Risk of tuberculous infection in an indigenous population from Amazonia, Brazil.

SETTING: Suruí Indians, Amazonia, Brazil. OBJECTIVE: To estimate the prevalence and the annual risk of infection (ARI) of tuberculosis (TB) in an indigenous population in Brazil. METHODS: We applied a method to estimate the prevalence of TB infection in populations with high bacille Calmette-Guérin (BCG) vaccine coverage. The method consisted of comparing levels of skin test reactivity in individuals tested with purified protein derivative (PPD) before and after stimulation with intradermal BCG. Fieldwork was carried out among the Suruí Indians (n = 993) in two phases, 3 months apart. RESULTS: A total of 645 subjects were tested. In pre-BCG revaccination, tuberculin skin test (TST) indurations averaged 5.9 mm (33.5% > or =10 mm). In post-BCG revaccination TST, indurations averaged 9.4 mm (48.7% > or =10 mm). Conversion from non-reactor to reactor was 54.4%. The ARI ranged from 1.2% to 2.2%. In the logistic regression, age and history of TB were the strongest independent predictors of TB infection. BCG scar and the number of individuals per house were also associated with infection. CONCLUSION: Tuberculous transmission is very high in the Suruí, surpassing the ARI reported for Brazil (0.6%). The epidemiology of TB in this indigenous population is related to unfavourable social and economic conditions, as well as to deficient health care services.

Malaria epidemiology in the Pakaanóva (Wari') Indians, Brazilian Amazon.

This paper reports the results of a longitudinal study of malaria incidence (1998-2002) among the Pakaanóva (Wari') Indians, Brazilian southwest Amazon region, based on data routinely gathered by Brazilian National Health Foundation outposts network in conjunction with the Indian health service. Malaria is present yearlong in the Pakaanóva. Statistically significant differences between seasons or months were not noticed. A total of 1933 cases of malaria were diagnosed in the Pakaanóva during this period. The P. vivax / P. falciparum ratio was 3.4. P. vivax accounted for 76.5% of the cases. Infections with P. malariae were not recorded. Incidence rates did not differ by sex. Most malaria cases were reported in children < 10 years old (45%). About one fourth of all cases were diagnosed on women 10-40 years old. An entomological survey carried out at two Pakaanóva villages yielded a total of 3.232 specimens of anophelines. Anopheles darlingi predominated (94.4%). Most specimens were captured outdoors and peak activity hours were noted at early evening and just before sunrise. It was observed that Pakaanóva cultural practices may facilitate outdoor exposure of individuals of both sexes and all age groups during peak hours of mosquito activities (e.g., coming to the river early in the morning for bathing or to draw water, fishing, engaging in hunting camps, etc). In a context in which anophelines are ubiquitous and predominantly exophilic, and humans of both sexes and all ages are prone to outdoor activities during peak mosquito activity hours, malaria is likely to remain endemic in the Pakaanóva, thus requiring the development of alternative control strategies that are culturally and ecologically sensitive.

Tuberculin reactivity and tuberculosis epidemiology in the Pakaanóva (Wari') Indians of Rondônia, south-western Brazilian Amazon.

OBJECTIVE: To investigate the characteristics of tuberculin skin test reactivity in the Pakaanóva Indians, in Amazonia, Brazil, after revaccination of all study participants with bacille Calmette-Guerin (BCG). METHODS: The investigation was designed as a post-BCG vaccination purified protein derivative (PPD) survey. Data included PPD readings, age, sex, nutritional status, place of residence, previous tuberculosis, physical examinations and BCG status. Bivariate and multivariate logistic regression analyses were conducted. RESULTS: About 90% (n = 505) of the total population participated. One third (32.1%) of the subjects presented induration > or = 10 mm at 72 h. Induration sizes showed weak linear correlation with age; differences between sexes were not observed. Skin reaction was not associated with nutritional status. Individuals with a history of tuberculosis were six times more likely to test positive. History of tuberculosis, age, and previous BCG vaccination were significantly associated with PPD reactivity in the multivariate analyses. CONCLUSION: The Pakaanóva showed a high proportion (58.4%) of non-reactors, even with a recent BCG booster. Sex differences in PPD reactivity were either not present or could not be demonstrated. The association between age and PPD reactivity resembles that observed in other Amazonian populations. The authors discuss the potential of PPD testing as a screening tool to enhance tuberculosis detection, especially in indigenous populations in Amazonia with limited access to health services.

Crab louse infestation in pre-Columbian America.

Until now, Pthirus pubis infestation in ancient human populations had only been recorded in the Old World. We found crab lice on South American mummified bodies from the Atacama Desert region. Crab louse eggs were found attached to the pubic hairs of a 2,000-yr-old Chilean mummy. Well-preserved adults were found in sediment and clothing from a Peruvian mummy dated 1,000 yr ago. Paleoparasitological evidence expands the knowledge of the distribution of this ectoparasite in ancient populations. As with many other parasites, pubic lice recorded in Andean populations show the antiquity of this parasite in the New World. It is likely that P. pubis entered the continent with early human migration to the New World.

Protein genetic studies among the Tupi-Mondé Indians of the Brazilian Amazonia.

A sample of 417 individuals belonging to three Tupi-Mondé-speaking tribes (Gavião, Surui, Zoró) were variously studied in relation to 26 genetic protein systems. Previous investigations performed among the Surui in relation to some of these systems were confirmed. The three groups do not depart markedly from the genetic pattern already established for South American Indians and show low inter-ethnic admixture. When these results are combined with those from 10 other Tupi tribes, two clear geographic groupings (southeastern and northwestern) can be discerned. Using different methods to evaluate the same genetic distance matrices, different patterns of association between the Tupi-Mondé populations were obtained. The populations are probably too similar among themselves, blurring finer relationships. Am. J. Hum. Biol. 10:711-722, 1998. © 1998 Wiley-Liss, Inc.

Mitochondrial DNA polymorphism in three Brazilian Indian tribes.

The first 360 base pairs of the mitochondrial DNA (mtDNA) major noncoding region from 82 individuals affiliated with the Brazilian Xavante, Zoró and Gavião tribes were sequenced. A total of 14 different lineages were observed, the largest number (8) being found among the Zoró. The latter share five lineages with the Gavião (who are their neighbors and are culturally similar to them), but only one with the Xavante. The lineages can be grouped into four clusters, previously identified by other authors. The 9 base pair deletion characteristic of Asian and Pacific populations occurs in 32% of the individuals, whose mtDNA was classified in five lineages, all grouped in one of the four clusters. Nucleotide diversity, as evaluated by three indices, are not much different from those observed in Indians from Central and North America, despite the fact that the Xavante consistently show lower numbers. These results do not confirm previous generalizations about the genetic diversity of Amerindians, and the need for additional studies in this system is stressed. © 1996 Wiley-Liss, Inc.