Evidence of at least two introductions of HIV-1 in the Amerindian Warao population from Venezuela

Spatial dynamics and epidemiology for AIDS in remote areas in French Guiana

Although AIDS care is generally improving in French Guiana, disparities among regions and certain key populations remain significant. The purpose of this study was to describe the spatial and clinical characteristics of people living with HIV (PLHIV) in remote areas in comparison to those followed in hospitals on the urban coast of French Guiana. The data presented were obtained from outpatient on primary care centers located in rural regions away from the urban coast. Data were compared with that from medical records of PLHIV treated in French Guiana's urban care. The evolution of the annual rate of discovery of HIV seropositivity indicates a lag in remote areas as compared to urban and coastal areas. In recent years, the epidemic appeared as particularly active in rural areas among Brazilian patients. The median age of PLHIV in remote areas was 43.8 years, the sex ratio (M/F) was 0.93. Nearly 37% of PLHIV were discovered with advanced disease (<200 CD4/mm3). The percentage of virological success after six months of HAART was 80% and 88% in remote areas and urban area, respectively. Efforts must be made to control and halt the spread of the HIV epidemic, as these remote sites represent strategic points.

Decreasing prevalence of Hepatitis B and absence of Hepatitis C Virus infection in the Warao indigenous population of Venezuela

Prevalence and molecular epidemiology studies for hepatitis B (HBV) and C (HCV) virus are scarce in Warao Amerindians from Venezuela, where an epidemic of human immunodeficiency virus type 1 (HIV-1) has recently been documented. To carry out a molecular epidemiology analysis of hepatitis B (HBV) and C (HCV) virus in Warao individuals from the Delta Amacuro State of Venezuela. A total of 548 sera were tested for serological and molecular markers for HBV and HCV. The prevalence of active infection (presence of HBV surface antigen, HBsAg), exposure to HBV (presence of Antibody to HBV core antigen, anti-HBc) and anti-HCV, was 1.8%, 13% and 0% respectively. HBV exposure was significantly lower in men below 18 years old and also lower than rates previously reported in other Amerindian communities from Venezuela. Thirty one percent (31%, 25/80) of individuals without evidence of HBV infection exhibited anti-HBs titer ≥ 10U.I / ml, being significantly more frequent in individuals younger than 20 years. A higher HBV exposure was observed among HIV-1 positive individuals (33% vs 11%, p <0.005). A high prevalence of occult HBV infection was also observed (5.6%, 11/195). Phylogenetic analysis of S gene and complete HBV genomes showed that F3 is the only circulating subgenotype, different from the F2 subgenotype found in 1991 in this population. These results suggest a recent introduction of subgenotype F3, with a low divergence among the isolates. These results highlight the importance of molecular epidemiology studies for viral control, and support the effectiveness of vaccination in reducing transmission of HBV.

The Evolving HIV-1 Epidemic in Warao Amerindians Is Dominated by an Extremely High Frequency of CXCR4-Utilizing Strains

We previously reported a high prevalence of HIV-1 infection in Warao Amerindians from Venezuela due to the rapid spread of a single B subtype strain. In this study we evaluated the coreceptor use of the HIV-1 strains infecting this Amerindian community. Sequences of the HIV-1 V3 loop from 56 plasma samples were genotyped for coreceptor use. An extremely high frequency of CXCR4 strains was found among HIV-1-infecting Waraos (47/49, 96%), compared to HIV-1 strains infecting the non-Amerindian Venezuelan population (35/79, 44%, p < 0.00001). Evolutionary analysis showed that a significant number of infections occurred between 1 and 12 months before collection and that a great proportion (50-70%) of HIV-1 transmissions occurred within the very early phase of infection (≤12 months). This is consistent with an initial infection dominated by an X4 strain or a very rapid selection of X4 variants after infection. This Amerindian population also exhibits the highest prevalence of tuberculosis in Venezuela, being synergistically bad prognostic factors for the evolution of morbidity and mortality in this vulnerable population.

Phylodynamics of major HIV-1 subtype B pandemic clades circulating in Latin America

OBJECTIVE

To obtain a comprehensive description of the evolutionary and demographic history of major HIV-1 subtype B pandemic (BPANDEMIC) clades circulating in Latin America.

DESIGN

A total of 6789 HIV-1 subtype B pol sequences collected from seven different Latin American countries between 1990 and 2011 were combined with BPANDEMIC reference sequences (n = 500) from the United States and France.

METHODS

Major BPANDEMIC clades were identified by maximum likelihood phylogenetic analysis with sequential pruning of ambiguously positioned taxa. Time scale and demographic reconstructions were performed using a Bayesian coalescent-based method.

RESULTS

We identified 12 major BPANDEMIC monophyletic lineages mainly composed by Latin American sequences and that together comprise 36% of all subtype B sequences from the region here included. Four clades belong to two major regional lineages that comprise sequences from at least two neighboring countries, whereas the other eight clades were country-specific. The median age of major Latin American BPANDEMIC clades encompass a period of two decades (1968-1988), although most of them probably arose before the early 1980s. All major clades seem to have experienced an initial period of exponential growth, with median epidemic growth rates that range from 0.50 yearto 0.94 year, followed by a recent decline in growth rate.

CONCLUSION

About one-third of HIV-1 subtype B infections in Latin America originated from the spread of a few BPANDEMIC founder strains probably introduced in the region since the late 1960s. Despite their initial successful dissemination, all major BPANDEMIC clades showed signs of subsequent epidemic stabilization.

Low child survival index in a multi-dimensionally poor Amerindian population in Venezuela

Background

Warao Amerindians, who inhabit the Orinoco Delta, are the second largest indigenous group in Venezuela.  High Warao general mortality rates were mentioned in a limited study 21 years ago. However, there have been no comprehensive studies addressing child survival across the entire population.

Objectives

To determine the Child Survival-Index (CSI) (ratio: still-living children/total-live births) in the Warao population, the principal causes of childhood death and the socio-demographic factors associated with childhood deaths.

Methods

We conducted a cross-sectional epidemiological survey of 688 women from 97 communities in 7 different subregions of the Orinoco Delta. Data collected included socio-demographic characteristics and the reproductive history of each woman surveyed. The multidimensional poverty index (MPI) was used to classify the households as deprived across the three dimensions of the Human Development Index. Multivariable linear regression and Generalized Linear Model Procedures were used to identify socioeconomic and environmental characteristics statistically associated with the CSI.

Findings

The average CSI was 73.8% ±26. The two most common causes of death were gastroenteritis/diarrhea (63%) and acute respiratory tract Infection/pneumonia (18%).  Deaths in children under five years accounted for 97.3% of childhood deaths, with 54% occurring in the neonatal period or first year of life.  Most of the women (95.5%) were classified as multidimensionally poor.  The general MPI in the sample was 0.56.   CSI was negatively correlated with MPI, maternal age, residence in a traditional dwelling and profession of the head of household other than nurse or teacher.

Conclusions

The Warao have a low CSI which is correlated with MPI and maternal age.  Infectious diseases are responsible for 85% of childhood deaths.  The low socioeconomic development, lack of infrastructure and geographic and cultural isolation suggest that an integrated approach is urgently needed to improve the child survival and overall health of the Warao Amerindians. 

HIV-1 epidemic in Warao Amerindians from Venezuela: spatial phylodynamics and epidemiological patterns

OBJECTIVES

We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study was to evaluate the extent and the dynamic of HIV-1 dissemination in eight Warao communities.

DESIGN AND SETTING

HIV-1 infection was evaluated in 576 Warao Amerindians from the Orinoco Delta. Partial HIV-1 pol sequences were analyzed to reconstruct the spatiotemporal and demographic dynamics of the epidemic.

RESULTS

HIV-1 antibodies were present in 9.55% of Warao Amerindians, ranging from 0 to 22%. A significantly higher prevalence was found in men (15.6%) compared with women (2.6%), reaching up to 35% in men from one community. All but one isolates were classified as subtype B. Warao's HIV-1 subtype-B epidemic resulted from a single viral introduction at around the early 2000s. After an initial phase of slow growth, the subtype B started to spread at a fast rate (0.8/year) following two major routes of migration within the communities.

CONCLUSION

A dramatic high prevalence was documented in almost all the communities of Warao Amerindians from the Orinoco Delta tested for HIV-1 infection. This epidemic resulted from the dissemination of a single HIV-1 subtype B founder strain introduced about 10 years ago and its size is probably doubling every year, creating a situation that can be devastating for this vulnerable Amerindian group.

The increasing prevalence of HIV-1 subtype C in Southern Brazil and its dispersion through the continent

The HIV-1 has evolved swiftly and the scenario of HIV-1 genetic diversity is constantly changing. In South America, recombinant forms of subtypes B, F1, and BF1 have historically driven the HIV-1 epidemic. In recent years, however, infection with subtype C has gained prominence as its prevalence increased in Southern Brazil as well as neighboring countries. Current studies point to a single introduction of closely related strains as the beginning of the Brazilian subtype C epidemic. However, the place of origin of these strains, date, and route of introduction are under continuous debate as well as the clinical outcomes of the emergence of subtype C. Therefore, this paper reviews the history of the HIV-1 subtype C in Brazil, particularly in the Southern region, covering its demographic and evolutionary history and the possible implications to the Brazilian AIDS epidemic as well as to neighboring countries.