Publications by authors named "Zacarias Da Silva"

Objective: In the 2020 UNAIDS HIV treatment goals, 90% of people living with HIV (PLHIV) should be diagnosed, 90% of these should receive antiretroviral treatment (ART) and 90% of these should be virally suppressed. We aimed to evaluate whether Guinea-Bissau fulfills the 2020 treatment goals for both for HIV-1 and HIV-2.

Design: By combining data from a general population survey, treatment records from HIV clinics across Guinea-Bissau and a biobank from patients attending the largest HIV clinics in Bissau, we estimated each column of the 90-90-90 cascade.

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Although the diversity (~35 species) and worldwide distribution of goats (Ruminantia, Bovidae, Caprinae) are significant, studies on the diversity of symbiont ciliates in these mammals are scarce in comparison to other ruminants. The present work is a review and checklist of species based on taxonomic, morphologic, and ecologic studies of rumen ciliate protozoa in goats, presenting geographic distribution and hosts, as well as estimating the macroevolutionary relationships of the species observed in the studies. To that end, all of the available literature on databases was reviewed, the schematic drawings were made based on information present in the original description of the taxa, and the phylogenetic relationships were inferred based on Maximum Likelihood and Bayesian Inference analyses.

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The family Ophryoscolecidae (Ciliophora, Entodiniomorphida) constitutes a diverse and monophyletic group of symbiotic ciliates of herbivorous mammals. The family includes approximately 200 species, distributed in three subfamilies and sixteen genera. The subfamily Diplodiniinae is the most diverse group in Ophryoscolecidae and comprises the genus Ostracodinium, which includes species with two retractable ciliary zones in the anterior body portion, a broad skeletal plate covering almost all the right surface of the body and a variable number of contractile vacuoles.

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Objective: Hepatitis B virus (HBV) and hepatitis C virus (HCV) are prevalent in West Africa. To address the WHO 2030 goals of a 90% reduction in incidence and a 65% reduction in mortality for both infections, we assessed the prevalence of HBV and HCV from surveys in the general population.

Methods: Participants in this cross-sectional survey were included from randomly selected houses in a demographic surveillance site in Bissau, Guinea-Bissau.

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Objective: In Guinea-Bissau, West Africa, we observed that having a smallpox vaccination scar was associated with lower HIV-1 prevalence, more strongly for women than men. If this represents a causal effect, the female/male HIV-1 prevalence ratio would increase for birth cohorts no longer receiving smallpox vaccination due to the phase-out of this vaccine.

Design: An ecological design using HIV surveys and information about smallpox vaccination coverage.

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Article Synopsis
  • There are two types of HIV: HIV-1, which spreads all over the world and is very aggressive, and HIV-2, which is mostly found in West Africa and is less harmful.
  • Even though scientists have known about AIDS for almost 40 years, there still isn't a cure or a vaccine for HIV, so they're looking for new ways to help control the virus and improve treatments.
  • Some people who are infected with HIV-1 can control the virus without medication, but it's hard to understand how they do it since they're very rare. Scientists think studying HIV-2 might help because it could show important differences that lead to better treatments or possibly a cure.
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Background: Discrimination among HIV types is important because HIV-2 is naturally resistant to some of the first-line drugs used in the treatment of HIV-1. We evaluated three assays for HIV-type discriminatory capacity: SD Bioline HIV 1/2 3.0 (Bioline), First Response HIV 1-2-0 Card Test (First Response) and Genie III HIV-1/HIV-2 (Genie III).

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Background: Being able to discriminate between HIV-1, HIV-2 and HIV-1/2 dual infection is imperative for the appropriate selection of antiretroviral therapy (ART) in regions with high HIV-2 endemicity.

Objectives: To evaluate Bio-Rad Geenius HIV-1/2 Confirmatory Assay against INNO-LIA HIV 1/2 Score and ImmunoComb HIV 1/2 BiSpot with an emphasis towards ability to discriminate between HIV-1, HIV-2 and HIV-1/2 dual infection.

Material And Methods: 131 samples from ART naïve HIV infected patients in Guinea-Bissau were selected retrospectively and tested with Geenius, INNO-LIA and Immunocomb.

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Background: The HIV-2 and HTLV-1 prevalences in Bissau have followed similar trends in surveys from 1996 and 2006 with HTLV-1 prevalences of 3.6% and 2.3%, respectively.

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A positive correlation between virus evolutionary rate and disease progression has been shown for human immunodeficiency virus type 1 (HIV-1) infection. Much less is known about HIV-2, the second causative agent of AIDS. We analyzed 528 HIV-2 V1-C3 sequences generated from longitudinal plasma samples that were collected from 16 study participants during a median observation time of 7.

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Background: HIV type 2 (HIV-2) is considered more benign and has fewer pathogenic consequences than HIV type 1 (HIV-1) for most infected individuals. However, reliable estimates of time to AIDS and mortality among those with HIV-2 infection are absent. We therefore aimed to compare the time to AIDS and mortality, and the CD4 T-cell dynamics between those infected with HIV-1 and HIV-2.

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Objective: Although Guinea-Bissau has the world's highest prevalence of HIV-2, it has been decreasing since 1987. Meanwhile, the prevalence of HIV-1 has been increasing. We describe both the prevalence and changes in incidence of HIV-2 and HIV-1 during the last 30 years of observation in the capital Bissau in Guinea-Bissau.

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Background: The live smallpox and Bacillus Calmette-Guérin (BCG) vaccinations have been associated with better adult survival in both Guinea-Bissau and Denmark. In Guinea-Bissau, human immunodeficiency virus (HIV)-1 became an important cause of death after smallpox vaccination was phased out globally in 1980. We hypothesised that smallpox and BCG vaccinations were associated with a lower prevalence of HIV-1 infection, and we tested this hypothesis in both Guinea-Bissau and Denmark.

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Introduction: Male circumcision (MC) reduces the risk of HIV, and this risk reduction may be modified by socio-cultural factors such as the timing and method (medical and traditional) of circumcision. Understanding regional variations in circumcision practices and their relationship to HIV is crucial and can increase insight into the HIV epidemic in Africa.

Methods: We used data from two retrospective HIV surveys conducted in Guinea-Bissau from 1993 to 1996 (1996 cohort) and from 2004 to 2007 (2006 cohort).

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The development of therapeutic and prophylactic HIV vaccines for African countries is urgently needed, but the question of what immunogens to use needs to be answered. One approach is to include HIV envelope immunogens derived from HIV-positive individuals from a geographically concentrated epidemic with more limited viral genetic diversity for a region-based vaccine. To address if there is a basis for a regional selected antibody vaccine, we have screened two regionally separate cohorts from Guinea-Bissau and Denmark for neutralizing antibody activity and antibody-dependent cellular cytotoxicity (ADCC) against local and nonlocal circulating HIV-1 strains.

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Objective: This article predicts the future epidemiology of HIV-2 in Caió, a rural region of Guinea Bissau; and investigates whether HIV-2, which has halved in prevalence between 1990 and 2007 and is now almost absent in young adults in Caió, can persist as an infection of the elderly.

Design: A mathematical model of the spread of HIV-2 was tailored to the epidemic in Caió, a village in Guinea-Bissau.

Methods: An age-stratified difference equation model of HIV-2 transmission was fitted to age-stratified HIV-2 incidence and prevalence data from surveys conducted in Caió in 1990, 1997 and 2007.

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The dynamic HIV-1 epidemic has resulted in the emergence of several different subtypes and recombinant forms that may differ in biological properties. A recombinant form of CRF02_AG and subsubtype A3 (A3/02) was recently described based on env sequencing and was associated with faster disease progression rates compared with its parental strains. Here, we performed near full-length sequencing of the A3/02 variant to characterize the recombination patterns of a potential novel and more pathogenic circulating recombinant form of HIV-1 in Guinea-Bissau.

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Problem: The introduction of antiretroviral therapy (ART) for HIV infection in sub-Saharan Africa has improved the quality of life of millions of people and reduced mortality. However, substantial problems with the infrastructure for ART delivery remain.

Approach: Clinicians and researchers at an HIV clinic in Guinea-Bissau identified problems with the delivery of ART by establishing a clinical database and by collaborating with international researchers.

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Article Synopsis
  • The study aimed to estimate how common hepatitis C virus (HCV) is and identify risk factors among HIV-infected patients in Guinea-Bissau.
  • A total of 576 HIV patients were tested, revealing that only 1.7% were positive for HCV antibodies, with all cases being genotype 2.
  • Patients over 50 years showed a higher likelihood of having HCV antibodies, but there were no significant differences in symptoms or signs between those with and without detectable HCV RNA, except for elevated amylase levels.
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Background: Co-infection with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) may lead to accelerated hepatic disease progression with higher rates of liver cirrhosis and liver-related mortality compared with HBV mono-infection. Co or super-infection with hepatitis Delta virus (HDV) may worsen the liver disease and complicate treatment possibilities.

Methods: In this cross-sectional study we included HIV-infected individuals who had a routine blood analysis performed at an HIV clinic in Bissau, Guinea-Bissau between the 28th of April and 30th of September 2011.

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Objective: To compare survival times of HIV-1 single and HIV-1 and HIV-2 dual-infected individuals.

Design: Prospective open cohort study.

Methods: We analysed data from 259 HIV-1-seroincident cases (either HIV-1 single or HIV-1 and HIV-2 dual-infected) from a cohort with long follow-up (~20 years) in order to study the influence of type of infection and infection order on mortality.

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We analyzed prevalence rates of syphilis (positive Treponema pallidum hemagglutinin antigen/T. pallidum particle antigen and venereal disease research laboratory test) among police officers in Guinea-Bissau from 1990 to 2010 and found a significant decline from 4.5% to 0.

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Objectives: To describe loss to follow-up (LTFU) at all stages of the HIV programme.

Design: A retrospective cohort study.

Setting: The HIV clinic at Hospital National Simão Mendes in Bissau, Guinea-Bissau.

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