• 1

    Tarimo DS, Killewo JZ, Minjas JN, Msamanga GI, 1996. Prevalence of intestinal parasites in adult patients with enteropathic AIDS in north-eastern Tanzania. East Afr Med J 73 :397–399.

    • Search Google Scholar
    • Export Citation
  • 2

    Gassama A, Sow PS, Fall F, Camara P, Gueye-N’diaye A, Seng R, Samb B, M’Boup S, Aidara-Kane A, 2001. Ordinary and opportunistic enteropathogens associated with diarrhea in Senegalese adults in relation to human immunodeficiency virus serostatus. Int J Infect Dis 5 :192–198.

    • Search Google Scholar
    • Export Citation
  • 3

    Gumbo T, Sarbah S, Gangaidzo IT, Ortega Y, Sterling CR, Carville A, Tzipori S, Wiest PM, 1999. Intestinal parasites in patients with diarrhea and human immunodeficiency virus infection in Zimbabwe. AIDS 13 :819–821.

    • Search Google Scholar
    • Export Citation
  • 4

    Colebunders R, Lusakumuni K, Nelson AM, Gigase P, Lebughe I, van Marck E, Kapita B, Francis H, Salaun JJ, Quinn TC, Piot P, 1988. Persistent diarrhoea in Zairian AIDS patients: an endoscopic and histological study. Gut 29 :1687–1691.

    • Search Google Scholar
    • Export Citation
  • 5

    Blanshard C, Jackson AM, Shanson DC, Francis N, Gazzard BG, 1992. Cryptosporidiosis in HIV-seropositive patients. QJM 85 :813–823.

  • 6

    Manabe YC, Clark DP, Moore RD, Lumadue JA, Dahlman HR, Belitsos PC, Chaisson RE, Sears CL, 1998. Cryptosporidiosis in patients with AIDS: correlates of disease and survival. Clin Infect Dis 27 :536–542.

    • Search Google Scholar
    • Export Citation
  • 7

    Cama VA, Bern C, Sulaiman IM, Gilman RH, Ticona E, Vivar A, Kawai V, Vargas D, Zhou L, Xiao L, 2003. Cryptosporidium species and genotypes in HIV-positive patients in Lima, Peru. J Eukaryot Microbiol 50 (Suppl):531–533.

    • Search Google Scholar
    • Export Citation
  • 8

    Tiangtip R, Jongwutiwes S, 2002. Molecular analysis of Cryptosporidium species isolated from HIV-infected patients in Thailand. Trop Med Int Health 7 :357–364.

    • Search Google Scholar
    • Export Citation
  • 9

    Guyot K, Follet-Dumoulin A, Lelievre E, Sarfati C, Rabodonirina M, Nevez G, Cailliez JC, Camus D, Dei-Cas E, 2001. Molecular characterization of Cryptosporidium isolates obtained from humans in France. J Clin Microbiol 39 :3472–3480.

    • Search Google Scholar
    • Export Citation
  • 10

    Alves M, Matos O, Pereira Da Fonseca I, Delgado E, Lourenco AM, Antunes F, 2001. Multilocus genotyping of Cryptosporidium isolates from human HIV-infected and animal hosts. J Eukaryot Microbiol Suppl :17S–18S.

    • Search Google Scholar
    • Export Citation
  • 11

    Gatei W, Greensill J, Ashford RW, Cuevas LE, Parry CM, Cunliffe NA, Beeching NJ, Hart CA, 2003. Molecular analysis of the 18S rRNA gene of Cryptosporidium parasites from patients with or without human immunodeficiency virus infections living in Kenya, Malawi, Brazil, the United Kingdom, and Vietnam. J Clin Microbiol 41 :1458–1462.

    • Search Google Scholar
    • Export Citation
  • 12

    Leav BA, Mackay MR, Anyanwu A, RM OC, Cevallos AM, Kindra G, Rollins NC, Bennish ML, Nelson RG, Ward HD, 2002. Analysis of sequence diversity at the highly polymorphic Cpgp40/15 locus among Cryptosporidium isolates from human immunodeficiency virus-infected children in South Africa. Infect Immun 70 :3881–3890.

    • Search Google Scholar
    • Export Citation
  • 13

    Morgan U, Weber R, Xiao L, Sulaiman I, Thompson RC, Ndiritu W, Lal A, Moore A, Deplazes P, 2000. Molecular characterization of Cryptosporidium isolates obtained from human immunodeficiency virus-infected individuals living in Switzerland, Kenya, and the United States. J Clin Microbiol 38 :1180–1183.

    • Search Google Scholar
    • Export Citation
  • 14

    Sturbaum GD, Reed C, Hoover PJ, Jost BH, Marshall MM, Sterling CR, 2001. Species-specific, nested PCR-restriction fragment length polymorphism detection of single Cryptosporidium parvum oocysts. Appl Environ Microbiol 67 :2665–2668.

    • Search Google Scholar
    • Export Citation
  • 15

    Garcia LS, Shimizu RY, 1997. Evaluation of nine immunoassay kits (enzyme immunoassay and direct fluorescence) for detection of Giardia lamblia and Cryptosporidium parvum in human fecal specimens. J Clin Microbiol 35 :1526–1529.

    • Search Google Scholar
    • Export Citation
  • 16

    Carella AV, Moss MW, Provost V, Quinn TC, 1995. A manual bead assay for the determination of absolute CD4+ and CD8+ lymphocyte counts in human immunodeficiency virus-infected individuals. Clin Diagn Lab Immunol 2 :623–625.

    • Search Google Scholar
    • Export Citation
  • 17

    Centers for Disease Control and Prevention, 1993. 1993 revised classification system for HIV infection and expanded surveillance case definition for AIDS among adolescents and adults. JAMA 269 :729–730.

    • Search Google Scholar
    • Export Citation
  • 18

    Goodgame RW, Genta RM, White AC, Chappell CL, 1993. Intensity of infection in AIDS-associated cryptosporidiosis. J Infect Dis 167 :704–709.

    • Search Google Scholar
    • Export Citation
  • 19

    Cranendonk RJ, Kodde CJ, Chipeta D, Zijlstra EE, Sluiters JF, 2003. Cryptosporidium parvum and Isospora belli infections among patients with and without diarrhoea. East Afr Med J 80 :398–401.

    • Search Google Scholar
    • Export Citation
  • 20

    Wuhib T, Silva TM, Newman RD, Garcia LS, Pereira ML, Chaves CS, Wahlquist SP, Bryan RT, Guerrant RL, Sousa Ade Q, de Queiroz TRBS, Sears CL, 1994. Cryptosporidial and microsporidial infections in human immunodeficiency virus-infected patients in northeastern Brazil. J Infect Dis 170 :494–497.

    • Search Google Scholar
    • Export Citation
  • 21

    Kelly P, Baboo KS, Ndubani P, Nchito M, Okeowo NP, Luo NP, Feldman RA, Farthing MJ, 1997. Cryptosporidiosis in adults in Lusaka, Zambia, and its relationship to oocyst contamination of drinking water. J Infect Dis 176 :1120–1123.

    • Search Google Scholar
    • Export Citation
  • 22

    Gomez Morales MA, Atzori C, Ludovisi A, Rossi P, Scaglia M, Pozio E, 1995. Opportunistic and non-opportunistic parasites in HIV-positive and negative patients with diarrhoea in Tanzania. Trop Med Parasitol 46 :109–114.

    • Search Google Scholar
    • Export Citation
  • 23

    Cegielski JP, Ortega YR, McKee S, Madden JF, Gaido L, Schwartz DA, Manji K, Jorgensen AF, Miller SE, Pulipaka UP, Msengi AE, Mwakyusa DH, Sterling CR, Reller LB, 1999. Cryptosporidium, enterocytozoon, and cyclospora infections in pediatric and adult patients with diarrhea in Tanzania. Clin Infect Dis 28 :314–321.

    • Search Google Scholar
    • Export Citation
  • 24

    Esteban JG, Aguirre C, Flores A, Strauss W, Angles R, Mas-Coma S, 1998. High Cryptosporidium prevalences in healthy Aymara children from the northern Bolivian Altiplano. Am J Trop Med Hyg 58 :50–55.

    • Search Google Scholar
    • Export Citation
  • 25

    Yu JR, Lee JK, Seo M, Kim SI, Sohn WM, Huh S, Choi HY, Kim TS, 2004. Prevalence of cryptosporidiosis among the villagers and domestic animals in several rural areas of Korea. Korean J Parasitol 42 :1–6.

    • Search Google Scholar
    • Export Citation
  • 26

    Newman RD, Zu SX, Wuhib T, Lima AA, Guerrant RL, Sears CL, 1994. Household epidemiology of Cryptosporidium parvum infection in an urban community in northeast Brazil. Ann Intern Med 120 :500–505.

    • Search Google Scholar
    • Export Citation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ASYMPTOMATIC CRYPTOSPORIDIUM HOMINIS INFECTION AMONG HUMAN IMMUNDEFICIENCY VIRUS–INFECTED PATIENTS IN TANZANIA

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  • 1 Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia; Kilimanjaro Christian Medical Centre, Moshi, Tanzania; Division of Infectious Diseases, Mount Sinai School of Medicine, New York, New York

Few data exist on the relative importance of individual Cryptosporidium species in acquired immunodeficiency syndrome cryptosporidiosis. We characterized 127 inpatients infected with human immunodeficiency virus (HIV) in Tanzania for their CD4 cell count and by stool analysis, including Cryptosporidium immunofluorescence and polymerase chain reaction-restriction fragment length polymorphism. Cryptosporidium was detected in patients both with and without diarrheal symptoms (defined as ≥ 3 liquid stools/day, 11 of 61 versus 11 of 66; P = not significant) and was a marker for low CD4 cell count (median = 124/μL versus 212/μL in Cryptosporidium-negative patients; P < 0.04). Cryptosporidium hominis was the predominant species in this region and was associated with a longer duration of symptoms, a higher rate of asymptomatic infection, and a lower CD4 cell count versus C. parvum-infected patients (P < 0.05). This study suggests there may be important differences in the natural history of Cryptosporidium infection in HIV-infected persons depending on parasite species.

Cryptosporidium is a major enteric pathogen of patients with acquired immunodeficiency syndrome (AIDS), with infection rates of 8–48% reported among African AIDS patients with diarrhea.14 Studies of patients with cryptosporidiosis indicate that a majority experience chronic diarrhea, while less than 15% have transient diarrhea or are asymptomatic.5,6 However, this asymptomatic rate may be an underestimate because relatively few AIDS patients without diarrhea have been tested for Cryptosporidium infection in such studies. Additionally, the relative clinical impact of the two major Cryptosporidium species that infect humans, C. hominis (also referred to as genotype 1) and C. parvum (also referred to as genotype 2), is poorly defined. A predominance of C. hominis infection has been observed in HIV-associated diarrhea patients in Peru7 and Thailand,8 C. parvum has been prevalent in Europe,9,10 while genotype data from Africa have been limited to only a few cases.1113

We performed a cross-sectional study of HIV-suspected inpatients in the Kilimanjaro region of Tanzania at the Kilimanjaro Christian Medical Centre, the Mawenzi Government Hospital, and the Kibong’oto National Tuberculosis Hospital from July to October 2002. Informed consent was obtained from all participants and the University of Virginia Human Investigation Committee and the Kilimanjaro Christian Medical Centre Ethics Committee reviewed and approved the project. The hospitals’ standard HIV testing and counseling procedures of the hospitals were maintained and no patient was tested for HIV for the purpose of entry into the study. Patients with previously documented or newly suspected HIV infection were eligible. Enrolled patients were asked if they were experiencing increased stool frequency (≥ 3 liquid stools/day), the duration if present, and a single blood and stool sample was obtained. This study took place before the era of widespread availability of anti-retroviral therapy in this region.

Stool specimens were tested for Cryptosporidium infection by immunofluorescence (IF) microscopy (MeriFluor™ Cryptosporidium/Giardia; Meridian Bioscience, Inc., Cincinnati, OH) and by a nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) according to the protocol of Sturbaum and others.14 DNA was isolated from aliquots of frozen stool using the QiAMP DNA stool mini kit (Qiagen, Valencia, CA) after two washes in sterile phosphate-buffered saline (PBS) and six cycles of freeze-thaw. For each PCR, water (no DNA) and positive control DNA from C. parvum oocysts were used to confirm absence of contamination and successful amplification, respectively. The PCR assay exhibited a sensitivity of 94% and a specificity of 96% versus the reference IF assay15 and detected five IF-negative infections. All positive PCR results were repeated for verification and a positive PCR or IF result was considered valid. In addition to Giardia, which was tested by the IF assay, other stool pathogens were evaluated as follows: an enzyme-linked immunosorbent assay (ELISA) for Entamoeba histolytica (E. histolytica II ELISA assay; Techlab, Blacksburg, VA), culture for enteric bacteria using Selenite F broth and deoxycholate citrate and MacConkey agars, and microscopy for ova and parasites on formalin-ether sediments.

Two hundred forty-five patients were enrolled and complete data were obtained from 156, of which 127 were HIV-1/2 positive by ELISA (Vironostika Uniform HIV plus O; Organon Teknika B.V., Boxtel, The Netherlands or GenScreen HIV 1/2, Bio-Rad Laboratories, Marnes la Coquette, France). Quantification of CD4 T cells was performed on EDTA-containing blood within four hours of collection using the Coulter Manual CD4 Count kit16 (Beckman Coulter, Hialeah, FL). Cryptosporidium infection was a marker for HIV infection in that 22 of 127 HIV-positive patients were infected versus 0 of 29 HIV-suspected but HIV-negative patients (P = 0.01). Clinical features of the HIV-positive population are summarized in Table 1. At least 53% (67 of 127) of patients met the AIDS surveillance case definition via a CD4 cell count < 200/μL.17 Diarrheal symptoms (≥ 3 liquid stools/day) were reported by 48% of the patients and had been present for an average of duration of one month.

Upon examining the relationships between Cryptosporidium infection, diarrheal symptoms, and CD4 cell count (Table 2), we found that Cryptosporidium-infected patients had lower CD4 cell counts than Cryptosporidium-negative patients (median = 124/μL versus 212/μL; P < 0.04). Similar to the findings of others,1,2 we found that diarrheal symptoms also correlated with a low CD4 cell count (median = 139/μL versus 226/μL; P = 0.02). We were surprised to find that asymptomatic infection with Cryptosporidium was common (11 of 66 versus the 11 of 61 symptomatic Cryptosporidium infection rate; P not significant), particularly given the low CD4 cell counts (median = 128/μL) of these patients. Indeed, this low CD4 cell count was a distinguishing feature of Cryptosporidium-infected asymptomatic patients (median = 128/μL versus 336/μL for Cryptosporidium-negative asymptomatic patients; P = 0.02), indicating that Cryptosporidium infection was a marker for advanced lymphopenia independent of diarrhea. Cryptosporidium loads estimated by the method of Goodgame and others18 were variable and did not significantly differ between patients with symptoms and those without symptoms (mean ± SD/mL of sediment = 15,000 ± 43,000 versus 5,600 ± 12,000; P not significant). Of note, only 1 of 11 Cryptosporidium-infected patients with diarrheal symptoms was co-infected with other enteric pathogens as tested (one with a Giardia co-infection and none with E. histolytica, Strongyloides, Salmonella, or Shigella co-infections).

Since Cryptosporidium was an important marker in this population for advanced CD4 lymphopenia, we sought to determine whether this risk was influenced by Cryptosporidium species. Of the 21 stool specimens that were PCR-positive for Cryptosporidium (one specimen was PCR−/IF+), RFLP analysis showed that 15 were C. hominis and 6 were C. parvum (Table 3). There was no association between species and diarrheal symptoms. However, the duration of symptoms in C. hominis-infected patients was longer than that of C. parvum-infected patients, and the rate of asymptomatic C. hominis infection was higher (14% versus 2% for C. parvum; P = 0.02). Interestingly, the median CD4 cell count of C. hominis-infected patients was lower than that of C. parvum-infected patients, and this was true for both symptomatic and asymptomatic groups. Again, there was no statistical difference in the average parasite load between C. hominis and C. parvum (mean ± SD/mL of sediment = 10,000 ± 37,000 versus 5,000 ± 8,000; P not significant).

The most important new findings in this study are the high rate of asymptomatic C. hominis infection in this population and the apparent preferential association of C. hominis infection with a low CD4 cell count. The 17% rate of asymptomatic Cryptosporidium carriage in this study is higher than the 1–5% asymptomatic rate previously reported in AIDS inpatients from many developing world sites.2,19,20 The high rate was not due to our use of a PCR-based assay (since 9 of 10 asymptomatic patients were also IF positive) and is surprising given the low CD4 cell count of this asymptomatic group (128/μL), since other studies have suggested that chronic symptoms are the norm in this CD4 range.5 We believe there may be an underappreciation of asymptomatic Cryptosporidium infection, at least in this region of Africa, given that most clinical data on cryptosporidiosis derives from series of patients with diarrhea and not asymptomatic controls.3,2123 It may be relevant that community-based studies from Bolivia24 and Korea25 have shown asymptomatic Cryptosporidium carriage rates of 8–32% in large numbers of healthy individuals. Another feature of our patient population was the low Cryptosporidium oocyst loads relative to what others have observed,18 which could be contributing to the relative lack of symptoms, or simply reflect biological variability or laboratory differences.

Important limitations of our study are the small sample size, the inherent risk of recall bias when evaluating diarrheal symptoms, and the lack endoscopy or serial stool examination. We are interested in determining if these asymptomatic Cryptosporidium-infected patients were transiently or chronically infected, and whether they were forever symptomatic, went on to become symptomatic in the future, or had symptoms in the remote past. One could speculate that the preferential detection of C. hominis in patients with low CD4 cell count is due to delayed clearance of the organism, perhaps from symptomatic infections acquired during the previous wet season when transmission and new infection are common.26 Highly powered, prospective longitudinal studies are needed to confirm our findings of asymptomatic C. hominis carriage with low CD4 cell count, and to determine whether such a relationship is cause versus effect.

Table 1

Clinical features of the human immunodeficiency virus–infected study population (n = 127) Kilimanjaro, Tanzania

Feature
Age, years (median, range)35 (18–65)
Sex (M:F)47:80
Cryptosporidium infection22 (17%)
CD4 cell count (median/μL)179
Symptoms of ≥ 3 liquid stools/day61 (48%); median duration = 1 month
Table 2

Relationships between Cryptosporidium infection, symptoms, and CD4 cell count*

≥ 3 liquid stools/dayAsymptomaticTotal
* CD4 cell values are reported as median/μL; the value was not available for one Cryptosporidium-positive asymptomatic patient. Statistical analyses were based on the Mann-Whitney test.
P < 0.04, comparing the median CD4 cell count of Cryptosporidium-positive vs. negative patients.
P < 0.04, comparing the median CD4 cell count of Cryptosporidium-negative asymptomatic patients versus positive/asymptomatic, negative/symptomatic, or positive/symptomatic groups.
§ P = 0.02, comparing the median CD4 cell count of patients with vs. without symptoms.
Cryptosporidium positive11 (CD4 = 124)11 (CD4 = 128)22 (CD4 = 124†)
Cryptosporidium negative50 (CD4 = 150)55 (CD4 = 336‡)124 (CD4 = 212†)
Total61 (CD4 = 139§)66 (CD4 = 226§)
Table 3

Comparison of Cryptosporidium hominis versus C. parvum infection*

C. hominisC. parvum
* CD4 cell counts/μL and duration of symptoms are reported as median values; the CD4 cell count was not available for one asymptomatic C. hominis-infected patient.
P = 0.009 comparing duration of symptoms of C. hominis vs. C. parvum-infected patients (by Mann-Whitney test).
P = 0.02 comparing rates of asymptomatic infection with C. hominis vs. C. parvum (by Fischer’s exact test).
§ P < 0.003 comparing CD4 cell counts of C. hominis vs. C. parvum-infected patients (by Mann-Whitney test).
Total15 (71%)6 (29%)
Association with symptoms6/61 (10%)5/61 (8%)
Duration of symptoms (months)4†0.3†
Association with asymptomatic infection9/66‡ (14%)1/66‡ (2%)
CD4 cell count55§256§

*

Address correspondence to Eric R. Houpt, Division of Infectious Diseases and International Health, University of Virginia, PO Box 801340, MR4 Building Room 2144, Charlottesville, VA 22908-1340. E-mail: erh6k@virginia.edu

Authors’ addresses: Eric R. Houpt, Oluma Y. Bushen, Anita Kohli, Amon Asgharpour, Cherie T. Ng, and Richard L. Guerrant, Division of Infectious Diseases and International Health, University of Virginia, PO Box 801340, MR4 Building Room 2144, Charlottesville, VA 22908-1340, Telephone: 434-243-9326, Fax: 434-924-0075, E-mails: erh6k@virginia.edu, ob3d@vurginia.edu, ak7t@virginia.edu, aa3z@virginia.edu, ctn8d@virginia.edu, and rlg9a@virginia.edu. Noel E. Sam, Venance Maro, Sendui Ole-Nguyaine, and John F. Shao, Kilimanjaro Christian Medical Centre, Moshi, Tanzania, E-mails: nsam@kcmc.ac.tz, venmaro@yahoo.co.uk, solengudr@yahoo.com, and jshao@kcmc.ac.tz. David P. Calfee, Division of Infectious Diseases, Mount Sinai School of Medicine, New York, NY 10029, E-mail: David.Calfee@msnyuhealth.org.

Acknowledgments: We thank Edward Mushi, Sr., Ruwaichi Uiso, and the other nurses involved in this study; Stanislaus Siriwa, Richard Tarimo, and Eline Ngomuo and the other clinical laboratory technicians; and all the patients who participated in this work. We also thank Dr. William Petri (University of Virginia) for helpful discussions and David Lyerly (Techlab, Inc.) for the E. histolytica II ELISA kits.

Financial support: This study was supported by the National Institutes of Health (grant U19 AI056872-01) and the Virginia Commonwealth Technology Research Fund.

Disclosure: None of the authors has a commercial or other association that might pose a conflict of interest.

REFERENCES

  • 1

    Tarimo DS, Killewo JZ, Minjas JN, Msamanga GI, 1996. Prevalence of intestinal parasites in adult patients with enteropathic AIDS in north-eastern Tanzania. East Afr Med J 73 :397–399.

    • Search Google Scholar
    • Export Citation
  • 2

    Gassama A, Sow PS, Fall F, Camara P, Gueye-N’diaye A, Seng R, Samb B, M’Boup S, Aidara-Kane A, 2001. Ordinary and opportunistic enteropathogens associated with diarrhea in Senegalese adults in relation to human immunodeficiency virus serostatus. Int J Infect Dis 5 :192–198.

    • Search Google Scholar
    • Export Citation
  • 3

    Gumbo T, Sarbah S, Gangaidzo IT, Ortega Y, Sterling CR, Carville A, Tzipori S, Wiest PM, 1999. Intestinal parasites in patients with diarrhea and human immunodeficiency virus infection in Zimbabwe. AIDS 13 :819–821.

    • Search Google Scholar
    • Export Citation
  • 4

    Colebunders R, Lusakumuni K, Nelson AM, Gigase P, Lebughe I, van Marck E, Kapita B, Francis H, Salaun JJ, Quinn TC, Piot P, 1988. Persistent diarrhoea in Zairian AIDS patients: an endoscopic and histological study. Gut 29 :1687–1691.

    • Search Google Scholar
    • Export Citation
  • 5

    Blanshard C, Jackson AM, Shanson DC, Francis N, Gazzard BG, 1992. Cryptosporidiosis in HIV-seropositive patients. QJM 85 :813–823.

  • 6

    Manabe YC, Clark DP, Moore RD, Lumadue JA, Dahlman HR, Belitsos PC, Chaisson RE, Sears CL, 1998. Cryptosporidiosis in patients with AIDS: correlates of disease and survival. Clin Infect Dis 27 :536–542.

    • Search Google Scholar
    • Export Citation
  • 7

    Cama VA, Bern C, Sulaiman IM, Gilman RH, Ticona E, Vivar A, Kawai V, Vargas D, Zhou L, Xiao L, 2003. Cryptosporidium species and genotypes in HIV-positive patients in Lima, Peru. J Eukaryot Microbiol 50 (Suppl):531–533.

    • Search Google Scholar
    • Export Citation
  • 8

    Tiangtip R, Jongwutiwes S, 2002. Molecular analysis of Cryptosporidium species isolated from HIV-infected patients in Thailand. Trop Med Int Health 7 :357–364.

    • Search Google Scholar
    • Export Citation
  • 9

    Guyot K, Follet-Dumoulin A, Lelievre E, Sarfati C, Rabodonirina M, Nevez G, Cailliez JC, Camus D, Dei-Cas E, 2001. Molecular characterization of Cryptosporidium isolates obtained from humans in France. J Clin Microbiol 39 :3472–3480.

    • Search Google Scholar
    • Export Citation
  • 10

    Alves M, Matos O, Pereira Da Fonseca I, Delgado E, Lourenco AM, Antunes F, 2001. Multilocus genotyping of Cryptosporidium isolates from human HIV-infected and animal hosts. J Eukaryot Microbiol Suppl :17S–18S.

    • Search Google Scholar
    • Export Citation
  • 11

    Gatei W, Greensill J, Ashford RW, Cuevas LE, Parry CM, Cunliffe NA, Beeching NJ, Hart CA, 2003. Molecular analysis of the 18S rRNA gene of Cryptosporidium parasites from patients with or without human immunodeficiency virus infections living in Kenya, Malawi, Brazil, the United Kingdom, and Vietnam. J Clin Microbiol 41 :1458–1462.

    • Search Google Scholar
    • Export Citation
  • 12

    Leav BA, Mackay MR, Anyanwu A, RM OC, Cevallos AM, Kindra G, Rollins NC, Bennish ML, Nelson RG, Ward HD, 2002. Analysis of sequence diversity at the highly polymorphic Cpgp40/15 locus among Cryptosporidium isolates from human immunodeficiency virus-infected children in South Africa. Infect Immun 70 :3881–3890.

    • Search Google Scholar
    • Export Citation
  • 13

    Morgan U, Weber R, Xiao L, Sulaiman I, Thompson RC, Ndiritu W, Lal A, Moore A, Deplazes P, 2000. Molecular characterization of Cryptosporidium isolates obtained from human immunodeficiency virus-infected individuals living in Switzerland, Kenya, and the United States. J Clin Microbiol 38 :1180–1183.

    • Search Google Scholar
    • Export Citation
  • 14

    Sturbaum GD, Reed C, Hoover PJ, Jost BH, Marshall MM, Sterling CR, 2001. Species-specific, nested PCR-restriction fragment length polymorphism detection of single Cryptosporidium parvum oocysts. Appl Environ Microbiol 67 :2665–2668.

    • Search Google Scholar
    • Export Citation
  • 15

    Garcia LS, Shimizu RY, 1997. Evaluation of nine immunoassay kits (enzyme immunoassay and direct fluorescence) for detection of Giardia lamblia and Cryptosporidium parvum in human fecal specimens. J Clin Microbiol 35 :1526–1529.

    • Search Google Scholar
    • Export Citation
  • 16

    Carella AV, Moss MW, Provost V, Quinn TC, 1995. A manual bead assay for the determination of absolute CD4+ and CD8+ lymphocyte counts in human immunodeficiency virus-infected individuals. Clin Diagn Lab Immunol 2 :623–625.

    • Search Google Scholar
    • Export Citation
  • 17

    Centers for Disease Control and Prevention, 1993. 1993 revised classification system for HIV infection and expanded surveillance case definition for AIDS among adolescents and adults. JAMA 269 :729–730.

    • Search Google Scholar
    • Export Citation
  • 18

    Goodgame RW, Genta RM, White AC, Chappell CL, 1993. Intensity of infection in AIDS-associated cryptosporidiosis. J Infect Dis 167 :704–709.

    • Search Google Scholar
    • Export Citation
  • 19

    Cranendonk RJ, Kodde CJ, Chipeta D, Zijlstra EE, Sluiters JF, 2003. Cryptosporidium parvum and Isospora belli infections among patients with and without diarrhoea. East Afr Med J 80 :398–401.

    • Search Google Scholar
    • Export Citation
  • 20

    Wuhib T, Silva TM, Newman RD, Garcia LS, Pereira ML, Chaves CS, Wahlquist SP, Bryan RT, Guerrant RL, Sousa Ade Q, de Queiroz TRBS, Sears CL, 1994. Cryptosporidial and microsporidial infections in human immunodeficiency virus-infected patients in northeastern Brazil. J Infect Dis 170 :494–497.

    • Search Google Scholar
    • Export Citation
  • 21

    Kelly P, Baboo KS, Ndubani P, Nchito M, Okeowo NP, Luo NP, Feldman RA, Farthing MJ, 1997. Cryptosporidiosis in adults in Lusaka, Zambia, and its relationship to oocyst contamination of drinking water. J Infect Dis 176 :1120–1123.

    • Search Google Scholar
    • Export Citation
  • 22

    Gomez Morales MA, Atzori C, Ludovisi A, Rossi P, Scaglia M, Pozio E, 1995. Opportunistic and non-opportunistic parasites in HIV-positive and negative patients with diarrhoea in Tanzania. Trop Med Parasitol 46 :109–114.

    • Search Google Scholar
    • Export Citation
  • 23

    Cegielski JP, Ortega YR, McKee S, Madden JF, Gaido L, Schwartz DA, Manji K, Jorgensen AF, Miller SE, Pulipaka UP, Msengi AE, Mwakyusa DH, Sterling CR, Reller LB, 1999. Cryptosporidium, enterocytozoon, and cyclospora infections in pediatric and adult patients with diarrhea in Tanzania. Clin Infect Dis 28 :314–321.

    • Search Google Scholar
    • Export Citation
  • 24

    Esteban JG, Aguirre C, Flores A, Strauss W, Angles R, Mas-Coma S, 1998. High Cryptosporidium prevalences in healthy Aymara children from the northern Bolivian Altiplano. Am J Trop Med Hyg 58 :50–55.

    • Search Google Scholar
    • Export Citation
  • 25

    Yu JR, Lee JK, Seo M, Kim SI, Sohn WM, Huh S, Choi HY, Kim TS, 2004. Prevalence of cryptosporidiosis among the villagers and domestic animals in several rural areas of Korea. Korean J Parasitol 42 :1–6.

    • Search Google Scholar
    • Export Citation
  • 26

    Newman RD, Zu SX, Wuhib T, Lima AA, Guerrant RL, Sears CL, 1994. Household epidemiology of Cryptosporidium parvum infection in an urban community in northeast Brazil. Ann Intern Med 120 :500–505.

    • Search Google Scholar
    • Export Citation
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