Topics in relativistic cosmology: Cosmology on the past lightcone and in modified gravitation

The lightcone gauge is a set of what are called the observational coordinates adapted to our past lightcone. We develop this gauge by producing a perturbed spacetime metric that describes the geometry of our past lightcone where observations are usually obtained. We then connect the produced observational metric to the perturbed Friedmann-Lemaître-Robertson-Walker metric in the standard general gauge or what is the so-called 1+3 gauge. We derive the relations between these perturbations of spacetime in the observational coordinates and those perturbations in the standard metric approach, as well as the dynamical equations for the perturbations in observational coordinates. We also calculate the observables in the lightcone gauge and rederive them in terms of Bardeen potentials to first order. A verification is made of the observables in the perturbed lightcone gauge with those in the standard gauge. The advantage of the method developed is that the observable relations are simpler than in the standard formalism. We use the perturbed lightcone gauge in galaxy surveys and galaxy number density contrast. The significance of the new gauge is that by considering the null-like light propagations, the calculations are much simpler since angular deviations are not considered. Standard cosmology based on General Relativity is generally believed to have serious shortcomings, such as the unexplained issues of dark matter and dark energy. As a remedy, many alternative theories of gravitation have been proposed over the years, one of which is ƒ(R) gravity. We explore classes of irrotational-fluid cosmological models in the context of ƒ(R) gravity in an attempt to put some theoretical and mathematical restrictions on the form of the ƒ(R) gravitational Lagrangian. In particular, we investigate the consistency of the linearised dust models for shear-free cases as well as in the limiting cases when either the gravito-magnetic or gravito-electric components of the Weyl tensor vanish. We also discuss the existence and consistency of classes of non-expanding irrotational spacetimes in ƒ(R)-gravity. Furthermore, we explore exact ƒ(R) gravity solutions that mimic Chaplygin-gas inspired ΛCDM cosmology. Starting with the original, generalized and modified Chaplygin gas equations of state, we reconstruct the forms of ƒ(R) Lagrangians. The resulting solutions are generally quadratic in the Ricci scalar, but have appropriate ΛCDM solutions in limiting cases. These solutions, given appropriate initial conditions, can be potential candidates for scalar field-driven early universe expansion (in ation) and dark energy-driven late-time cosmic acceleration

A fixed-dose 24-hour regimen of artesunate plus sulfamethoxypyrazine-pyrimethamine for the treatment of uncomplicated Plasmodium falciparum malaria in eastern Sudan

BACKGROUND: Artemisinin-based combination therapy is increasingly being adopted as first-line antimalarial therapy. The choice of appropriate therapy depends on efficacy, cost, side effects, and simplicity of administration. METHODS: the efficacy of fixed co-formulated (f) artesunate-sulfamethoxypyrazine-pyrimethamine (AS+SMP f) administered at time intervals of 12 hours for a 24-hour therapy was compared with the efficacy of the same drug given as a loose combination (AS+SMP l) with a dose interval of 24 hours for 3 days for the treatment of uncomplicated Plasmodium falciparum malaria in eastern Sudan. RESULTS: seventy-three patients (39 and 34 in the fixed and the loose regimen of AS+SMP respectively) completed the 28-days of follow-up. On day 3; all patients in both groups were a parasitaemic but one patient in the fixed group of AS+SMP f was still febrile. Polymerase chain reaction genotyping adjusted cure rates on day 28 were 92.3% and 97.1% (P > 0.05) for the fixed and loose combination of AS+SMP respectively. Three (4.1%) patients (one in the fixed and two patients in the loose group of AS+SMP) in the study suffered drug-related adverse effects. Gametocytaemia was not detected during follow-up in any of the patients. CONCLUSION: both regimens of AS+SMP were effective and safe for the treatment of uncomplicated P. falciparum malaria in eastern Sudan. Due to its simplicity, the fixed dose one-day treatment regimen may improve compliance and therefore may be the preferred choice

Self-reported fever, treatment actions and malaria infection prevalence in the northern states of Sudan

BACKGROUND: The epidemiology of fevers and their management in areas of low malaria transmission in Africa is not well understood. The characteristics of fever, its treatment and association with infection prevalence from a national household sample survey in the northern states of Sudan, an area that represents historically low parasite prevalence, are examined in this study. METHODS: In October-November 2009, a cluster sample cross-sectional household malaria indicator survey was undertaken in the 15 northern states of the Sudan. Data on household assets and individual level information on age, sex, whether the individual had a fever in the last 14 days and on the day of survey, actions taken to treat the fever including diagnostic services and drugs used and their sources were collected. Consenting household members were asked to provide a finger-prick blood sample and examined for malaria parasitaemia using a rapid diagnostic test (RDT). All proportions and odds ratios were weighted and adjusted for clustering. RESULTS: Of 26,471 respondents 19% (n = 5,299) reported a history of fever within the last two weeks prior to the survey and 8% had fever on the day of the survey. Only 39% (n = 2,035) of individuals with fever in last two weeks took any action, of which 43% (n = 875) were treated with anti-malarials. About 44% (n = 382) of malaria treatments were done using the nationally recommended first-line therapy artesunate+sulphadoxine-pryrimethamine (AS+SP) and 13% (n = 122) with non-recommended chloroquine or SP. Importantly 33.9% (n = 296) of all malaria treatments included artemether monotherapy, which is internationally banned for the treatment of uncomplicated malaria. About 53% of fevers had some form of parasitological diagnosis before treatment. On the day of survey, 21,988 individuals provided a finger-prick blood sample and only 1.8% were found positive for Plasmodium falciparum. Infection prevalence was higher among individuals who had fever in the last two weeks (OR = 3.4; 95%CI = 2.6 - 4.4, p < 0.001) or reported fever on the day of survey (OR = 6.2; 95%CI = 4.4 - 8.7, p < 0.001) compared to those without a history of fever. CONCLUSION: Across the northern states of the Sudan, the period prevalence of fever is low. The proportion of fevers that are likely to be malaria is very low. Consequently, parasitological diagnosis of all fevers before treatment is an appropriate strategy for malaria case-management. Improved regulation and supervision of health workers is required to increase the use of diagnostics and remove the practice of prescribing artemisinin monotherapy

Use and limitations of malaria rapid diagnostic testing by community health workers in war-torn Democratic Republic of Congo

<p>Abstract</p> <p>Background</p> <p>Accurate and practical malaria diagnostics, such as immunochromatographic rapid diagnostic tests (RDTs), have the potential to avert unnecessary treatments and save lives. Volunteer community health workers (CHWs) represent a potentially valuable human resource for expanding this technology to where it is most needed, remote rural communities in sub-Saharan Africa with limited health facilities and personnel. This study reports on a training programme for CHWs to incorporate RDTs into their management strategy for febrile children in the Democratic Republic of Congo, a tropical African setting ravaged by human conflict.</p> <p>Methods</p> <p>Prospective cohort study, satisfaction questionnaire and decision analysis.</p> <p>Results</p> <p>Twelve CHWs were trained to safely and accurately perform and interpret RDTs, then successfully implemented rapid diagnostic testing in their remote community in a cohort of 357 febrile children. CHWs were uniformly positive in evaluating RDTs for their utility and ease of use. However, high malaria prevalence in this cohort (93% by RDTs, 88% by light microscopy) limited the cost-effectiveness of RDTs compared to presumptive treatment of all febrile children, as evidenced by findings from a simplified decision analysis.</p> <p>Conclusions</p> <p>CHWs can safely and effectively use RDTs in their management of febrile children; however, cost-effectiveness of RDTs is limited in zones of high malaria prevalence.</p

Low referral completion of rapid diagnostic test-negative patients in community-based treatment of malaria in Sierra Leone

ABSTRACT

Impact of combining intermittent preventive treatment with home management of malaria in children less than 10 years in a rural area of Senegal: a cluster randomized trial

<p>Abstract</p> <p>Background</p> <p>Current malaria control strategies recommend (i) early case detection using rapid diagnostic tests (RDT) and treatment with artemisinin combination therapy (ACT), (ii) pre-referral rectal artesunate, (iii) intermittent preventive treatment and (iv) impregnated bed nets. However, these individual malaria control interventions provide only partial protection in most epidemiological situations. Therefore, there is a need to investigate the potential benefits of integrating several malaria interventions to reduce malaria prevalence and morbidity.</p> <p>Methods</p> <p>A randomized controlled trial was carried out to assess the impact of combining seasonal intermittent preventive treatment in children (IPTc) with home-based management of malaria (HMM) by community health workers (CHWs) in Senegal. Eight CHWs in eight villages covered by the Bonconto health post, (South Eastern part of Senegal) were trained to diagnose malaria using RDT, provide prompt treatment with artemether-lumefantrine for uncomplicated malaria cases and pre-referral rectal artesunate for complicated malaria occurring in children under 10 years. Four CHWs were randomized to also administer monthly IPTc as single dose of sulphadoxine-pyrimethamine (SP) plus three doses of amodiaquine (AQ) in the malaria transmission season, October and November 2010. Primary end point was incidence of single episode of malaria attacks over 8 weeks of follow up. Secondary end points included prevalence of malaria parasitaemia, and prevalence of anaemia at the end of the transmission season. Primary analysis was by intention to treat. The study protocol was approved by the Senegalese National Ethical Committee (approval 0027/MSP/DS/CNRS, 18/03/2010).</p> <p>Results</p> <p>A total of 1,000 children were enrolled. The incidence of malaria episodes was 7.1/100 child months at risk [95% CI (3.7-13.7)] in communities with IPTc + HMM compared to 35.6/100 child months at risk [95% CI (26.7-47.4)] in communities with only HMM (aOR = 0.20; 95% CI 0.09-0.41; <it>p </it>= 0.04). At the end of the transmission season, malaria parasitaemia prevalence was lower in communities with IPTc + HMM (2.05% versus 4.6% <it>p </it>= 0.03). Adjusted for age groups, sex, <it>Plasmodium falciparum </it>carriage and prevalence of malnutrition, IPTc + HMM showed a significant protective effect against anaemia (aOR = 0.59; 95% CI 0.42-0.82; <it>p </it>= 0.02).</p> <p>Conclusion</p> <p>Combining IPTc and HMM can provide significant additional benefit in preventing clinical episodes of malaria as well as anaemia among children in Senegal.</p

Feasibility and acceptability of home-based management of malaria strategy adapted to Sudan's conditions using artemisinin-based combination therapy and rapid diagnostic test

<p>Abstract</p> <p>Background</p> <p>Malaria remains a major public health problem especially in sub-Saharan Africa. Despite the efforts exerted to provide effective anti-malarial drugs, still some communities suffer from getting access to these services due to many barriers. This research aimed to assess the feasibility and acceptability of home-based management of malaria (HMM) strategy using artemisinin-based combination therapy (ACT) for treatment and rapid diagnostic test (RDT) for diagnosis.</p> <p>Methods</p> <p>This is a study conducted in 20 villages in Um Adara area, South Kordofan state, Sudan. Two-thirds (66%) of the study community were seeking treatment from heath facilities, which were more than 5 km far from their villages with marked inaccessibility during rainy season. Volunteers (one per village) were trained on using RDTs for diagnosis and artesunate plus sulphadoxine-pyrimethamine for treating malaria patients, as well as referral of severe and non-malaria cases. A system for supply and monitoring was established based on the rural health centre, which acted as a link between the volunteers and the health system. Advocacy for the policy was done through different tools. Volunteers worked on non-monetary incentives but only a consultation fee of One Sudanese Pound (equivalent to US$0.5).</p> <p>Pre- and post-intervention assessment was done using household survey, focus group discussion with the community leaders, structured interview with the volunteers, and records and reports analysis.</p> <p>Results and discussion</p> <p>The overall adherence of volunteers to the project protocol in treating and referring cases was accepted that was only one of the 20 volunteers did not comply with the study guidelines. Although the use of RDTs seemed to have improved the level of accuracy and trust in the diagnosis, 30% of volunteers did not rely on the negative RDT results when treating fever cases. Almost all (94.7%) the volunteers felt that they were satisfied with the spiritual outcome of their new tasks. As well, volunteers have initiated advocacy campaigns supported by their village health committees which were found to have a positive role to play in the project that proved their acceptability of the HMM design. The planned system for supply was found to be effective. The project was found to improve the accessibility to ACTs from 25% to 64.7% and the treatment seeking behaviour from 83.3% to 100% before- and after the HMM implementation respectivly.</p> <p>Conclusion</p> <p>The evaluation of the project identified the feasibility of the planned model in Sudan's condition. Moreover, the communities as well as the volunteers found to be satisfied with and supportive to the system and the outcome. The problem of treating other febrile cases when diagnosis is not malaria and other non-fever cases needs to be addressed as well.</p

Community acceptability of use of rapid diagnostic tests for malaria by community health workers in Uganda

<p>Abstract</p> <p>Background</p> <p>Many malarious countries plan to introduce artemisinin combination therapy (ACT) at community level using community health workers (CHWs) for treatment of uncomplicated malaria. Use of ACT with reliance on presumptive diagnosis may lead to excessive use, increased costs and rise of drug resistance. Use of rapid diagnostic tests (RDTs) could address these challenges but only if the communities will accept their use by CHWs. This study assessed community acceptability of the use of RDTs by Ugandan CHWs, locally referred to as community medicine distributors (CMDs).</p> <p>Methods</p> <p>The study was conducted in Iganga district using 10 focus group discussions (FGDs) with CMDs and caregivers of children under five years, and 10 key informant interviews (KIIs) with health workers and community leaders. Pre-designed FGD and KII guides were used to collect data. Manifest content analysis was used to explore issues of trust and confidence in CMDs, stigma associated with drawing blood from children, community willingness for CMDs to use RDTs, and challenges anticipated to be faced by the CMDs.</p> <p>Results</p> <p>CMDs are trusted by their communities because of their commitment to voluntary service, access, and the perceived effectiveness of anti-malarial drugs they provide. Some community members expressed fear that the blood collected could be used for HIV testing, the procedure could infect children with HIV, and the blood samples could be used for witchcraft. Education level of CMDs is important in their acceptability by the community, who welcome the use of RDTs given that the CMDs are trained and supported. Anticipated challenges for CMDs included transport for patient follow-up and picking supplies, adults demanding to be tested, and caregivers insisting their children be treated instead of being referred.</p> <p>Conclusion</p> <p>Use of RDTs by CMDs is likely to be acceptable by community members given that CMDs are properly trained, and receive regular technical supervision and logistical support. A well-designed behaviour change communication strategy is needed to address the anticipated programmatic challenges as well as community fears and stigma about drawing blood. Level of formal education may have to be a criterion for CMD selection into programmes deploying RDTs.</p

Progress towards implementation of ACT malaria case-management in public health facilities in the Republic of Sudan: a cluster-sample survey

<p>Abstract</p> <p>Background</p> <p>Effective malaria case-management based on artemisinin-based combination therapy (ACT) and parasitological diagnosis is a major pillar within the 2007-2012 National Malaria Strategic Plan in the Sudan. Three years after the launch of the strategy a health facility survey was undertaken to evaluate case-management practices and readiness of the health facilities and health workers to implement a new malaria case-management strategy.</p> <p>Methods</p> <p>A cross-sectional, cluster sample survey was undertaken at public health facilities in 15 states of Sudan. Data were collected using quality-of-care assessment methods. The main outcomes were the proportions of facilities with ACTs and malaria diagnostics; proportions of health workers exposed to malaria related health systems support activities; and composite and individual indicators of case-management practices for febrile outpatients stratified by age, availability of ACTs and diagnostics, use of malaria diagnostics, and test result.</p> <p>Results</p> <p>We evaluated 244 facilities, 294 health workers and 1,643 consultations for febrile outpatients (425 < 5 years and 1,218 ≥ 5 years). Health facility and health worker readiness was variable: chloroquine was available at only 5% of facilities, 73% stocked recommended artesunate and sulfadoxine/pyrimethamine (AS+SP), 51% had the capacity to perform parasitological diagnosis, 53% of health workers had received in-service training on ACTs, 24% were trained in the use of malaria Rapid Diagnostic Tests, and 19% had received a supervisory visit including malaria case-management. At all health facilities 46% of febrile patients were parasitologically tested and 35% of patients were both, tested and treated according to test result. At facilities where AS+SP and malaria diagnostics were available 66% of febrile patients were tested and 51% were both, tested and treated according to test result. Among test positive patients 64% were treated with AS+SP but 24% were treated with artemether monotherapy. Among test negative patients only 17% of patients were treated for malaria. The majority of ACT dispensing and counseling practices were suboptimal.</p> <p>Conclusions</p> <p>Five years following change of the policy from chloroquine to ACTs and 3 years before the end of the new malaria strategic plan chloroquine was successfully phased out from public facilities in Sudan, however, an important gap remained in the availability of ACTs, diagnostic capacities and coverage with malaria case-management activities. The national scale-up of diagnostics, using the findings of this survey as well as future qualitative research, should present an opportunity not only to expand existing testing capacities but also to implement effective support interventions to bridge the health systems gaps and support corrective case-management measures, including the discontinuation of artemether monotherapy treatment.</p

Community participation for malaria elimination in tafea province, vanuatu: part ii. social and cultural aspects of treatment-seeking behaviour

Background: Early diagnosis and prompt effective case management are important components of any malaria elimination strategy. Tafea Province, Vanuatu has a rich history of traditional practices and beliefs, which have been integrated with missionary efforts and the introduction of modern constructions of health. Gaining a detailed knowledge of community perceptions of malarial symptomatology and treatment-seeking behaviours is essential in guiding effective community participation strategies for malaria control and elimination