Amazonas the most southern federal

Amazonas, the most southern federal state of Venezuela, is bordering Colombia to the west and Brazil to the east. Half of the AP1903 belongs to one of eighteen indigenous ethnic groups with the Yanomami representing one of the largest Amerindian communities. These seminomadic Indians live on both sides of the frontier between Venezuela and Brazil. On the Venezuelan side, about 12,000 Yanomami inhabit the vast forest area where the Orinoco originates and the Casiquiare river bifurcates towards the southern Amazon (Metzger et al., 2008; Humboldt, 1812). In a traditional Yanomami village, all persons live under one common roof, shabono, consisting of a circular open wooden construction that accommodates up to 400 people. Daily life takes place “open air” and the night is spent in hammocks. Many shabonos are difficult to reach and are several days walking distance to the nearest health post. It is estimated that around 5000 Yanomami have retreated into the deep jungle with little or no contact to Western culture (Metzger et al., 2008). As forest-dwelling people, Yanomami hunt monkeys as a food source and incorporate them as household\'s pets. Overall, P. vivax is predominant in Amazonas with roughly 85% of all detected parasites, but the distribution pattern of the malaria species is variable and contingent upon the geographic settlement of the ethnic groups. For example, a pilot study conducted in Yanomami communities from the Upper Orinoco revealed that nearly half of the malaria positive samples were P. malariae (Metzger et al., 2008). In contrast, no infections caused by P. malariae were detected among indigenous Piaroa from the Middle Orinoco basin (Rodulfo et al., 2007). Interestingly, Yanomami communities have also the highest P. falciparum rates (40.3%) compared to other ethnic groups in the region (8.7–22.4%) (Metzger et al., 2009). The current study was carried out to identify and characterize Plasmodium species in the Venezuelan Amazon. Specifically, we investigated quartan malaria cases in Yanomami communities living in remote areas of the Alto Orinoco Casiquiare Biosphere Reserve where humans and non-humans live in such close vicinity that they could be concurrent reservoirs of transmission.
Materials and methods
Results
Discussion All quartan malaria parasites analyzed in this study would be P. malariae, if they had been found fifteen years earlier. However, as Fandeur et al. (2000) detected some 100% identical strains in monkeys in 1999, twelve of the 33 parasites had to be named P. brasilianum. Based on phylogenetic analysis standards, P. malariae and P. brasilianum are one species (Fig. 1), and the punctual differences are not more than differences between strains of other Plasmodium species (Tables 1 and 2). So far, the host made the difference, as the infected host has been the classification determinant for P. malariae and P. brasilianum. Our findings show that this distinction criterion no longer applies. Malaria history surmises that 500years ago, Old World Humans introduced P. malariae to the New World; some of the parasites crossed the species barrier, adapted to New World monkeys and became P. brasilianum, the simian quartan malaria parasite of Latin America (Coatney et al., 2003). This hypothesis was challenged later; based on genetic diversity assumptions, it was reasoned that quartan parasites jumped from monkey to man and became human P. malariae (Tazi and Ayala, 2011). Though directions of the cross-species transfer are opposing, the two hypotheses share the common element of “host switching” which implies host specificity of P. brasilianum and P. malariae to monkey and man, respectively. Our results allow an alternative view. For the first time, quartan malaria parasites, which are identical to those found in naturally infected primates of Latin America, were detected in naturally infected humans. Thus, our results provide evidence that quartan parasites are able to cross host species boundaries with impunity and that humans and non-human primates—in conditions of close contact—share quartan parasites without host specificity. Moreover, it can be speculated that P. brasilianum and P. malariae neither are distinct species, as the name suggests, nor are they distinct variants of one species, which became specialized on different hosts after switching, but are rather the same quartan malaria parasite species—an anthropozoonosis—circulating freely between monkeys and humans.