Infectious Diseases of Poverty - Latest Articles

Inferring the potential risks of H7N9 infection by spatiotemporally characterizing bird migration and poultry distribution in eastern China

Benyun Shi — 2013-05-03T00:00:00Z

Background In view of the rapid geographic spread and theincreased number of confirmed cases of novel influenza A(H7N9) virusinfections in eastern China, we developed a diffusion model tospatiotemporally characterize the impacts of bird migration andpoultry distribution on the geographic spread of H7N9 infection.Methods The three types of infection risks were estimatedfor 12 weeks, from February 4 to April 28, 2013, including (i) therisk caused by bird migration, (ii) the risk caused by poultrydistribution, and (iii) the integrated risk caused by both birdmigration and poultry distribution. To achieve this, we firstdeveloped a method for estimating the likelihood of bird migrationbased on available environmental and meteorological data. Then, weadopted a computational mobility model to estimate poultrydistribution based on annual poultry production and consumption ofeach province/municipality. Finally, the spatiotemporal risk mapswere created based on the integrated impact of both bird migrationand poultry distribution. Results: In the study of risk estimation caused by bird migration, the likelihood matrix was estimated based on the 7-day temperature, from February 4 to April 28, 2013. It was found the estimated migrant birds mainly appear in the southeastern provinces of Zhejiang, Shanghai and Jiangsu during Weeks 1 to 4, and Week 6, followed by appear in central eastern provinces of Shandong, Hebei, Beijing, and Tianjin during Weeks 7 to 9, and finally appear in northeastern provinces of Liaoning, Jilin, and Heilongjiang during Weeks 10 to 12.In the study of risk estimation caused by birdmigration, the likelihood matrix was estimated based on the 7-daytemperature, from February 4 to April 28, 2013. It was found theestimated migrant birds mainly appear in the southeastern provincesof Zhejiang, Shanghai and Jiangsu during Weeks 1 to 4, and Week 6,followed by appearing in central eastern provinces of Shandong, Hebei,Beijing, and Tianjin during Weeks 7 to 9, and finally appear innortheastern provinces of Liaoning, Jilin, and Heilongjiang duringWeeks 10 to 12.In the study of risk caused by poultry distribution, poultrydistribution matrix was created to show the probability of poultrydistribution. Although the fact that the majority of the initialinfections are reported in Shanghai and Jiangsu province, therelative risk of H7N9 infection estimated based on the poultrydistribution model predicted that Jiangsu may have a slightly higherlikelihood of H7N9 infection than that in Zhejiang and Shanghai, ifwe only take the probability of poultry distribution intoconsideration.In the study of integrated risk caused by both bird migration andpoultry distribution, the higher risk in southeastern provincesoccurred during the first 8 weeks, and that in central easternprovinces appeared during Weeks 8 to 12, and that in northeastern provinces since Week 12.Therefore, it is necessary to regulate the poultry markets as long as thepoultry-to-poultry transmission is not so well understood.Conclusion With reference to the reported infection cases,the demonstrated risk mapping results will provide guidance inactive surveillance and control of human H7N9 infections by takingintensive intervention in poultry markets.

Views of health service providers on obstacles to tuberculosis control in Ghana

Joshua Amo-Adjei — 2013-05-02T00:00:00Z

Background: Although Ghana does not fall into the category of those countries which have a high burden of tuberculosis (TB), the disease does present considerable economic and health limitations to individuals infected with, and affected by, the disease, as well as to the health system in general. Despite this fact, insufficient studies have been done on the key barriers to controlling the disease. This paper presents results from an exploratory study on the constraints of controlling TB in Ghana based on the opinions of health service providers. Methods: In-depth interviews were conducted with frontline health workers involved in TB control in the country. Participants were purposively selected from a pool of national and regional, and district and facility level coordinators of the National Tuberculosis Control Programme (NTP). One key informant was also selected from an international non-governmental organisation (NGO) involved in TB-related activities in Ghana. Observations were utilised to complement the study. Data were analysed inductively. Results: Respondents identified the following as being constraints to TB control: clinical complication, bottlenecks in funding administration, quality of physical infrastructure, competition for attention and funding, unsatisfactory coordination between TB and HIV control programmes, a poor public-private partnership, and weak monitoring and evaluation of interventions. Conclusions: This paper provides evidence of some key barriers to TB control. The barriers, as reported, were generally health system-based. Although this list of barriers is not exhaustive, it would be useful to take them into account when planning for TB control, thus adopting a more rounded approach to TB management in the country. As well as that, further studies should be done to explore patients’ views on health service-related barriers to TB control.

China¿s biggest, most neglected health challenge: Non-communicable diseases

Shenglan Tang — 2013-04-05T00:00:00Z

Background: Over the past two decades, international health policies focusing on the fight against the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), tuberculosis (TB), malaria, and those diseases that address maternal and child health problems, among others, have skewed disease control priorities in China and other Asian countries. Although these are important health problems, an epidemic of chronic, non-communicable diseases (NCDs) in China has accounted for a much greater burden of disease due to the ongoing rapid socioeconomic and demographic transition.DiscussionAlthough NCDs currently account for more than 80% of the overall disease burden in China, they remain very low on the nation’s disease control priorities, attracting marginal investment from central and local governments. This leaves the majority of patients with chronic conditions without effective treatment. International organizations and national governments have recognized the devastating social and economic consequences caused by NCDs in low- and middle-income countries, including China. Yet, few donor-funded projects that address NCDs have been implemented in these countries over the past decade. Due to a lack of strong support from international organizations and national governments for fighting against NCDs, affected persons in China, especially the poor and those who live in rural and less developed regions, continue to have limited access to the needed care. Costs associated with frequent health facility visits and regular treatment have become a major factor in medical impoverishment in China. This article argues that although China's ongoing health system reform would provide a unique opportunity to tackle current public health problems, it may not be sufficient to address the emerging threat of NCDs unless targeted steps are taken to assure that adequate financial and human resources are mapped for effective control and management of NCDs in the country.SummaryThe Chinese government needs to develop a domestically-driven and evidence-based disease control policy and funding priorities that respond appropriately to the country’s current epidemiological transition, and rapid sociodemographic and lifestyle changes.

Smear positive pulmonary tuberculosis among diabetic patients at the Dessie referral hospital, Northeast Ethiopia

hiwot amare — 2013-03-27T00:00:00Z

Background: Tuberculosis (TB) is an infectious disease which is still a major cause of morbidity and mortality throughout the world. People with diabetes mellitus (DM) have a three times higher risk of developing active TB than people without diabetes. However, there is not enough credible information on the burden of pulmonary tuberculosis (PTB) among DM patients in Ethiopia, in general, and in the city of Dessie, in particular. Therefore, this study aims to determine the prevalence and associated risk factors of smear positive PTB among diabetic patients at a referral hospital in Dessie. Methods: A cross-sectional study was conducted from February 2012 to April 2012. Patient demographic characteristics were collected using a pre-tested standard questionnaire format. Spot-morning-spot sputum specimens were collected from the study participants and examined for acid-fast bacilli using direct microscopy by the Ziehl-Neelsen staining technique. Data was entered and analyzed using the SPSS version 16 statistical software and p-value <0.05 was considered as statistically significant. Results: Out of 225 TB suspected diabetic patients, 52% were males and 48% were females. Their ages ranged from 12 to 82 years, with a mean age of 47.2 years. Urban residence (AOR: 5.5; 95% CI: 1.07–28.20), history of TB (AOR: 13.4; 95% CI: 2.74–65.73), contact with TB patients in the family (AOR: 9.4; 95% CI: 1.822–48.50), and long duration of DM (AOR: 8.89; 95% CI: 1.88–58.12) were independently associated with the development of active TB in people living with DM. Conclusions: The prevalence of smear positive PTB was 6.2% in TB suspected diabetic patients, which is higher compared with the general population (0.39%). Patients with a previous history of contact with TB patients, as well as those who had prolonged diabetes, were more prone to have PTB. Therefore, screening of diabetic patients for PTB infection during follow-up is necessary.

In vitro gene silencing of independent phosphoglycerate mutase (iPGM) in the filarial parasite Brugia malayi

Prashant Singh — 2013-03-25T00:00:00Z

Background: The phosphoglycerate mutase (PGM) enzyme catalyzes the interconversion of 2- and 3-phosphoglycerate in the glycolytic /gluconeogenic pathways that are present in the majority of cellular organisms. They can be classified as cofactor-dependent PGM (dPGM) or cofactor-independent PGM (iPGM). Vertebrates, yeasts, and many bacteria have only dPGM, while higher plants, nematodes, archaea, and many other bacteria have only iPGM. A small number of bacteria, including Escherichia coli and certain archaea and protozoa, contain both forms. The silencing of ipgm in Caenorhabditis elegans (C. elegans) has demonstrated the importance of this enzyme in parasite viability and, therefore, its potential as an anthelmintic drug target. In this study, the role of the Brugia malayi (B. malayi) ipgm in parasite viability, microfilaria release, embryogenesis, and in vivo development of infective larvae post-gene silencing was explored by applying ribonucleic acid (RNA) interference studies. Results: The in vitro ipgm gene silencing by small interfering RNA (siRNA) leads to severe phenotypic deformities in the intrauterine developmental stages of female worms with a drastic reduction (~90%) in the motility of adult parasites and a significantly reduced (80%) release of microfilariae (mf) by female worms in vitro. Almost half of the in vitro-treated infective L3 displayed sluggish movement. The in vivo survival and development of siRNA-treated infective larvae (L3) was investigated in the peritoneal cavity of jirds where a ~45% reduction in adult worm establishment was observed. Conclusion: The findings clearly suggest that iPGM is essential for both larval and adult stages of B. malayi parasite and that it plays a pivotal role in female worm embryogenesis. The results thus validate the Bm-iPGM as a putative anti-filarial drug target.

Time to tackle clonorchiasis in China

Men-Bao Qian — 2013-02-19T00:00:00Z

Recent publication of the global epidemiology of clonorchiasis and its relationship with cholangiocarcinoma in the journal of Infectious Diseases of Poverty has stressed the importance of Clonorchis sinensis infection. To further demonstrate its threat on public health, especially in China, comparisons between clonorchiasis and hepatitis B are made in terms of epidemiology, clinical symptoms and carcinogenicity, disability, as well as changing trends. Furthermore, major problems and prioritized researches are argued, from basic biology to intervention. Imbalance between the majority of infected population and the minority of researches in China urges for more work from Chinese scientists and international cooperation.

On the exoneration of Dr. William H. Stewart: debunking an urban legend

Brad Spellberg — 2013-02-18T00:00:00Z

Background: It is one of the most infamous quotes in the history of biomedicine: “It is time to close the book on infectious diseases, and declare the war against pestilence won.” Long attributed to the United States Surgeon General, Dr. William H. Stewart (1965-1969), the statement is frequently used as a foil by scientific and lay authors to underscore the ever-increasing problems of antibiotic-resistant and emerging infections. However, the primary source for the quote has never been identified. Methods: We undertook a comprehensive search of multiple databases encompassing medical literature, news articles, and congressional records to attempt to identify sources for the quote. Results: No source of the quote was identified. However, a trail of source documents was identified that clearly serves as the basis for subsequent, incorrect attribution of the quote to Dr. Stewart. In multiple source documents, Dr. Stewart made statements to the opposite effect, clearly recognizing that infectious diseases had not been conquered. The urban legend was created by a combination of lack of primary witnesses to the originating speech, misunderstanding of points made by Dr. Stewart in the speech, and increasing societal concern about emerging and re-emerging infectious diseases. Conclusions: Attribution to Dr. Stewart of a belief that it was time to close the book on infectious diseases is an urban legend; he never made any such statement. Numerous other verifiable sources, however, confirm that other people in academia adopted this belief. Dr. Stewart should no longer be cited in this regard, and should be replaced with verifiable sources.

Epidemiology and interactions of Human Immunodeficiency Virus -- 1 and Schistosoma mansoni in sub-Saharan Africa

Humphrey Mazigo — 2013-01-24T00:00:00Z

Human Immunodeficiency Virus-1/AIDS and Schistosoma mansoni are widespread in sub-Saharan Africa and co-infection occurs commonly. Since the early 1990s, it has been suggested that the two infections may interact and potentiate the effects of each other within co-infected human hosts. Indeed, S. mansoni infection has been suggested to be a risk factor for HIV transmission and progression in Africa. If so, it would follow that mass deworming could have beneficial effects on HIV-1 transmission dynamics. The epidemiology of HIV in African countries is changing, shifting from urban to rural areas where the prevalence of Schistosoma mansoni is high and public health services are deficient. On the other side, the consequent pathogenesis of HIV-1/S. mansoni co-infection remains unknown. Here we give an account of the epidemiology of HIV-1 and S. mansoni, discuss co-infection and possible biological causal relationships between the two infections, and the potential impact of praziquantel treatment on HIV-1 viral loads, CD4+ counts and CD4+/CD8+ ratio. Our review of the available literature indicates that there is evidence to support the hypothesis that S. mansoni infections can influence the replication of the HIV-1, cell-to-cell transmission, as well as increase HIV progression as measured by reduced CD4+ T lymphocytes counts. If so, then deworming of HIV positive individuals living in endemic areas may impact on HIV-1 viral loads and CD4+ T lymphocyte counts.

Elimination of tropical disease through surveillance and response

Xiao-Nong Zhou — 2013-01-03T00:00:00Z

Surveillance and response represent the final crucial steps in achieving effective control and particularly elimination of communicable diseases as recognized in the area of neglected tropical diseases (NTDs), applied in increasing numbers in endemic countries with ongoing control and elimination programmers. More and more national NTD elimination initiatives are scheduled based on the innovative and effective One world-One health perspective to detect pockets of transmission and disease reintroduction. Resource-constrained countries, which carry the heaviest NTD burdens, face various challenges how to strengthen the health system as well as developing effective and novel tools for surveillance and response tailored to local settings. Surveillance-response approaches take place in two different stages corralling the basic components of the surveillance-response system for NTD elimination. Six different research priorities have been identified:1)dynamic mapping of transmission, 2) near real-time capture of population dynamics, 3) modelling based on a minimum essential database/dataset, 4) implementation of mobile health (m-health) and sensitive diagnostics, 5) design of effective response packages tailored to different transmission settings and levels, and 6) validation of approaches and responses packages.

Assessing the impact of TB/HIV services integration on TB treatment outcomes and their relevance in TB/HIV monitoring in Ghana

Gloria Ansa — 2012-12-24T00:00:00Z

Background: The impact of the human immunodeficiency virus (HIV) on tuberculosis (TB), and the implications for TB and HIV control, is a public health challenge in Ghana – almost a quarter (23%) of all TB cases were HIV positive in 2010. The integration of TB/HIV services has therefore emerged as an essential component of the national response to TB and HIV. The aim is to reduce fragmentation, improve access, enhance efficiency and improve quality of care. Ghana’s TB/HIV policy comprises three linked sets of activities: effective implementation of the Stop TB Strategy for TB control, improved HIV prevention and care, and the implementation of additional TB/HIV activities. Different models of service delivery with increasing integration of TB/HIV activities are expected to provide greater access to more comprehensive care. The objective of this paper is to assess the impact of TB/HIV integration on TB treatment outcomes and to explore the usefulness of TB treatment outcomes as TB/HIV indicators. Methods: A before-and-after study to observe the introduction of TB/HIV activities into TB programmes in three hospitals with different levels of integration was conducted. Anonymised patient data was collated from TB registers from each facility, and analysed to determine if TB treatment outcomes changed significantly after integration. Results: TB treatment success was 50% (95% CI 49 – 52) prior to, and 69% (95% CI 65 – 73) after, integration (Χ2 43.96, p < 0.00). Treatment success increased from 43% to 53% at the one-stop shop (OSS), from 69% to 78% at the partially integrated site (PIS) and substantially from 46% to 78% at the referral site (RS) (Χ2 64.54; p<0.01). Defaults and cases transferred out reduced from 14.3% and 15.3% prior to integration, to 1.4% and 9.0% after integration, respectively, accounting for a significant increase in treatment success. Death rates remained high at 18% in all cases studied and 25% in HIV-associated cases after integration. Conclusion: TB/HIV integration may improve TB treatment success, but its exact impact is difficult to ascertain due to non-specificity and design limitations. TB mortality may be more useful as an indicator for monitoring TB/HIV activities in Ghana.