Objective: To assess the occurrence and pattern of Toll-like receptor 4 (TLR4) co-segregated genotypes among children with Plasmodium falciparum malaria in Nigeria. Methods: In this case-control study, a total of 79 Plasmodium falciparum infected children aged 2–7 years and 105 age-matched uninfected controls of Yoruba descents in Lagos were studied. The extracted DNA samples were used for TLR4 genotyping at codons 299 (Asp> Gly) and 399 (Thr >Ile) by PCR-restriction fragment length poly-morphism. Malaria infection was diagnosed by blood smear microscopy and infected children were stratified into asymptomatic, uncomplicated and severe malaria sub-groups. Malnutrition was determined by measuring the mid upper arm circumference and anemia was defined as hemoglobin<11 g/dL. Results: The proportions of children with acute malnutrition and severe anemia were 12.0%and 3.2%, respectively. Parasitemia and malnutrition were not correlated and four distinct patterns of TLR4 genotypes were found in the study population: Asp299Asp/Thr399Thr (90.2%), Asp299Gly/Thr399Thr (4.3%), Gly299Gly/Thr399Thr (3.8%) and Asp299Gly/Thr399Ile (1.6%). These genotypes did not differ significantly (P>0.05) in frequency between infected and non-infected children. However, low and high occur-rences of the TLR4 Asp299Asp/Thr399Thr and Asp299Gly/Thr399Thr genotypes were observed in the severe malaria subgroup. Conclusions: This study reveals a protective role for TLR4 Asp299Gly/Thr399Ile and Asp299Asp/Thr399Thr genotypes against severe malaria in Nigerian children.

INTRODUCTIONMicrobial burden involving parvovirus B19 infection has been recognised as a major cause of morbidity and mortality in sickle cell anaemia (SCA) patients. Given the recent reports of parvovirus B19 infection in Nigeria and the role of inflammation in sickle cell crisis, knowledge of the relationship between the two may be essential for deploying appropriate interventions in infected patients. This study determined the serum levels of tumour necrosis factor alpha (TNF-α) and C-reactive protein (CRP) as inflammatory markers in Nigerian SCA patients with and without parvovirus B19 infections.

METHODSA total of 64 SCA patients aged 5-25 years and 41 age-matched apparently healthy volunteers with haemoglobin genotypes AA or AS were enrolled with consent into the study. Parvovirus B19 infection and serum levels of TNF-α and CRP were determined by the ELISA method.

RESULTSThe overall prevalence rate of parvovirus B19 infection in the study subjects was 13.3%. This rate further showed gender variation and negative correlation with age. Significant (p < 0.05) increases in serum CRP and TNF-α levels, with further elevation in unsteady state SCA patients, were observed in comparison with the control. Unlike the control, 29.6% and 21.9% of the SCA patients elicited TNF-α and CRP above threshold levels, respectively. Parvovirus B19 infection was found to elicit greater increases in these inflammatory markers than in infected non-SCA controls.

CONCLUSIONWe conclude that parvovirus B19 infection is common in this environment, and that serum TNF-α and CRP are predictors of clinical inflammatory episodes in infected SCA patients.

Adolescent ; Adult ; Anemia, Sickle Cell ; blood ; virology ; C-Reactive Protein ; metabolism ; Case-Control Studies ; Child ; Child, Preschool ; Enzyme-Linked Immunosorbent Assay ; Female ; Genotype ; Hemoglobins ; Humans ; Inflammation ; Male ; Nigeria ; Parvoviridae Infections ; blood ; Parvovirus B19, Human ; Tumor Necrosis Factor-alpha ; blood ; Young Adult

Objective To assess the occurrence and pattern of Toll-like receptor 4 (TLR4) co-segregated genotypes among children with Plasmodium falciparum malaria in Nigeria. Methods In this case-control study, a total of 79 Plasmodium falciparum infected children aged 2–7 years and 105 age-matched uninfected controls of Yoruba descents in Lagos were studied. The extracted DNA samples were used for TLR4 genotyping at codons 299 (Asp > Gly) and 399 (Thr > Ile) by PCR-restriction fragment length polymorphism. Malaria infection was diagnosed by blood smear microscopy and infected children were stratified into asymptomatic, uncomplicated and severe malaria sub-groups. Malnutrition was determined by measuring the mid upper arm circumference and anemia was defined as hemoglobin < 11 g/dL. Results The proportions of children with acute malnutrition and severe anemia were 12.0% and 3.2%, respectively. Parasitemia and malnutrition were not correlated and four distinct patterns of TLR4 genotypes were found in the study population: Asp299Asp/Thr399Thr (90.2%), Asp299Gly/Thr399Thr (4.3%), Gly299Gly/Thr399Thr (3.8%) and Asp299Gly/Thr399Ile (1.6%). These genotypes did not differ significantly (P > 0.05) in frequency between infected and non-infected children. However, low and high occurrences of the TLR4 Asp299Asp/Thr399Thr and Asp299Gly/Thr399Thr genotypes were observed in the severe malaria subgroup. Conclusions This study reveals a protective role for TLR4 Asp299Gly/Thr399Ile and Asp299Asp/Thr399Thr genotypes against severe malaria in Nigerian children.