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[Display omitted] • We found high levels of asymptomatic malaria parasite carriage amongst adolescents in south western Nigeria. • There was a high prevalence of Plasmodium malariae and P. ovale with P. falciparum in asymptomatic infections. • There were low levels of co-infection in symptomatic infections. Asymptomatic malaria parasite carriers do not seek anti-malarial treatment and may constitute a silent infectious reservoir. In order to assess the level of asymptomatic and symptomatic carriage amongst adolescents in a highly endemic area, and to identify the risk factors associated with such carriage, we conducted a cross-sectional survey of 1032 adolescents (ages 10–19 years) from eight schools located in Ibadan, southwestern Nigeria in 2016. Blood films and blood spot filter paper samples were prepared for microscopy and DNA analysis. The prevalence of asymptomatic malaria was determined using microscopy, rapid diagnostic tests and PCR for 658 randomly selected samples. Of these, we found that 80% of asymptomatic schoolchildren were positive for malaria parasites by PCR, compared with 47% and 9%, determined by rapid diagnostic tests and microscopy, respectively. Malaria parasite species typing was performed using PCR targeting the mitochondrial CoxIII gene, and revealed high rates of carriage of Plasmodium malariae (53%) and Plasmodium ovale (24%). Most asymptomatic infections were co-infections of two or more species (62%), with Plasmodium falciparum + P. malariae the most common (35%), followed by P. falciparum + P. malariae + P. ovale (21%) and P. falciparum + P. ovale (6%). Single infections of P. falciparum , P. malariae and P. ovale accounted for 24%, 10% and 4% of all asymptomatic infections, respectively. To compare the species composition of asymptomatic and symptomatic infections, further sample collection was carried out in 2017 at one of the previously sampled schools, and at a nearby hospital. Whilst the species composition of the asymptomatic infections was similar to that observed in 2016, the symptomatic infections were markedly different, with single infections of P. falciparum observed in 91% of patients, P. falciparum + P. malariae in 5% and P. falciparum + P. ovale in 4%. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Consumption of chloroquine (CQ) and subtherapeutic drug levels in blood are considered to be widespread in areas where malaria is endemic. A cross-sectional study was performed with 405 Nigerian children to assess factors associated with the presence of CQ in blood and to examine correlations of drug levels with malaria parasite species and densities. Infections with Plasmodium species and parasite densities were determined by microscopy and PCR assays. Whole-blood CQ concentrations were measured by high-performance liquid chromatography. Plasmodium falciparum, P. malariae, and P. ovale were observed in 80, 16, and 9% of the children, respectively, and CQ was detected in 52% of the children. CQ concentrations were >17 and <100 nmol/liter in 25% of the children, 100 to 499 nmol/liter in 14% of the children, and > or =500 nmol/liter in 13% of the children. Young age, attendance at health posts, and absence of parasitemia were factors independently associated with CQ in blood. With increasing concentrations of CQ, the prevalence of P. falciparum infection and parasite densities decreased. However, at concentrations corresponding to those usually attained during regular prophylaxis (> or =500 nmol/liter), 62% of children were still harboring P. falciparum parasites. In contrast, no infection with P. malariae and only one infection with P. ovale were observed in children with CQ concentrations of > or =100 nmol/liter. These data show the high prevalence of subcurative CQ concentrations in Nigerian children and confirm the considerable degree of CQ resistance in that country. Subtherapeutic drug levels are likely to further promote CQ resistance and may impair the development and maintenance of premunition in areas where malaria is endemic.

Malnutrition interacting with infectious and parasitic diseases are the main causes of the appalling mortality in childhood in the tropics. The most important single safeguard against these in infancy is breast feeding and the trend now evident to abandon this is a disaster which demands urgent attention. Reasons for this trend are discussed. Efforts to control infectious diseases, other than smallpox, have had little success and the emergence and spread of dengue haemorrhagic fever in S.E. Asia have added new dimensions to the problem. Malaria is still widely prevalent in the tropics and falciparum malaria, holoendemic in much of Africa, remains a major cause of death with its most serious impact on pregnant women and children. The emergence and spread of drug resistant strains of this parasite in parts of the world is a cause for serious concern. Quartan malaria is also an insidious corruptor of health in childhood and commonly causes the nephrotic syndrome. Neonatal jaundice, often associated with G6PD deficiency, is increasing in frequency in urban areas of Africa and now constitutes a significant hazard to the newborn and requires urgent investigation. These problems in tropical paediatrics indicate the need for urgent reappraisal of our role as a profession in the affairs of the tropical developing world.

Prior to longitudinal studies into the effects of malaria upon the immune response, nutritional status and haematological indices in young children in northern Nigeria, the degree of malarial endemicity in the area has been established. Field work was carried out in the wet seasons of 1976 and 1977 and the dry season of 1977 (April). Seasonal variation in transmission has been demonstrated. Age-specific parasite prevalence rates and splenic indices confirm previous studies that this northern part of the Guinea savannah belt of West Central Africa is an holoendemic area.

A specific relationship between P. malariae and the nephrotic syndrome, originally postulated on epidemiologic evidence, has been substantiated by clinical, pathologic and immunologic observations. It would appear that quartan malaria causes an immune complex nephritis in some individuals that, once established, is sustained by mechanisms not yet fully explained but which may involve an autoimmune process. Evidence to support an immunologic pathogenesis of the renal lesions is provided by the presence of immunoglobulin, complement (C3) and quartan malarial antigen in biopsy specimens studied by immunofluorescence microscopy. In early cases in which some patients respond to treatment, fluorescence is coarsely granular but in late cases in which patients are unresponsive to treatment, fluorescence tends to be diffuse. Renal histology is distinctive and does not conform to any of the categories included in the conventional classification of the nephrotic syndrome in childhood. The basic lesion consists of thickening of glomerular capillary walls, leading to eventual obliteration of capillary lumina, and accompanying mesangial sclerosis leads ultimately to total glomerular sclerosis. A unique feature of electron microscopy is the presence of small lacunae scattered throughout the thickened capillary basement membrane. Histologic grading for severity of lesions shows positive correlation with response to treatment and immunofluorescence appearances. Prognosis is, in general, poor. The large majority of patients do not respond to treatment with prednisolone, azathioprine or cyclophosphamide, and prednisolone administration causes severe hypertension and other serious complications in a high proportion of patients.