Parasites and their protection against COVID-19- Ecology or Immunology?

Ssebambulidde, Kenneth; Segawa, Ivan; Abuga, Kelvin M.; Nakate, Vivian; Kayiira, Anthony; Ellis, Jayne; Tugume, Lillian; Kiragga, Agnes; Meya, David B.

doi:10.1101/2020.05.11.20098053

Cited by 21 publications

(31 citation statements)

References 26 publications

(36 reference statements)

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“…Although SARS-CoV-2 is a new human pathogen, few studies have shown that conditions eliciting non-specific immune response such as BCG vaccination 37 38 and recurrent parasitic infections 39 may render some protection against COVID-19. Thus, widespread routine BCG vaccination and rampant parasitic infections in communities in Ethiopia and other African countries might have contributed to milder COVID-19 in such settings.…”

Section: Discussionmentioning

confidence: 99%

COVID-19 in Oromia Region of Ethiopia: a review of the first 6 months’ surveillance data

et al. 2021

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IntroductionDespite unrelenting efforts to contain its spread, COVID-19 is still causing unprecedented global crises. Ethiopia reported its first case on 13 March 2020 but has an accelerated case load and geographical distribution recently. In this article, we described the epidemiology of COVID-19 in Oromia Region, the largest and most populous region in Ethiopia, during the early months of the outbreak.MethodsWe analysed data from the COVID-19 surveillance database of the Oromia Regional Health Bureau. We included all reverse transcription-PCR-confirmed cases reported from the region between 13 March and 13 September 2020.ResultsCOVID-19 was confirmed in 8955 (5.5%) of 164 206 tested individuals. The test positivity rate increased from an average of 1.0% in the first 3 months to 6.3% in August and September. About 70% (6230) of the cases were men; the mean age was 30.0 years (SD=13.3), and 90.5% were <50 years of age. Only 64 (0.7%) of the cases had symptoms at diagnosis. Cough was the most common among symptomatic cases reported in 48 (75.0%), while fever was the least. Overall, 4346 (48.5%) have recovered from the virus; and a total of 52 deaths were reported with a case fatality rate of 1.2%. However, we should interpret the reported case fatality rate cautiously since in 44 (84.6%) of those reported as COVID-19 death, the virus was detected from dead bodies.ConclusionDespite the steady increase in the number of reported COVID-19 cases, Ethiopia has so far avoided the feared catastrophe from the pandemic due to the milder and asymptomatic nature of the disease. However, with the current pattern of widespread community transmission, the danger posed by the pandemic remains real. Thus, the country should focus on averting COVID-19-related humanitarian crisis through strengthening COVID-19 surveillance and targeted testing for the most vulnerable groups.

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Section: Discussionmentioning

confidence: 99%

COVID-19 in Oromia Region of Ethiopia: a review of the first 6 months’ surveillance data

et al. 2021

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“…One of them stipulates that helminths could worsen COVID-19 severity, due to their immunomodulatory effects involving type 2 immune response (52, 53). An alternative hypothesis is that pre-exposure to helminths infection could reduce the risk of severe COVID-19 outcomes, through a downregulation in the production of proinflammatory cytokines involved in the hyperinflammation of the lungs and ‘cytokine storm’ commonly observed in severe and fatal COVID-19 disease (18, 19).…”

Section: Discussionmentioning

confidence: 99%

“…We selected prevalence of malaria, soil-transmitted helminths, filariasis and schistosomiasis as indicators of prior exposure to endemic infections based on the literature (18,19,48,57) and on consultation with parasitology experts. Prior exposure to malaria was measured using age-standardised predicted parasite prevalence rate for children two to ten years of age for Plasmodium falciparum , and in all ages for Plasmodium vivax .…”

Section: Supplementary Filementioning

confidence: 99%

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Country differences in transmissibility, age distribution and case-fatality of SARS-CoV-2: a global ecological analysis

Favas

Jarrett

Ratnayake

et al. 2021

Preprint

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Introduction SARS-CoV-2 has spread rapidly across the world yet the first pandemic waves in many low-income countries appeared milder than initially forecasted through mathematical models. Hypotheses for this observed difference include under-ascertainment of cases and deaths, country population age structure, and immune modulation secondary to exposure to endemic parasitic infections. We conducted a country-level ecological study to describe patterns in key SARS-CoV-2 outcomes by country and region and to explore possible associations of the potential explanatory factors with these outcomes. Methods We collected publicly available data at country level and compared them using standardisation techniques. We then explored the association between exposures and outcomes using alternative approaches: random forest (RF) regression and linear (LM) regression. We adjusted for potential confounders and plausible effect modifications. Results Altogether, data on the mean time-varying reproduction number (mean R_t) were available for 153 countries, but standardised averages for the age of cases and deaths and for the case-fatality ratio (CFR) could only be computed for 61, 39 and 31 countries respectively. While mean R_t was highest in the WHO Europe and Americas regions, median age of death was lower in the Africa region even after standardisation, with broadly similar CFR. Population age was strongly associated with mean R_t and the age-standardised median age of observed cases and deaths in both RF and LM models. The models highlighted other plausible roles of population density, testing intensity and co-morbidity prevalence, but yielded uncertain results as regards exposure to common parasitic infections. Conclusions The average age of a population seems to be an important country-level factor explaining both transmissibility and the median age of observed cases and deaths, even after age-standardisation. Potential associations between endemic infections and COVID-19 are worthy of further exploration but seem unlikely, from this analysis, to be key drivers of the variation in observed COVID-19 epidemic trends. Our study was limited by the availability of outcome data and its causally uncertain ecological design, with the observed distribution of age amongst reported cases and deaths suggesting key differences in surveillance and testing strategy and capacity by country and the representativeness of case reporting of infection. Research at subnational and individual level is needed to explore hypotheses further.

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“…The immune profile of healthy Ethiopians shows evidence of chronic immune activation with significant low naïve cells but high activated memory cells, of both CD4+ and CD8+ T-cell subpopulations (Borkow et al, 2000;Hazenberg et al, 2000;Kassu et al, 2003;Tsegaye et al, 2003). Such immune characteristics in Ethiopians as compared to Europeans led us to the assumption that these could contribute to the phenomenon of milder COVID-19 symptomatology, as commonly found in SSA and elsewhere in the world (Chatterjee et al, 2020;Ssebambulidde et al, 2020). The postulation is that persistent immune activation due to continuous infections with parasites skews the immune system of populations in LMICs toward TH2 type and Treg immune responses that counteract the symptomatology associated with TH1 hyperinflammation.…”

Section: Impact Of Parasite-driven Microbiome Change On the Pathogenesis Of Covid-19mentioning

confidence: 97%

Interrogating the Impact of Intestinal Parasite-Microbiome on Pathogenesis of COVID-19 in Sub-Saharan Africa

et al. 2021

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Parasites and their protection against COVID-19- Ecology or Immunology?

Cited by 21 publications

References 26 publications

COVID-19 in Oromia Region of Ethiopia: a review of the first 6 months’ surveillance data

COVID-19 in Oromia Region of Ethiopia: a review of the first 6 months’ surveillance data

Country differences in transmissibility, age distribution and case-fatality of SARS-CoV-2: a global ecological analysis

Interrogating the Impact of Intestinal Parasite-Microbiome on Pathogenesis of COVID-19 in Sub-Saharan Africa

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