• Parasites, Hosts and Diseases
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• v.25 no.2
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• pp.110-122
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• 1987

The rabbits were infected with Clonorchis sinensis and were treated with praziquantel at the dose of $50{\;}mg/kg{\times}2회{\times}2$ days after 1,2,4,8 weeks and 7 months from the infection. Their livers were observed histopathologically 1, 4 and 12 weeks after treatment. The findings are summarized as below. 1. The changes of the liver in control rabbits were relatively mild until 2 weeks after infection. However, widening and thickening of bile ducts, proliferation of biliary epithelium and periductal fibrosis were moderate after 4 weeks from infection and those changes were severe after 8 weeks and 7 months. Goblet cell metaplasia was found after 8 weeks from infection. 2. The mild changes of 2-week infection group were completely recovered by 4 weeks after the treatment. In the groups of 4 or more weeks after infection, the changes of bile ducts became milder in the degree after the treatment, but were still found 12 weeks after the treatment. As the infection duration was passed, more severe changes were observed after the treatment. In this context, it is concluded that the liver changes of acute clonorchiasis in the early two weeks are reversible by treatment while chronic biliary epithelial changes are irreversible. Therefore, early treatment should be recommended as possible to minimize the remaining histopathological changes of liver in clonorchiasis.

• Journal of dental hygiene science
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• v.22 no.3
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• pp.180-190
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• 2022

Background: Like direct infection from COVID-19, psychological concern about infection could affect health. Concern about COVID-19 infection was associated with individual habits to practice rules for preventing infection. Therefore, this study aimed to check occupational types and whether to practice tooth brushing after lunch depending on the occupation of economic workers and find correlations between concerns about infection due to COVID-19 pandemic and tooth brushing after lunch. Methods: The raw data was from the community health survey conducted in 2020. Among 229,269 adult participants aged 19 years and older, 138,970 economic workers were included in the final analysis. The chi-squared test was used to find differences in psychological concerns due to the COVID-19 pandemic. According to the participants, the rate of practicing tooth brushing after lunch was based on COVID-19-related psychological concerns. Multiple logistic regression analysis was conducted to check the influence of psychological concerns due to the COVID-19 pandemic on the rate of practicing tooth brushing after lunch. Results: According to occupational classifications, professionals and office workers and career soldiers had 1.551- and 1.581-times higher practicing rates than managers, respectively, whereas machine operators, agricultural and fishery sector workers, and daily laborers had lower practicing rates. Regarding COVID-19-related psychological concerns, the group with a lower concern about infection had a 1.076 times higher practicing rate than that with greater concern. The group with greater concern about blame from neighbors had 1.119 times higher practicing rate than that with lower concern. Conclusion: The correlations between higher economic workers' concerns about infection and blame from neighbors and higher recognition of the necessity to prevent COVID-19 and practice tooth brushing after lunch were confirmed. It is necessary to prepare measures for practicing tooth brushing after lunch suitable to the characteristics of occupational types and work environments of economic workers.

• Parasites, Hosts and Diseases
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• v.45 no.1 s.141
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• pp.27-32
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• 2007

The status of Dirofilaria immitis infection was assessed in pet dogs of Busan, Korea, and chemoprophylactic effects of microfilaricidal medication were evaluated. A total of 294 pet dogs older than 6 mo were examined, 217 of which had been maintained indoors, and 77 had been kept outdoors. The $Snap^R$ kit and direct microscopic examinations of the peripheral blood were used. The mean overall parasite positive rates were 10.2% and 6.5%, respectively. Outdoor dogs evidenced adult worm infection rate of 31.2% and microfilaria infection rate of 18.2%. The indoor dogs, however, evidenced adult worm infection rate of 2.8% and microfilaria infection rate of 2.3%. The prevalence in males was more than 2 times that of females. The changing pattern of infection rates by age evidenced a gradual increase, from 2- to 6-year-old dogs, after which, a decrease in infection rates was noted. With regard to chemoprophylaxis, the infection rates of complete and incomplete chemoprophylaxis groups were found to be 2-3 times lower than that of the non-chemoprophylaxis group. The results of the present study indicate that the risk of exposure to D. immitis in pet dogs is quite high, particularly in male outdoor dogs, and chemoprophylactic measures were quite effective.

• Journal of Sericultural and Entomological Science
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• v.27 no.2
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• pp.20-27
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• 1985

This study was carried out to investigate the histological changes after the infection of nuclear and cytoplasmic polyhedrosis viruses(NPV, CPV) and the resistance to the viruses in various varieties of the silkworm fed on artificial diet. The results obtained were as follows; Among four varieties of silkworm tested, Jam 107$\times$Jam 108 was more resistant than the other varieties tested and Jam 119$\times$Jam 120 was the most resistant to CPV. In case of peroral infection with NPV, Jam 107$\times$Jam 108 showed lower mortality than the remained varieties in low concentration (104/ml). However, all varieties showed high mortality as the concentration of viruses was increased. With infection of CPV, the varieties showed high mortality at the concentration of 107 and 108/ml, while Jam 119$\times$Jam 120 showed the lowest mortality at virus concentration of 104/ml. The fat bodies, epidermal cells and tracheal epithelial cells showed high susceptibility to NPV to break the cells completely and liberate the debris to the body cavity. The CPV infected only the cylindrical cells of mid-gut and formed polyhedrons. In some cells, CPV was liberated to gastral cavity. In the electrophoretic pattern of hemolymph protein of silkworm larvae infected with NPV, bands were dimmed and disappeared as symptom aggravated after infection. Electrophoretic pattern of homolymph proteins of silkworm larvae infected with CPV showed no numerical difference at the later stage of infection, and one or two bands was observed along with lowering the concentrations.

• Parasites, Hosts and Diseases
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• v.27 no.3
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• pp.197-202
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• 1989

This study was performed to observe the susceptibility of dogs and cats as definitive hosts of Paragonimus ilektsuenensis. The metacercariae of this luke were obtained from Sesarma dehaani collected at a focus near the mouth of Sumjin river in November, 1986 and February, 1987. The larvae isolated from the crabs were introduced Per os into 7 albino rats, 2 dogs and 3 cats. The adults were recovered from the experimental animals, End they were morphologically observed and measured. The results were as follows: 1. The recovery rate of adult worms at 42 days after infection was 53.3% from three albino rats, 21.0% from a dog and 12.7% from two cats. Most of the worms were recovered from the worm capsules in the lungs. 2. The size of worms recovered from albino rats, a dog, and cats 42 days after infection aver-aged $6.3{\times}3.2mm,{\;}6.3{\times}3.0mm,{\;}or{\;}6.2{\times}3.5mm$, respectively. There were little differences in the morphology of worms by different experimental animals. 3. The size of eggs from a dog was $88.9{\times}49.3{\mu\textrm{m}}$, and that from cats was $84.3{\times}53.7{\mu\textrm{m}}$ on average. Dogs and cats were good definitive hosts of p. iloktsuenensis. This fact suggests that human infection by this luke may be possible if the metacercariae were ingested.

• Journal of Environmental Health Sciences
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• v.39 no.1
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• pp.32-42
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• 2013

Objectives: Cryptosporidium, a protozoan parasite, has been recognized as a frequent cause of waterborne disease due to its extremely strong resistance against chlorine disinfection. Although there has as yet been no report of a Cryptosporidium outbreak through drinking water in Korea, it is important to estimate the health risk of Cryptosporidium in water supply systems because of the various infection cases in human and domestic animals and frequent detection reports on their oocysts in water environments. Methods: This study evaluated the annual infection risk of Cryptosporidium in tap water using the quantitative microbial risk assessment technique. Exposure assessment was performed upon the results of a national survey on Cryptosporidium on the water sources of 97 large-scale water purification plants in Korea, water treatment efficacy, and daily unboiled tap water consumption. The estimates of the US Environmental Protection Agency on the mean likelihood of infection from ingesting one oocyst were applied for effect assessment. Results: Using probabilistic methods, mean annual infection risk of Cryptosporidiosis by the intake of tap water was estimated to fall within the range of $2.3{\times}10^{-4}$ to $1.0{\times}10^{-3}$ (median $5.7{\times}10^{-4}$). The risk in using river sources was predicted to be four times higher than with lake sources. With 0.5-log higher removal efficacy, the risk was estimated to be $1.8{\times}10^{-4}$, and could then be lowered by one-third. Conclusions: These estimations can be compared with acceptable risk and then used to determine the adequacy and priority of various drinking water quality strategies such as the establishment of new treatment technology.

• Korean Journal of Veterinary Service
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• v.21 no.4
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• pp.431-437
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• 1998

Argulus spp, a small group of parasitic curstaceans called Branchiura, is particularly important in freshwater acquaculture. We investigated the infection of Argulus to several different species of fishes and therapy effect of masoten. Argulus japonicus was collected from Okjeong lake, Chonbuk province and experlmen-tally infected to freshwater fishes from July to August 1998. The results were as follows ; 1. The shape of a Agulus is an oval and dorsoventrally flattened, with first maxillae and second maxillae, and four pairs of legs. 2. The size of the adult stage of A japonicus was 3.2-5.0$\times$2.3-2.9mm in female and 1.5-3.1$\times$1.6-2.9mm in male. 3. In the trial of experimental infection with A japonicus to non-scaled fishes, Parasilurus asotus and Ictalurus punctalus, were infected and some of them died after severe infection. However, A japonica was not infected at all. 4. Masoten treatment for A japonicus was effective at 0.2 ppm once a day for 3 days and parasites on the surface of fishes disappeared after five days.

• IMMUNE NETWORK
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• v.15 no.2
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• pp.83-90
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• 2015

Evaluation and screening of vaccines against tuberculosis depends on development of proper cost effective disease models along with identification of different immune markers that can be used as surrogate endpoints of protection in preclinical and clinical studies. The objective of the present study was therefore evaluation of subcutaneous model of M.tuberculosis infection along with investigation of different immune biomarkers of tuberculosis infection in BALB/c mice. Groups of mice were infected subcutaneously with two different doses : high ($2{\times}10^6CFU$) and low doses ($2{\times}10^2CFU$) of M.tuberculosis and immune markers including humoral and cellular markers were evaluated 30 days post M.tuberculosis infections. Based on results, we found that high dose of subcutaneous infection produced chronic disease with significant (p<0.001) production of immune markers of infection like $IFN{\gamma}$, heat shock antigens (65, 71) and antibody titres against panel of M.tuberculosis antigens (ESAT-6, CFP-10, Ag85B, 45kDa, GroES, Hsp-16) all of which correlated with high bacterial burden in lungs and spleen. To conclude high dose of subcutaneous infection produces chronic TB infection in mice and can be used as convenient alternative to aerosol models in resource limited settings. Moreover assessment of immune markers namely mycobacterial antigens and antibodies can provide us valuable insights on modulation of immune response post infection. However further investigations along with optimization of study protocols are needed to justify the outcome of present study and establish such markers as surrogate endpoints of vaccine protection in preclinical and clinical studies in future.

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.55-75
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• 1974

Transovarial transmission of cytoplamic polyhedrosis virus in the silkworm was studied by observing the phenomena of induction, interference and virulence enhancement in the larvae from moths inoculated with hexagonal Polyhedra of cytoplasmic polythedrosis virus. The experimental results obtained are as followings. 1. The effect of inoculation with tetragonal polyhedra of cytoplasmic polyhedrosis virus on the rate of infective induction with hexagonal polyhedron virus and with hexagonal plus tetragonal polyhedron viruses in the larvae from moths infected with hexagonal polyhedron virus was studied. Infection rate was higher by 40 to 60 percent in the larvae from infected female group than in tile larvae from noninfected female group. 2. In the studies of the effect of formalin-feeding on the induction of infection with hexagonal polyhedron virus, infection rate was higher by 40 percent in the larvae from infected female group than in the larvae from noninfected female group. However, there was no significant difference in the infection rates between the two formalin-concentration groups. 3. The effect of cold treatment on the induction of infection with hexagonal polyhedron virus was studied. Infection rate was higher by 50 percent in the larvae from infected female group than ill the larvae from noninfected female group. No difference was found in the infection rates of the two treatment groups of 12 and 48 hours. 4. The phenomena of induction and interference were studied by observing rate of infection with hexagonal polyhedron virus induced by the inoculation with tetragonal polyhedron virus. The degree of interference of primary hexagonal polyhedron virus by secondary tetragonal Ployhedron virus was increased as the dosage of secondary virus was increased. At the concentration of 1${\times}$10$\^$8/m1 of the secondary virus, the degree of interference was similar to. that of control group. On the other hand, infection with tetragonal polyhedron virus at low concentration was interfered by the primary virus. At the concentration of 1N10f/m1 of tetragonal polyhedron virus, however, the rate of infection with tetragonal polyhedron virus was increased sharply, which is still lower by 30 percent than that of control group. 5. In the studies of induction and virulence enhancement, based on the 1ate of mixed infection with hexagonal and tetragonal polyhedron viruses, the highest difference of infection rate between experimental group and control group exceeded 40 percent when the concentration of tetragonal polyhedron virus was 1${\times}$10$\^$7/m1. However, the infection rate of control group was not affected by concentrations of tetragonal polyhedron virus.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.3
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• pp.193-197
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• 2009

Background: Though it is clear that many types of viruses can infect the oral mucosa, its condition for infection is unclear. The purpose of this study was to analyze the conditions for viral infection of normal oral mucosa and explore the possibility of topical gene therapy to oral mucosa using a viral vector. Methods: Freshly taken fragments of the palate and the tongue of mice were used for organ culture. The specimens were exposed to green fluorescent protein (GFP)-adenoviral vector for 1 hour except for the control. Initial viral titer was $6.3{\times}10^{11}\;pfu/ml$ and the virus was diluted to working concentrations. The dilution ratio was 1:1,000 ($6.3{\times}10^8\;pfu/ml$), 1:10,000 ($6.3{\times}10^7\;pfu/ml$), and 1:100,000 ($6.3{\times}10^6\;pfu/ml$). They were then cultured on a stainless steel wire mesh in an organ culture dish. The specimens were stereoscopically examined every 24 hours for 6 days, after which they were fixed and analyzed through immunohistochemical methods Results: There was no visible expression in the control, $6.3{\times}10^6\;pfu/ml$, and $6.3{\times}10^7\;pfu/ml$ groups. Initial expression was observed at 24 hours after infection in both the palate and the tongue in $6.3{\times}10^8\;pfu/ml$ and the expression significantly increased until 3 days in the palate and 2 days in the tongue after infection (P<0.05). In both groups, the expression was mostly observed at the resection margin. Immunohistochemical studies showed that the epithelial cells were positive to GFP. Conclusion: The present study showed that topically applied adenovirus containing specific genetic information of GFP could successfully transduce GFP in normal oral epithelial cells at the resection margin in organ culture in terms of dose and exposure time.