Combined Utilisation of Rapid Assessment Procedures for Loiasis (RAPLOA) and Onchocerciasis (REA) in Rain forest Villages of Cameroon

BACKGROUND: Individuals with high microfilarial loads of Loa loa are at increased risk of neurologic serious adverse (SAE) events following ivermectin treatment against onchocerciasis. RAPLOA (Rapid Assessment Procedure for loiasis), a newly developed rapid assessment procedure for loiasis that relates the prevalence of key clinical manifestation of loiasis (history of eye worm) to the level of endemicity of the infection (prevalence of high intensity), is a very useful tool to identify areas at potential risk of L. loa post ivermectin treatment encephalopathy. In a perspective of treatment decision making in areas of co-endemicity of loiasis/onchocerciasis, it would be advantageous (both in time and cost savings) for national onchocerciasis control programmes to use RAPLOA and the Rapid epidemiologic assessment for onchocerciasis (REA), in combination in given surveys. Since each of the two rapid assessment tools have their own specificities, the workability of combining the two methods needed to be tested. METHODS: We worked in 10 communities of a forest area presumed co-endemic for loiasis and onchocerciasis in the North-West Province of Cameroon where the mass-treatment with ivermectin had not been carried out. A four-step approach was used and comprised: (i) generating data on the prevalence and intensity of loiasis and onchocerciasis in an area where such information is scarce; (ii) testing the relationship between the L. loa microfilaraemia prevalence and the RAPLOA prevalence, (iii) testing the relationship between the O. volvulus microfiladermia prevalence and the REA prevalence, (iv) testing the workability of combining RAPLOA/REA by study teams in which a single individual can perform the interview for RAPLOA and the nodule palpation for REA. RESULTS: The microfilaraemia prevalence of loiasis in communities ranged from 3.6% to 14.3%. 6 (0.61%) individuals had L. loa microfilarial loads above 8000 mf/ml but none of them attained 30,000 mf/ml, the threshold value above which the risk of developing neurologic SAE after ivermectin treatment is very high. None of the communities surveyed had RAPLOA prevalence above 40%. All the communities had microfiladermia prevalence above 60%. The microfiladermia results could be confirmed by the rapid epidemiologic method (nodule palpation), with all the 10 communities having REA prevalence above 20%. For the first time, this study has demonstrated that the two rapid assessment procedures for loiasis and onchocerciasis can be carried out simultaneously by a survey team, in which a single individual can administer the questionnaire for RAPLOA and perform the nodule palpation for REA. CONCLUSION: This study has: (i) Revealed that the Momo valley of the North West province of Cameroon is hyperendemic for onchocerciasis, but is of lower level of endemicity for L. loa. (ii) Confirmed the previous relationships established between RAPLOA and the L. loa microfilaraemia prevalence in one hand and between the REA and the O. volvulus microfiladermia prevalence in another hand (iii) Shown that RAPLOA and REA could be used simultaneously for the evaluation of loiasis and onchocerciasis endemicity in areas targeted by the African Programme for onchocerciasis Control for community-directed treatment with ivermectin (CDTI).     

PKLR- GBA region shows almost complete linkage disequilibrium over 70 kb in a set of worldwide populations

Haplotype diversity in a genomic region of approximately 70 kb in 1q21 between genes PKLR and GBA was characterized by typing one single nucleotide polymorphism (SNP) in PKLR, two SNPs in GBA and one short tandem repeat polymorphism (STRP) in PKLR in 1792 chromosomes from 17 worldwide populations. Two other SNPs in GBA were typed in three African populations. Most chromosomes carried one of either two phylogenetically distinct haplotypes with different alleles at each site. Allele diversity at the STRP was tightly linked to haplotype background. Linkage disequilibrium (LD) was highly significant for all SNP pairs in all populations, although it was, on average, slightly higher in non-African populations than in sub-Saharan Africans. Variation at PKLR-GBA was also tightly linked to that at the GBA pseudogene, 16 kb downstream from GBA. Thus, a 90 kb-long LD block was observed, which points to a low recombination rate in this region. Detailed haplotype phylogeny suggests that the chimpanzee GBA haplotype is not one of the two most frequent haplotypes. Based on variability at the PKLR STRP and on the geographical distribution of LD, the expansion of the two main haplotypes may have predated the "Out of Africa" expansion of anatomically modern humans. LD and STRP variability in non-Africans are approximately 87% of those in Africans, in contrast with other loci; this implies that the "out of Africa" bottleneck may have had a broad distribution of effects across loci.     

The analysis of variation of mtDNA hypervariable region 1 suggests that Eastern and Western Pygmies diverged before the Bantu expansion

The Eastern Pygmies from Zaire and Western Pygmies from Cameroon, Congo, and the Central African Republic represent the two principal groups of African Pygmies. In the "recent divergence" hypothesis in which Western Pygmies are thought to be the result of hybridization between the ancestors of Eastern Pygmies and Bantu farmers who penetrated the equatorial belt and came into contact with Pygmies around 2-3 kiloyears ago. On the basis of recent archaeological research in the tropical rain forest, we propose a "pre-Bantu divergence" hypothesis, which posits the separation between the ancestors of Eastern and Western Pygmies earlier than 18 kiloyears ago. In order to test the two hypotheses, we analyzed the variation of the hypervariable region 1 of the mitochondrial DNA in the Mbenzele, Western Pygmies of the Central African Republic, and compared our results with those of previous mtDNA and Y chromosome studies. Distribution, sequence variation, and age of haplogroups along with genetic distances among populations, estimates of divergence times, and simulations based on the coalescent approach were found to be congruent with the pre-Bantu divergence but failed to support the recent divergence hypothesis.     

Blood biochemistry reflects seasonal nutritional and reproductive constraints in the eurasian badger (Meles meles)

Physiological responses to nutritional and reproductive constraints were explored in a wild population of Eurasian badgers (Meles meles) inhabiting Wytham Woods, Oxfordshire, United Kingdom. We compared seasonal blood levels of lipid and protein compounds to variables describing the sex, age, body condition, wounds, testes position, and flea abundance of the badgers. We found seasonal variations in albumin/globulins and urea/creatinine ratios matched by differences in body condition. High creatinine, urea, and triglycerides levels were obtained in animals in poor nutritional condition and with low levels of body fat. The maintenance of urea/creatinine ratios indicates that the badger does not demonstrate a stage of protein conservation in periods of food scarcity during the summer or periods of cold weather. Hypercholesterolaemia, especially in fat animals, was confirmed. We also offer baseline levels of metabolites commonly used in clinical biochemistry for their further use in the analysis of the status and the management of wild badger populations.     

Geographic patterns of mtDNA diversity in Europe

Genetic diversity in Europe has been interpreted as a reflection of phenomena occurring during the Paleolithic ( approximately 45,000 years before the present [BP]), Mesolithic ( approximately 18,000 years BP), and Neolithic ( approximately 10,000 years BP) periods. A crucial role of the Neolithic demographic transition is supported by the analysis of most nuclear loci, but the interpretation of mtDNA evidence is controversial. More than 2,600 sequences of the first hypervariable mitochondrial control region were analyzed for geographic patterns in samples from Europe, the Near East, and the Caucasus. Two autocorrelation statistics were used, one based on allele-frequency differences between samples and the other based on both sequence and frequency differences between alleles. In the global analysis, limited geographic patterning was observed, which could largely be attributed to a marked difference between the Saami and all other populations. The distribution of the zones of highest mitochondrial variation (genetic boundaries) confirmed that the Saami are sharply differentiated from an otherwise rather homogeneous set of European samples. However, an area of significant clinal variation was identified around the Mediterranean Sea (and not in the north), even though the differences between northern and southern populations were insignificant. Both a Paleolithic expansion and the Neolithic demic diffusion of farmers could have determined a longitudinal cline of mtDNA diversity. However, additional phenomena must be considered in both models, to account both for the north-south differences and for the greater geographic scope of clinical patterns at nuclear loci. Conversely, two predicted consequences of models of Mesolithic reexpansion from glacial refugia were not observed in the present study.     

RELATIONSHIPS BETWEEN PHOTOSYNTHETIC CAPACITY AND LEAF STRUCTURE IN SEVERAL SHADE PLANTS

Leaf structure, photosynthetic characteristics and related physiological parameters have been studied in three ornamental shade species: Fatsia japonica, Cissus rhombifolia (relatively light-tolerant plants), and Philodendron scandens (obligate shade plant). Species were grown in a shadehouse. Maximum photosynthetic photon flux density was 470 μmol m^-2 s^-1. Net rate of CO₂ uptake at light saturation (maximum Pn) in Fatsia was 6.90 ± 1.27 μmol m^-2 s^-1. In Cissus and Philodendron values were about 30% and 63% less respectively, than those measured in Fatsia. The nitrogen content, relative dry wt, specific leaf dry wt (SLDW), chlorophyll a/b ratio, and nitrogen to chlorophyll ratio were lower in Philodendron. However, leaf thickness in Philodendron (296 ± 17 μm) was about 54% and 160% higher, respectively, than in Fatsia and Cissus, and the ratio between mesophyll cell area and leaf surface area (A^mes/A) was nearly similar in the three species. However Philodendron exhibited a percentage of palisade parenchyma about three times lower than that observed in the two other species. The chloroplast number per mm of cell wall in transverse sections (chloroplast density) in the palisade parenchyma was fairly constant (about 65), irrespective of species. The “chloroplast density” in the spongy parenchyma of Philodendron was about 53% and 63%, respectively, of Fatsia and Cissus values. In Fatsia and Cissus chloroplast ultrastructure seems to change gradually and continuously from sun to shade type with the depth from the adaxial to abaxial surface. Special emphasis was given in order to determine the structural parameters best correlated with maximum Pn between the different species. In this way chloroplast number in transverse sections (chloroplast number) and the ratio between chloroplast area and leaf surface area (A^chl/A) were the parameters best correlated with maximum Pn, and stomatal frequency was also a good determinant of maximum Pn. However, leaf thickness, SLDW, and even A^mes/A ratio were weakly correlated with maximum Pn.     

Staphylococcus prevails in the skin microbiota of long-term immunodeficient mice

Host-commensal relationships in the skin are a complex system governed by variables related to the host, the bacteria and the environment. A disruption of this system may lead to new steady states, which, in turn, may lead to disease. We have studied one such disruption by characterizing the skin microbiota in healthy and immunodepressed (ID) mice. A detailed anatomopathological study failed to reveal any difference between the skin of healthy and ID mice. We sequenced the 16S rDNA V1-V2 gene region to saturation in 10 healthy and 10 ID 8 week-old mice, and found than all of the healthy and two of the ID mice had bacterial communities that were similar in composition to that of human skin, although, presumably because of the uniform raising conditions, less interindividual variation was found in mice. However, eight ID mice showed microbiota dominated by Staphylococcus epidermidis. Quantitative PCR amplification of 16S rDNA gene and of the Staphylococcus-specific TstaG region confirmed the previous results and indicated that the quantitative levels of Staphylococcus were similar in both groups while the total number of 16S copies was greater in the healthy mice. Thus, it is possible that, under long-term immunodeficiency, which removes the acquired but not the native immune system, S.epidermidis may inhibit the growth of other bacteria but does not cause a pathogenic state.