Rapid detection of Leishmania infantum infection in dogs: a comparative study using fast agglutination screening test (FAST) and direct agglutination test (DAT) in Iran

Clinical and Epidemiologic Features of Visceral Leishmaniasis in Children: A 6-year Study from an Iranian Referral Hospital

BACKGROUND

Visceral leishmaniasis (VL) is an emerging zoonosis disease that is endemic in the northwestern and southern part of Iran. This study aimed to evaluate the clinical characteristics and laboratory findings of the children with VL hospitalized at Children Medical Center Hospital (CMC), Tehran, Iran.

METHODS

A retrospective study was performed based on studied medical records of children with a final diagnosis of VL from 2011 to 2016. For each patient's demographics, clinical laboratory findings and treatment were examined.

RESULTS

The clinical features of 17 children were examined and the most frequent symptoms were fever (94.1%, n=16), pallor, loss of appetite (76.5%, n=13), splenomegaly (82.4%, n=14) and hepatomegaly (58.8%, n=10). The most frequent laboratory abnormalities were hematological including anemia (94.1%, n=16), leukopenia (52.9%, n=9) and thrombocytopenia (70.5%, n=12). In order to detect anti-Leishmania antibodies, DAT was performed in 11 patients and 82% of them were positive (titers ≥ 1: 3200). In addition, rK39 was used in 9 cases and 7 children (78%) had positive results. Direct parasitology revealed the presence of amastigotes of Leishmania in bone marrow aspirate (BMA) stained by Giemsa stain in 9 patients (69%, among 13 children).

CONCLUSION

Leishmaniasis is a regional disease therefore management and control of disease, particularly in an endemic area, as well as detection of new emerging foci are recommended.

A recombinant Plasmodium vivax apical membrane antigen-1 to detect human infection in Iran

In Iran, Plasmodium vivax is responsible for more than 80% of the infected cases of malaria per year. Control interventions for vivax malaria in humans rely mainly on developed diagnostic methods. Recombinant P. vivax apical membrane antigen-1 (rPvAMA-1) has been reported to achieve designing rapid, sensitive, and specific molecular diagnosis. This study aimed to perform isolation and expression of a rPvAMA-1, derived from Iranian patients residing in an endemic area. Then, the diagnostic efficiency of the characterized Iranian PvAMA-1 was assessed using an indirect ELISA method. For this purpose, a partial region of AMA-1 gene was amplified, cloned, and expressed in pET32a plasmid. The recombinant His-tagged protein was purified and used to coat the ELISA plate. Antibody detection was assessed by indirect ELISA using rPvAMA-1. The validity of the ELISA method for detection of anti-P. vivax antibodies in the field was compared to light microscopy on 84 confirmed P. vivax patients and compared to 84 non-P. vivax infected individuals. The ELISA cut-off value was calculated as the mean+2SD of OD values of the people living in malaria endemic areas from a south part of Iran. We found a cut-off point of OD=0.311 that showed the best correlation between the sera confirmed with P. vivax infection and healthy control sera. A sensitivity of 81.0% and specificity of 84.5% were found at this cut off titer. A good degree of statistical agreement was found between ELISA using rPvAMA-1 and light microscopy (0.827) by Kappa analysis.

The development and clinical evaluation of second-generation leishmaniasis vaccines

Infection with Leishmania parasites results in a range of clinical manifestations and outcomes. Control of Leishmania parasite transmission is extremely difficult due to the large number of vectors and potential reservoirs, and none of the current treatments are ideal. Vaccination could be an effective strategy to provide sustained control. In this review, the current global situation with regard to leishmaniasis, the immunology of Leishmania infection and various efforts to identify second generation vaccine candidates are briefly discussed. The variety of clinical trials conducted using the only current second generation vaccine approved for clinical use, LEISH-F1+MPL-SE, are described. Given that epidemiological evidence suggests that reducing the canine reservoir also positively impacts human incidence, efforts at providing a vaccine for leishmaniasis in dogs are highlighted. Finally, potential refinements and surrogate markers that could expedite the introduction of a vaccine that can limit the severity and incidence of leishmaniasis are discussed.

Rapid detection of human Leishmania infantum infection: a comparative field study using the fast agglutination screening test and the direct agglutination test

This study aimed to evaluate the performance of a fast agglutination screening test (FAST) for serodiagnosis of human Leishmania infantum infection in Iran. FAST is based on the direct agglutination test (DAT) but combines with a higher parasite concentration and is performed with only one serum dilution. The validity of FAST for the detection of L. infantum infection in the field was compared with the direct agglutination test on 110 confirmed or patients suspected of infection with leishmaniasis, 177 healthy individuals and 41 patients with other infectious diseases who were from northwestern and southern parts of Iran. In this study, we found a 1:1600 cut-off point empirically by seeking the best correlation (90.8) between sera confirmed with visceral leishmaniasis and healthy control sera. A sensitivity of 95.4% (95% CI, 91.4-99.4) and specificity of 88.5% (95% CI, 84.2-92.8) were found with 1:1600 as a cut-off titer when DAT-confirmed cases were compared with the control groups. A good degree of agreement was found between FAST and DAT (90.8%) by Kappa analysis. FAST requires 2 h for reading the results versus the 12-18 h needed for DAT. As FAST is simple, rapid, sensitive and non-invasive and does not require a higher volume of antigens or much expertise, it can be used for screening and serodiagnosis of human L. infantum infection.