Cutaneous leishmaniasis in Tupí-Mondé Amerindians from the Brazilian Amazonia

Sex bias in infectious disease epidemiology: patterns and processes

BACKGROUND

Infectious disease incidence is often male-biased. Two main hypotheses have been proposed to explain this observation. The physiological hypothesis (PH) emphasizes differences in sex hormones and genetic architecture, while the behavioral hypothesis (BH) stresses gender-related differences in exposure. Surprisingly, the population-level predictions of these hypotheses are yet to be thoroughly tested in humans.

METHODS AND FINDINGS

For ten major pathogens, we tested PH and BH predictions about incidence and exposure-prevalence patterns. Compulsory-notification records (Brazil, 2006-2009) were used to estimate age-stratified ♂:♀ incidence rate ratios for the general population and across selected sociological contrasts. Exposure-prevalence odds ratios were derived from 82 published surveys. We estimated summary effect-size measures using random-effects models; our analyses encompass ∼0.5 million cases of disease or exposure. We found that, after puberty, disease incidence is male-biased in cutaneous and visceral leishmaniasis, schistosomiasis, pulmonary tuberculosis, leptospirosis, meningococcal meningitis, and hepatitis A. Severe dengue is female-biased, and no clear pattern is evident for typhoid fever. In leprosy, milder tuberculoid forms are female-biased, whereas more severe lepromatous forms are male-biased. For most diseases, male bias emerges also during infancy, when behavior is unbiased but sex steroid levels transiently rise. Behavioral factors likely modulate male-female differences in some diseases (the leishmaniases, tuberculosis, leptospirosis, or schistosomiasis) and age classes; however, average exposure-prevalence is significantly sex-biased only for Schistosoma and Leptospira.

CONCLUSIONS

Our results closely match some key PH predictions and contradict some crucial BH predictions, suggesting that gender-specific behavior plays an overall secondary role in generating sex bias. Physiological differences, including the crosstalk between sex hormones and immune effectors, thus emerge as the main candidate drivers of gender differences in infectious disease susceptibility.

The failure of pharmaceuticals and the power of plants: medicinal discourse as a critique of modernity in the Amazon

This paper examines how caregivers' medicinal discourse serves as an indirect critique of modernization, urbanization and development in the Brazilian Amazon. When caregivers in two peri-urban neighborhoods, Triunfo and Bairro da Luz, discuss medicinal plants they highlight the positive aspects of phytotherapy and associate it with traditional rural lifestyles. In contrast, they tend to emphasize the shortcomings of pharmaceuticals, which they link to modernity and urbanization. This discourse, which juxtaposes plants/tradition/positive with pharmaceuticals/modern/negative, contains counterhegemonic commentary about the failures of modernization, urbanization and development. While state sponsored development was supposed to bring prosperity to the Amazon, for many residents, like those in Bairro de Luz and Triunfo, it did not. In fact, some say development made their lives worse, claiming that poverty and poor health are among the prices they have paid. Due to the shortcomings of modernization and urbanization in other areas of their life, caregivers are ambivalent about biomedicine and the pharmaceuticals they associate with it. Moreover, because medicinal plant remedies embody traditional values, asserting they are stronger, more potent, better and more effective, especially in an urban context, is a moral commentary on the shortcomings of modernity. Finally, by insisting that traditional plant remedies are better at curing the health problems that result from modern, urban lifestyles, they are subtly asserting the superiority of tradition over modernity.

Leishmanial antigens in the diagnosis of active lesions and ancient scars of American tegumentary leishmaniasis patients

Cutaneous biopsies (n = 94) obtained from 88 patients with American tegumentary leishmaniasis were studied by conventional and immunohistochemical techniques. Specimens were distributed as active lesions of cutaneous leishmaniasis (n = 53) (Group I), cicatricial lesions of cutaneous leishmaniasis (n = 35) (Group II) and suggestive scars of healed mucosal leishmaniasis patients (n = 6) (Group III). In addition, active cutaneous lesions of other etiology (n = 24) (Group C1) and cutaneous scars not related to leishmaniasis (n = 10) (Group C2) were also included in the protocol. Amastigotes in Group I biopsies were detected by routine histopathological exam (30.2%), imprint (28.2%), culture (43.4%), immunofluorescence (41.4%) and immunoperoxidase (58.5%) techniques; and by the five methods together (79.3%). In Group II, 5.7% of cultures were positive. Leishmanial antigen was also seen in the cytoplasm of macrophages and giant cells (cellular pattern), vessel walls (vascular pattern) and dermal nerves (neural pattern). Positive reaction was detected in 49 (92.5%), 20 (57%) and 4 (67%) biopsies of Groups I, II and III, respectively. Antigen persistency in cicatricial tissue may be related to immunoprotection or, on the contrary, to the development of late lesions. We suggest that the cellular, vascular and neural patterns could be applied in the immunodiagnosis of active and cicatricial lesions in which leishmaniasis is suspected.

Hardships of contact: enamel hypoplasias in Tupí-Mondé Amerindians from the Brazilian Amazonia

This paper presents an assessment of enamel defects (hypoplasias) in the permanent anterior teeth of three Tupí-Mondé-speaking groups from the Brazilian Amazonia: the Gavião, Suruí, and Zoró. These are native societies that experienced the onset of permanent contact with Brazilian national society in different periods of the 20th century. Tupí-Mondé dentition is highly hypoplastic, which is possibly related to exposure to adverse health and nutritional conditions. Data for the Gavião, Suruí, and Zoró are in agreement with results from other populations that show that certain teeth, the maxillary central incisors and the mandibular canines in particular, tend to be more hypoplastic. Although all types of teeth show hypoplasia concentrations at some enamel zones, there is substantial intertooth variation in the age at which peaks occur. It is argued that hypoplasia concentrations at certain ages are unlikely to be related to postweaning stresses for the Tupí-Mondé. Statistically significant associations between presence of enamel defects and deficits in physical growth (height-for-age) were detected in children 7-11 years of age. Diachronic assessment of enamel defects, which rested upon the potential of enamel as "memory" of past periods of systemic physiological perturbation, allowed us to unravel aspects related to the dynamics of Tupí-Mondé life during the 20th century. Frequencies of enamel zones with defects peaked during the contact years of each of the Tupí-Mondé groups, attesting to the extreme social and biological hardships that characterized the contact experiences of these native societies with Brazilian national society.