Tuberculosis and gender: exploring the patterns in a case control study in Malawi.

BACKGROUND: In many populations there is an excess of tuberculosis in young women and older men. We explored possible explanations for these patterns, concentrating on human immunodeficiency virus (HIV) status, pregnancy, smoking, cooking smoke exposure, contact with tuberculosis cases within the household or outside, and gender differences in health service usage and diagnostic delay. DESIGN: Case control study in Karonga District, Malawi. METHODS: Cases were new tuberculosis patients with bacteriological or histological evidence of tuberculosis. Controls were selected in the community using field-based random sampling. RESULTS: The study included 598 tuberculosis cases and 992 controls, with an excess of tuberculosis in young females and older males. This was more marked in HIV-positive individuals. HIV infection was a similarly strong risk factor for tuberculosis in both men and women. Tuberculosis was associated with having a family or household contact with tuberculosis for both men and women. For women, but not men, contacts outside the close family and household were also a risk factor for tuberculosis. Tuberculosis was not associated with current or recent pregnancy, or with smoking or smoke exposure. There were no differences between men and women in health service usage or delay. CONCLUSIONS: In this population, HIV infection and contacts with known tuberculosis patients are important determinants of the gender distribution of cases

High girth column-weight-two LDPC codes based on distance graphs

Copyright © 2007 G. Malema and M. Liebelt. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.LDPC codes of column weight of two are constructed from minimal distance graphs or cages. Distance graphs are used to represent LDPC code matrices such that graph vertices that represent rows and edges are columns. The conversion of a distance graph into matrix form produces an adjacency matrix with column weight of two and girth double that of the graph. The number of 1's in each row (row weight) is equal to the degree of the corresponding vertex. By constructing graphs with different vertex degrees, we can vary the rate of corresponding LDPC code matrices. Cage graphs are used as examples of distance graphs to design codes with different girths and rates. Performance of obtained codes depends on girth and structure of the corresponding distance graphs.Gabofetswe Malema and Michael Liebel

Qualitative and quantitative detection of SARS-CoV-2 RNA in untreated wastewater in Western Cape Province, South Africa

Recent studies have shown that the detection of SARS-CoV-2 genetic material in wastewater may provide the basis for a surveillance system to track the environmental dissemination of this virus in communities. An effective wastewater-based epidemiology (WBE) system may prove critical in South Africa (SA), where health systems infrastructure, testing capacity, personal protective equipment and human resource capacity are constrained. In this proof-of-concept study, we investigated the potential of SARS-CoV-2 RNA surveillance in untreated wastewater as the basis for a system to monitor COVID-19 prevalence in the population, an early warning system for increased transmission, and a monitoring system to assess the effectiveness of interventions. The laboratory confirmed the presence (qualitative analysis) and determined the RNA copy number of SARS-CoV-2 viral RNA by reverse transcription polymerase chain reaction (quantitative) analysis from 24-hour composite samples collected on 18 June 2020 from five wastewater treatment plants in Western Cape Province, SA. The study has shown that a WBE system for monitoring the status and trends of COVID-19 mass infection in SA is viable, and its development and implementation may facilitate the rapid identification of hotspots for evidence-informed interventions

Quasi-cyclic LDPC codes of column-weight two using a search algorithm

Copyright © 2007 G. Malema and M. Liebelt. This is an Open Access article distributed under the Creative Commons Attributions License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article introduces a search algorithm for constructing quasi-cyclic LDPC codes of column-weight two. To obtain a submatrix structure, rows are divided into groups of equal sizes. Rows in a group are connected in their numerical order to obtain a cyclic structure. Two rows forming a column must be at a specified distance from each other to obtain a given girth. The search for rows satisfying the distance is done sequentially or randomly. Using the proposed algorithm regular and irregular column-weight-two codes are obtained over a wide range of girths, rates, and lengths. The algorithm, which has a complexity linear with respect to the number of rows, provides an easy and fast way to construct quasi-cyclic LDPC codes. Constructed codes show good bit-error rate performance with randomly shifted codes performing better than sequentially shifted ones.Gabofetswe Malema and Michael Liebel

Human immunodeficiency virus increases the risk of tuberculosis due to recent re-infection in individuals with latent infection.

BACKGROUND: Human immunodeficiency virus associated tuberculosis (TB) disease can follow reactivation of latent Mycobacterium tuberculosis infection or recent (re-)infection with M. tuberculosis. If contemporary TB cases share identical M. tuberculosis strains (i.e., are 'clustered'), the episode is likely to have followed recent (re-)infection, irrespective of evidence of previous latent infection. METHODS: Individuals experiencing a first TB episode between 1996 and 2008 in Karonga District, Northern Malawi, were included if information on M. tuberculosis infection status (from tuberculin tests) before 1990 and a DNA fingerprint from the TB episode were available. We explored differences in proportion clustered by prior M. tuberculosis infection status and HIV status, adjusting for age, sex, bacille Calmette-Guérin scar status and time since tuberculin testing. RESULTS: Of 79 HIV-negative TB cases, those with previous M. tuberculosis infection were much less likely to be clustered than cases without prior infection (29% vs. 77%, adjusted OR = 0.15, 95%CI 0.04-0.59). Among 119 HIV-positive TB cases, clustering was similar in both groups (88% vs. 84%, adjusted OR = 1.85, 95%CI 0.41-8.29). DISCUSSION: HIV infection appears to increase the risk of TB following recent re-infection in patients with latent M. tuberculosis infection. Our results add to the mounting evidence that HIV-associated TB mainly follows recent M. tuberculosis infection

The Shepard

An unaccompanied hymn

Tuberculosis and gender: exploring the patterns in case control study in Malawi

Background: In many populations there is an excess of tuberculosis in young women and older men. We explored possible explanations for these patterns, concentrating on human immunodeficiency virus (HIV) status, pregnancy, smoking, cooking smoke exposure, contact with tuberculosis cases within the household or outside, and gender differences in health service usage and diagnostic delay. Design: Case control study in Karonga District, Malawi. Methods: Cases were new tuberculosis patients with bacteriological or histological evidence of tuberculosis. Controls were selected in the community using field-based random sampling. Results: The study included 598 tuberculosis cases and 992 controls, with an excess of tuberculosis in young females and older males. This was more marked in HIV-positive individuals. HIV infection was a similarly strong risk factor for tuberculosis in both men and women. Tuberculosis was associated with having a family or household contact with tuberculosis for both men and women. For women, but not men, contacts outside the close family and household were also a risk factor for tuberculosis. Tuberculosis was not associated with current or recent pregnancy, or with smoking or smoke exposure. There were no differences between men and women in health service usage or delay. Conclusions: In this population, HIV infection and contacts with known tuberculosis patients are important determinants of the gender distribution of cases

Tuberculosis: associations with HIV and socioeconomic status in rural Malawi.

Tuberculosis (TB) is associated with human immunodeficiency virus (HIV) infection, increasing age and male sex, but less is known about other risk factors in developing countries. As part of the Karonga Prevention Study in northern Malawi, we conducted a retrospective cohort study in the general population to assess risk factors for the development of TB. Individuals were identified in 1986-89 and TB cases diagnosed up to 1996 were included. TB was confirmed in 62/11,059 (0.56%) HIV negative individuals and 7/182 (3.9%) HIV positive individuals (relative risk 7.1, 95% confidence interval 3.2-15.7). This association was little altered by adjustment for age, sex or socioeconomic factors. The risk of TB was higher in those aged over 30 years than in younger individuals, in men than in women, in those engaged in occupations other than farming than in subsistence farmers, in those living in households with burnt brick dwellings than in those with less well built dwellings, and in those with some schooling than in those with none. These associations persisted after adjusting for age, sex, HIV status and population density. The absolute risks of TB were low in this study due to the passive follow-up and strict diagnostic criteria. The relative risk with HIV was of a similar magnitude to that measured elsewhere. Increased risks of TB with age and in men are expected. Associations with measures of higher socioeconomic status were unexpected. They may reflect a greater likelihood of diagnosis in this group