scholarly journals Assessing the uncertainty around age-mixing patterns in HIV transmission inferred from phylogenetic trees

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249013
Author(s):  
David Niyukuri ◽  
Peter Nyasulu ◽  
Wim Delva
Keyword(s):  
Phylogenetic Trees ◽  
Hiv Transmission ◽  
Sequence Data ◽  
Age Groups ◽  
Sampling Strategy ◽  
Sub Saharan Africa ◽  
Age Difference ◽  
Men And Women ◽  
Hiv Prevention Strategies ◽  
Mixing Patterns

Understanding age-mixing patterns in Human Immunodeficiency Virus (HIV) transmission networks can enhance the design and implementation of HIV prevention strategies in sub-Saharan Africa. Due to ethical consideration, it is less likely possible to conduct a benchmark study to assess which sampling strategy, and sub-optimal sampling coverage which can yield best estimates for these patterns. We conducted a simulation study, using phylogenetic trees to infer estimates of age-mixing patterns in HIV transmission, through the computation of proportions of pairings between men and women, who were phylogenetically linked across different age groups (15–24 years, 25–39 years, and 40–49 years); and the means, and standard deviations of their age difference. We investigated also the uncertainty around these estimates as a function of the sampling coverage in four sampling strategies: when missing sequence data were missing completely at random (MCAR), and missing at random (MAR) with at most 30%—50%—70% of women in different age groups being in the sample. The results suggested that age-mixing patterns in HIV transmission can be unveiled from proportions of phylogenetic pairings between men and women across age groups; and the mean, and standard deviation of their age difference. A 55% sampling coverage was sufficient to provide the best values of estimates of age-mixing patterns in HIV transmission with MCAR scenario. But we should be cautious in interpreting proportions of men phylogenetically linked to women because they may be overestimated or underestimated, even at higher sampling coverage. The findings showed that, MCAR was the best sampling strategy. This means, it is advisable not to use sequence data collected in settings where we can find a systematic imbalance of age and gender to investigate age-mixing in HIV transmission. If not possible, ensure to take into consideration the imbalance in interpreting the results.

scholarly journals 1146Assessing the uncertainty around age-mixing patterns in HIV transmission inferred from phylogenetic trees

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Peter Nyasulu
Keyword(s):  
Phylogenetic Trees ◽  
Hiv Transmission ◽  
Age Difference ◽  
Transmission Network ◽  
Age Group ◽  
Younger Women ◽  
Prevention Interventions ◽  
Younger Men ◽  
Mixing Patterns ◽  
Set Up

Abstract Introduction Understand age-mixing patterns in HIV transmission is a key to design and implement HIV prevention interventions. As such, the use of phylogenetic tree seems promising since this approach is based on data from a transmission network. Methods Through a simulation study, we used transmission clusters computed from phylogenetic trees to investigate age-mixing patterns. From transmission clusters, we estimated a transmission network using pairings. We inferred measurements, which depict age-mixing patterns in transmission i.e. ‘proportions of men/women of a certain age-group paired with women/men of another age-group’, and mean, median, and standard deviation of average age difference between women/men with their respective pairs. We investigated the uncertainty around these measurements as a function of sampling coverage in different sequence missingness scenarios. Results According to the simulation set-up of age mixing in partnership, there are relationships, which are less likely and others highly likely. Explicitly, partnerships between younger men (<25 years) and older women (25 to 50 years) are less likely to happen in the sexual network, whereas partnership between younger women (<25 years) and older men (25 to 50 years) are more likely to happen as are age group relationship having intermediate magnitude in partnership. Conclusion Transmission clusters allow us to strive with more improved information regarding cross-generation transmission. It enables us to understand the importance of age mixing beyond describing the mean age difference, and that one needs to consider the variation of age differences between pairs of individuals as well as among the partners of a given individual.

scholarly journals Mediterranean Ant Nest Beetles (Carabidae: Paussus): Out of Africa and Asia

2019 ◽  
Vol 2 ◽  
Author(s):  
Wendy Moore ◽  
James Robertson ◽  
Peter Nagel ◽  
Andrea Di Giulio
Keyword(s):  
Molecular Phylogenetics ◽  
Sequence Data ◽  
General Rule ◽  
Sampling Strategy ◽  
Species Group ◽  
Sub Saharan Africa ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Ant Nest ◽  
Sub Saharan

Endemic to the Palaeotropic and southern Palaearctic regions, ant nest beetles (Carabidae: Paussus) are specialized predators that depend on ants for their survival. This obligate relationship has driven extreme morphological adaptations that obscured our understanding of Paussus species relationships and subgeneric clades for centuries. Molecular phylogenetics has revealed patterns of relationship with high levels of convergence, and as a general rule, areas of endemism are better predictors of monophyly than overall morphology. For example, the species rich fauna of Madagascar is the product of one dispersal event from Africa approximately 2.6 million years ago, after which Malagasy ant nest beetles undertook one of the fastest species radiations ever documented within animals. With their center of diversity in sub-Saharan Africa, the Paussus fauna of the Mediterranean is relatively depauperate with only seven species described from north of the Sahara. Pre-molecular subgeneric classifications, which were based on overall morphology, suggest that these seven species represent five species group lineages. Here, we use molecular sequence data from five genes and a taxon-sampling strategy aimed at investigating the biogeographic origins of five Mediterranean species. We find that the present-day Mediterranean fauna, unlike that of Madagascar, is the result of five separate dispersal events, four from the Afrotropical Region and one from the Indomalayan Region. Implications of associated host ant shifts are also explored.

scholarly journals Biomedical prevention: what is the current status?

2010 ◽  
Vol 4 (5) ◽  
pp. 679-682
Author(s):  
David D. Celentano ◽  
Wendy W. Davis ◽  
Chris C. Beyrer
Keyword(s):  
Male Circumcision ◽  
Hiv Transmission ◽  
Sub Saharan Africa ◽  
Current Status ◽  
Post Exposure Prophylaxis ◽  
Biomedical Hiv Prevention ◽  
Hiv Prevention Strategies ◽  
Biomedical Prevention ◽  
Sub Saharan ◽  
Exposure Prophylaxis

Abstract Biomedical HIV prevention strategies for primary or secondary prevention of HIV transmission can be seen as an adjunct to behavioral prevention approaches. These interventions include vaccination, female controlled vaginal microbicides, male circumcision, treatment of sexually transmitted infections that cause genital ulceration, Pre-Exposure Prophylaxis (PREP) and Post-Exposure Prophylaxis (PEP). This article reviews results from recent randomized controlled trials of novel biomedical prevention approaches and discusses interpretation of the results. The only intervention consistently demonstrating reductions in HIV transmission was adult male circumcision in Sub-Saharan Africa. Results of PREP trials will be available in the next several years.

Examining HIV-related stigma and discrimination in Ghana: what are the major contributors?

Sexual Health ◽  
2013 ◽  
Vol 10 (3) ◽  
pp. 253 ◽  
Author(s):  
Eric Y. Tenkorang ◽  
Adobea Y. Owusu
Keyword(s):  
Hiv Transmission ◽  
Ordinary Least Squares ◽  
Sub Saharan Africa ◽  
Factual Knowledge ◽  
Men And Women ◽  
Highly Educated ◽  
Stigma And Discrimination ◽  
Related Stigma ◽  
High Knowledge ◽  
Sub Saharan

Background Although AIDS-related stigma and discrimination are considered detrimental to HIV prevention activities, not many studies have attempted to understand stigma and discrimination in sub-Saharan Africa, particularly Ghana. Methods: Using the 2008 Ghana Demographic and Health Survey and applying the ordinary least-squares technique, this study examined what influences AIDS-related stigma and discrimination among men and women in Ghana. Results: The results indicate that Ghanaian men and women with relatively high knowledge about HIV/AIDS had low stigmatising and discriminatory attitudes (b = –0.097, P < 0.01; b = –0.083, P < 0.01), respectively. On the other hand, respondents who endorsed more myths about HIV transmission had high stigma and discriminatory attitudes. Women who had ever tested for their HIV serostatus reported significantly lower levels of stigma and discrimination (b = –0.085, P < 0.01) compared with those who had not tested for HIV. Individuals who are highly educated, employed and in wealthy households all reported significantly lower levels of stigma and discrimination compared with those who are uneducated, unemployed and in poorer households. Conclusion: AIDS-related stigma and discrimination can be reduced by encouraging HIV testing, and ensuring that Ghanaians understand and have factual knowledge regarding the transmission of the disease.

ADOLESCENT SEXUALITY AND THE HIV EPIDEMIC IN YAOUNDÉ, CAMEROON

2004 ◽  
Vol 36 (5) ◽  
pp. 597-616 ◽  
Author(s):  
N. LYDIÉ ◽  
N. J. ROBINSON ◽  
B. FERRY ◽  
E. AKAM ◽  
M. DE LOENZIEN ◽  
...  
Keyword(s):  
Young Women ◽  
Hiv Transmission ◽  
Sexual Partners ◽  
Hiv Prevalence ◽  
Large Male ◽  
Age Difference ◽  
Susceptibility To Infection ◽  
Risky Behaviours ◽  
Mixing Patterns ◽  
Using Data

Adolescents are the focus of many interventions that aim to prevent HIV transmission. In order for these interventions to be effective, it is essential to understand adolescents' sexual behaviour. Using data collected in Yaoundé, Cameroon, in 1997, the study analysed risk exposure and HIV prevalence among 426 men and 510 women aged 15–24. Although risky behaviours seem to be more prevalent among young men, their HIV prevalence remains under 1%. In contrast, HIV prevalence is high among young women (7·5%), even those who report having had few sexual partners. Mixing patterns among sexual partners, and especially the age difference between men and women, do not seem to be sufficient to explain the large male–female discrepancy in HIV prevalence that is evident in these data. The results are therefore probably due to a greater susceptibility to infection of young women than men. This study highlights the necessity of reinforcing prevention campaigns among youth and fighting the obstacles that continue to impede the use of condoms in this population.

RTS,S/AS01, a vaccine targeting pre-erythrocytic stages of Plasmodium falciparum

2017 ◽  
Vol 1 (6) ◽  
pp. 533-537
Author(s):  
Lorenz von Seidlein ◽  
Borimas Hanboonkunupakarn ◽  
Podjanee Jittmala ◽  
Sasithon Pukrittayakamee
Keyword(s):  
Protective Efficacy ◽  
Age Groups ◽  
Sub Saharan Africa ◽  
Phase Iii ◽  
European Medicines Agency ◽  
Older Children ◽  
Pivotal Phase ◽  
Malaria Epidemiology ◽  
Maximum Benefit ◽  
Sub Saharan

RTS,S/AS01 is the most advanced vaccine to prevent malaria. It is safe and moderately effective. A large pivotal phase III trial in over 15 000 young children in sub-Saharan Africa completed in 2014 showed that the vaccine could protect around one-third of children (aged 5–17 months) and one-fourth of infants (aged 6–12 weeks) from uncomplicated falciparum malaria. The European Medicines Agency approved licensing and programmatic roll-out of the RTSS vaccine in malaria endemic countries in sub-Saharan Africa. WHO is planning further studies in a large Malaria Vaccine Implementation Programme, in more than 400 000 young African children. With the changing malaria epidemiology in Africa resulting in older children at risk, alternative modes of employment are under evaluation, for example the use of RTS,S/AS01 in older children as part of seasonal malaria prophylaxis. Another strategy is combining mass drug administrations with mass vaccine campaigns for all age groups in regional malaria elimination campaigns. A phase II trial is ongoing to evaluate the safety and immunogenicity of the RTSS in combination with antimalarial drugs in Thailand. Such novel approaches aim to extract the maximum benefit from the well-documented, short-lasting protective efficacy of RTS,S/AS01.

A Study on Knowledge, Attitude, Awareness and Practice About HIV/AIDS among different age group of Karachi, Pakistan

2017 ◽  
Vol 3 (3) ◽  
pp. 328-333
Author(s):  
Safia Mehmood ◽  
Sheema Zia ◽  
Nida Aziz ◽  
Omama Sajid
Keyword(s):  
Hiv Transmission ◽  
Age Groups ◽  
World Population ◽  
Major Barrier ◽  
Initial Stage ◽  
Awareness Programs ◽  
And Gender ◽  
Strongly Agree ◽  
High Level ◽  
Lack Of Knowledge

The AIDS is one of the most complicated health problems of the 21st century and it threatens the world population. AIDS spread at an alarming rate. This was a descriptive study to determine the knowledge, awareness, and practice about HIV among different age groups. The study carried out in Karachi, Pakistan during the period of January 2016-april 2016, in which 82 peoples are participated; 65 peoples having age in between 18-30, people’s lies in 31-40 years, while only 4 peoples having age above 40. From which 91% peoples thought HIV is dangerous virus and 51% peoples having misconception that it cause AIDS on initial stage and does not have any effect on CD4+. Majority of peoples aware about transmission of AIDS through intercourse, and during pregnancy. But the study show the high level of misbelieve also in mode of transmission that HIV transmit through sweat, saliva etc. Majority of the peoples have knowledge that HIV-1 is the most common type found worldwide. Also large number of peoples have knowledge that HIV weak immune system by destroying CD4+ and require long exposure to progress AIDS. Less than 15% of peoples strongly agree that AIDS is common in women. This misconception reflex the lack of knowledge and awareness in the HIV transmission and gender relation. Also majority of peoples thought that lack of knowledge is major barrier in the proper cure of disease. So increasing knowledge by awareness programs; sexual prevention; by starting national testing resources and curing poverty will cured AIDS in Pakistan. Newly drugs are introduced which can stop the progression of AIDS.

scholarly journals Challenges in evaluating the use of viral sequence data to identify HIV transmission networks for public health

2020 ◽  
Vol 12 (s1) ◽  
Author(s):  
Rami Kantor ◽  
John P. Fulton ◽  
Jon Steingrimsson ◽  
Vladimir Novitsky ◽  
Mark Howison ◽  
...  
Keyword(s):  
Public Health ◽  
United States ◽  
Hiv Transmission ◽  
Sequence Data ◽  
The United States ◽  
Viral Sequence ◽  
Transmission Networks ◽  
New Methods ◽  
Hiv Epidemic ◽  
The World

AbstractGreat efforts are devoted to end the HIV epidemic as it continues to have profound public health consequences in the United States and throughout the world, and new interventions and strategies are continuously needed. The use of HIV sequence data to infer transmission networks holds much promise to direct public heath interventions where they are most needed. As these new methods are being implemented, evaluating their benefits is essential. In this paper, we recognize challenges associated with such evaluation, and make the case that overcoming these challenges is key to the use of HIV sequence data in routine public health actions to disrupt HIV transmission networks.

scholarly journals ‘Too old to test?’: A life course approach to HIV-related risk and self-testing among midlife-older adults in Malawi

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Cheryl Johnson ◽  
Moses Kumwenda ◽  
Jamilah Meghji ◽  
Augustine T. Choko ◽  
Mackwellings Phiri ◽  
...  
Keyword(s):  
Older Adults ◽  
Life Course ◽  
Hiv Testing ◽  
Sexual Risk ◽  
Age Groups ◽  
Sub Saharan Africa ◽  
Treatment As Prevention ◽  
Sexual Risk Taking ◽  
Rural And Urban ◽  
Self Testing

Abstract Background Despite the aging HIV epidemic, increasing age can be associated with hesitancy to test. Addressing this gap is a critical policy concern and highlights the urgent need to identify the underlying factors, to improve knowledge of HIV-related risks as well as uptake of HIV testing and prevention services, in midlife-older adults. Methods We conducted five focus group discussions and 12 in-depth interviews between April 2013 and November 2016 among rural and urban Malawian midlife-older (≥30 years) men and women. Using a life-course theoretical framework we explored how age is enacted socially and its implications on HIV testing and sexual risk behaviours. We also explore the potential for HIV self-testing (HIVST) to be part of a broader strategy for engaging midlife-older adults in HIV testing, prevention and care. Thematic analysis was used to identify recurrent themes and variations. Results Midlife-older adults (30–74 years of age) associated their age with respectability and identified HIV as “a disease of youth” that would not affect them, with age protecting them against infidelity and sexual risk-taking. HIV testing was felt to be stigmatizing, challenging age norms, threatening social status, and implying “lack of wisdom”. These norms drove self-testing preferences at home or other locations deemed age and gender appropriate. Awareness of the potential for long-standing undiagnosed HIV to be carried forward from past relationships was minimal, as was understanding of treatment-as-prevention. These norms led to HIV testing being perceived as a threat to status by older adults, contributing to low levels of recent HIV testing compared to younger adults. Conclusions Characteristics associated with age-gender norms and social position encourage self-testing but drive poor HIV-risk perception and unacceptability of conventional HIV testing in midlife-older adults. There is an urgent need to provide targeted messages and services more appropriate to midlife-older adults in sub-Saharan Africa. HIVST which has often been highlighted as a tool for reaching young people, may be a valuable tool for engaging midlife-older age groups who may not otherwise test.

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