B cell analysis of ethnic groups in Mali with differential susceptibility to malaria

ABSTRACT: BACKGROUND: Several studies indicate that people of the Fulani ethnic group are less susceptible to malaria compared to those of other ethnic groups living sympatrically in Africa, including the Dogon ethnic group. Although the mechanisms of this protection remain unclear, the Fulani are known to have higher levels of Plasmodium falciparum-specific antibodies of all Ig classes as compared to the Dogon. However, the proportions of B cell subsets in the Fulani and Dogon that may account for differences in the levels of Ig have not been characterized. METHODS: In this cross-sectional study, venous blood was collected from asymptomatic Fulani (n=25) and Dogon (n=25) adults in Mali during the malaria season, and from P. falciparum-naive adults in the U.S. (n=8). At the time of the blood collection, P. falciparum infection was detected by blood-smear in 16% of the Fulani and 40% of the Dogon volunteers. Thawed lymphocytes were analysed by flow cytometry to quantify B cell subsets, including immature and naive B cells; plasma cells; and classical, activated, and atypical memory B cells (MBCs). RESULTS: The overall distribution of B cell subsets was similar between Fulani and Dogon adults, although the percentage of activated MBCs was higher in the Fulani group (Fulani: 11.07% [95% CI: 9.317 - 12.82]; Dogon: 8.31% [95% CI: 6.378 - 10.23]; P=0.016). The percentage of atypical MBCs was similar between Fulani and Dogon adults (Fulani: 28.3% [95% CI: 22.73 - 34.88]; Dogon: 29.3% [95% CI: 25.06 - 33.55], but higher than U.S. adults (U.S.: 3.0% [95% CI: -0.21 - 6.164]; P<0.001). Plasmodium falciparum infection was associated with a higher percentage of plasma cells among Fulani (Fulani infected: 3.3% [95% CI: 1.788 - 4.744]; Fulani uninfected: 1.71% [95% CI: 1.33 - 2.08]; P=0.011), but not Dogon adults. CONCLUSION: These data show that the malaria-resistant Fulani have a higher percentage of activated MBCs compared to the Dogon, and that P. falciparum infection is associated with a higher percentage of plasma cells in the Fulani compared to the Dogon, findings that may account for the higher levels of P. falciparum antibodies in the Fulani.     

Menstrual hut visits by Dogon women: a hormonal test distinguishes deceit from honest signaling

In humans the interests of males and females may conflict withrespect to the attribution of paternity. If a female has conceivedthrough adultery, or changes mates while she is in early pregnancy,she may protect her reproductive investment by misassigningpaternity. In Mali, West Africa, Dogon males attempt to preventfemale deception by mandating honest advertisement of menstruation(Strassmann, 1992). This advertisement takes place at a menstrualhut where women are on display to all the members of their husband'slineage. Knowledge of the timing of menstruation is pivotalbecause no other physiological event is as useful in paternityassessments. In this article I use hormonal data and a censusof menstrual hut visits to quantify female compliance with themenstrual taboos. The sample includes 93 women who providedurine samples twice weekly for 10 weeks. Analysis of urinarysteroid hormone metabolites (pregnanediol-3-glucuronide andestrone-3-glucuronide) demonstrates that the women went to themenstrual huts during 86% of all menses and, with the exceptionof one woman who may have been spotting, they never went tothe menstrual huts during pregnancy or amenorrhea. Thus themenstrual taboos of the Dogon were effective in eliciting honestsignals of female reproductive status (pregnant, amenorrheic,or cycling). This study is the first to use hormonal data totest the honesty of a human behavior in a nonlaboratory setting.It also establishes the feasibility of urinary enzyme immunoassaysas a tool for studying human reproduction in remote populations.[Behav Ecol 7: 304-315 (1996)]     

Associations between the IL-4 -590 T allele and Plasmodium falciparum infection prevalence in asymptomatic Fulani of Mali

In this study, we compared the genotype and allele frequencies of the IL-10 -1087 A/G and IL-4 -590 C/T single nucleotide polymorphisms in asymptomatic subjects of two sympatric ethnic tribes differing in susceptibility to malaria, the Fulani and the Dogon in Mali. The genotype data was correlated with ethnicity and malariometric indexes. A statistically significant inter-ethnic difference in allele and genotype frequency for both loci was noted (P<0.0001). Within the Fulani, the prevalence of Plasmodium falciparum infection, as detected by both microscopy and PCR, was associated with the IL-4 -590 T allele (P=0.005 and P=0.0005, respectively), whereas, no such associations were seen in the Dogon. Inter-ethnic differences in spleen rates, higher in the Fulani than the Dogon, were seen between T carriers (TT and CT) of both groups (P<0.0001). Parasite densities and number of concurrent clones did not vary between IL-4 genotypes within any of the studied groups. These results suggest an association between the IL-4 -590 T allele and P. falciparum prevalence within the Fulani but not the Dogon. No associations between IL-10 genotypes and studied malariometric indexes were observed in any of the two communities.     

A new polymorphism of thyroxin-binding globulin in three African groups (Mali) with endemic nodular goitre

Summary The thyroxin-binding globulin (TBG) polymorphism was investigated in three African groups: two belonged to the Bwa villages of Mali, and the third was a Dogon group living in the same area. The Bwa groups were characterized by the occurrence of nodular goitres, whereas the Dogon population did not show similar pathological symptoms. Females were more affected by goitre than males in the affected villages. The TBG polymorphism enabled us to demonstrate the presence of an undescribed allele (TBG C1) in these populations. The frequency of the TBG S allele was also higher than previously published in other African groups. We observed a disequilibrium in the distribution of the C and S alleles in the population, with an excess of homozygous TBG S individuals. No clear relationship between the TBG polymorphism and the number of nodules can be drawn.     

Genetic origins of the Dogon population in the Arrondissement of Boni (Mali).

A study of probabilities of origin of genes was carried out on a Dogon population in Mali, spread over four massifs separated from each other by about 20 kilometers. Within each village, the founder contributions are very disparate and show that each village has a very specific origin. Therefore, the exchange of wives between massifs has not resulted in a homogenization of the population, which has remained strongly structured into four relatively independent isolates.     

Endogamy among the Dogon of Boni, Mali

This paper examines factors influencing endogamy in a Dogon population in Mali. Situated in Boni district, this population of about 5000 individuals is distributed over fifteen villages located on four independent massifs. This population is strongly endogamous (only 4% of all marriages are contracted with neighbouring ethnic groups), and each massif shows high endogamy. The roles of lineage, residence in the same village, and geographical distance in mating choice are examined. These different factors are successively analysed using log-linear statistical models and the results offer a more precise interpretation of endogamy in this population.     

Different antibody- and cytokine-mediated responses to Plasmodium falciparum parasite in two sympatric ethnic tribes living in Mali

The Fulani are known to be less susceptible to Plasmodium falciparum malaria infections and to have lower parasitaemia despite living under similar malaria transmission intensity compared with other ethnic tribes. The aim of the present study was to examine whether the Fulani were more polarised towards Th2 as reflected by higher numbers of malaria-specific IL-4- and IL-10-producing cells and lower numbers of IFN-gamma- and IL-12-producing cells as compared to their neighbour ethnic tribe, the Dogon of Mali. Total IgE and both anti-malaria IgE and IgG antibodies were measured by ELISA and the numbers of IL-4-, IFN-gamma-, IL-10- and IL-12-producing cells were enumerated using enzyme-linked ImmunoSpot assay (ELISPOT). Numbers of parasite clones were detected by polymerase chain reaction (PCR). The study was performed outside the transmission period and all individuals included were asymptomatic. The results revealed that the Fulani were less parasitised, had fewer circulating parasite clones in their blood, had significantly higher anti-malaria IgG and IgE antibodies and higher proportions of malaria-specific IL-4- and IFN-gamma-producing cells compared to the Dogon. The higher antigen-specific production of IL-4 among the Fulani was statistically significant both before and after adjustment for level of spontaneous cytokine production, while greater IFN-gamma production only attained statistical significance after adjustment for spontaneous levels. Taken together, the association of higher anti-malarial IgE and IgG antibodies and increased numbers of specific IL-4- and IFN-gamma-producing cells compared to the ethnic sympatric tribe, the Dogon, may assist in explaining the lower susceptibility to malaria observed in the Fulani.     

A recovery story that heals

It is one thing to talk about intergenerational trauma and substance abuse in general terms, and quite another to get an experiential sense of what it is like for someone dealing with it firsthand. In a profoundly courageous presentation, Mabel Kudralook Smith, who is originally from Barrow, presents her personal story. She takes to heart the notion that to heal, you have to talk about those matters that are causing you pain. Such accounts are healing because they allow the storyteller to pull together a coherent narrative that helps make sense of what she or he has experienced. The narratives often provide a sense of release as the teller is no longer expending energy on keeping personal or family secrets and being ashamed. Such stories are also healing for the audience, because they allow others, through the sharing of experience, to better understand what the speaker has endured and learned. If the listeners have faced similar issues, the narratives can inspire them to embark on or persist in their own similar journies.     

Life-history theory, fertility and reproductive success in humans

According to life-history theory, any organism that maximizes fitness will face a trade-off between female fertility and offspring survivorship. This trade-off has been demonstrated in a variety of species, but explicit tests in humans have found a positive linear relationship between fitness and fertility. The failure to demonstrate a maximum beyond which additional births cease to enhance fitness is potentially at odds with the view that human fertility behaviour is currently adaptive. Here we report, to our knowledge, the first clear evidence for the predicted nonlinear relationship between female fertility and reproductive success in a human population, the Dogon of Mali, West Africa. The predicted maximum reproductive success of 4.1+/-0.3 surviving offspring was attained at a fertility of 10.5 births. Eighty-three per cent of the women achieved a lifetime fertility level (7-13 births) for which the predicted mean reproductive success was within the confidence limits (3.4 to 4.8) for reproductive success at the optimal fertility level. Child mortality, rather than fertility, was the primary determinant of fitness. Since the Dogon people are farmers, our results do not support the assumptions that: (i) contemporary foragers behave more adaptively than agriculturalists, and (ii) that adaptive fertility behaviour ceased with the Neolithic revolution some 9000 years ago. We also present a new method that avoids common biases in measures of reproductive success.     

Blacks as me: narrative identity

This commentary responds to genetic testing of African ancestry through a series of personal narratives that reveal a complex, intimate, and individualised process of identity formation. The author discusses both how her family and others outside her family have fostered and challenged her sense of black identity. She concludes by maintaining that racial identity is not in the genes but in the world in which we live and the stories we construct and are able to maintain.     

The function of menstrual taboos among the dogon

Menstrual taboos are nearly ubiquitous and assume parallel forms in geographically distant populations, yet their function has baffled researchers for decades. This paper proposes that menstrual taboos are anticuckoldry tactics. By signaling menstruation, they may advertise female reproductive status to husbands, affines, and other observers. Females may therefore have difficulty in obfuscating the timing of the onset of pregnancy. This may have three consequences: (a) males are better able to assess their probabilities of paternity and to direct their parental investment toward genetic offspring; (b) adulterous pregnancies are more easily detected and penalized, enhancing sexual fidelity; and (c) males avoid marrying pregnant females by relying on menstruation as evidence of nonpregnancy. This hypothesis is tested with 29 months of field data on menstrual taboos among the Dogon of Mali. Key results include the following: (a) cuckoldry is a major Dogon concern, (b) menstrual huts advertise female reproductive status, (c) husbands impose the taboos upon their wives, (d) female defiance of the taboos is undetectable and probably rare, and (e) informants think that the taboos help husbands and patrilineages to avoid cuckoldry. Thus the anti-cuckoldry hypothesis provides helpful insight into the menstrual taboos of the Dogon and should be tested among other populations. This research was supported by The Evolution and Human Behavior Program at the University of Michigan (through Dick Alexander), the L.S.B. Leakey Foundation, and the National Science Foundation (BNS-8612291). Beverly Strassmann is a National Institutes of Health postdoctoral fellow at the Reproductive Sciences Program, University of Michigan. Her primary research interest is human evolutionary ecology, with recent emphasis on menstruation in natural fertility populations, the effect of polygyny on female fitness, and reproductive endocrinology.     

Baobab (<Emphasis Type="Italic">Adansonia digitata</Emphasis> L.) and Tamarind (<Emphasis Type="Italic">Tamarindus indica</Emphasis> L.) Management Strategies in the Midst of Conflict and Change: A Dogon Case Study from Mali

The tree management practices of a Dogon village in Mali, West Africa were investigated to learn how a rural population adapts its strategies to cope with institutional change, climate change, unequal land distribution, and expanding market access. A range of methodologies was used, including semi-structured interviews, seasonal calendars, community mapping and matrices. Special focus was given to baobab (Adansonia digitata L.) and tamarind (Tamarindus indica L.), two highly used and valuable trees within this community. This research reveals that community members have realized that traditional management practices are no longer effective in dealing with the impacts of these transitions, and highlights the fact that management practices, while historically uniform, have begun to diverge in recent years based on unequal land and water endowments within the village. Understanding the rights and abilities of all users to access and protect these species is crucial to their conservation.     

Giving an Account of One’s Pain in the Anthropological Interview

In this paper, I analyze the illness stories narrated by a mother and her 13-year-old son as part of an ethnographic study of child chronic pain sufferers and their families. In examining some of the moral, relational and communicative challenges of giving an account of one’s pain, I focus on what is left out of some accounts of illness and suffering and explore some possible reasons for these elisions. Drawing on recent work by Judith Butler (Giving an Account of Oneself, 2005), I investigate how the pragmatic context of interviews can introduce a form of symbolic violence to narrative accounts. Specifically, I use the term “genre of complaint” to highlight how anthropological research interviews in biomedical settings invoke certain typified forms of suffering that call for the rectification of perceived injustices. Interview narratives articulated in the genre of complaint privilege specific types of pain and suffering and cast others into the background. Giving an account of one’s pain is thus a strategic and selective process, creating interruptions and silences as much as moments of clarity. Therefore, I argue that medical anthropologists ought to attend more closely to the institutional structures and relations that shape the production of illness narratives in interview encounters.     

Interethnic differences in antigen-presenting cell activation and TLR responses in Malian children during Plasmodium falciparum malaria

The Fulani ethnic group from West Africa is relatively better protected against Plasmodium falciparum malaria as compared to other sympatric ethnic groups, such as the Dogon. However, the mechanisms behind this lower susceptibility to malaria are largely unknown, particularly those concerning innate immunity. Antigen-presenting cells (APCs), and in particular dendritic cells (DCs) are important components of the innate and adaptive immune systems. Therefore, in this study we investigated whether APCs obtained from Fulani and Dogon children exhibited differences in terms of activation status and toll-like receptor (TLR) responses during malaria infection. Lower frequency and increased activation was observed in circulating plasmacytoid DCs and BDCA-3+ myeloid DCs of infected Fulani as compared to their uninfected counterparts. Conversely, a higher frequency and reduced activation was observed in the same DC subsets obtained from peripheral blood of P. falciparum-infected Dogon children as compared to their uninfected peers. Moreover, infected individuals of both ethnic groups exhibited higher percentages of both classical and inflammatory monocytes that were less activated as compared to their non-infected counterparts. In line with APC impairment during malaria infection, TLR4, TLR7 and TLR9 responses were strongly inhibited by P. falciparum infection in Dogon children, while no such TLR inhibition was observed in the Fulani children. Strikingly, the TLR-induced IFN-γ release was completely abolished in the Dogon undergoing infection while no difference was seen within infected and non-infected Fulani. Thus, P. falciparum infection is associated with altered activation status of important APC subsets and strongly inhibited TLR responses in peripheral blood of Dogon children. In contrast, P. falciparum induces DC activation and does not affect the innate response to specific TLR ligands in Fulani children. These findings suggest that DCs and TLR signalling may be of importance for the protective immunity against malaria observed in the Fulani.     

The ‘successful’ return: Caribbean narratives of migration,family, and gender

Research on female migrant caregivers has tended to focus upon the emotional and social problems they encounter working abroad, given women's traditional role as caregivers for their own families. This article analyses how Caribbean women who have returned after a period abroad as domestic workers inscribe their migration experiences within the gendered narrative of the good relative who migrates to help the family left behind and therefore deserves social recognition in the community of origin. It argues that this narrative allows the women to both affirm and reinterpret local family and gender roles within the context of migration. This analysis points to the close connection between narrative structures, accounts of migration experiences, and self‐presentations and suggests that narratives about family and gender roles not only reflect people's lives, but are also a malleable resource that can be (re)shaped to validate a variety of life‐courses.     

Demographic anthropology in the study of matrimonial exchanges in a Dogon isolate

The Dogon population of Boni lives in the south-Sahelian bush of Mali, on several abrupt mountains. It forms a community within which each of its members finds a spouse. This criterion of membership is based on a concept of population taken in the “genetic sense”. This population is small (5000 persons approximately) and it forms a genetic isolate. Matrimonial exchanges are very important in the process of evolution of populations thus it can be useful to construct explanatory models. Different analysis levels allow to better describe a phenomenon resulting from a complex system of interdependent factors.

-the global analysis is quantitative and shows the high endogamic level observed within each village and each mountain,

-the qualitative analysis, motivated by a genetic study associated to criteria of choice of the spouse.

-an anthropological analysis will be presented as a third possible level in the matrimonial market analysis. It consists of investigating alliance cycles based on the study of brother-sister pairs and implying three marriages. The high frequency of the type of cycle raises questions and incites to researching a coherent interpretation.

     

Actions,Action Sequences and Habits: Evidence That Goal-Directed and Habitual Action Control Are Hierarchically Organized

Behavioral evidence suggests that instrumental conditioning is governed by two forms of action control: a goal-directed and a habit learning process. Model-based reinforcement learning (RL) has been argued to underlie the goal-directed process; however, the way in which it interacts with habits and the structure of the habitual process has remained unclear. According to a flat architecture, the habitual process corresponds to model-free RL, and its interaction with the goal-directed process is coordinated by an external arbitration mechanism. Alternatively, the interaction between these systems has recently been argued to be hierarchical, such that the formation of action sequences underlies habit learning and a goal-directed process selects between goal-directed actions and habitual sequences of actions to reach the goal. Here we used a two-stage decision-making task to test predictions from these accounts. The hierarchical account predicts that, because they are tied to each other as an action sequence, selecting a habitual action in the first stage will be followed by a habitual action in the second stage, whereas the flat account predicts that the statuses of the first and second stage actions are independent of each other. We found, based on subjects'' choices and reaction times, that human subjects combined single actions to build action sequences and that the formation of such action sequences was sufficient to explain habitual actions. Furthermore, based on Bayesian model comparison, a family of hierarchical RL models, assuming a hierarchical interaction between habit and goal-directed processes, provided a better fit of the subjects'' behavior than a family of flat models. Although these findings do not rule out all possible model-free accounts of instrumental conditioning, they do show such accounts are not necessary to explain habitual actions and provide a new basis for understanding how goal-directed and habitual action control interact.     

Painful languages of the body: experiences of headache among women in two peruvian communities

This exploratory study focuses on the understandings of and experiences with headache in two settings in Peru: the Quechua-speaking district of Ayacucho, in southern Peru, and a poor urban district of Lima Metropolitana. More specifically, it explores the personal and collective meanings constructed around women’s headache experiences. Structured and open-ended interviews were administered to patients suffering headache to elicit interpretations of headache episodes. An analysis of the collected narratives suggests that headache is often comprehended in a polysemic framework, where meanings ascribed in bodily, emotional, family, and social terms articulate individual and shared notions of suffering within larger contexts of social dislocation. Often woven into experiences of solitude, headache accounts are lived and told in dynamic temporal spaces, and narrate dissolution of family ties and tensions associated with women’s roles. The results underscore the significance of patients’ subjective interpretations of painful experiences and underscore the connections between bodily and emotional pain and distress experienced at family, community, and larger social levels.     

Growing up abroad: Italian and Romanian migrants’ partial transitions to adulthood

Drawing on in-depth interviews with young Italians and Romanians, representing two of the largest “old” and “new” European populations in Britain, this paper examines migrants’ experiences in the spheres of work, family and “home”, and their narratives of “growing up” abroad, to enhance our understanding of youth transitions to adulthood in the context of intra-EU migration. Contrary to accounts that see migration as a strategy to either delay or advance adulthood, our analysis offers a more complex picture, showing how migration may unevenly affect transitions to adulthood, advancing some, and delaying others. Furthermore, we extend debates around the meaning of adulthood, illustrating the central role migration plays in generating feelings of “growing up”, even when traditional markers of adulthood are absent, and how these are negotiated transnationally in relation to home-based peers, in ways that combine old and new understandings of adulthood.     

Farmer Choice of Sorghum Varieties in Southern Mali

In southern Mali and throughout the semiarid tropics, small-scale family farmers are faced with the challenge of producing adequate harvests in difficult biophysical and socioeconomic environments. Professional plant breeders have had much difficulty developing modern varieties that outperform farmers’ traditional varieties in these environments, in part because of an incomplete understanding of why farmers choose the varieties they grow. Improved understanding of farmers’ varietal choices can contribute to collaboration between farmers and formal plant breeders. Based on a 15-month field study in Dissan, Mali, we examine farmer's choices among their traditional sorghum varieties in terms of one or more than one variety, and short-cycle or long-cycle varieties, and the interaction between these two choices. Results support our general hypothesis that farmers choose varieties to optimize outputs in the face of variation in the growing environment and in human managed inputs such as labor and tools.