Hasan Keshavarz

Tehran University of Medical Sciences | TUMS · Department of Medical Parasitology and Mycology

Background: Toxoplasma gondii infection (toxoplasmosis) has the potential to cause a serious disease in immunocompromised patients and can be fatal in this population. We conducted a systematic review and meta-analysis to assess comprehensively the pooled seroprevalence of toxoplasmosis among immunocompromised patients including HIV/AIDS patients,...

Introduction As the cause of RBC infection and splenomegaly, malaria remains a major parasitic disease in the world. New specific biomarkers such as MicroRNAs (miRNAs) are developed to accurately diagnose malaria and clarify its pathologic changes. This study aimed at evaluating changes in the plasma miRNAs markers of Plasmodium vivax in patients w...

To improve serodiagnostic methods for diagnosis of acute from chronic toxoplasmosis, an economical in-house ELISA for measuring Toxoplasma-specific IgG, IgM and IgG avidity has been developed and assessed based on use of various T. gondii antigens, including SAG1, GRA7 and a combination of SAG1 and GRA7 (SAG1+GRA7) as well as Toxoplasma lysate anti...

Objectives The aim of the current study was to assess prevalence of Toxoplasma infection and its associated risk factors in women of childbearing-age in central Iran. Results Of 400 serum samples assessed for anti- T. gondii antibodies, 81 (20.25%) samples were positive for anti- T. gondii antibodies, including 74 positive samples (91.3%) for anti...

Objective: To predict future trends in the incidence of malaria cases in the southeast of Iran as the most important area of malaria using Seasonal Autoregressive Integrated Moving Average (SARIMA) model, and to check the effect of meteorological variables on the disease incidence. Methods: SARIMA method was applied to fit a model on malaria incide...

Background: One of the main obstacles to malaria control in the world has been the emergence of resistance in Plasmodium falciparum to chloroquine and other anti-malarial drugs. This study aimed to review studies in Iran on resistance in P. falciparum and P. vivax to drugs, and to reveal the mechanisms and molecular markers of resistance of these t...

Chronic granulomatous disease (CGD) described as an essential immunodeficiency problem of phagocytic cells resulting in a phagocyte dysfunction and inability to kill a spectrum of bacteria and fungi. Despite the fact that CGD patients are more susceptible to intracellular infections, visceral leishmaniasis has been reported rarely in these cases. H...

Background: Pathogenic intestinal protozoa are considered as a serious public health problem in developing countries. This study aimed to elucidate the overall prevalence and spatial distribution of three common human pathogenic intestinal protozoan infections in Iran. Methods: Six English and Persian databases were explored for published papers o...

Risk of mother-to-child transmission of Toxoplasma gondii during pregnancy is much greater in women who are exposed to primary T. gondii infection (toxoplasmosis) after conception compared to those who were exposed to the infection before conception. Therefore, laboratory tests that help classify recent primary toxoplasmosis are important tools for...

Background Direct agglutination test (DAT) as a simple, accurate and reliable method, has been widely used for serodiagnosis of visceral leishmaniasis (VL) during the last three decades. The present study is a systematic review and meta-analysis to evaluate the diagnostic accuracy of DAT for serodiagnosis of human VL. Methods Electronic databases,...

Regarding preparing and serving foods, food handlers have an influential role in the spreading of foodborne infections. Due to the great potential to cause foodborne infections, intestinal parasites (IPs) are considered a significant public health problem in today's societies. In Iran, despite several regional reports, national data on IPs prevalen...

This study showed that raw vegetables have a substantial level of parasitic contamination and this contamination can pose health risk to consumers of edible raw vegetables. Moreover, given the role of edible vegetables in people's diets, efforts should be made toward public training on the proper washing and disinfecting of vegetables. The use of w...

Sarcocystis is a genus of eucoccidian parasites, which globally infects humans and various animals. In addition to economic losses in livestock industries, the parasite is a zoonosis that infects humans through contaminated beef and pork with the parasite sarcocysts. Therefore, this study was carried out to assess Sarcocystis contamination in beef...

Background: Mediterranean form of visceral leishmaniasis (VL) is endemic among some provinces of Iran. The pre­sent study was designed to determine the prevalence of canine visceral leishmaniasis (CVL) in the owned dogs of the rural areas of Alborz Province near Tehran as the capital of Iran. Methods: This study conducted on 303 owned dogs that sel...

Background: agglutination test (DAT) as simple, accurate and non-expensive tool that has been used widely for serodiagnosis of visceral leishmaniasis (VL) during the last three decades. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of DAT for serodiagnosis of human VL. Methods: Electronic databases, includin...

Background: Direct agglutination test (DAT) as simple, accurate and reliable method that has been used widely for serodiagnosis of visceral leishmaniasis (VL) during the last three decades. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of DAT for serodiagnosis of human VL. Methods: Electronic databases, incl...

Background: Direct agglutination test (DAT) as simple, accurate and non-expensive tool that has been used widely for serodiagnosis of visceral leishmaniasis (VL) during the last three decades. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of DAT for serodiagnosis of human VL. Methods: Electronic databases, i...

Background: Direct agglutination test (DAT) as a simple, accurate and reliable method, has been widely used for serodiagnosis of visceral leishmaniasis (VL) during the last three decades. The present study is a systematic review and meta-analysis to evaluate the diagnostic accuracy of DAT for serodiagnosis of human VL. Methods: Electronic databases...

Background: The aim of the present study was to develop a simple, portable and rapid assay for serodiagnosis of toxoplasmosis based on recombinant Toxoplasma gondii (T. gondii) SAG1 (rSAG1) and GRA7 (rGRA7) proteins. Methods: The rSAG1 and rGRA7 proteins were expressed in Escherichia coli (E. coli) and purified in a single step by immobilized meta...

Background: Toxoplasmosis, a protozoan parasitic disease caused by Toxoplasma gondii (T. gondii), has been a serious human and veterinary medicine problem with global distribution. In the current study, we assessed immunogenisity and protective efficiency of a novel dual-promoter DNA vaccine, harboring SAG1 and GRA7 genes, from RH strain of Toxopla...

The article's abstract is no available.

Background: Toxoplasmosis is an infectious disease caused by the coccidian protozoan parasite Toxoplasma gondii. The infection is life-threatening in congenital form because of transmission of the parasite from mother to fetus. In order to investigate the prevalence of congenital toxoplasmosis, the present study was performed for detection of IgG...

Leishmaniasis is a growing health problem in many parts of the world and efforts to find vaccine against the disease are a public health priority. Live attenuated vaccines are the gold standard for protection against intracellular pathogens such as Leishmania spp. Defined genetic alteration of the Leishmania genome can be achieved using a gene-targ...

Background: Toxoplasma gondii is an intracellular protozoan parasite distributed worldwide. Although the infection is benign in immunocompetent individuals, it is life threatening and complicated in immunocompromised patients and fetuses of pregnant women who received their first exposure to T. gondii during the pregnancy. Prolactin (PRL) is a horm...

Objectives: Latent toxoplasmosis modifies various hormones and behaviors in infected hosts and possibly involves in etiology of different neurologic and psychiatric disorders. The aim of the current study was to assess possible associations between latent toxoplasmosis and testosterone concentration in Toxoplasma infected and free subjects. Briefl...

Background The aim of this study was to prepare curcumin nanoemulsion (CR-NE) to solve the problems associated with poor water solubility and low bioavailability of CR and to test its efficiency in the treatment of acute and chronic toxoplasmosis in mouse models. Materials and methods CR-NE 1% was prepared using spontaneous emulsification by soybe...

Background: The aim of this study was to prepare curcumin nanoemulsion (CR-NE) to solve the problems associated with poor water solubility and low bioavailability of CR and to test its efficiency in the treatment of acute and chronic toxoplasmosis in mouse models. Materials and methods: CR-NE 1% was prepared using spontaneous emulsification by soyb...

In the current study, performance of electrochemiluminescence immunoassay (ECLIA) in detection of anti-toxoplasma IgG in human sera was compared with that of enzyme-linked immunosorbent assay (ELISA). Furthermore, performance of an in house Dot-ELISA in detection of anti-toxoplasma IgG was compared with that of ECLIA and ELISA. In total, 219 human...

Background Toxoplasma gondii is a protozoan parasite with worldwide distribution, infecting a broad-range of humans and warm-blooded animals. In the current study, role of this parasite on secondary sex ratio and risk of miscarriage was investigated. Methods In this cross-sectional study, 850 cord blood samples were collected in Tehran, Iran, 2014–...

Genetically modifying Leishmania major by eliminating essential virulence genes have been proposed as potential vaccine candidates. p27 is a COX component that is responsible for ATP synthesis. In this study a new mutant of Leishmania major (L. major) (MRHO/IR/75/ER) lacking the p27 gene (Lmp27-/-) was produced via homologous recombination, marking...

Background Cutaneous leishmaniasis (CL) is one of the world health problems. Leishmania major is the etiological agent of zoonotic cutaneous leishmaniasis (ZCL). Promastigote and amastigote are two morphological forms of Leishmania parasites that express different proteins and p27 is an important gene encoding cytochrome c oxidase (COX) component....

Background Natural polysaccharides such as chitosan (CS) are widely used as antimicrobial agents. In recent years, and considering that CS has a strong antimicrobial potential, interest has been focused on antimicrobial activity of chitosan nanoparticles (CS NPs). The main factors affecting the antibacterial activity of chitosan include molecular w...

Background Natural polysaccharides such as chitosan (CS) are widely used as antimicrobial agents. In recent years, and considering that CS has a strong antimicrobial potential, interest has been focused on antimicrobial activity of chitosan nanoparticles (CS NPs). The main factors affecting the antibacterial activity of chitosan include molecular w...

Toxoplasmosis, a parasitic disease caused by Toxoplasma gondii, has possible irreparable consequences in immunocompromised patients and fetuses. Finding an effective method of prevention, such as vaccination, is crucial because of the global distribution of the parasite and the lack of effective anti-toxoplasmosis drugs. The Sag1 and Gra7 antigens...

Treatment of toxoplasmosis is necessary in congenital form and immunocompromised patients. Atovaquone is a powerful suppressor of protozoan parasites with a broad-spectrum activity, but an extremely low water solubility and bioavailability. In this study, nanoemulsion of this drug was prepared with grape seed oil using spontaneous emulsification me...

A family of reticulocyte-binding proteins of Plasmodium vivax (PvRBP) is localised at the apical pole of the merozoites and appears to bind to reticulocytes specifically and has also been involved in identifying host cells. Protein component produced by the Pvrbp2c gene is highly antigenic. The aim of this study was to detect the genetic diversity...

Toxoplasmosis is an infectious disease caused by the coccidian parasite Toxoplasma gondii. Diagnosis is based on serological methods with detection of specific IgG and IgM antibodies. The present study was performed to compare the sensitivity and specificity of soluble antigen of T. gondii, RH strain obtained from mice and cell culture in ELISA met...

Background The objective of this study was to find an appropriate approach to asymptomatic malaria in elimination setting through a systematic review. Methods A broad search was conducted to find articles with the words ‘malaria’ in their titles and ‘asymptomatic’ or ‘submicroscopic’ in their texts, irrespective of the type of study conducted. The...

A total of 54 raw wastewater samples collected from three urban treatment plants and two slaughterhouses in Tehran, Iran, were assessed for the presence of the Giardia cysts using immunofluorescence with monoclonal antibodies. To characterize the cysts at the molecular level, the three genetic loci were amplified and sequenced. The assemblages A (3...

Background Visceral leishmaniasis (VL) has strong links with poverty, substantial medical and veterinary impacts. This review aimed to focus in studies published during 1994–2016 on VL in southeastern Iran. Methods The present review is based on expert knowledge and historical studies published during the past 23 yr (1994–2016) on VL in southeaste...

Background We aimed to quicken and simplify the detection of Plasmodium in blood samples by developing and testing a pan-Plasmodium real-time PCR for accurate screening of individuals suspected of malaria. Methods A single primer/probe set for pan-species Plasmodium-specific real time PCR targeting a conserved region of the small subunit 18S ribos...

The present study was performed to compare the soluble, whole and excretory/secretary antigens of Toxoplasma gondii (RH strain) in diagnosis of toxoplasmosis by ELISA method. Tachyzoites of T. gondii, RH strain were injected in intra-peritoneal cavity of BALB/c mice, after 4 days tachyzoites were harvested by peritoneal washing of the mice. For sol...

Background: This study was performed to induce conversion of RH strain tachyzoites of Toxoplasma gondii to bradyzoites by pH changing of the culture medium. Methods: HeLa cell monolayers were infected at a 1:1 tachyzoite to cell ratio. Four hours after infection, the culture medium was removed and replaced with culture medium and 5% FCS, adjuste...

In recent years, decreasing annual rainfalls in some countries and population growth have led to a shortage of freshwater resources. Thus, recycled wastewaters has been suggested for agricultural activities. Contamination of wastewaters with pathogens is a major concern for the use of these waters. This study aimed to (i) investigate the occurrence...

Five municipal and domestic wastewater treatment plants, most of which had secondary treatment systems formed by activated sludge, were studied during 2013–2014 in Tehran. The study was done in order to evaluate their efficiency in terms of removal of Cryptosporidium and Giardia by (oo)cyst recovery in effluent samples using immunofluorescence with...

Visceral leishmaniasis (VL) or kala-azar mainly affects children in endemic areas. This study was conducted to determine the seroprevalence of VL using direct agglutination test (DAT) in children living in rural districts of Alborz Province located 30 km from Tehran capital city of Iran. Multi-stage cluster random sampling was applied. Blood sample...

Background: Canine visceral leishmaniasis (CVL) is not only an emerging veterinary concern but also a public health threat in endemic areas. The aim of this study was to assess the efficacy, immunogenicity and safety of two doses of aluminum hydroxide (alum) precipitated Leishmania major (Alum-ALM) mixed with BCG plus imiquimod against CVL. Method...

Toxoplasma gondii is an obligate intracellular protozoan parasite that infects humans and animals. T. gondii surface antigen 1 (SAG1) is an appropriate antigen with high specificity and sensitivity for the detection of T. gondii infection in humans and animal hosts. The aim of this study was to determine the seroprevalence of T. gondii infection us...

Species of Microsporidia have been known as opportunistic obligate intracellular parasites particularly in immunocompromised patients. Enterocytozoon bieneusi is one of most prevalent intestinal microsporida parasites in HIV(+)/AIDS patients. In this study, intestinal microsporidia infection was determined in HIV(+)/AIDS patients using microscopic...

Apical Membrane antigen 1 (AMA-1) is positioned on the surface of merozoite and it may play a role in attack to red blood cells. The main aim of present study was to determine the genetic variation, as well as, to detect of selection at domain I of AMA-1 gene Plasmodium vivax isolates in Iran. Blood samples were collected from 58 patients positive...

Background: Tehran University of Medical Sciences has two streams of medical student admission: an established high school entry (HSE) route and an experimental graduate entry (GE) route. Aim: To compare the cognitive skills, personality traits and moral characteristics of HSE and GE students admitted to this university. Methods: The personal...

Based on recent studies, there are controversial reports on the capacity of tissue cyst forming of Toxoplasma gondii RH strain. In this study, the capacity was evaluated by in vivo and in vitro experiments. RH strain was subcutaneously inoculated to ten Wistar rats. After one month, their blood, brain, tongue and diaphragm were collected and evalua...

Background: Treatment of vivax malaria with primaquine prevents the risk of relapse. This study was designed to assess the efficacy of 8 weeks of primaquine treatment in prevention of relapse in patients with vivax malaria in south and south-east Iran by SSCP-PCR and sequencing. Methods: A total of 163 symptomatic vivax malaria cases were follow...

Toxoplasma gondii is an obligate intracellular parasite that infects humans at high prevalence rates. The virulent RH strain of T. gondii is generally considered to have lost its cyst forming capacity. This study performed to obtain tissue cysts in mice infected with tachyzoites of RH strain treated with sulfadiazine (SDZ). It provides the opportun...

Past studies have stated that the parasitostatic effect of IFN-γ is most likely due to the starvation of Toxoplasma gondii for tryptophan in the host cell. The aim of this study was to evaluate the direct effect of two new Naphthalene-Sulfonyl-Indole compounds as competitive molecules for tryptophan on viability and infectivity of Toxoplasma tachyz...

The diagnosis of visceral leishmaniasis (VL) in humans and animal reservoir hosts is difficult, particularly in rural areas where the disease is endemic and laboratory facilities are limited. This study aimed to develop a latex agglutination test (LAT) for the rapid detection of anti-Leishmania antibodies against the A2 antigen derived from the ama...

Toxoplasmic encephalitis is caused by reactivation of bradyzoites to rapidly dividing tachyzoites of the apicomplexan parasite Toxoplasma gondii in immunocompromised hosts. Diagnosis of this life-threatening disease is problematic, because it is difficult to discriminate between these 2 stages. Toxoplasma PCR assays using gDNA as a template have be...