BackgroundThe gene for sickle hemoglobin (HbS) is a prime example of natural selection. It is generally believed that its current prevalence in many t

Although the α+ thalassemias almost certainly confer protection against death from malaria, this has not been formally documented. We have conducted a study involving 655 case patients with rigorously defined severe malaria and 648 controls, frequency matched on area of residence and ethnic group. The prevalence of both heterozygous and homozygous α+ thalassemia was reduced in both case patients with severe malaria (adjusted odds ratios [ORs], 0.73 and 0.57; 95% confidence intervals [95% CIs], 0.57-0.94 and 0.40-0.81; P = .013 and P = .002, respectively, compared with controls) and among the subgroup of children who died after admission with severe malaria (OR, 0.60 and 0.37; 95% CI, 0.37-1.00 and 0.16-0.87; P = .05 and P = .02, respectively, compared with surviving case patients). The lowest ORs were seen for the forms of malaria associated with the highest mortality—coma and severe anemia complicated by deep, acidotic breathing. Our study supports the conclusion that both heterozygotes and homozygotes enjoy a selective advantage against death from Plasmodium falciparum malaria.

The α-thalassaemias are the commonest genetic disorders of humans. It is generally believed that this high frequency reflects selection through a survival advantage against death from malaria; nevertheless, the epidemiological description of the relationships between α-thalassaemia, malaria, and other common causes of child mortality remains incomplete. We studied the α⁺-thalassaemia-specific incidence of malaria and other common childhood diseases in two cohorts of children living on the coast of Kenya. We found no associations between α⁺-thalassaemia and the prevalence of symptomless Plasmodium falciparum parasitaemia, the incidence of uncomplicated P. falciparum disease, or parasite densities during mild or severe malaria episodes. However, we found significant negative associations between α⁺-thalassaemia and the incidence rates of severe malaria and severe anaemia (haemoglobin concentration < 50 g/l). The strongest associations were for severe malaria anaemia (> 10,000 P. falciparum parasites/μl) and severe nonmalaria anaemia; the incidence rate ratios and 95% confidence intervals (CIs) for α⁺-thalassaemia heterozygotes and homozygotes combined compared to normal children were, for severe malaria anaemia, 0.33 (95% CI, 0.15,0.73; p = 0.006), and for severe nonmalaria anaemia, 0.26 (95% CI, 0.09,0.77; p = 0.015). Our observations suggest, first that selection for α⁺-thalassaemia might be mediated by a specific effect against severe anaemia, an observation that may lead to fresh insights into the aetiology of this important condition. Second, although α⁺-thalassaemia is strongly protective against severe and fatal malaria, its effects are not detectable at the level of any other malaria outcome; this result provides a cautionary example for studies aimed at testing malaria interventions or identifying new malaria-protective genes.

Both the sickle cell trait (HbAS) and α⁺‐thalassaemia are common in many tropical areas. While their individual haematological effects are well described, few studies describe their effects when inherited together. We present data from the Kenyan coast, which suggest that HbAS and α⁺‐thalassaemia may interact to produce specific effects on haematological parameters. Overall, the difference in Hb concentrations between non‐thalassaemics (αα/αα) and α⁺‐thalassaemia homozygotes (−α/−α) was greater in non‐HbAS (HbAA) (0·63 g/dl) than in HbAS children (0·25 g/dl). HbAS also ameliorated both the reduced mean cell volume and mean cell haemoglobin normally associated with the −α/−α genotype. Potential mechanisms and implications are discussed.

Adolescents and young people are arguably the most dynamic and challenging group among populations living with HIV. The adherence to anti-retroviral treatment ( ART) is often low among HIV-positive youth, thus creative and context specific interventions are necessary. We aimed at evaluating the usability and effectiveness of the pilot digital peer support platform - ELIMIKA, implemented in Mombasa, Kenya. We applied a pre-post-test design. Data collection consisted of two parts: pre- and post-online knowledge and behavior questionnaires, and a mid-term usability survey. From 90 recruited participants, 81 completed the pre-and post-questionnaires. Overall, the participants were satisfied with the main features of the web platform and stated that they would use it again ( 95%). However, there was not a significant change in knowledge and behavior, but adherence intentions after 3 months intervention period have improved. This study provides valuable information on feasibility, evaluation and challenges of eHealth intervention in Kenya that supports further research in this area.