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Leishmania parasites as the causative agent of leishmaniasis belong to Trypanosomatidae family. Parasite, vector, vertebrate host and environment are major factors in pathogenesis of Leishmania. 
Parasite dependent factors are virulence factors which exist in Leishmania species such as LPG, GP63. In recent years, the importance of these factors in the field of vaccine and drug has been considered by researchers. Sand fly biting behavior and salivary gland proteins are vector dependent factors which are effective in the Leishmania pathogenesis. Age, gender, nutrition, immune system, infectious diseases, genetic, occupation, socio-economic characteristics, and habitat are vertebrate host mediated factors. Temperature, rainfall, wind and its speed, soil, and continuous changes in climate are also environmental factors. Therefore the aim of this study was to evaluate the pathogenesis of Leishmania parasites.
 

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Background & objectives: Parasitic diseases are one of the health problems of all societies and are considered as barriers to progress socioeconomic development, especially in most developing countries. This study evaluated the frequency of intestinal parasites in patients referred to hospitals affiliated with Ardabil University of Medical Sciences in 2018.
Methods: a total of 409 stool samples were collected from laboratories of Imam Khomeini and Bouali hospitals and then transferred to the parasitology lab in the medical and paramedical school. Samples were evaluated using direct, concentration and culture methods. Data were analyzed using SPSS software version 21.
Results: Out of 409 samples, 22 cases (5.4%) were infected with intestinal parasites. Among them, 5.3% and 5.4% of infected cases were men and women respectively. Also, the rate of infection to the protozoans and helminths was 3.7% and 1.7% respectively. Among the positive cases, the highest percentage of infection was related to Giardia and Blastocystis.
The infection rate of each parasite among all patients and positive cases was 1.2% and 22.7% respectively.
Conclusion: The present study showed that intestinal protozoan infection, especially Giardia lamblia and Blastocystis hominis are high in Ardabil city, and therefore special infection control measures are urgently needed.
 

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Leishmaniasis is a tropical parasitic disease that has become a major health challenge in many countries of the world. Not only has not been found any effective vaccine or treatment for the disease eradication, but also the advent of drug resistance is also increasing. Therefore, it is vital to take a precise attention to the physiochemical cycles of the Leishmania parasite and to identify its biochemical pathways. One of the most important biochemical pathways of host and parasite is the arginase and nitric oxide cycles. By using L-arginine, arginase plays an important role in the metabolic pathways, particularly in ornithine production, polyamines biosynthesis and cellular activities, including proliferation and cell survival. Furthermore, L-arginine, can act as a substrate for inducible nitric oxide synthase (iNOS), which leads to the synthesis of nitric oxide (NO), thereby activating the cellular immune system and clearing intracellular parasites. High Arginase activity reduces the parasite load inside the host cell, and since lymphocytes need L-arginine for their activity, its deficiency impairs the response of host immune cells. Also, parasites arginase alone can determine the fate of Leishmania parasite within the host cell. The aim of this study was to provide a comprehensive overview of various studies on the arginase activity of both parasite and host and its direct impacts on the immune system and pathogenicity of the Leishmania parasite.
 

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Background & objectives: Impaired immune system provides favorable conditions for colonization by Acanthamoeba in the human body. In this case control study, we compared the molecular and culture methods in identifying Acanthamoeba in the nasal and oral secretions of HIV⁺/HIV^­ human.
Methods: In a current case control study, nasal and oral discharge of 53, HIV⁺ patients and 53, HIV^­ people were evaluated. The nasal and oral secretions of each patient were prepared by sterile swabs and transferred to the laboratory. All samples were cultured but only the positive samples used for molecular analysis.
Results: By cultivation method, of the 53, HIV⁺ patients, a total of 11 samples, including 5 nasal and 6 oral samples, were contaminated with Acanthamoeba. Of the 53, HIV­­ people, 3 samples of nasal discharge were contaminated with this parasite. The molecular method approved the contamination of 10 samples, including 5 oral and 5 nasal samples from HIV⁺ patients with this parasite. Statistical analysis showed the rate of infection in HIV⁺ patients was significantly different compared to HIV^­ people
Conclusion: The results of the current study showed that the rate of Acanthamoeba infection in HIV⁺ patients was higher than that of HIV^- individuals. Also, considering that in the control group (HIV- individuals) only the nasal discharge were infected with the parasite, it seems that in the case group (HIV + patients) the infection of the oral discharge with the parasites is due to the  entry of its cysts into the nose and transmission to the mouth

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Background & objectives:  Fleas are clinically important parasites for affecting human health. These insects are carriers of some pathogens such as Yersinia pestis, Rickettsia typhi, Q fever, Tularemia and Bartonella henselae which are infectious for humans and animals. The aim of this cross –sectional study was to detection of Rickettsia, Bartonella and Wolbachia pathogens in infected Ctenocephalides canis and Pulex irritans using molecular method in West and Northwest of Iran.
Methods: The present study is a, descriptive, cross-sectional study (prevalence rate=10%, confidence level=95%,  error rate=5%) which  performed on samples collected from five provinces including  Kermanshah, Kurdistan, Azerbaijan Western, Lorestan and Hamedan for 13 months from May 2018 to June 2019. In this study, samples were collected by optical trap, human prey and direct isolation of the sample from the host and identified in the parasitology laboratory using valid diagnostic keys. The prevalence of Rickettsia, Bartonella and Wolbachia in the collected samples was detected using polymerase chain reaction (PCR). Amplification and sequencing of gltA, pap31 and 16SrRNA genes were used for molecular diagnosis of  Rickettsia, Bartonella, and Wolbachia respectively.
Results: The collected samples included 918(47.39%) fleas of C.canis and 1019 (52.60%) fleas of P.irritant. The PCR products of each gene was subject to sequencing. In this study, 12.9% , 5.21% and 5.21% of fleas were positive for  Wolbachia , Rickettsia and Bartonella, respectively .
Conclusion: Bartonella, Rickettsia and Welbachia are vector borne infectious agent. Due to their high pathogenicity and easily transmission among insect and human, monitoring of insects is essential for the controlling of the infection and preserving the public health in endemic area.

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Background & Objectives: Cold Plasma is an emerging non-thermal, chemical-free, environmentally friendly disinfection technology. Plasma-activated water has received considerable attention from researchers in recent years. Despite extensive studies on the antibacterial effects of plasma-activated water, its anti-eukaryotic effects have not been identified. In humans, Acanthamoeba causes granulomatous encephalitis, skin ulcers, and Acanthamoeba keratitis. Considering the health importance of Acanthamoeba, this study investigated the anti-amoeba  effect of plasma-activated water on trophozoites and cysts of Acanthamoeba castellanii.
Methods: In this study, plasma-activated water prepared by the cold atmospheric plasma method.Physicochemical properties of produced water were evaluated by measuring pH, hydrogen peroxide, nitrite, and nitrate. To assess the effect of plasma-activated water on A. castellanii, trophozoites and cysts were exposed to plasma-activated water for 0.5, 1, 2, 3, 4, and 5 hours. Three replicates were examined each time. At the mentioned times, cell viability was calculated by trypan-blue staining and counting on a hemocytometer, and the results were statistically analyzed.
Results: Based on the physicochemical results, the mean pH of plasma-activated water in this study was about 3.4, and the amount of hydrogen peroxide, nitrate, and nitrite were 102, 737, and 36.94 μM, respectively. The present study showed that plasma-activated water killed A. castellanii trophozoites after three hours of exposure and A. castellanii cysts after four hours of exposure. On the other hand, some trophozoites gradually became cysts after exposure to plasma-activated water. These cysts became more resistant to plasma-activated water and inactivated after five hours of exposure.
Conclusion: In this study, for the first time, the effect of plasma-activated water on A. castellanii was investigated. The results of the present study showed that plasma-activated water is able to inactivate A. castellanii trophozoites and cysts. Therefore, plasma-activated water can be used to disinfect and inactivate A. castellanii.

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Background & objectives: Fishes are one of the most important sources of zoonotic parasites throughout the world. This study aimed to determine helminthic parasites of Fish caught in the Aras River.
Methods: During 2020-2021, a number of 100 fishes including 20 Cyprinus carpio, 10 Hypophthalmichthys molitrix, 5 Hypophthalmichthys nobilis, 12 Silurus glanis, 5 Aspius aspius, 15 Ratilus rutilus, 3 Sander lucioperca, 22 Luciobarbus capito, and 8 Abramis brama were caught. All parts of the fish body (scales, gills, eyes, muscles, gastrointestinal tract) were examined for Helminthes parasites. After clearing and temporarily staining with Lactophenol-Azokarmin, morphological characters of worms were analyzed using a calibrated microscope equipped with a camera.
Results: After examining and evaluating the samples, 18 (18%) of the fish were infected with at least with one helminthic parasite. The species and percent of infection were as follows: Ligula intestinalis plerocercoid: Cyprinus carpio 40%, Ratilus rutilus 13.33%, Abramis brama 12.5% in the abdominal cavity. Bothriocephalus sp.: Cyprinus carpio 5% in the intestine. Diplozoon sp.: Cyprinus carpio 5% and Ratilus rutilus each 6.7% in gills. Dactylogyrus sp.: Cyprinus carpio 10%, Abramis brama 12.5% in gills. Clinostomum sp. metacercariae: Cyprinus carpio 5% infected with metacercaria in gills and abdominal cavity.
Conclusion: Among the investigated types of fish, the highest level of infection with helminthic parasites was found in common carp. Also, among the helminthic parasites found, the highest frequency is related to Ligula intestinalis, followed by Dactylogyrus

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Background & objectives: Toxoplasma gondii is an obligate intracellular parasite with global distribution. Diagnosis of Toxoplasma gondii infection with high sensitivity and specificity is very important in managing and treating this disease. The purpose of this study is serological and molecular investigation of toxoplasmosis using B1 gene in HIV- positive patients referred to hospitals affiliated with Iran University of Medical Sciences.
Methods: In this study, 660 blood samples were collected from HIV/AIDS- positive patients referred to hospitals affiliated with Iran University of Medical Sciences. Patient samples were examined for the presence of IgG and IgM antibodies against Toxoplasma gondii using an ELISA kit. Genomic DNA was extracted from the patient's serum, as well as peripheral blood mononuclear cell (PBMC) and whole blood samples, and then Real time-PCR was performed.
Results: Although IgG antibody against Toxoplasma gondii was positive in 158 (23.9%) patients out of 660 HIV- positive patients, IgM antibody was positive in 5 (0.76%) patients. The results of Real-Time PCR showed that 7 (1.06%) patients were positive in PBMC samples, of which five patients were positive for IgM antibodies against Toxoplasma gondii while two patients had high- level Toxoplasma IgG antibody titers.
Conclusion: The results of the study indicate that the Real-time PCR method using PBMC DNA samples is a suitable method for the diagnosis of toxoplasmosis. This method, together with the antibody test, especially the high titer of Toxoplasma IgG antibodies, can be helpful in the diagnosis of toxoplasmosis.
 

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Background: Pneumocystis jirovecii (P. jirovecii) causes Pneumocystis pneumonia (PCP) in people, especially the immunocompromised ones. It is also one of the serious causes of numerous lung problems in affected patients. Since documented data about P. jirovecii is not available in patients with pulmonary infections in Tehran, this study aimed to investigate the molecular epidemiology and parasitology of Pneumocystis to determine the frequency of the organism infection.
Methods: Bronchoalveolar lavage (BAL) samples were collected for 367 patients hospitalized in the lung department of Shariati Hospital in Tehran from July 2022 to July 2023. The samples were analyzed using Giemsa staining and molecular methods. After DNA extraction from samples, Nested polymerase chain reaction (Nested PCR) was employed for the amplification of the 18SrRNA gene and identification of P. jirovecii. The PCR products of Nested PCR were sequenced for final confirmation. 
Results: Out of 367 samples, only one sample (0.27%) and 28 samples (6.7%) were found to be positive through parasitology and NestedPCR analysis, respectively. P. jirovecii was detected in seven (25%) and 21 (75%) immunocompromised and immunocompetent patients, respectively. Fever, shortness of breath and dry cough were the most common clinical symptoms among patients with Pneumocystosis. Patients with pulmonary disorders are prone to colonization by pneumocystis, which increases the risk of pneumocystosis and makes them a reservoir for transmission to susceptible people.
Conclusion: It can be concluded that patients with distinct lung disease are prone to colonization by Pneumocystis and, importantly, are at risk of infection. Also, according to the current study, Nested PCR was a suitable method for detecting P. jirovecii organisms because it had a very high sensitivity and specificity.
 

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Background: Opportunistic pathogens such as Cryptosporidium, Isospora belli, Blastocystis, etc. cause various gastrointestinal and non-digestive diseases in people with HIV. These symptoms are especially severe in people with HIV who have a CD4 count of less than 200. This study aimed to determine the prevalence of parasitic infections in people living with HIV in Tabriz.
Methods: This cross-sectional and descriptive study was performed on137 people with HIV referred to Behavioral Disease Counseling Centers in Tabriz, 2019-2021. Then, after receiving written consent, fecal samples were collected and evaluated for the detection of parasitic infections using direct methods, Ziehl-Neelsen and Trichrome Weber stain.
Results: A total of 137 stool samples were collected, including 93 males and 44 females. Most of them were in the age range of 20-60 years. The overall frequency of parasitic infections was 57.7% and the highest prevalence was related to Blastocystis 24.1% and Cryptosporidium 14.6%.
Conclusion: Due to the relatively high prevalence of parasitic infections, especially Blastocystis and Cryptosporidium in people with HIV in Tabriz, which can endanger the health of these patients, essential interventions, including personal hygiene training to control and prevent infection with these pathogens, seem to be necessary.
 

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