Evaluation of the accuracy of a multi-infection screening test based on a multiplex immunoassay targeting imported diseases common in migrant populations

BACKGROUND

We aimed to evaluate the performance of a novel multiplex serological assay, able to simultaneously detect IgG of six infections, as a screening tool for imported diseases in migrants.

METHODS

Six panels of 40 (n = 240) anonymized serum samples with confirmed infections were used as positive controls to assess the multiplex assay's sensitivity. One panel of 40 sera from non-infected subjects was used to estimate the seropositivity cutoffs, and 32 non-infected sera were used as negative controls to estimate each serology's sensitivity and specificity. The multi-infection screening test was validated in a prospective cohort of 48 migrants from endemic areas. The sensitivity of the Luminex assay was calculated as the proportion of positive results over all positive samples identified by reference tests. The specificity was calculated using 32 negative samples. Uncertainty was quantified with 95 % confidence intervals using receiver operating characteristic analyses.

RESULTS

The sensitivity/specificity were 100 %/100 % for HIV (gp41 antigen), 97.5 %/100 % for Hepatitis B virus (HBV-core antigen), 100 %/100 % for Hepatitis C virus (HCV-core antigen), 92.5 %/90.6 % for strongyloidiasis [31-kDa recombinant antigen (NIE)], 97.5 %/100 % for schistosomiasis (combined serpin Schistosoma mansoni and S.haematobium antigens) and 95 %/90.6 % for Chagas disease [combined Trypanosoma cruzi kinetoplastid membrane protein-11 (KMP11) and paraflagellar rod proteins 2 (PFR2) antigens]. In the migrant cohort, antibody response to the combination of the T.cruzi antigens correctly identified 100 % individuals, whereas HBV-core antigen correctly identified 91.7 % and Strongyloides-NIE antigen 86.4 %.

CONCLUSIONS

We developed a new, robust and accurate 8-plex Luminex assay that could facilitate the implementation of screening programmes targeting migrant populations.

Sporotrichoid dissemination of cutaneous leishmaniasis possibly triggered by a diagnostic puncture

We present the images of a cutaneous leishmaniasis with sporotrichoid dissemination in a Spanish woman who was living in Bolivia for six months. A diagnostic puncture of the ulcer could have been the trigger for the lymphatic dissemination.

Positive direct antiglobulin test in post-artesunate delayed haemolysis: more than a coincidence?

Background

Delayed haemolysis is a frequent adverse event after treatment with artesunate (AS). Removing once-infected “pitted” erythrocytes by the spleen is the most accepted mechanism of haemolysis in these cases. However, an increasing number of cases with positive direct antiglobulin test (DAT) haemolysis after AS have been reported.

Methods

All malaria cases seen at Hospital Clinic of Barcelona between 2015 and 2017 were retrospectively reviewed. Clinical, parasitological and laboratory data from patients treated with intravenous artesunate—specifically looking for delayed haemolysis and DAT—was collected.

Results

Among the 36 severe malaria patients treated with artesunate at the hospital, 10 (27.8%) developed post-artesunate delayed haemolysis. Out of these, DAT was performed in six, being positive in four of them (at least 40%). DAT was positive only for complement—without IgG—suggesting drug-dependent immune-haemolytic anaemia of the immune-complex type. Three of the four patients were treated with corticosteroids and two also received blood transfusion, with a complete recovery.

Conclusions

Drug-induced auto-immune phenomena in post-artesunate delayed haemolysis may be underreported and must be considered. The role of corticosteroids should be reassessed.

Association of caspase-1 polymorphisms with Chagas cardiomyopathy among individuals in Santa Cruz, Bolivia

INTRODUCTION:

Trypanosoma cruzi (Tc) infection is usually acquired in childhood in endemic areas, leading to Chagas disease, which progresses to Chagas cardiomyopathy in 20-30% of infected individuals over decades. The pathogenesis of Chagas cardiomyopathy involves the host inflammatory response to T. cruzi, in which upstream caspase-1 activation prompts the cascade of inflammatory chemokines/cytokines, cardiac remodeling, and myocardial dysfunction. The aim of the present study was to examine the association of two caspase-1 single nucleotide polymorphisms (SNPs) with cardiomyopathy.

METHODS:

We recruited infected (Tc+, n = 149) and uninfected (Tc-, n = 87) participants in a hospital in Santa Cruz, Bolivia. Cardiac status was classified (I, II, III, IV) based on Chagas cardiomyopathy-associated electrocardiogram findings and ejection fractions on echocardiogram. Genotypes were determined using Taqman probes via reverse transcription-polymerase chain reaction of peripheral blood DNA. Genotype frequencies were analyzed according to three inheritance patterns (dominant, recessive, additive) using logistic regression adjusted for age and sex.

RESULTS:

The AA allele for the caspase-1 SNP rs501192 was more frequent in Tc+ cardiomyopathy (classes II, III, IV) patients compared to those with a normal cardiac status (class I) [odds ratio (OR) = -2.18, p = 0.117]. This trend approached statistical significant considering only Tc+ patients in class I and II (OR = -2.64, p = 0.064).

CONCLUSIONS:

Caspase-1 polymorphisms may play a role in Chagas cardiomyopathy development and could serve as markers to identify individuals at higher risk for priority treatment.