Evaluation of antibody serology to determine current helminth andPlasmodium falciparuminfections in a co-endemic area in Southern Mozambique
Authors: Santano Rebeca , Rubio Rocío , Grau-Pujol Berta , Escola Valdemiro , Muchisse Osvaldo , Cuamba Inocência , Vidal Marta , Ruiz-Olalla Gemma , Aguilar Ruth , Gandasegui Javier , Demontis Maria , Jamine Jose Carlos , Cossa Anélsio , Sacoor Charfudin , Cano Jorge , Izquierdo Luis , Chitnis Chetan E. , Coppel Ross L , Chauhan Virander , Cavanagh David , Dutta Sheetij , Angov Evelina , van Lieshout Lisette , Zhan Bin , Muñoz José , Dobaño Carlota , Moncunill Gemma 
Published: January 2022

Background

Soil-transmitted helminths (STH),Schistosomaspp. andPlasmodium falciparumare parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure.

Methodology

We evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 fromSchistosomaspp., and 16 fromP. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference.

Principal findings

IgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosomaspp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure.

Conclusions

We provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers could be used as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens.

AUTHOR SUMMARY

Parasitic worms andPlasmodium falciparum, the causal agent of malaria, are among the most relevant parasitic diseases of our time and efforts are under way for their control and, ultimately, elimination. An accurate diagnosis is relevant for case management, but also allows calculating the prevalence and evaluating the effectiveness of treatment and control measures. Unfortunately, current diagnostic methods for parasitic worms are not optimal and many infections remain undetected. As forP. falciparum, current diagnostic techniques are satisfactory but do not allow for ascertaining exposure, which is relevant for evaluating control measures. Here we investigated the utility of measuring antibodies to these parasites as a diagnostic method. Our results indicate that it is possible to detect current infection with parasitic worms andP. falciparumusing antibody detection with a moderate to high accuracy. We also show that antibodies could distinguish a population from Southern Mozambique, where these infections are prevalent, from a Spanish population never exposed to those parasites. Importantly, we used a platform that allows for the simultaneous detection of immunoglobulins to different parasites, which would be extremely useful as a tool to integrate control and elimination programs for several pathogens.