Asymptomatic Plasmodium Parasites among Adults in Eastern Uganda: A Case of Donor Blood Screening at Mbale Regional Blood Bank

Asymptomatic malaria infection prevailing risks for human health and malaria elimination

There has been a consistent rise in malaria cases in the last few years. The existing malaria control measures are challenged by insecticide resistance in the mosquito vector, drug résistance in parasite populations, and asymptomatic malaria (ASM) in healthy individuals. The absence of apparent malaria symptoms and the presence of low parasitemia makes ASM a hidden reservoir for malaria transmission and an impediment in malaria elimination efforts. This review focuses on ASM in malaria-endemic countries and the past and present research trends from those geographical locations. The harmful impacts of asymptomatic malaria on human health and its contribution to disease transmission are highlighted. We discuss certain crucial genetic changes in the parasite and host immune response necessary for maintaining low parasitemia leading to long-term parasite survival in the host. Since the chronic health effects and the potential roles for disease transmission of ASM remain mostly unknown to significant populations, we offer proposals for developing general awareness. We also suggest advanced technology-based diagnostic methods, and treatment strategies to eliminate ASM.

Asymptomatic falciparum Malaria and its Effects on Type 2 Diabetes Mellitus Patients in Lagos, Nigeria

Background

Asymptomatic malaria (ASM) constitutes a reservoir of malaria parasites that sustain transmission and threaten elimination efforts. Studies have also shown a significant relation between insulin resistance and malaria infection. However, data on the clinical effects of ASM and its patterns of carriage among adult malaria patients is limited.

Objectives

To determine the prevalence of ASM due to Plasmodium falciparum among adult type 2 diabetes (T2DM) patients in Lagos, Nigeria; to assess the diagnostic performance of light microscopy and histidine-rich protein 2 rapid diagnostic test (HRP-2 RDT); and to determine the effects of ASM on glycemic control and anemia.

Materials and Methods

This cross-sectional study enrolled 208 afebrile, nonobese, nonhypertensive T2DM patients, aged 40-70 years, undergoing treatment (adherence, ≥95%) at six private health facilities in Lagos, Nigeria, between March and August 2015. Sociodemographic data were obtained using a semi-structured questionnaire and clinical case files. Venous blood samples were collected and processed for fasting blood sugar estimation, packed cell volume determination and malaria parasite detection by HRP2-RDT, light microscopy and polymerase chain reaction (PCR).

Results

The mean age of the patients was 54.5 years. ASM was diagnosed in 16.8%, 7.2% and 4.3% of the patients by PCR, light microscopy and HRP2-RDT, respectively. ASM was significantly (P < 0.05) associated with poor glycemic control, anemia and insulin resistance. The overall parasitemia ranged from 85 to 3789 parasites/μL (median, 1580 parasites/μL). Benchmarking against the PCR results, light microscopy and rapid diagnostic tests were found to have a sensitivity (95% confidence interval) of 42.9% (26.5-59.3) and 22.9% (12.1-39), respectively, in diagnosing ASM.

Conclusion

This study revealed that T2DM patients in Lagos, Nigeria, are potential reservoirs of asymptomatic Plasmodium falciparum, which has a significantly negative effect on glycemic control and anemia. The study also found PCR to be the most effective diagnostic method.

Transfusional Malaria and Associated Factors at the National Blood Transfusion Center of Niamey-Niger

SUMMARY

Problem. Transfusional malaria is an accidental transmission of Plasmodium via a blood transfusion. Its magnitude is underestimated and very little data on the assessment of this risk are available in Niger.

OBJECTIVE

This study aimed to determine the prevalence of plasmodial infection of blood bags at the National Blood Transfusion Center of Niamey (NBTC).

METHODOLOGY

A cross-sectional study to diagnose Plasmodium infection by microscopy and Rapid Diagnostic Test (RDT) was carried out during the rainy season (September to November 2015). Blood grouping was performed by the BETH-VINCENT technique.

RESULTS

One thousand three hundred and fifty-seven (1357) blood bags were collected. One hundred and fifty-seven (11.6%) of the donors were infected with Plasmodium by microscopy and 2.4% (9/369) by rapid diagnostic test. All infections were with P. falciparum (100%). The mean parasite density was 197 parasites/μL (SD=281; [80: 2000]). There were no significant differences in infection prevalence between the ABO blood groups (p = 0.3) or the rhesus positivity (p=08). There is also no significant difference in temporal (p = 0.1) and spatial (p = 0.6) distribution.

CONCLUSION

The transmission of transfusional malaria during the rainy season is a fact in Niger. Such risks were independent of the ABO blood type and positivity for the rhesus antigen. Pretransfusion diagnosis or posttransfusion therapy should be instituted to prevent it.