Malaria parasitemia in apparently healthy blood donors in north-central Nigeria.

OBJECTIVE: To determine the prevalence of transmissible malaria in apparently healthy blood donors in the city of Jos in north-central Nigeria. METHODS: We collected blood specimens from individuals who had passed the screening criteria for blood donation. We created thin and thick blood films using the blood film template provided by the World Health Organization (WHO). The films were allowed to air dry; then, we stained them using a 3% Giemsa solution and examined them microscopically. In specimens that tested positive the malaria species was identified. RESULTS: The highest prevalence of malaria was in donors aged between 31 and 40 years (65.1%), whereas the lowest prevalence was in donors aged 20 years or younger (25.0%). Plasmodium falciparum was the predominant species (98.0%); the least prevalent was Plasmodium malariae (2.0%). In male donors the prevalence of malaria parasitemia was 62.0%; the prevalence in female donors was 62.5%. Among paid donors the malaria parasitemia rate was 82.3%, compared with 22.4% in volunteer donors. Donors who reported their occupation as businessperson (individual who engages in commercial trade, mostly outdoors in a market environment) had the highest prevalence, at 94.3%; students had the lowest prevalence, at 31.9%. CONCLUSION: A high percentage of blood donors in Jos, Nigeria, actually harbor malaria, which is cause for concern and more careful donor screening by healthcare professionals in that region is warranted.

FOXP3 gene expression in a tuberculosis case contact study.

Regulatory T lymphocytes (T(regs)) that express FOXP3 are involved in the beneficial attenuation of immunopathology, but are also implicated in down-regulation of protective responses to infection. Their role in tuberculosis (TB) is unknown. We classified 1272 healthy TB contacts according to their tuberculin skin test (TST) and interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) results and 128 TB cases, and studied the expression of FOXP3 and interleukin (IL)-10 in blood samples. Compared to the uninfected contact group (TST(-), ELISPOT(-)), we observed higher levels of FOXP3 mRNA in blood from TB patients (< 0.001), but IL-10 expression was slightly lower (P = 0.04). In contrast, FOXP3 expression levels were significantly lower (P = 0.001) in the recently infected contacts (TST(+), ELISPOT(+)) but there was no difference for IL-10 (P = 0.74). We hypothesize that during early/subclinical TB, most of which will become latent, FOXP3(+) T(regs) may be sequestered in the lungs, but when TB becomes progressive, FOXP3 reappears at increased levels in the periphery. While these findings do not reveal the role, beneficial or harmful, of T(regs) in TB, they emphasize the probable importance of these cells.

Rising ELISPOT count prior to the onset of symptoms of full-blown tuberculosis disease.

The relationship between the T-cell response to mycobacterial antigens and the likelihood of progression to disease has not been defined. We report a rapidly rising ELISPOT count in a 55-year-old man with evidence of Mycobacterium tuberculosis infection prior to the onset of symptoms of disease. This case illustrates the possible utility of quantitative changes in the ELISPOT count in predicting progression from M. tuberculosis infection to disease.