Skip to main content
PMC home page
Sultan Qaboos University Medical Journal logoLink to Sultan Qaboos University Medical Journal
. 2007 Apr;7(1):35–40.

Prevalence and Clinical Features of Blastocystis hominis Infection among Patients in Sebha, Libya

Mohammed A Al-Fellani 1,*, Abdul H Khan 1, Rugaia M Al-Gazoui 1, Mabrouk K Zaid 2, Mahmoud A Al-Ferjani 2
PMCID: PMC3086416  PMID: 21654943

Abstract

Objective:

To determine the prevalence and seasonal variation, and to assess the clinical manifestations and treatment of blastocystosis in Libyan patients.

Methods:

Three thousand six hundred and forty five stool samples were screened for Blastocystis hominis using normal saline and iodine solution preparations. The clinical features of 108 patients were described, in whom B. hominis was the only parasite isolated. Fifty symptomatic patients were treated with 1500 mg metronidazole daily for 7 days and their stools were re-investigated for B. hominis.

Results:

B. hominis was found in 969 (26.58 %) of 3645 stool specimens examined. The infection of B. hominis was significantly more (p < 0.05) in summer than in winter over a three year period. In a prospective study of 108 patients, the most common symptoms with stools positive only for B. hominis were diarrhoea (84.94 %), abdominal pain (66.66 %), flatulence (17.20 %) and vomiting (16.12 %). High concentration of B. hominis cells were found more in symptomatic patients than asymptomatic ones (9.20 cells per 40 X field versus 4.06 respectively) with statistically significant differences (p < 0.001). Patients with B. hominis responded to metronidazole and were fully cured after 7 days.

Conclusion:

The occurrence of B. hominis infections in outpatients are probably related to weather conditions, with the suggestion that the hot, dry weather of the Sebha region favors the development and transmission of this organism. B. hominis infections might have a role in some pathological conditions, resulting in gastrointestinal symptoms.

Keywords: Blastocystis, Seasonal variation, Culture, Diarrhoea

Infection by Blastocystis hominis occurs all over the world, but is commonly found in developing countries.1,2 Practicing physicians and gastroenterologists usually have low awareness of the association of B. hominis with human disease. These infections are overlooked in clinical laboratories. The Centre for Disease Control and Prevention also considered it to be a pathogenic protozoan.3 B. hominis is now increasingly recognized as a possible cause of gastrointestinal disorders.4–7 A subgroup of B. hominis could possibly be pathogenic in some patients.8 The specific pathogenic potential of B. hominis has not been defined.9–12

The results of a recent study in Sebha, Libya, revealed that B. hominis was the most frequent isolate in all stool specimens submitted for analysis,13 but the clinical significance of B. hominis infection in the Libyan population has not been documented so far.

In the present study, the aim was to investigate the prevalence of B. hominis among patients attending the Central Laboratory in Sebha, Libya and to describe the clinical presentations of patients parasitized only with B. hominis infection in Libyan communities.

METHODS

This prospective study was performed in Sebha city, Fezzan Province, South-Western Libya. This region is characterized by a hot and dry climate. It is an arid and desert area with a population of over one hundred thirty thousand. Most people work in agriculture.

A total of 3,645 stool samples were collected (from the beginning of January to the end of December 2005) from outpatients attending the Central Laboratory in Sebha, Libya, for routine examination of intestinal parasites. Soon after the collection of stool specimens, two faecal smears were prepared (normal saline and Lugol’s iodine) from each sample. These preparations were examined under both a low power (10 X) and a high power (40 X) of microscope to detect possible B. hominis.

The seasonal prevalence of B. hominis was recorded among 8,089 patients, who attended the Central Laboratory in Sebha, over a 3 year period from January 2003 to December 2005.

A prospective study on 108 patients parasitized exclusively with B. hominis was performed. Clinical information on patients with stools which tested positive for B. hominis was obtained by sending a survey questionnaire to practicing physicians at the Al-Jadeed clinic in Sebha, Libya. The numbers of B. hominis cells in faecal materials were counted with a 40 X field microscope.

Ninety three patients harboured only B. hominis and presented with gastrointestinal symptoms (diarrhoea with or without abdominal pain and flatulence or vomiting) were treated for seven days with metronidazole 500 mg three times per day for 7 days. Only fifty patients returned back for a follow up examination. Stool samples from these patients were re-examined for B. hominis after completion of the therapy.

The positive rate of B.hominis was expressed as a percentage (number, sex, seasonal variation, diarrhoea etc) and statistical analysis was carried out using the independent sample t-test. P-values of < 0.05 and 0.001 were considered statistically significant.

RESULTS

The prevalence of B. hominis was found to be 26.58 % among outpatients at the Central Laboratory in Sebha. Of the 3,645 patients examined, 1,925 (52.81 %) were males and 1,720 (47.18 %) were females. A total of 558 (28.98 %) males and 411 (23.89 %) females were harbouring B. hominis. The highest positivity (10.28 %) rate was found in the 21 to 40 age group.

The seasonal variation of B. hominis among patients attending the Central Laboratory in Sebha is presented in Table 1. The prevalence of B. hominis was found to be significantly more (p<0.05) in summer than in winter.

Table 1 :

Seasonal variation of B. hominis among patients attending the Central Laboratory in Sebha

Year Summer season* Winter season** Total investigated
No. No. Positive No. No. Positive No. No. Positive***
2003 2572 458 (17.80) 1855 279 (15.04) 4427 737 (16.64)
2004 2264 497 (21.95) 1398 267 (19.09) 3662 764 (20.86)
2005 2336 640 (27.39) 1309 329 (25.13) 3645 969 (26.58)
Open in a new tab

Figures in parentheses indicate percentages.

*

April to October.

**

November to March.

***

p < 0.05 versus comparison with summer and winter season.

The clinical presentations of 93 patients parasitized exclusively with B. hominis are shown in Table 2. The most frequent manifestation was diarrhoea (84.94%). Sixty-four (68.81%) patients had two or more gastrointestinal complaints. Twenty-nine patients (31.18 %) had only one clinical feature (25 had diarrhoea and 4 had cramping abdominal pain). Forty-nine patients (52.68 %) had two gastrointestinal complaints (33 had diarrhoea with cramping abdominal pain, 6 had diarrhoea with vomiting, 2 had vomiting with cramping abdominal pain and 8 had cramping abdominal pain with flatulence). Fifteen patients (16.12 %) had three clinical symptoms of blastocystosis (7 had diarrhoea with cramping abdominal pain and vomiting, 8 had diarrhoea with cramping abdominal pain and flatulence).

Table 2:

Clinical Manifestations of 93 Symptomatic Patients

Clinical symptoms No. of cases
Diarrhoea 79 (84.94)
Cramping abdominal pain 62 (66.66)
Flatulence 16 (17.20)
Vomiting / Nausea 15 (16.12)
Open in a new tab

Parasitized exclusively by B. hominis.

Figures in parentheses indicate percentages.

The intensity of B. hominis among symptomatic and asymptomatic individuals is presented in Table 3. The mean number of B. hominis was significantly higher (p<0.001) in symptomatic patients than in asymptomatic individuals (9.20 ± 2.41 organisms per 40 X field, versus 4.06 ± 1.86 respectively). Two infected persons, in whom B. hominis cells were found 10 and 12 per 40 X field, were entirely asymptomatic.

Table 3:

Intensity of B. hominis Infection among Blastocystosis Patients.

Category No. of organisms No. of cases and (%) Mean of No. ± SD Intensity of B. hominis
No. of organisms Mean of No. ± SD
Symptoms 93 (86.11) Positive for B. hominis with gastrointestinal symptoms More than 7 9.20±2.41** (8 to 30)*
Symptoms 15 (13.88) Positive for B. hominis without trointestinalsymptoms Less than 5 4.06±1.86 (2 to 12)*
Open in a new tab
*

Range of No. of B. hominis cells per 40 X field.

**

p < 0.001 versus comparison with number of B. hominis cells among asymptomatic individuals.

B. hominis were not found in stools from patients upon the completion of the 7 day therapeutic course of metronidazole. All fifty patients showed clinical improvement and were fully cured using 1500 mg of metronidazole daily for 7 days.

DISCUSSION

Physicians usually have low awareness that B. hominis is a cause of human disease. The number of infections appears to be high in most populations, however, the frequency is grossly underestimated. Asymptomatic shedding of B. hominis provides an appropriate environment for its transmission to other subjects. Recently B. hominis has been considered as potential pathogen. 5–7

Infections of B. hominis may be an important pubic health problem in Libyan communities. 30–32 So far, only one study has been carried out on the prevalence of B. hominis among patients attending the Central Laboratory in Sebha, Libya.13 This study was carried out to investigate the prevalence, seasonal variation and the association between the presence of B.hominis and gastrointestinal symptoms among patients.

The results of this study show that B. hominis was detected in 26.58 % of stool specimens examined. Very similar prevalence have been described in other parts of the world: 25% in Jordan,3 32% in Pakistan,6 18% in Bethesda,14 31% in Egypt,20 25.78% in Venezuela,24 26.5% in Brazil29 and 22.9% in Argentina33 [Table 4]. However, higher prevalence of B. hominis has been reported in other countries of the world: 36% in Tanzania,23 40.7% in Philippines,25 36.9% in Thailand,26 and 46.9% in Venezuela.34 In the present study, the prevalence of B. hominis was higher than previously reported among the same population. This may be due to improvement in detection of B. hominis infection in clinical laboratories, but infections with this organism may have also increased in the population. In the Libyan Arab Jamahiriya, the rapid socio-economic development, agriculture practices and the enormous increase in the number of foreign workers from neighbouring countries may have lead to a substantial increase of intestinal parasites in the country. Prior research has shown that immigrants and refugees from developing countries have a higher incidence of B. hominis.

Table 4:

Prevalence of B. hominis in various countries/states of the world.

Reference Country / Locality % of B. hominis
Wang et al2 Community population in China 3.7
Nimri3 Preschool children in Jordan 25.0
Yakoob et al6 Outpatients in Pakistan 32.0
Al-Fellani et al13 Outpatients in Libya 18.5
Zierdt14 Community population in Bethesda 18.0
Garcia et al.15 Outpatients in Los Angeles 12.0
Babock et al.16 Population in Nepal 10.0
Markell and Udkow17 Outpatients in San Francisco 12.0
Sheehan et al.18 Outpatients in New York 11.0
Kain et al.19 Outpatients Vancouver 13.0
El Masry et al.20 Outpatients in Egypt 31.0
Doyle et al.21 Outpatients in Canada 3.2
Martin-Sanchez et al.22 Primary school children in Spain 19.4
Gomez Morales et al.23 Outpatients in Tanzania 36.0
Requena et al.24 Food handlers in Venezuela 25.8
Eleonor et al.25 Children in Philippines 40.7
Leelayoova et al.26 Army personal in Thailand 36.9
Suresh and Smith27 Outpatients in United Kingdom 3.9
Khan and Khalife28 Food handlers in Saudi Arabia 8.5
Nascimento and Moitinho29 Community population in Brazil 26.5
Present study Outpatients in Libya 26.58
Open in a new tab

In the present study, males were more infected (28.98%) with B. hominis than females (23.89%). The difference was significant (p<0.05). Several studies have reported significantly higher prevalence in male than female patients.2, 3, 12

The parasitological examination of faecal samples revealed that the incidence of B. hominis is widespread throughout the year with a particular peak in the summer season. The high incidence of B. hominis in the Sebha region may be due to the dry climatic conditions that favour the survival and transmission of this organism in the population throughout the year. This is in contrary to other parts of the world, where infections of B. hominis are commonest during the premonsoonal months, spring and winter seasons.16, 20, 27

The most prominent gastrointestinal symptoms in 93 patients parasitized exclusively by B. hominis were diarrhoea (84.94%), cramping abdominal pain (66.66%) and nonspecific gastrointestinal symptoms such as flatulence (17.20%) and nausea or vomiting (16.12%). These symptoms were similar to the one reported previously in patients infected with B. hominis. 2–8, 20

In the present study, the number of B. hominis was significantly higher (p < 0.001) in the stools of symptomatic patients than in asymptomatic individuals (more than seven cells with mean number 9.20 ± 2.41 versus less than five with mean number 4.06 ± 1.86).

Several studies have reported detecting more than five cells of B. hominis per 40 X field in stool samples from symptomatic patients.3, 7, 20, 35 In addition five or more B. hominis cells per oil immersion field (100 X) have been detected in symptomatic patients.22,36–38 The mean numbers of B. hominis cells in the stools of symptomatic patients were significantly higher than asymptomatic patients.5, 7

Several studies reported severe symptoms in patients with high numbers of B. hominis,9, 20 however, this correlation was not found in others.21, 22, 40

In the present study, among asymptomatic subjects (except two cases) the number of B. hominis cells found was less than five per 40 X field. Similarly less than five organisms (fewer than three) per 40 X microscopic fields among stool samples of apparently healthy subjects have been reported.3, 24 Large numbers of B. hominis were also observed in faeces of some asymptomatic individuals.12, 22, 41

In this prospective study, the physicians of Health Centre Al-Jadeed in Sebha successfully treated fifty patients infected with B. hominis with metronidazole 500 mg three times per day for 7 days. In all these patients, no other parasites were demonstrated in the faecal specimens. All patients responded to the therapy and symptoms disappeared after 7 to 10 days. Moreover, B. hominis was not detected in the stools of patients after 7 days.

This suggests that the gastrointestinal symptoms in all these patients (positive only for B. hominis) are probably due to B. hominis infection. Metronidazole has been suggested as the first line chemotherapeutic agent for treatment of B. hominis infection.42–44 However, some authors reported that metronidazole did not eradicate the B. hominis completely and was effective only in some individuals.6, 45, 46

In conclusion, we report that B.hominis is a common intestinal protozoa infection in Sebha and with higher prevelance in warm and hot seasons of the year. In patients with blastocystosis, gastrointestinal symptoms are more likely to be associated with intensity of B. hominis. Further research to evaluate the pathogenic potential of this organism is needed.

REFERENCES

  • 1.Stenzel DJ, Boreham PFL. Blastocystis hominis Revisited. Clin Microbiol Rev. 1996;9:563–584. doi: 10.1128/cmr.9.4.563. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Wang KX, Li CP, Wang J, Cui YB. Epidemiological survey of Blastocystis hominis in Huainan City, Anhui Province, China. World J Gastroenterol. 2002;8:928–932. doi: 10.3748/wjg.v8.i5.928. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Nimri LF. Evidence of an epidemic of Blastocystis hominis infections in preschool children in northern Jordan. J Clin Microbiol. 1993;31:2706–2708. doi: 10.1128/jcm.31.10.2706-2708.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Zaman V. In: Blastocystis hominis. Oxford Textbook of Medicine. Third Edition. Weatherall DJ, Ledigham JGG, Warrell D, editors. Oxford: Oxford University Press; 1996. p. 887. [Google Scholar]
  • 5.Barahona RL, Maguina VC, Naquira VC, Terashima IA, Tello R. Human blastocystosis: prospective study symptomatology and associated epidemiological factors. Rev Gastroenterol Peru. 2003;23:29–35. [PubMed] [Google Scholar]
  • 6.Yakoob J, Jafri W, Jafri N, et al. Irritable bowel syndrome: in search of an etiology: role of Blastocystis hominis. Am J Trop Med Hyg. 2004;70:383–385. [PubMed] [Google Scholar]
  • 7.El-Shazly AM, Abdel-Magied AA, El-Beshbishi SN, et al. Blastocystis hominis among symptomatic individuals in Talkha Center, Dakahlin Governorate. Egypt J Egypt Soc Parasitol. 2005;35:653–666. [PubMed] [Google Scholar]
  • 8.Tungtrongchitr A, Manatsathit S, Kositchaiwt C, et al. Blastocystis hominis infection in irritable bowel syndrome patients. Southeast Asian J Trop Med Public Health. 2004;35:705–710. [PubMed] [Google Scholar]
  • 9.Nimri LF, Batchoun R. Intestinal colonization of symptomatic and asymptomatic schoolchildren with Blastocystis hominis. J Clin Microbiol. 1994;32:2865–2866. doi: 10.1128/jcm.32.11.2865-2866.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 10.Taamasri P, Mungthin M, Raugsin R, Tongupprakarn B, Areekul W, Leelayoova S. Transmission of Blastocystis related to the quality of drinking water. Southeast Asian J Trop Med Public Health. 2002;31:112–117. [PubMed] [Google Scholar]
  • 11.Te-Lichen, Che-chang C, Hsin-Paichen, Chang-phone F, Chih-Peilin Wan-Leong C, Cheng-Yiliu Clinical charactesistics and endoscpic findings associated with Blastocystis hominis in healthy adults. Am J Trop Med Hyg. 2003;69:213–216. [PubMed] [Google Scholar]
  • 12.Leder K, Hellard ME, Sinclair MI, Fairley CK, Wolfe R. No correlation between clinical symptoms and Blastocystis hominis in immunocompetent individuals. J Gastroenterol Hepatol. 2005;20:1390–1394. doi: 10.1111/j.1440-1746.2005.03868.x. [DOI] [PubMed] [Google Scholar]
  • 13.Al-Fellani MA, Abdulrahman DM, Khan AH, Abousaif AA. Prevalence of intestinal parasites in Sebha, Libya. Garyounis Med J. 2005;22:16–21. [Google Scholar]
  • 14.Zierdt CH. Blastocystis hominis, a protozoan parasite and intestinal pathogen of human beings. Clin Microbiol Newsl. 1983;5:57–59. [Google Scholar]
  • 15.Garcia LS, Bruckner DA, Clancy MN. Clinical relevance of Blastocystis hominis. Lancet. 1984;I:1233–1234. (Letter). [PubMed] [Google Scholar]
  • 16.Babcock D, Houston R, Kumaki D, Shlim D. Blastocystis hominis in Kathmandu, Nepal. N Engl J Med. 1985;313:1419. (Letter). [PubMed] [Google Scholar]
  • 17.Markell EK, Udkow MP. Blastocystis hominis pathogen or fellow traveller? Am J Trop Med Hyg. 1986;35:1023–1026. doi: 10.4269/ajtmh.1986.35.1023. [DOI] [PubMed] [Google Scholar]
  • 18.Sheehan DJ, Raucher BG, McKitrick JC. Association of Blastocystis hominis with signs and symptoms of human disease. J Clin Microbiol. 1986;24:548–550. doi: 10.1128/jcm.24.4.548-550.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Kain KC, Noble MA, Freeman HJ, Barteluk RL. Epidemiology and clinical features associated with Blastocystis hominis infection. Diagn Microbiol Infect Dis. 1987;8:235–244. doi: 10.1016/0732-8893(87)90055-1. [DOI] [PubMed] [Google Scholar]
  • 20.El Masry NA, Bassily S, Farid Z, Aziz AG. Potential clinical significance of Blastocystis hominis in Egypt. Trans R Soc Trop Med Hyg. 1990;84:695. doi: 10.1016/0035-9203(90)90152-5. [DOI] [PubMed] [Google Scholar]
  • 21.Doyle PW, Helgason MM, Mathias RG, Proctor EM. Epidemiology and pathogenicity of Blastocystis hominis. J Clin Microbiol. 1990;28:116–121. doi: 10.1128/jcm.28.1.116-121.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22.Martin-Sanchez AM, Canut-Blasco A, Rodriguez-Hernandez J, Montes-Martinez I, Garcia-Rodriguez JA. Epidemiology and clinical significance of Blastocystis hominis in different population groups in Salamanca (Spain) Eur J Epidemiol. 1992;8:553–559. doi: 10.1007/BF00146376. [DOI] [PubMed] [Google Scholar]
  • 23.Gomez Morales MA, Atzori C, Ludovisi A, Rossi P, Scaglia M, Pozio E. Opportunistic and non-opportunistic parasites in HIV-positive and negative patients with diarrhea in Tanzania. Trop Med Parasitol. 1995;46:109–114. [PubMed] [Google Scholar]
  • 24.Requena I, Hernandez Y, Ramsay M, Salazar C, Devera R. Prevalence of Blastocystis hominis among food handlers from Caroni municipality, Bolivar State. Vevezuela: Cad Saude Publica. 2003;19:1721–1727. doi: 10.1590/s0102-311x2003000600016. [DOI] [PubMed] [Google Scholar]
  • 25.Eleonor TB, Vicente YB, Winifreda UD, Hyun HK, Dong-II C. Infection status of intestinal parasites in children living in residential institutions in Metro Malina, the Philippines. Korean J Parasitol. 2004;42:67–70. doi: 10.3347/kjp.2004.42.2.67. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Leelayoova S, Rangsin R, Taamasri P, Naaglor T, Thathaisong U, Mungthin M. Evidence of water- borne transmission of Blastocystis hominis. Am J Trop Med Hyg. 2004;70:658–662. [PubMed] [Google Scholar]
  • 27.Suresh K, Smith H. Comparison of methods for detecting Blastocystis hominis. Eur J Microbiol Infect Dis. 2004;23:509–511. doi: 10.1007/s10096-004-1123-7. [DOI] [PubMed] [Google Scholar]
  • 28.Khan ZA, Al-Khalife IS. Prevalence of Blastocystis hominis among “healthy” food handlers in Dammam, Saudi Arabia. J Egypt Soc Parasitol. 2005;35:395–401. [PubMed] [Google Scholar]
  • 29.Nascimento SA, Moitinho MD. Blastocystis hominis and other intestinal parasites in a community of Pitannga City Parana State, Brazil. Rev Inst Med Trop. 2005;47:213–217. doi: 10.1590/s0036-46652005000400007. [DOI] [PubMed] [Google Scholar]
  • 30.Narkewicz MR, Janoff EN, Sokol RJ, Levin MJ. Blastocystis hominis gastroenteritis in a haemophiliac with acquired immune deficiency syndrome. J Pediatr Gastroenterol Nutr. 1989;8:125–128. doi: 10.1097/00005176-198901000-00023. [DOI] [PubMed] [Google Scholar]
  • 31.Lee MJ. Pathogenicity of Blastocystis hominis. J Clin Microbiol. 1991;29:2089. doi: 10.1128/jcm.29.9.2089-.1991. (Letter). [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Gugliemetti P, Fantoni A, Sansoni A, Rossolini A. Prevalenza e significato clinico di Blastocystis hominis in bambini sintomatici e asintomatici autoctoni e provenienti da aree tropicali. Rev Parassit. 1993;10:15–24. [Google Scholar]
  • 33.Minvielle MC, Pezzani BC, Cordoba MA, Deluca MM, Apeztequina MC, Basualdo JA. Epidemiological survey of Giardia spp. and Blastocystis hominis in an Argentinian rural community. Korean J Parasitol. 2004;42:121–127. doi: 10.3347/kjp.2004.42.3.121. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 34.Velasquez V, Caldera R, Wong W, et al. Blastocystosis: a high prevalence of cases found in patients form Health Center of Soledad, Anzoateni State, Venezuela. Rev Soc Bras Med Trop. 2005;38:356–357. doi: 10.1590/s0037-86822005000400017. [DOI] [PubMed] [Google Scholar]
  • 35.Zuckerman MJ, Ho H, Hooper L, Anderson B, Polly SM. Frequency of recovery of Blastocystis hominis in clinical practice. J Gastroenterol. 1990;12:525–532. doi: 10.1097/00004836-199010000-00008. [DOI] [PubMed] [Google Scholar]
  • 36.Vannatta JB, Adamson BD, Mullican K. Blastocystis hominis infection presenting as recurrent diarrhoea. Ann Inter Med. 1985;102:495–496. doi: 10.7326/0003-4819-102-4-495. [DOI] [PubMed] [Google Scholar]
  • 37.Zaki M, Daoud AS, Pugh RNH, Al-Ali F, AL-Mutairi G, Al-Saleh Q. Clinical report of Blastocystis hominis infection in children. J Trop Med Hyg. 1991;94:118–122. [PubMed] [Google Scholar]
  • 38.Logar J, Andlovic A, Poljsak-Prijatelj M. Incidence of Blastocystis hominis in patients with diarrhoea. J Infect. 1994;28:151–154. doi: 10.1016/s0163-4453(94)95580-8. [DOI] [PubMed] [Google Scholar]
  • 39.Tasova Y, Sahin B, Koltes S, Paydas S. Clinical significance and frequency of Blastocystis hominis in Turkish patients with haematological malignancy. Acta Med Okayama. 2000;54:133–136. doi: 10.18926/AMO/32298. [DOI] [PubMed] [Google Scholar]
  • 40.Shilm DR, Hoge CW, Rajah R, Rabold JG, Echeverria P. Is Blastocystis hominis a cause of diarrhoea in travellers? A prospective control study in Nepal. Clin Infect Dis. 1995;21:97–101. doi: 10.1093/clinids/21.1.97. [DOI] [PubMed] [Google Scholar]
  • 41.Svenungsson B, Lagergren A, Ekwall E. Enteropathogens in adult patients with diarrhoea and healthy control subjects: a 1-year prospective study in a Swedish clinic for infectious diseases. Clin Infec Dis. 2000;30:770–778. doi: 10.1086/313770. [DOI] [PubMed] [Google Scholar]
  • 42.Stenzel DJ, Boreham PFL. Bacteria-like endosymbionts in Blastocystis spp. Int J Parasitol. 1994;24:147–149. doi: 10.1016/0020-7519(94)90070-1. [DOI] [PubMed] [Google Scholar]
  • 43.Rao K, Sekar U, Iraivan KT, Abraham G, Soundararajan P. Blastocystis hominis: an emerging cause of diarrhoea in renal transplant recipients. J Assoc Physician India. 2003;51:719–721. [PubMed] [Google Scholar]
  • 44.Nasirudeen AMA, Hian YE, Singh M, Tan KSW. Metronidazole induces programmed cell death in the protozoan parasite Blastocystis hominis. Microbiol. 2004;150:33–43. doi: 10.1099/mic.0.26496-0. [DOI] [PubMed] [Google Scholar]
  • 45.Horiki N, Kandera Y, Maruyama M, Fujita Y, Tachibana H. Intestinal blockage by carcinoma and Blastocystis hominis infection. Am J Trop Med Hyg. 1999;60:400–402. doi: 10.4269/ajtmh.1999.60.400. [DOI] [PubMed] [Google Scholar]
  • 46.Moghaddam DD, Ghadirian E, Azami M. Blastocystis hominis and the evaluation of efficacy of metronidazole and trimethopri/ sulfamethoxazole. Parasitol Res. 2005;96:273–275. doi: 10.1007/s00436-005-1363-1. [DOI] [PubMed] [Google Scholar]

Articles from Sultan Qaboos University Medical Journal are provided here courtesy of Sultan Qaboos University

RESOURCES