Journal of Arthropod-Borne Diseases最新文献

Cutaneous leishmaniasis is a neglected and parasitic vector borne diseases that is endemic in tropical and subtropical countries, including Iran. The aim of this study was to explain the present status of CL in Iran. This report is based on data that recorded by cutaneous leishmaniasis surveillance system in 2019, and evaluated in Center for Communicable Diseases Management in Ministry of Health in Iran. Iran has been considered an endemic area for cutaneous leishmaniasis in the world. Dependent to activities for cutaneous leishmaniasis control the number of cases decreased from 23202 in 2008 (Incidence rate 32 per 100000) to 13124 in 2019 (Incidence rate 15.8 per 100000), more cases reported from September to December, in 2019, 46% of cases had one lesion and 21% had 2 lesions, 85% of cases diagnosed when the diameter of lesions had 3 centimeters and bellows. Although the Leishmania control program began in 1977, the incidence of the disease has dropped dramatically since 2008 when the new cutaneous leishmaniasis control program have been implemented. Although in some areas the incidence of the disease increased, but the implementation of the new program has reduced the number of cases, in order to continue reducing the disease, permanent support for the control programs is needed.

Background: Phlebotomus papatasi is known as the main vector of zoonotic cutaneous leishmaniasis. This study aimed to investigate the effect of geographical and bioclimatic factors on the Ph. papatasi distribution.

Methods: A total of 34 villages were selected, and sampling was performed three times using 120 sticky traps in each selected village. All the collected species were mounted and identified their species. The densities of Ph. papatasi were measured in all the villages and entered into ArcMap as a point layer. The required bioclimatic and environmental variables were extracted from the global climate database and The normalized difference vegetation index was obtained from the MODIS satellite imagery, also, all variables entered into ArcMap as raster layers, so The numerical value of each independent variable in the cell where the selected village is located in this, was extracted using spatial analyst tools and the value to point submenu. All the data were finally entered into IBM SPSS, and the relationship was examined between the number of collected Ph. papatasi and the independent variables using Spearman's correlation test.

Results: A total of 1773 specimens of Ph. papatasi were collected. The findings of this study showed that max temperature of warmest month, temperature annual range, temperature seasonality, mean diurnal range, precipitation seasonality, mean temperature of driest and warmest quarter were positively associated with the density of Ph. papatasi.

Conclusion: Air temperature and precipitation were shown as the most significant factors in the distribution of Ph. papatasi.

Background: Ticks are forced vertebrate ectoparasites, including humans, and are vectors of serious diseases such as Crimean Congo Hemorrhagic Fever, Relapsing Fever, and various forms of encephalitis. Spatial assessment of the prevalence of ticks and detection of high risk areas for tick-borne disease transmission and evaluation of ecological measures are key aims of this research.

Methods: Ticks were collected using standard methods from 27 villages in the region of Sarab County in north-eastern Iran during the four seasons of 2018-2019 and identified using valid keys. The calculations of indices for biodiversity were based on the Margalef index, Shannon-Weiner index and Simpson index. R2.15 Statistical software was used for statistical analysis of indices of biodiversity, and ArcMap10.4.1 software, IDW and GeneralG methods were used. Analysis were used to investigate spatial distribution and to determine important tick hotspots.

Results: A total of 2500 animals surveyed, 35% of them were infected. In total, 1416 ticks were caught, 74.6 %, 23.9% and 1.4 % were adult, nymph and larvae respectively. 94% of the ticks were hard ticks including 6 genera. According to the Margalef diversity index, the highest species biodiversity was related to summer (1.4234), and the lowest was related to winter (0.7379).

Conclusion: Large hotspot area was found in the central part of the study area. The area of study was very prone to tick-borne disease transmission in terms of tick diversity and tick species richness. Tick-borne disease control is an important measure.

Background: This study was performed to evaluate in vitro and in vivo Leishmanicidal potential of morphine (Mph), imiquimod (IQ), and their combination.

Methods: Leishmania infantum promastigote and amastigote assays were performed at the presence of 0.015-150μM Mph, 0.04-416μM IQ, and their combination. The inhibition effects of these drugs on promastigotes were evaluated after 24, 48, and 72h. The cytotoxic effects of the drugs were evaluated by MTT as well as flow cytometry after 72h. We explored the therapeutic effects of Mph and IQ in BALB/c mice at the end of the treatment using parasite load determination and cytokine assay. One group of mice received Mph for three weeks before infection.

Results: The results of promastigote and amastigote assays showed the cytotoxic effects of the drugs at low concentrations. The cytotoxic effects were higher on promastigotes than amastigotes (p< 0.05). There was a negative correlation between drug concentration and amastigote/promastigote viability. Imiquimod alone or combined with Mph showed remarkable cytotoxic effects at all concentrations (p< 0.05). Flow cytometry results revealed apoptosis in the parasite following exposure to the drug combinations. Accordingly, the reduction of parasite loads in the spleen and liver was observed (p< 0.05) with simultaneous increases in IFN-γ and IL-4. We believe that the in vivo leishmanicidal effect was mediated by Mph through IL-4 and by IQ through both IL-4 and IFN-γ.

Conclusion: Results pointed out the promising effects of Mph and IQ at low concentrations, especially when combined.

Background: Seasonal activity patterns of mosquitoes are essential as baseline knowledge to understand the transmission dynamics of vector-borne diseases. This study was conducted to evaluate the monthly dynamics of the mosquito populations and their relation to meteorological factors in Mazandaran Province, north of Iran.

Methods: Mosquito adults and larvae were collected from 16 counties of Mazandaran Province using different sampling techniques, once a month from May to December 2014. "Index of Species Abundance" (ISA) along with "Standardized ISA" (SISA) was used for assessing the most abundant species of mosquitoes based on the explanations of Robert and Hsi. Pearson's correlation coefficient (R) was used to assess the relationships between the monthly population fluctuations and meteorological variables.

Results: Overall, 23750 mosquitoes belonging to four genera and nineteen species were collected and identified. The highest population density of mosquitoes was in July and the lowest in May. The ISA/SISA indices for Culex pipiens were both 1 for larvae and 1.25/0.973 for adults in total catch performed in human dwellings. For Cx. tritaeniorhynchus, the ISA/SISA were 1.68/0.938 in pit shelter method. A significant positive correlation was observed between population fluctuations of Cx. tritaeniorhynchus and mean temperature (R: 0.766, P< 0.027).

Conclusion: The results indicated that the mosquitoes are more active in July, and Cx. pipiens and Cx. tritaeniorhynchus were the most abundant species. Considering the potential of these species as vectors of numerous pathogens, control programs can be planed based on their monthly activity pattern in the area.

Background: Ticks are considered as the main vectors for the transmission of various pathogens such as relapsing fever and CCHF to humans. This study was investigated the biodiversity indices and medically importance of ticks in North Khorasan Province, Northeast of Iran during 2015-2019.

Methods: Specimens were captured from infested ruminants including cows, sheep, and goats. Additionally, tick collections also were performed on non-domesticated creatures such as turtles, rodents, and hedgehogs. Specimens were identified using valid identification keys. Species diversity, species richness and evenness indices have been calculated to estimate species biodiversity of ticks.

Results: A total of 1478 adult ticks were collected. The specimens were from two families: Ixodidae (90.05%) and Argasidae (9.95%), 6 genera and 17 species including: Rhipicephalus sanguineus (55.9%), Rhipicephalus bursa (13.4%), Hyalomma marginatum (9.5%), Hyalomma anatolicum (9.5%), Hyalomma asiaticum (0.2%), Hyalomma aegyptium (0.5%), Hyalomma scupense (1.3%), Hyalomma sp (1.2%), Haemaphysalis sulcata (0.7%), Haemaphysalis erinacea (0.1%), Haemaphysalis inermis (0.1%), Haemaphysalis punctata (0.2%), Haemaphysalis concinna (0.1% Boophilus annulatus (1.2), and Dermacentor marginatus (6.1%) among hard ticks as well as Argas persicus (91.8%) and Argas reflexus (8.2%) amongst soft ticks. Rhipicephalus sanguineus, Rh. Bursa, Hy. marginatum and Hy. anatolicum were known as the most frequent species of hard ticks. Tick's species richness, Shannon diversity index and Simpson index in this area were S= 17, H'= 1.69, D= 0.294 respectively.

Conclusion: Based on tick distribution veterinary authority, public health organizations and other officials should act for implementation of disease prevention.

Background: Malaria is a major public health problem in Nigeria with 97% of its population with high morbidity and mortality. Mosquitoes play an important role in the transmission of malaria parasites. This study was conducted to evaluate the current resistance status of Anopheles gambiae to insecticides.

Methods: Larvae of An. gambiae was collected from three zones; A, B and C differentiated on the basis of variation in agricultural ecosystems between August and November, 2018 in the northeast and northwestern parts of Nigeria. They were carefully reared to adult stage and insecticidal susceptibility tests were conducted.

Results: The mosquitoes tested showed high levels of resistance to all the insecticides used with the exception of malathion. Study zone A, recorded 74% mortality after 24h to deltamethrin compared to 81% from zone B and 82% from zone C, respectively. Mosquitoes from zone B exposed to DDT had the highest level of resistance at 37% compared to 40% and 53% from zones A and C, respectively. Resistant to bendiocarb was also observed, with zone A having the lowest mortality of 44% compared to 48% from zone C and 55% from Zone B, respectively. According to the results of knockdown tests, mosquitoes from Zone A exposed to deltamethrin recorded the lowest knockdown across the study locations while zone B recorded the lowest knockdown for DDT.

Conclusion: The results of the study provide an insight into the current status of An. gambiae to four major insecticides in northern Nigeria as guideline for mosquitocontrol.

Background: Cytochrome P450-dependent monooxygenases are a very important metabolic system involve in insecticide resistance. This study was conducted to find the association between the expression level of cytochrome P450 (CYP450) and permethrin-resistance level among four strains of the German cockroach Blattella germanica (L) (Blattodea: Ectobiidae).

Methods: Three field strains of German cockroach with different frequency of exposure to pesticides, and a laboratory susceptible strain were used in the present study. Insecticide susceptibility bioassays were carried out to detect resistance to permethrin. The concentration of CYP450 in each strain was determined using ion-exchange HPLC chromatography. Biochemical assays was performed to analyse CYP450 activities.

Results: The resistance ratios (RR) to permethrin among three field strains were 3.29, 4.10 and 6.17-fold comping with the susceptible stain. The CYP450 activity of three field strains was 1.6, 2.4 and 2.7 times higher than in the susceptible stain. The amount of CYP450 per mg of protein was significantly different between the susceptible and the three resistant strains. The resistant cockroaches showed a relatively high expression of CYP450 enzymes. A strong correlation was found between permethrin resistance level and total concentration of CYP450 enzymes.

Conclusion: The results of current study show that more frequent usage of a pyrethroid insecticide cause the metabolic insecticide resistance to rise in German cockroach. Therefore, there is a ratio correlation between resistance level and monooxygenases activities in insect. Thus, the control program must be managed according to history of pesticide usage.

Background: Malaria is the third most important infectious disease in the world. WHO propose programs for controlling and elimination of the disease. Malaria elimination program has begun in first phase in Iran from 2010. Climate factors play an important role in transmission and occurrence of malaria infection. The main goal is to investigate the spatial distribution of incidence of malaria during April 2011 to March 2018 in Hormozgan Province and its association with climate covariates.

Methods: The data included 882 confirmed cases gathered from CDC in Hormozgan University of Medical Sciences. A Poisson-Gamma Random field model with Bayesian approach was used for modeling the data and produces the smoothed standardized incidence rate (SIR).

Results: The SIR for malaria ranged from 0 (Abu Musa and Haji Abad districts) to 280.57 (Bandar-e-Jask). Based on model, temperature (RR= 2.29; 95% credible interval: (1.92-2.78)) and humidity (RR= 1.04; 95% credible interval: (1.03-1.06)) had positive effect on malaria incidence, but rainfall (RR= 0.92; 95% credible interval: (0.90-0.95)) had negative impact. Also, smoothed map represent hot spots in the east of the province and in Qeshm Island.

Conclusion: Based on the analysis of the study results, it was found that the ecological conditions of the region (temperature, humidity and rainfall) and population displacement play an important role in the incidence of malaria. Therefore, the malaria surveillance system should continue to be active in the region, focusing on high-risk areas of malaria.