cohort study

Abstract

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in a spectrum of clinical presentations. Evidence from Africa indicates that significantly less COVID-19 patients suffer from serious symptoms than in the industrialized world. We and others previously postulated a partial explanation for this phenomenon, being a different, more activated immune system due to parasite infections. Here, we aimed to test this hypothesis by investigating a potential correlation of co-infection with parasites with COVID-19 severity in an endemic area in Africa. Methods: Ethiopian COVID-19 patients were enrolled and screened for intestinal parasites, between July 2020 and March 2021. The primary outcome was the proportion of patients with severe COVID-19. Ordinal logistic regression models were used to estimate the association between parasite infection, and COVID-19 severity. Models were adjusted for sex, age, residence, education level, occupation, body mass index, and comorbidities. Findings: 751 SARS-CoV-2 infected patients were enrolled, of whom 284 (37.8%) had intestinal parasitic infection. Only 27/255 (10.6%) severe COVID-19 patients were co-infected with intestinal parasites, while 257/496 (51.8%) non-severe COVID-19 patients were parasite positive ( p <0.0001). Patients co-infected with parasites had lower odds of developing severe COVID-19, with an adjusted odds ratio (aOR) of 0.23 (95% CI 0.17–0.30; p <0.0001) for all parasites, aOR 0.37 ([95% CI 0.26–0.51]; p <0.0001) for protozoa, and aOR 0.26 ([95% CI 0.19–0.35]; p <0.0001) for helminths. When stratified by species, co-infection with Entamoeba spp., Hymenolopis nana, Schistosoma mansoni , and Trichuris trichiura implied lower probability of developing severe COVID-19. There were 11 deaths (1.5%), and all were among patients without parasites ( p = 0.009). Interpretation: Parasite co-infection is associated with a reduced risk of severe COVID-19 in African patients. Parasite-driven immunomodulatory responses may mute hyper-inflammation associated with severe COVID-19. Funding: European and Developing Countries Clinical Trials Partnership (EDCTP) – European Union, and Joep Lange Institute (JLI), The Netherlands. Trial registration: Clinicaltrials.gov: NCT04473365

Intestinal parasitic infections among patients referred to hospitals affiliated to Shiraz University of Medical Sciences, southern Iran: a retrospective study in pre- and post-COVID-19 pandemic

“…The results of this retrospective study during the COVID-19 pandemic showed that most of the inpatients were patients with severe COVID-19, and the number of outpatients was reduced. Wolday et al ( 2021 ) reported that the patients co-infected with parasites had lower odds of developing severe COVID-19. It has been hypothesized that the low incidence rates of COVID-19 could result from increased exposure to parasites in some countries (Głuchowska et al 2021 ).…”

Immunomodulatory Potential of Non-Classical HLA-G in Infections including COVID-19 and Parasitic Diseases

“…Taking into account that, in parasite endemic areas of COVID-19 cases, the severity of the disease and numbers of deaths decreased mainly due to patient coinfections with parasites, it seems that the effect of some pathogens such as parasites restricting HLA-G expression can be further considered in future studies [ 118 , 119 ]. Unlike other viral or bacterial coinfections that negatively impact respiratory viral diseases such as COVID-19, some parasitic infections could modulate disease severity and the clinical outcome of other infectious diseases such as COVID-19 via intricate molecular networks involving HLA-G, IL-10/TGF-β, and Treg cells [ 103 , 118 , 120 ].…”

The Fight Against Severe COVID-19: Can Parasitic Worms Contribute?

“…However, other evidence indicates that COVID-19 lethality rates are significantly lower in Sub-Saharan Africa than in the industrialized world (25). Wolday et al (26) carried out a prospective observational cohort study to investigate whether there was a potential correlation between co-infection with intestinal parasites and the severity of COVID-19 in two sites in an endemic area of Ethiopia in Sub-Saharan Africa. The study revealed that patients co-infected with parasites had lower odds of developing severe COVID-19, with an adjusted odds ratio (aOR) of 0.23 (p < 0.0001) for all parasites, an aOR of 0.37 (p < 0.0001) for protozoa, and an aOR of 0.26 (p < 0.0001) for helminths.…”