1992年起臺灣地區開放引進東南亞地區勞工，在外籍勞工腸道寄生蟲檢查項目中，人芽囊原蟲(Blastocystis hominis)是最常被發現的寄生蟲。由過去的調查中得知，臺灣南部外籍勞工人芽囊原蟲的盛行率為18.1%。個案報告曾顯示受到人芽囊原蟲感染的患者在臨床上會出現糞便中含有大量的白血球、直腸出血、嗜伊紅性白血球增多、貧血等症候。然而迄今在流行病學研究，人芽囊原蟲感染族群是否會有血液學上之變化則尚未發現。本研究針對高雄地區某醫院經硫汞-碘-福馬林離心沉澱法(merthiolate-iodine-formalin concentration sedimentation method, MIFC method) 實施腸道寄生蟲篩檢的121位泰國籍男性勞工同時配合進行血液學常規檢查(hematological examination)，經多變項迴歸分析排除來自年齡的影響後，探討人芽囊原蟲的感染者是否會產生在血液學上的變化。
接受檢查的121位泰國籍男性勞工有17人 (14.0%) 感染人芽囊原蟲，感染其它寄生蟲的有15位 (12.4%)，這些樣本則不予列入統計。由血液學常規檢查結果顯示：人芽囊原蟲感染者的白血球總數(6,500+400 /μl)顯著低於未感染者(7,430+160/μl, p<0.05)，這變化主要來自於感染者的嗜中性球數(3,200+390 /μl)低於未感染者(4,230+150/μl, p<0.05)。在血色素部份，人芽囊原蟲感染者(13.9+0.3 g/dl)低於未感染者(14.5+0.1 g/dl, p<0.05)；而血球容積的結果，人芽囊原蟲感染者(41.4+0.6%)亦低於未感染者(42.9+0.3%, p<0.05)。

Blastocystis hominis found in stool specimen was the most frequently identified parasite among foreign workers from Southeast Asia in Taiwan since 1992. Clinical symptoms in B. hominis patients include fecal leukocytes, rectal bleeding, eosinophilia, and anemia. Among foreign workers in Southern Taiwan the prevalence of B. hominis was 18.1%. This study evaluated foreign workers in Taiwan to determine if infection with B. hominis was associated with hematological changes. This study surveyed 121 male Thai workers who had both hematological examination and stool parasite screening by merthiolate-iodine-formalin concentration sedimentation method in their quarantine physical examination. Hematological values were compared in workers with and without B. hominis infection. Multiple regressions were used to adjust for age. Among 121 male Thai workers, 17 (14.0 %) were infected with B. hominis, and 15 (12.4 %) with any other intestinal parasite. Those infected with any parasite other than B. hominis were excluded from further analysis. The workers infected with B. hominis had lower WBC count (6,500+400 /μl) than those who were not (7,430+160 /μl). It was mainly caused by reduced neutrophil count (3,200+390 vs. 4,230+150 /μl). Hemoglobin (13.9+0.3 g/dl vs. 14.5+0.1 g/dl) and hematocrit (41.4+0.6 % vs. 42.9+0.2 %) were also reduced in B. hominis infected workers. B. hominis was associated with reduced neutrophil count, hemoglobin and hematocrit in male Thailand workers. The mechanism of such reduction warrants further investigation.

1 Cheng HH, Huang YH, Huang MJ, Huang WP, Tsai MH, Chen HC, Lan WS. Epidemiologic survey of Blastocystis hominis infection among alien laborers in southern Taiwan. The 6th Asian-Pacific Congress for Parasitic Zoonoses, 2000, Taipei, p80
2. Lu SC, Lee HY, Lee SY, Wang CJ. Intestinal parasites among primary school children and junior high school on Green Island, Taiwan. Chin J Parasitol 1989; 2: A20.
4. Lu SC, Chen CY, Chiu PC, Kao CY, Shen YZ. Preliminary report of parasitic infections among primary school children in Hsiulin District of Hualien County, Taiwan. Chin J Parasitol 1990; 3:119.
5. Lu SC, Huang KT. Parasitic infections among children in Haiduann District of Taitung County, Taiwan. Chin J Parasitol 1992; 5:97.
6. 林益卿、楊佩玉、洪偉洲、洪錫慶、王家慶：外籍勞工腸道寄生蟲感染率之調查。公共衛生1998；24：251-8
7 Stenzel DJ, Boreham PFL. Blastocystis hominis revisited. Clin Microbiol Rev 1996; 9: 563-84
8 Huang YH, Shin JW, Blastocystis hominis: A long-term ignored intestinal parasite Chi Pub Heal 2000 Aug 19(4): P250-260
9 Guignard S et al., Prevalence of enteroparasites in a residence for children in the Cordoba Province, Argentina. Eur J Epidemiol 2000 Mar; 16(3): 287-93
10 Svenungsson B et al., Enteropathogens in adult patients with diarrhea and healthy control subjects: a 1-year prospective study in a Swedish clinic for infectious diseases. Clin Infect Dis 2000 May; 30 (5): 770-8
11 Rivero-Rodriguez Z et al., Intestinal parasites in school children at a public institution in Maracaibo municipality, Venezuela Invest Clin 2000 Mar; 41 (1): 37-57
12 Ayadi A et al., Dientamoeba fragilis: pathogenic flagellate? Bull Soc Pathol Exot 1999 Dec; 92 (5):299-301
13 Rajah Salim H et al., Blastocystis in animal handlers. Parasitol Res 1999 Dec; 85 (12): 1032-3
14 Mercado R et al., Seasonal variation of intestinal protozoa infections in outpatients of the north section of Santiago, Chile. 1995-1996. Bol Chil Parasitol 1999 Jan-Jun; 54 (1-2): 41-4
15 Logar J, Andlovic A, Poljsak-prijateli M. Incidence of Blastocystis hominis in patiens with diarrhoea. J Infect 1994; 28 151-4
16 Doyle PW, Helgason MM, Mathias RG, Proctor EM. Epideminology and pathogenicity of Blastocysis hominis. J Clin Microbiol 1990; 28: 116-21
17 Zierdt CH. Blastocystis hominis, an intestinal protozoan parasite of man. Public Health Lab 1978; 36: 147-60.
18 Johnson AM, Thanou A, Boreham PFL, Baverstock PR. Blastocystis hominis: phylogenetic affinities determined by rRNA sequence comparison. Exp Parasitol 1989; 68: 283-8.
19 Jiang JB, He JG. Taxonomic status of Blastocystis hominis. Parasitol Today 1993; 9: 2-3
20 Blastocystis hominis: commensal or pathogen? [editorial]. Lancet 1991; 337: 521-22
21 Arribas JM et al., Acute infectious lymphocytosis associated to Giardia lamblia and Blastocystis hominis coinfection An Esp Pediatr 2001 May; 54 (5): 518-20
22 American Academy of Pediatrics. Blastocystis hominis. In: Peter G, ed. 1997 Red Book: Report of the Committee on Infectious Diseases. 24th ed. Elk Grove Village, IL: American Academy of Pediatrics 1997:153
23 Sadek Y, el-Fakahany AF, Lashin AH et al. Intestinal parasites among food-handlers in Qualyobia Governorate, with reference to the pathogenic parasite Blastocystis hominis. J Egypt Soc Parasitol 1997; 27: 471- 78.
24 Jelinek T, Peyerl G, Loscher T et al. The role of Blastocystis hominis as a possible intestinal pathogen in travellers. J Infect 1997; 35: 63-6
25 Cirioni O, Giacometti A, Drenaggi D, Ancarani F, Scalise. Prevalence and clinical relevance of Blastocystis hominis in diverse patient cohorts Eur J Epidemiol 1999 Apr; 15 (4): 389-93
26 King YL, Chung WC, Liu JD. A case report of Blastocystis hominis infection. Abstract of the 14th Annul Meet Meeting of Chinese Society of Parasitology –1996:C6
27 Barret JP et al., Infestations and chronic infections in foreign pediatric patients with burns: is there a role for specific protocols? J Burn Care Rehabil 1999 Nov-Dec; 20 (6): 482-6
28 Hoffbrand, Pettit, Essential Haematology, 3rd, 1993
29 Samuel I, Introduction to Hematology, 2nd, 1990
30 Sapero J.J. and D.K. Lawless (1942). The MIF stain-preservation technique for the identification of intestinal protozoa. Am. J. Trop. Med. Hyg. 2:613-619
31 Horiki N et al., Intestinal blockage by carcinoma and Blastocystis hominis infection. Am J Trop Med Hyg 1999 Mar; 60 (3): 400-2
32 Weigel MM, Calle A, Armijos RX, Vega IP, Bayas BV, Montenegro CE. The effect of chronic intestinal parasitic infection on maternal and perinatal outcome. Int J Gynaecol Obstet 1996 Jan; 52 (1): 9-17
33 Dagci H, Ustun S, Taner MS, Ersoz G, Karacasu F, Budak S. Protozoon infections and intestinal permeability. Acta Trop 2002 Jan; 81(1):1-5
34 Cararscosaa, M., Martinez, J., Perez-Castrillon, J.L., 1996. Haemorrhagic proctosigmoiditis and B. hominis infection. Ann. Int. Mrd. 15(2), 278-279
35 Roitt, Brostoff,Male, Immunology,6th, Mosby, 2001, p53
36 Hoffbrand, Pettit, Essential Haematology, 3rd, Blackwell, 1993,p146
37 Kim JM, Jung HC, Im K, Cho YJ, Kim CY Interleukin-8 gene expression in the human colon epithelial cell line, HT-29, exposed to Entamoeba histolytica Korean J Parasitol 1995; 33(4): 357-364
38 Stenson WF, Zhang Z, Riehl T, Stanley SL Jr. Amebic infection in the human colon induces cyclooxygenase-2. Infect Immun 2001 May; 69 (5): 3382-8
39 Denney CF, Eckmann L, Reed SL (1999) Chemokine secretion of human cells in response to Toxoplasma gondii infection. Infect Immun 67:1547-1552
40 Long HY, Handschack A, Konig W, Ambrosch A. Blastocystis hominis modulates immune responses and cytokine release in colonic epithelial cells.Parasitol Res 2001 Dec;87(12):1029-30