Schistosoma mansoni PCR+-infected individuals in the Sudan present elevated systemic levels of chemokines when compared to uninfected and egg+ cohorts

Abstract

Infections withSchistosoma mansoni remain a major health problem in the Sudan where endemic communities, such as those in Kassala and Khartoum states, continue to face severe social-economic difficulties. Our previous immunoepidemiological findings revealed different immune [cytokine and S. mansoni egg (SEA) antibody] profiles in individuals with active infections (eggs in stool n = 110), individuals positive for S. mansoni via polymerase chain reaction (PCR) using sera (Sm PCR + n = 63) and those uninfected (Sm uninf). As antibody responses to eggs and worms are known to change during infection, we have expanded the profiling further by determining levels of adult worm (SWA) antibodies and nine chemokines in the serum of each individual in the three different cohorts.With the exception of C-C motif chemokine ligand (CCL)2, all measured chemokines were significantly higher in SmP CR + individuals when compared to the egg + group and in addition they also presented elevated levels of SWA-specific immunoglobulin (Ig)G2. Multivariable regression analysis further revealed that infection per se was strongly linked to SWA-specific IgG3 levels and CCL5 was strongly associated with a Sm PCR + diagnostic state. In the absence of PCR diagnostics that recognize juvenile worms or schistosomulae motives, identifying schistosome-specific traits should provide better insights into current prevalence rates in endemic communities and, in doing so, take into consideration PCR + non-egg + individuals in current treatment programmes.

Distinct Schistosoma mansoni-Specific Immunoglobulin Subclasses Are Induced by Different Schistosoma mansoni Stages—A Tool to Decipher Schistosoma mansoni Infection Stages

“…In a recent study from Cha et al, it was revealed that schistosomiasis continues to burden populations in non-stable communities of the Sudan [1]. In correlation with our previous studies from the Sudan [2,3], Cha and colleagues also found strong associations between infection and available latrines-since infections are obtained in fresh water sources from snails releasing cercariae, the infectious stage. Thus, despite large-scale programmes designed to tackle schistosomiasis [4], this chronic helminth infection remains a severely neglected tropical disease in the Sudan [5].…”

“…This group could be individuals with dying, menopausal or single worm infections, or an early infection. In terms of schistosome-specific antibody levels, this group showed increased levels of worm-specific IgG2 [3] but lower egg-specific IgG4 levels when compared to egg-positive individuals [2].…”

“…Few studies however, have investigated the relationship between the parasite stage-specific antibody production and a clinical diagnostic status. Our previous studies identified a further cohort-namely SmPCR + egg − individuals [2,3]. Upon testing egg (SEA)-or worm (SWA)-specific antibody levels, we determined that both infected groups (egg + and SmPCR + ) had higher SWAspecific IgG3 and IgG4, and SEA-specific IgG4, than uninfected individuals.…”

“…Next, a multivariate regression analysis was performed following a combination of all measured SEA-and SWA-specific Igs from our previous studies (Elfaki, 2016, Arndts, 2019 with our new data gathered in this study (Table 2). Interestingly, SEA-specific IgG4 remained the only schistosome-specific Ig strongly associated with infection per se, and SEA-specific IgE was highly associated with egg + individuals when compared to SmPCR + individuals.…”

“…Using a combination of diagnostic techniques, our earlier studies on a cohort of Sudanese individuals living in a Schistosoma mansoni-endemic area revealed a further subset of infected individuals that were positive for S. mansoni via PCR but had no detectable eggs in stool samples [2,3]. This group could be individuals with dying, menopausal or single worm infections, or an early infection.…”