The role of Blastocystis hominis as a possible intestinal pathogen in travellers.

The role of Blastocystis hominis as a pathogen for man has been controversially discussed, while travel history has been implicated as a risk factor of infection. Few controlled studies of the association between B. hominis and symptomatic diseases have been performed. Therefore, a case-control study among 795 German tourists returning from tropical countries was conducted. The prevalence of the organism among patients with and without symptoms was assessed. Blastocystis hominis was detected in 69 of 469 (14.7%) patients with diarrhoea and in 21 of 326 (5.7%) controls. However, other organisms causing diarrhoea were detected in 18 of the 69 (26.1%) symptomatic patients with B. hominis. Thus, 51 of 469 (10.8%) symptomatic patients had B. hominis in the absence of other pathogens in their stool, significantly more than in the asymptomatic group (5.2%; P = 0.005). Irrespective of the development of symptoms, the organism was most frequently acquired during journeys to the Indian subcontinent. The results of this study suggest that B. hominis is associated with development of diarrhoea in travellers to tropical destinations and that frequently concurrent infections with other organisms occur.

Evaluation of an antigen-capture enzyme immunoassay for detection of Entamoeba histolytica in stool samples.

In order to identify the prevalence of Entamoeba histolytica in tourists with diarrhoea returning from countries of the developing world, sensitivity and specificity of a commercially available enzyme immunoassay (EIA) kit for the detection of Entamoeba histolytica coproantigen in stool were evaluated. Five hundred seventy-seven specimens from 469 patients were examined by microscopy and EIA. Sixty-two specimens from 49 patients were considered positive for Entamoeba histolytica. Compared with microscopic examination of stool samples, the EIA was found to be slightly more sensitive (90.3% vs. 87.1%) and was 97.7% specific for Entamoeba histolytica.

Giardiasis in travellers: evaluation of an antigen-capture ELISA for the detection of Giardia lamblia-antigen in stool.

Diagnosis of giardiasis relies largely on the microscopical detection of trophozoites or cysts in feces. However, this method is labour- and time-intensive and depends highly on the skill of an experienced microscopist. In order to identify the prevalence of Giardia lamblia in travellers returning from overseas, we evaluated sensitivity and specificity of a commercially available ELISA kit for the detection of Giardia-lamblia-antigen in stool. Nine hundred seventy-eight stool samples from 795 patients were examined by microscopy (iron-hematoxyilin-stain, SAF-concentration) and ELISA. Altogether, Giardia infection could be detected in 74 subjects. On evaluation of all samples, the ELISA turned out to be more sensitive than microscopy (95.5% vs. 81.8%) and 99.7% specific for Giardia lamblia. Especially with microscopy, the examination of more than one stool specimen did improve diagnostic sensitivity. It seems therefore advisable to retain the practise of examining at least three stool samples before considering a patient as not infected. The coproantigen-ELISA is especially advantageous in situations where only a single stool sample can be examined. It should not, however, replace microscopical examination of stool specimens for ova and parasites since other potential pathogens would otherwise escape detection.

Voluntary blood donor recruitment: a strategy to reduce transmission of HIV-1, hepatitis-B and syphilis in Kinshasa, Zaïre.

We evaluated the use of voluntary blood donor recruitment in Kinshasa, Zaïre, as a means of reducing transmission of HIV-1 and other infectious agents by blood transfusion. Between January 1, 1989, and April 7, 1989, 2,237 blood donors were enrolled in the study at the transfusion centre of the Mama Yemo Hospital. Each donor was tested for antibodies to HIV-1 confirmed by IFA and Western blot, Treponema pallidum, antibodies to hepatitis B virus (HBV) core antigen and screened for the presence of the HBV surface antigen. Test results were related to the data of the blood donors: age, sex, haematocrit, voluntary blood donor, family member donor, paid donor. The serological results of all donors for Anti-HIV-1. Anti-HBc, HBsAg and TPHA were 4.8%, 70.9%, 13.1% and 13.3% respectively. Lower seroprevalence rates were found among voluntary blood donors. However, only TPHA seroprevalence was significantly lower in voluntary blood donors (8.4%, 23/275) compared with paid donors (15.2%, 87/571) (p less than 0.01). A greater proportion of voluntary donors provides a store of blood which allows more extensive screening of blood for HIV-1 and other infectious diseases. Voluntary blood donor recruitment is critical for the provision of safe blood supplies in Kinshasa.

Prevention of transfusion-associated HIV transmission in Kinshasa, Zaire: HIV screening is not enough.

The purpose of this study was to develop a strategy to reduce transfusion-related HIV transmission which went beyond the limits of routine HIV screening of blood donors. Current blood transfusion practices were assessed in 1044 patients for whom staff physicians had requested a transfusion between 5 September and 19 October, 1988. Children under 5 years of age with malaria, and pregnant women with acute anaemia requiring blood transfusion were the two highest risk groups. Many of the transfusions were given without an obvious medical indication; 22.7% (214 out of 955) of the recipients were transfused without prior laboratory tests [haemoglobin (Hb) or haematocrit (Hct)], 7.2% with Hb greater than 6g/100ml or Hct greater than 25% and 16.6% without clinical signs of severe anaemia (pulse less than 100/min without shortness of breath). The data of this study were used to organize a workshop for all the physicians responsible for blood transfusions in Kinshasa and two nearby health zones. A consensus statement on the indications for blood transfusion was developed. Subsequently, transfusion centres adopted this consensus statement instead of previous guidelines.