Case 3Case 3報告人報告人 :: 胡鴻祥胡鴻祥

時間時間 :94071:9407133

指導老師指導老師 :: 盧章智主任盧章智主任

Previously healthy 32-year-old woman,Previously healthy 32-year-old woman, diarrheadiarrhea, , alternating with constipation, alternating with constipation, abdominal discomfort, vomiting, anorexia, abdominal discomfort, vomiting, anorexia, intense fatigue, myalgia, and other "flu-intense fatigue, myalgia, and other "flu-like" symptoms for several weeks ,went to like" symptoms for several weeks ,went to her internist for treatment her internist for treatment No traveling history but remarked that her No traveling history but remarked that her symptoms had developed a few days after symptoms had developed a few days after she attended a June wedding in Floridashe attended a June wedding in Florida several other guests at the wedding had several other guests at the wedding had developed developed similarsimilar symptoms symptoms

Routine tests for enteric pathogens were Routine tests for enteric pathogens were reported as being negative

Modified acid-fast-stainedModified acid-fast-stained smear revealed smear revealed spherical structures approximately 8 to spherical structures approximately 8 to 10 μm in diameter, showing a range of 10 μm in diameter, showing a range of intensity from colorless to intensity from colorless to dark red dark red

The spherical structures showed The spherical structures showed auto-auto-fluorescencefluorescence when viewed using a UV when viewed using a UV microscope.microscope.

Q1.Which intestinal protozoan parasite Q1.Which intestinal protozoan parasite might bemight becausing this patient's symptoms? causing this patient's symptoms? Explain yourExplain youranswer based on the results of answer based on the results of laboratory tests. laboratory tests.

Ans:Ans:

1.Cyclospora cayetanensis1.Cyclospora cayetanensis

2.2. 因為在因為在 modified acid-fast stainmodified acid-fast stain 中卵中卵囊會被染成紅色而且在囊會被染成紅色而且在 uv microscopeuv microscope下會自己發光下會自己發光 ,, 再加上再加上 oocystoocyst 大小大小 8-18-100μmμm

                

              

Q2:List two other protozoan Q2:List two other protozoan parasites which might be confused parasites which might be confused with this parasite.with this parasite.How may these three parasites be How may these three parasites be distinguished from each other? distinguished from each other?

Ans:Ans:

1.1. Cryptosporidium Parvum Cryptosporidium Parvum

2.2. Isopora belluiIsopora bellui

Cyclospora cayetanensisCyclospora cayetanensis 的的 oocystoocyst通常很少存在通常很少存在 ,, 若存在的話若存在的話 ,, 會會 8-8-1010μm,μm, 且有些會含且有些會含 granules or have granules or have a bubbly appearance(wrinkled a bubbly appearance(wrinkled cellphone), cellphone), auto-fluorescenceauto-fluorescence when viewed using a UV when viewed using a UV microscope.microscope.

Cryptosporidium Parvum Cryptosporidium Parvum 不會有不會有auto-fluorescenceauto-fluorescence when viewed when viewed using a UV microscopeusing a UV microscope 而他的而他的oocystoocyst 大小約大小約 4-54-5μmμm

Isopora belluiIsopora bellui 的的 oocystoocyst 會會 auto-auto-fluorescencefluorescence when viewed using a when viewed using a UV microscopeUV microscope 且形狀為且形狀為 oblongoblong 而且而且較其他兩者為大較其他兩者為大

Q3:How does this patient's history Q3:How does this patient's history correlate with this diagnosis? correlate with this diagnosis?

Ans:Ans:1.Diarrhea1.Diarrhea2.Abdominal discomfort, vomiting, 2.Abdominal discomfort, vomiting,

anorexia, intense fatigue, myalgia, anorexia, intense fatigue, myalgia, and other "flu-like" symptoms and other "flu-like" symptoms

3.Several other guests at the wedding 3.Several other guests at the wedding had developed similar symptom had developed similar symptom

4.The routine tests for enteric 4.The routine tests for enteric pathogens were reported as being pathogens were reported as being negative negative

Q4:Where have outbreaks of this Q4:Where have outbreaks of this infection occurred? infection occurred?

Ans:Ans:

Since 1990, at least 11 foodborne Since 1990, at least 11 foodborne outbreaks of cyclosporiasis, outbreaks of cyclosporiasis, affecting approximately 3600 affecting approximately 3600 persons, have been documented persons, have been documented in the United States and Canada. in the United States and Canada.

Q5:Does this parasite cause more Q5:Does this parasite cause more serious illness in serious illness in immunocompromisedimmunocompromisedindividuals? individuals?

Ans:Ans:

In an immunocompromised host, In an immunocompromised host, onset is more insidious, and the onset is more insidious, and the condition becomes chroniccondition becomes chronic

Q6:Should the patient be treated? If Q6:Should the patient be treated? If so, how? so, how?

Ans:Ans:This disease can be self-limited and we This disease can be self-limited and we

can give supportive treatmrnt first but can give supportive treatmrnt first but if the symptom became severe,we can if the symptom became severe,we can prescribe prescribe TrimethoprimTrimethoprim--sulfamethoxazole(Immunocompetent sulfamethoxazole(Immunocompetent host: 160 mg TMP/800 mg SMZ PO bid host: 160 mg TMP/800 mg SMZ PO bid for 7 dfor 7 dImmunocompromised host: 160 mg Immunocompromised host: 160 mg TMP/800 mg SMZ PO qid for 10 d, TMP/800 mg SMZ PO qid for 10 d, followed by prophylaxis with 160 mg followed by prophylaxis with 160 mg TMP/800 mg SMZ 3 times/wkTMP/800 mg SMZ 3 times/wk))

Q7:How can this infection be Q7:How can this infection be controlled and prevented?controlled and prevented?

Ans:Ans:

1. 1. Practice good hygiene. Practice good hygiene.

2. 2. Avoid water that might be Avoid water that might be contaminated. contaminated.

3. Avoid food that might be 3. Avoid food that might be contaminated. contaminated.

4. Take extra care when 4. Take extra care when traveling.traveling.

When freshly passed in stools, the oocyst is not infective (thus, direct fecal-oral transmission cannot occur; this differentiates Cyclospora from another important coccidian parasite, Cryptosporidium).  In the environment , sporulation occurs after days or weeks at temperatures between 22°C to 32°C, resulting in division of the sporont into two sporocysts, each containing two elongate sporozoites .  Fresh produce and water can serve as vehicles for transmission and the sporulated oocysts are ingested (in contaminated food or water) .  The oocysts excyst in the gastrointestinal tract, freeing the sporozoites which invade the epithelial cells of the small intestine .  Inside the cells they undergo asexual multiplication and sexual development to mature into oocysts, which will be shed in stools .  The potential mechanisms of contamination of food and water are still under investigation.

Thanks for your attentionThanks for your attention

參考資料參考資料 ::

1.1.Medical parasitology,7Medical parasitology,7thth

2.The 10-minute Diagnosis Manual2.The 10-minute Diagnosis Manual

3.Home page:Division of parasitic 3.Home page:Division of parasitic diseasedisease

4.Home page:E-medicine4.Home page:E-medicine