2001 Fiscal Year Final Research Report Summary
Actual transmission modes of pathogenic Entamoeba histolytica and Cryptosporidium
| Project/Area Number |
12576008
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
寄生虫学(含医用動物学)
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| Research Institution | Nagasaki University |
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Principal Investigator |
KANBARA Hiroji Nagasaki University, Inst. of Trop. Med., Professor, 熱帯医学研究所, 教授 (20029789)
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| Co-Investigator(Kenkyū-buntansha) |
YANAGI Tetsuo Nagasaki University, Inst. of Trop. Med., Research Associate, 熱帯医学研究所, 助手 (10174541)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Parasitic protozoa in digestive tract / Cryptosporidium / Entamoeba histolytica / Entamoeba dispar / Philippines / Nepal / Sero-epidemiology |
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| Research Abstract |
Recently, new taxonomic classification of Entamoeba histolytica and Cryptosporidium have been established using new genetic technology. This drove us to reexamine the transmission mode of really pathogenic species of two parasites. We conducted epidemiological surveys of two species in the Philippines and Nepal where these infections are commonly seen. Obtained results are
1. Pathogenic species ( Entamoeba histolytica ) and non-pahtogenic species ( Edispar) coexisted in all the area examined, but the proportion of E. h. in all cyst carriers was varied from 10 % to 30 % in different localities.
2. High prevalence of cyst-carriers was seen in a densely populated house condition, indicating direct contact between persons is the first risk-factor for transmission.
3. The peak ofasymptomatic cyst-carriers of E. h. and E. d was seen in young generation ( 5-20 years ) of both sexes, whereas severe symptomatic infections ( liver abscess ) were exclusively found in male adults ( 20-60 years ).
4. Seropositive cases to E. h. were also highest in young population, indicating E. h. infections are commonly short.
5. The mode of Cryptosporidium infection seems to be similar to E. A, judging from the sero-positive pattern.
6. Asymptomatic oocyst-carriers of Cryptosporidium were not found.
7. The mode of infection ofAscaris lumbricoides and Giardia lamblia seems to be different from that of E. h. and Cryptosporidium.
Our results indicated that ordinal control methods such as improvement of the water-supply system and toilets may. not be effective for reduction of E. h. and Cryptosporidium.
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