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Comparative data on the distribution of non-Hodgkin lymphoma (NHL) subtypes in Southern Africa (SAF) is scarce. In this study, five expert haematopathologists classified 487 consecutive cases of NHL from SAF using the World Health Organization classification, and compared the results to North America (NA) and Western Europe (WEU). Southern Africa had a significantly lower proportion of low-grade (LG) B-NHL (34·3%) and a higher proportion of high-grade (HG) B-NHL (51·5%) compared to WEU (54·5% and 36·4%) and NA (56·1% and 34·3%). High-grade Burkitt-like lymphoma was significantly more common in SAF (8·2%) than in WEU (2·4%) and NA (2·5%), most likely due to human immunodeficiency virus infection. When SAF patients were divided by race, whites had a significantly higher frequency of LG B-NHL (60·4%) and a lower frequency of HG B-NHL (32·7%) compared to blacks (22·5% and 62·6%), whereas the other races were intermediate. Whites and other races had a significantly higher frequency of follicular lymphoma and a lower frequency of Burkitt-like lymphoma compared to blacks. The median ages of whites with LG B-NHL, HG B-NHL and T-NHL (64, 56 and 67 years) were significantly higher than those of blacks (55, 41 and 34 years). Epidemiological studies are needed to better understand these differences., (© 2015 John Wiley & Sons Ltd.)

We address the problem of comparing interindividual genomic sequence diversity between two populations. Although the methods are general, for concreteness we focus on comparing two human immunodeficiency virus (HIV) infected populations. From a viral isolate(s) taken from each individual in a sample of persons from each population, suppose one or multiple measurements are made on the genetic sequence of a coding region of HIV. Given a definition of genetic distance between sequences, the goal is to test if the distribution of interindividual distances differs between populations. If distances between all pairs of sequences within each group are used, then data-dependencies arising from the use of multiple sequences from individuals invalidates the use of a standard two-sample test such as the t-test. Where this problem has been recognized, a typical solution has been to apply a standard test to a reduced dataset comprised of one sequence or a consensus sequence from each patient. Disadvantages of this procedure are that the conclusion of the test depends on the choice of utilized sequences, often an arbitrary decision, and exclusion of replicate sequences from the analysis may needlessly sacrifice statistical power. We present a new test free of these drawbacks, which is based on a statistic that linearly combines all possible standard test statistics calculated from independent sequence subsamples. We describe statistical power advantages of the test and illustrate its use by application to nucleotide sequence distances measured from HIV-1 infected populations in southern Africa (GenBank accession numbers AF110959--AF110981) and North America/Europe. The test makes minimal assumptions, is maximally efficient and objective, and is broadly applicable.

We review here the epidemiologic and clinical aspects of tropical spastic paraparesis, human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy (TSP/HAM) as observed in Europe and in Africa. Europe is not an endemic region for HTLV-I (seroprevalence in blood donors, < 0.03%), and TSP/HAM is thus rarely observed in European countries. Most of the few patients suffering from TSP/HAM are first- or second-generation immigrants from HTLV-I endemic areas (mostly the West Indies), and the clinicoepidemiologic aspects of these patients are similar to those seen in endemic areas. However, rare cases occur in European-born subjects with or without risk factors for HTLV-I infection, which raises the possibility of limited foci areas in Europe. Although Africa is considered as a primary HTLV-I endemic area, with at least a few million infected inhabitants, epidemiologic data on the situation of TSP/HAM in Africa remain scarce. Relatively few cases of patients with TSP/HAM have been reported in Africa, including some clusters in Zaire (prevalence, 50/100,000) and in South Africa and sporadically in the main cities of some Western, Central, and Eastern African countries. The paucity of clinical and epidemiologic data on TSP/HAM may be linked to several factors, including the paucity of neurologists, the lack of laboratory and radiologic facilities, and the chronicity of the disease, along with the limited number of field epidemiologic studies performed on this topic and the wide diversity of causes (toxic, nutritional, and infectious) of chronic myelopathies as seen on the African continent.

The association between normal alleles at the CTG repeat and two nearby polymorphisms in the myotonin protein kinase gene, the Alu insertion/deletion polymorphism and the myotonic dystrophy kinase (DMK)(G/T) intron 9/HinfI polymorphism, has been analyzed in South African Negroids, a population in which myotonic dystrophy (DM) has not been described. South African Negroids have a CTG allelic distribution that is significantly different from that in Caucasoids and Japanese: the CTG repeat lengths of > or = 19 are very rare. The striking linkage disequilibrium between specific alleles at the Alu polymorphism (Alu(ins) and Alu(del)), the HinfI polymorphism (HinfI-1 and HinfI-2), and the CTG repeat polymorphism seen in Caucasoid (Europeans and Canadians) populations was also found in the South African Negroid population. Numerous haplotypes, not previously described in Europeans, were, however, found. It thus seems likely that only a small number of these "African" chromosomes were present in the progenitors of all non-African peoples. These data provide support for the "out of Africa" model for the origin of modern humans and suggest that the rare ancestral DM mutation event may have occurred after the migration from Africa, hence the absence of DM in sub-Saharan Negroid peoples.

A mathematical model was developed to assess the effect of various assumed prevalence rates of maternal human immunodeficiency virus (HIV) infection on perinatally acquired HIV infections and child survival. The model indicates that for children younger than 5 years, countries with low baseline mortality rates will experience greater relative increases in child mortality rates and larger proportions of HIV-caused deaths in children than countries with high mortality rates. It also suggests that perinatal HIV infection could become the most common cause of deaths in children in the developed world if maternal infection rates reach 2% to 3%. Rates of 25% to 30% would be needed to produce a similar effect in the developing world. Child survival gains in the last three decades in the developed world could be quickly erased at low levels of maternal HIV infection, but gains would not be completely offset in the developing world until more than 40% of mothers became infected with HIV. When basic demographic information and the maternal HIV infection rate are known, the model permits a direct assessment of infant and child mortality caused by HIV. It can also be used to estimate the prevalence of maternal HIV infection when values for all other variables are known.