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Introduction: One  of  the  most  important  health  problems  of  the  country  is  parasitic  infections, specially  intestinal  parasites  which  have  relatively  high  prevalence  rate  through  out  the  world. Theses  infections  can  cause  iron  deficiency  anemia, physical  and  mental  retardation  among  children  and  family  members.  Since  mothers  come  to  account  as  the  base  of  the  family  and  each  their  deviation  of  health  can  consider  as  a  risk  factor  for  them  and  the  other  family  members, this  study  was  conducted  to  determining  prevalence  rate  of  intestinal  parasitic  infections  among  mothers  and  associated  demographic  factors.
Materials  and  Methods:  This  survey  is  a  descriptive  analytical  study  which  cross-sectionaly  was  done  based  on  systematic  randomized  sampling  method  on  1650.  Mothers  in  three  regions  of  the  town.  Their  feces  were  examined  three  times  by  formalin  ether  concentration  technique.  Of course  for  gathering  data  about  demographic  factors, questionires  were  filled  all  infected  mothers.
Results: of  1650  case, 801  mothers (48.5%)  were  infected  by  intestinal  infections:110  mothers  (13.73%) m were  infected  by  pathogenic  intestinal  infection, Giardia  lambia 89 case (5.39%)  was  the  commonest  infection, entamoeba  histolytica  12  cases  (72%), hymenolepsis  nana  5  cases (3%), ascaris  3  case (1.18%)  and  tenia  saginata  1 cases  (0.6%)  respectively. 691  mothers  (869.2%)  were  infected  by  nonpathologenic  intestinal  infection.  E.coli  313  case(19%), blastocystic  hominis  267  cases  (16.18%), endolimax  nana 67  cases (4%), lodamoeba  buetschlii 34  cases, (25%)  and  chilomastix  mesnili  10  cases  (0/6%)  respectively.
Conclusion:  In this  survey, there  was  no  significant  relationship  between  infection  rate  and  demographic  factors  like  age, job, level  of  literary  and  residence  region. However  the  findings  showed  that  the  highest  rate  of  pathogenic  intestinal  parasitic  infections  were  7.8%  (43 cases) in  down  town, 6.72%  (37  cases)  in  town  center  and  5.45%  (30  cases)  in  uptown.

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Introduction: Alimentary  parasitic  infections  are  still  one  of  the  main  problem  in  developing  countries, and  their  relation  with  environmental  factors  are  important.  Since  children  are  more  vulnerable  to  these  infections, in  basic  researchers  this  group  is  more  targeted.
Materials  and  Methods:  This  descriptive-analytical  cross-sectional  study  was  carried  out  on  1-13  years  children  who  were  living  in  Shahrak-e-Valiasr  Arak.  Simple  random  sampling  was  used  for  selecting  385  children.  Three  days  collected  feces  samples  from  each  person  were  examined  using  formaline-ether  concentration  technique. Data  were  analyzed  by  Chi  square  method.
Results:  The  results  showed  a  prevalence  of  42.3%  of  intestinal  parasitic  infections  in the  children. From  these, 17.4%  were  pathogen  parasits. The  highest  prevalence  was  reported  for  Giardia  lambia  (16.6%).  Girls  were  more  infected  than  boys.  The  level  of  infection  was  significantly  increased  by  age. The  prevalence  of  the  infection  was  more  in  orphans  or  in  children  who  had  uneducated  parents.
Conclusion:  Since  date  indicated  of  a  high  prevalence  of  intestinal  parasitic  infections  in  the  children. It  is  suggested  to  use  washed  and  clean  vagetables   and  fruits  and  also  emphasize  on  personal  and  environmental  hygiene.

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Introduction: There is difference between susceptibility or resistance to infectious diseases such as cystic and alveolar Eclinococcosis in human and animals, that is due to the difference between individual host factors and immunologic responses. This study is done to investigate the resistance and susceptibility markers (HLA) in Hydatid patients and healthy persons. Materials and Methods: This analythical (case-control) study is carried out on 60 patients with confirmed cystic echinococcosis and 30 healthy individuals living in Arak. Blood samples were gathered and tested by microlymphocytotoxicity method. At first diagnostic kits with specific antiserusms for each antigen (28 antigens) were provided and then lymphocytes were separated. After dye and stabling with formalin and based on cells morphology, results were seen by invert microscope. Data was analyzed using Odds Ratio, Relative Risk, Preventive Fraction, Aetiologic Fraction and Chi square test. Results: Results showed that HLA-A1 was significantly higher in patients (p<0.05), and people having this antigen are more susceptible for the infection. In spite, HLA-A10 was higher is healthy individuals (p<0.05) and have a preventive effect in disease involvement. Other investigated antigens had no signigicant difference in the two groups. For more accurate results molecular investigation is needed. Conclusion: In individuals having HLA-A1 there is more chance for cyst growth in confronting hydatosis and this individuals are more susceptible to the disease. But in individuals having HLA- A10 there is less chance for cyst growth in confronting hydatosis and this antigen have a preventive effect against hydatid cyst.

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Background: The purpose of this study was to identify the effect of health education according to health belief model (HBM) on the adoption of preventive behaviors of infection with giardia lamblia by primary school students in Arak. Materials and Methods: In a randomized quasi-experimental case study, 1200 students were randomly divided into two equal groups of test (instruction) and control (non-instruction). The sample size for giardiosis identification tests included 300 students, who had been equally and randomly selected from the control and test groups. Health education was according to HBM and its impact on the students' lifestyle-related patterns of behavior was considered. Results: Paring nails in the test group, significantly increased after education while it decreased significantly in the control group. The number of students who carried a glass for drinking slightly increased, but it remarkably decreased in the control group. The number of students who applied soap after using the restrooms remarkably increased in both the test and control groups. The relationship between not paring nails and infection with giardia lamblia was statistically significant. Additionally, after education, the ratio of reduction of infection with giardia lamblia in the test group to its increase in the control group was statistically significant. Conclusion: Preventive behaviors significantly improved and appeared influential in the reduction of infection with giardia lamblia. Thus, using a HBM in prevention of parasitic infections along with instructing the parents are suggested for prevention of parasitic infections.