Assessment of Recombinant A2-Latex Agglutination Test (RA2-LAT) and RA2-ELISA for Detection of Canine Visceral Leishmaniasis: A Comparative Field Study with Direct Agglutination Test in Northwestern Iran

BACKGROUND

This study aimed to set-up latex agglutination test (LAT) and ELISA based on recombinant A2 from Iranian strain of Leishmania (L.) infantum (rA2-Ag) and evaluated for detection of anti-Leishmania antibodies in dogs compared to standard direct agglutination test (DAT).

METHODS

The rA2-Ag was synthesized under a part of the A2 gene sequences which contain immune dominant sequences and less number of repetitive sequences. Latex beads, 0.8 μm (Sigma, USA) were sensitized with rA2-Ag. The tests were carried out on sera collected from 350 ownership dogs including symptomatic (n=67), asymptomatic (n=230) canine visceral leishmaniasis (CVL), and (n=53) uninfected domestic dogs as control group.

RESULTS

Anti-leishmanial antibodies were detected in 97 (27.7%), 96 (27.4%) and 29 (%9) of the serum samples by using DAT, rA2-ELISA, and rA2-latex, respectively with ≥1:320 as a cut-off titer when DAT-confirmed cases were compared with the control groups. A combined sensitivity of 52% and specificity of 82.40% for rA2-ELISA and 23.8% and specificity 95.38%, respectively were found with ≥1:320 as a cut-off titer when DAT-confirmed cases were compared with the control groups. The concordance between rA2-ELISA and rA2 latex compared with DAT as a gold standard serological test for VL were found 73.7% and 77.5%, respectively.

CONCLUSION

A good degree of agreement was found between rA2-ELISA and DAT (73.7%). rA2-ELISA could detect more seropositive serum samples than rA2-LAT and it may be recommended as an alternative tool for the diagnosis of CVL.

Modification on Direct Agglutination Antigen Preparation for Simplified Sero-Diagnosis of Human and Canine Visceral Leishmaniasis

BACKGROUND

Visceral leishmaniasis is systematic serous parasitic disease with public health importance. Zoonotic form of visceral leishmaniasis is wide spread in Mediterranean basin and South America regions. Direct agglutination test (DAT) is an accurate, reliable and non-expensive serological test for the diagnosis of visceral leishmaniasis in human and canines but the antigen preparation involves some limitations. This study aimed to compare the conventional production of DAT antigen with our modified DAT antigen and then assessed on human and dog pooled sera.

METHODS

Conventional DAT antigen has been prepared at the School of Public Health, Tehran University of Medical Sciences and some modifications were carried out on it, which named as modified DAT antigen. Three positive and one negative human and dog pooled serum were separately used for the comparison of modified DAT with conventional DAT antigen batches with one-month interval for a period of 9 months.

RESULTS

A good concordance was observed between modified DAT compared to conventional DAT antigens for the detection of visceral leishmaniasis on human (100%) and dog (94.4%) pooled sera, respectively.

CONCLUSION

Since the modified DAT antigen could be reduced the preparation time from 3 days to several hours and a good degree of agreement was found between modified DAT and convention DAT antigen batches, it can be used as a simple and easy tool for screening and serodiagnosis of human and canine L. infantum infection.

Molecular Detection and Identification of Zoonotic Microsporidia Spore in Fecal Samples of Some Animals with Close-Contact to Human

BACKGROUND

Microsporidia species are obligatory intracellular agents that can infect all major animal groups including mammals, birds, fishes and insects. Whereas worldwide human infection reports are increasing, the cognition of sources of infection particularly zoonotic transmission could be helpful. We aimed to detect zoonotic microsporidia spore in fecal samples from some animals with close - contact to human.

METHODS

Overall, 142 fecal samples were collected from animals with closed-contact to human, during 2012-2013. Trichrome - blue staining were performed and DNA was then extracted from samples, identified positive, microscopically. Nested PCR was also carried out with primers targeting SSU rRNA gene and PCR products were sequenced.

RESULTS

From 142 stool samples, microsporidia spores have been observed microscopically in 15 (10.56%) samples. En. cuniculi was found in the faces of 3 (15%) small white mice and 1 (10%) laboratory rabbits(totally 2.81%). Moreover, E. bieneusi was detected in 3 (10%) samples of sheep, 2 (5.12%) cattle, 1 (10%) rabbit, 3 (11.53%) cats and 2 (11.76%) ownership dogs (totally 7.74%). Phylogenetic analysis showed interesting data. This is the first study in Iran, which identified E. bieneusi and En. Cuniculi in fecal samples of laboratory animals with close - contact to human as well as domesticated animal and analyzed them in phylogenetic tree.

CONCLUSION

E. bieneusi is the most prevalent microsporidia species in animals. Our results can also alert us about potentially zoonotic transmission of microsporidiosis.