Effects of geographical and climatic factors on cystic echinococcosis in south-western Iran.

Cystic echinococcosis (CE) is caused by the larval form of Echinococcus granulosus that can cause serious health and economic problems in the endemic foci. CE is globally distributed in various climatic conditions from circumpolar to tropical latitudes. Iran is an important endemic area with a spectrum of weather conditions. The aim of this study was to determine the effects of geo-climatic factors on the distribution of livestock CE in south-western Iran (SWI) in 2016 to 2018. Data of livestock CE were retrieved from veterinary organizations of four provinces of SWI. The geo-climatic factors, including mean annual temperature (MAT), minimum MAT (MinMAT), maximum MAT (MaxMAT), mean annual rainfall (MAR), elevation, mean annual evaporation (MAE), sunny hours, wind speed, mean annual humidity (MAH), slope, frost days and land cover, were analysed using geographical information systems (GIS) approaches. The statistical analysis showed that MAR, frost days, elevation, slope and semi-condensed forest land cover were positively and MAE, MAT, MaxMAT, MinMAT and salt and salinity land cover were negatively correlated with CE occurrence. MAE was shown to be a predictive factor in the stepwise linear logistic regression model. In short, the current GIS-based study found that areas with lower evaporation were the main CE risk zones, though those with lower temperature and higher rainfall, altitude and slope, especially where covered with or in close proximity of semi-condensed forest, should be prioritized for consideration by health professionals and veterinarians for conducting control programmes in SWI.

Genotyping and phylogenetic analysis of unusually located hydatid cysts isolated from humans in north-east Iran.

Despite several studies conducted to determine the genotypes of cystic echinococcosis (CE) agents in humans and other intermediate hosts, the relationship between parasite genotype and clinical presentation of hydatidosis is yet to be well defined. The aim of this study was to compare the genotypes/haplotypes of CE agents of human extra-hepatopulmonary hydatid cysts and common hydatid cysts of the liver. A comparative analysis was carried out between partial cox1 sequences of ten extra-hepatopulmonary hydatid cysts, two liver cysts and reliable sequences from the GenBank database. All the studied hydatid cysts had the Echinococcus granulosus sensu stricto (G1-G2-G3) genotypes. The liver CE cysts were caused by common G1 genotype, while six of the extra-hepatopulmonary cysts had genotypes different from common G1 cysts. The sequences of these six isolates were identical to the G2 and G3 genotypes of E. granulosus sensu stricto; the kidney and peritoneum cysts and most of the brain cysts were identified as G2 genotype, while G3 genotype was only reported in a cyst belonging to the pelvic region. Given the observed differences between the sequences of hydatid cysts, it seems that the replacement of hydatid cysts in organs other than the liver and lungs can be related to their genotypes and probably intra-genotypic characteristics. It was hypothesized that in each geographic area, less frequent genotypes were likely to be more consistent with placement in the host's unusual organs.