Bruno de Sousa

Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax – Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)

Background Plasmodium vivax shows a small prevalence in West and Central Africa due to the high prevalence of Duffy negative people. However, Duffy negative individuals infected with P. vivax have been reported in areas of high prevalence of Duffy positive people who may serve as supply of P. vivax strains able to invade Duffy negative erythrocytes. We investigated the presence of P. vivax in two West African countries, using blood samples and mosquitoes collected during two on-going studies. Methodology/Findings Blood samples from a total of 995 individuals were collected in seven villages in Angola and Equatorial Guinea, and 820 Anopheles mosquitoes were collected in Equatorial Guinea. Identification of the Plasmodium species was achieved by nested PCR amplification of the small-subunit rRNA genes; P. vivax was further characterized by csp gene analysis. Positive P. vivax-human isolates were genotyped for the Duffy blood group through the analysis of the DARC gene. Fifteen Duffy-negative individuals, 8 from Equatorial Guinea (out of 97) and 7 from Angola (out of 898), were infected with two different strains of P. vivax (VK210 and VK247). Conclusions In this study we demonstrated that P. vivax infections were found both in humans and mosquitoes, which means that active transmission is occurring. Given the high prevalence of infection in mosquitoes, we may speculate that this hypnozoite-forming species at liver may not be detected by the peripheral blood samples analysis. Also, this is the first report of Duffy negative individuals infected with two different strains of P. vivax (VK247 and classic strains) in Angola and Equatorial Guinea. This finding reinforces the idea that this parasite is able to use receptors other than Duffy to invade erythrocytes, which may have an enormous impact in P. vivax current distribution.

Sabotage-tolerance and trust management in desktop grid computing

The success of grid computing in open environments like the Internet is highly dependent on the adoption of mechanisms to detect failures and malicious sabotage attempts. It is also required to maintain a trust management system that permits one to distinguish the trustable from the non-trustable participants in a global computation. Without these mechanisms, users with data-critical applications will never rely on desktop grids, and will rather prefer to support higher costs to run their computations in closed and secure computing systems. This paper discusses the topics of sabotage-tolerance and trust management. After reviewing the state-of-the-art, we present two novel techniques: a mechanism for sabotage detection and a protocol for distributed trust management. The proposed techniques are targeted at the paradigm of volunteer-based computing commonly used on desktop grids.

Europe's men need their own health strategy.

A recent European report on men’s health shows that it lags behind that of women. Alan White and colleagues analyse the problems and call for more policy, practice, and research aimed specifically at men

Potential threat of malaria epidemics in a low transmission area, as exemplified by São Tomé and Príncipe

BackgroundPlasmodium falciparum is the major cause of malaria infection in the island of São Tomé, in the Republic of São Tomé and Príncipe (STP), with an incidence of 40 - 50% before 2004. Since 2004, through the coordination of the Ministry of Health of STP and their Centro Nacional de Endemias (CNE), an integrated malaria control programme has been intensively deployed on the island of São Tomé. Malaria morbidity and mortality decreased by 95% after three years of effective intervention. In the low transmission settings, however, malaria seasonal fluctuation can be a potential problem directly related to epidemics if ongoing control measures are interrupted. Studies on a number of associated factors with malaria epidemics and the measures taken to respond to outbreaks are presented.MethodsThe integrated malaria control programme included indoor residual spraying (IRS), long-lasting insecticidal nets (LLINs), intermittent preventive therapy for pregnant women, as well as early diagnosis and prompt treatment with artemisinin-based combination therapy (ACT). Regular implementation of an island-wide IRS programme was carried out yearly in 2004-2007, and enhanced throughout the island in 2009. Malaria incidence and prevalence were estimated based on passive case detection and mass screening, respectively. Slide positivity rates were used for monitoring the beginning of a malaria epidemic or a seasonal peak.ResultsA steep decline of ca. 95% of malaria morbidity and mortality was observed between 2004 and 2008 with use of the combined control methods. Malaria incidence was 2.0%, 1.5%, and 3.0% for 2007, 2008, and 2009, respectively. In April 2008, a cross-sectional country-wide surveillance showed malaria prevalence of 3.5%, of which 95% cases were asymptomatic carriers. Only 50% of asymptomatic carriers were cured with ACT treatment, while 90% of the symptomatic patients were cured by ACT treatment as confirmed with a follow up study. Malaria morbidity increased by three-fold during the first half of 2009 as compared to the same period in 2008. Over this period of six months, severe malaria was also noted in all age groups and malaria mortality increased by two-fold in children less than five years old. After an emergency IRS was deployed, with increased use of LLINs, and an active search of asymptomatic carriers was followed and given complete ACT treatment, malaria incidence decreased to less than 1% in the second half of 2009.ConclusionAt the initial stage of the integrated malaria control programme, IRS contributed to the visible effect on the rapid reduction of malaria morbidity and mortality, while this programme highlights an urgent demand for the improvement of other measures, particularly promotion of LLINs usage, with close monitoring of asymptomatic carriers and with ACT treatment in malaria transmission hotspots. In addition, both daily reports and a regular active surveillance to prevent malaria outbreaks should be established permanently, so that a fast response to epidemics can be effectively made when necessary.

The QueuePusher: Enabling Queue Management in OpenFlow

The evolution of Software-Defined Networking and the overall acceptance of protocols such as OpenFlow, demonstrates the added value of decoupling the data plane from the control plane. Existing SDN Controllers enable the expected flexibility from such networks by dynamically providing a fine-grained control of each flow. However, hardware-specific configurations, such as the creation of queues or other mechanisms is out of the scope of these controllers. This work presents an extension to a well known OpenFlow controller (Floodlight) to efficiently handle the management of Traffic Control Queues in OpenFlow switches, resorting to a RESTful northbound interface. The obtained results demonstrate further possibility of developing innovative on-demand resource reservation mechanisms in SDN without adding unbearable overheads.

A diagnostic plot for estimating the tail index of a distribution

The problem of estimating the tail index in heavy-tailed distributions is very important in many applications. We propose a new graphical method that deals with this problem by selecting an appropriate number of upper order statistics. We also investigate the methods theoretical properties are investigated. Several real datasets are analyzed using this new procedure and a simulation study is carried out to examine its performance in small, moderate and large samples. The results suggest that the new procedure overcomes many of the shortcomings present in some of the most common techniques—for example, the Hill and Zipf plots—used in the estimation of the tail index, and it performs very competitively when compared with other adaptive threshold procedures based on the asymptotic mean squared error of the Hill estimator.

Therapeutic Potential of Caspofungin Combined with Trimethoprim-Sulfamethoxazole for Pneumocystis Pneumonia: A Pilot Study in Mice

Pneumocystis pneumonia (PcP) is a major cause of mortality and morbidity in immunocompromised patients. There are limited alternative therapeutic choices to trimethoprim-sulfamethoxazole (TMP-SMX) which is the standard first line therapy/prophylaxis for PcP. The efficacy of low doses of caspofungin and caspofungin in association with TMP-SMX standard-prophylactic dose was evaluated in an experimental model of Pneumocystis. Susceptibility of Pneumocystis spp. to low doses of caspofungin and caspofungin/TMP-SMX was evaluated in Balb/c immunosuppressed mice, infected intranasally with P. murina. Caspofungin was administered once daily at 0.1 mg/kg, 0.05 mg/kg, and 0.001 mg/kg and TMP-SMX was administered by oral gavage (12.25 mg/62.5 mg/day), for 21 days. Efficacy was calculated based on the reduction in organism burden determined through quantitative fluorescent-based real-time PCR (qPCR). Serum β-1,3-D-glucan was measured as an additional marker of infection. The present data showed that caspofungin demonstrated anti-Pneumomocystis effect. However, the doses administrated were too low to achieve Pneumocystis eradication, which suggests that echinocandin treatment should not be administrated as mono-therapy. After 21 days of treatment, P. murina was not detected in the lungs of mice with either TMP-SMX or caspofungin/TMP-SMX. The results showed that, even at the lowest concentrations tested, the efficacy of caspofungin in association with TMP-SMX was higher than the efficacy of either drug used alone. The administration of caspofungin/TMP-SMX was at least 1.4 times more effective against P. murina infection than TMP-SMX used alone. The most promising result was achieved with the combination of caspofungin 0.05 mg/kg/day with TMP-SMX 12.5 mg–62.5 mg/day, which reduced the parasite burden to undetectable levels immediately at the 14th day of treatment, showing a highly marked anti-Pneumomocystis effect. These data suggest that the administration of low doses of caspofungin in combination with low doses of TMP-SMX may provide an improved treatment protocol for Pneumocystis infection clearance.

What influences national and foreign physicians’ geographic distribution? An analysis of medical doctors’ residence location in Portugal

BackgroundThe debate over physicians’ geographical distribution has attracted the attention of the economic and public health literature over the last forty years. Nonetheless, it is still to date unclear what influences physicians’ location, and whether foreign physicians contribute to fill the geographical gaps left by national doctors in any given country. The present research sets out to investigate the current distribution of national and international physicians in Portugal, with the objective to understand its determinants and provide an evidence base for policy-makers to identify policies to influence it.MethodsA cross-sectional study of physicians currently registered in Portugal was conducted to describe the population and explore the association of physician residence patterns with relevant personal and municipality characteristics. Data from the Portuguese Medical Council on physicians’ residence and characteristics were analysed, as well as data from the National Institute of Statistics on municipalities’ population, living standards and health care network. Descriptive statistics, chi-square tests, negative binomial and logistic regression modelling were applied to determine: (a) municipality characteristics predicting Portuguese and International physicians’ geographical distribution, and; (b) doctors’ characteristics that could increase the odds of residing outside the country’s metropolitan areas.ResultsThere were 39,473 physicians in Portugal in 2008, 51.1% of whom male, and 40.2% between 41 and 55 years of age. They were predominantly Portuguese (90.5%), with Spanish, Brazilian and African nationalities also represented. Population, Population’s Purchasing Power, Nurses per capita and Municipality Development Index (MDI) were the municipality characteristics displaying the strongest association with national physicians’ location. For foreign physicians, the MDI was not statistically significant, while municipalities’ foreign population applying for residence appeared to be an additional positive factor in their location decisions. In general, being foreigner and male resulted to be the physician characteristics increasing the odds of residing outside the metropolitan areas. However, among the internationals, older doctors were more likely to reside outside metropolitan areas. Being Spanish or Brazilian (but not of African origin) was found to increase the odds of being based outside the Lisbon and Oporto metropolitan areas.ConclusionsThe present study showed the relevance of studying one country’s physician population to understand the factors driving national and international doctors’ location decisions. A more nuanced understanding of national and foreign doctors’ location appears to be needed to design more effective policies to reduce the imbalance of medical services across geographical areas.

Dynamics of cytokines and immunoglobulins serum profiles in primary and secondary Cryptosporidium parvum infection: Usefulness of Luminex® xMAP technology

Infection by Cryptosporidium parvum triggers a complex array of innate and adaptive cell mediated immune response, playing an important role in controlling the infection. To date, there are no studies applying the Luminex® xMAP technology to determine profiles of cytokines and immunoglobulins in the context of an infection by C. parvum. In this study, we analyzed these immune mediators in the serum of immunocompetent mice inoculated with C. parvum oocysts, using Luminex, to understand how the immune system responds to an infection by this parasite. Animal sera were also analyzed by ELISA to determine the expressed immunoglobulin isotype profile, and compare the obtained trend with data obtained by Luminex. Specific-pathogen-free BALB/C mice were inoculated with oocysts of C. parvum at days 0 and 22. Peripheral blood was aseptically collected from sacrificed mice on several time points, and immune mediators were evaluated in serum samples. Infection was confirmed by the presence of C. parvum DNA in feces by a nested-PCR assay (60-kDa glycoprotein). Luminex results showed predominance in the secretion of IgG1 and IgG2a, confirmed by ELISA, which also showed that IgG1 is the major immunoglobulin isotype produced during the infection. The analysis of cytokines suggests a preferential Th(1) over the Th(2) response, with increased production of TNF-α, IFN-γ and GM-CSF. This work contributed to a better understanding of the immune response to the infection by C. parvum, as well as demonstrated the advantage of Luminex® xMAP technology to study immune mediators, using small sample volumes.

An examination of the association between premature mortality and life expectancy among men in Europe.

BACKGROUND A feature of the health of men across Europe is their higher rates of premature mortality and shorter life expectancy at birth than women. Following the publication of the first State of Mens Health in Europe report, we sought to explore possible reasons. METHOD We analyzed trends in life expectancy at birth in 19 European Union member states (EU19) between 1999 and 2008 using mortality data obtained from Eurostat. We then used Pollards decomposition method to identify the contribution of deaths from different causes and at different age groups to differences in life expectancy. RESULTS Between 1999 and 2008, life expectancy at birth in the EU19 increased by 2.74 years for men and by 2.09 years for women. Most of these improvements were due to reductions in mortality at ages >60, with cardiovascular disease accounting for approximately half these improvements for men. In 2008, life expectancy of men in the EU19 was 5.92 years lower than that of women. Deaths from all major groups of causes, and at all ages, contributed to this gap, with external causes contributing 0.96 years, cardiovascular disease 1.80 years and neoplasms 1.61 years. CONCLUSION Improvements in the life expectancy at birth of men and women have mostly occurred at older ages. There has been little improvement in the high rate of premature death in younger men, suggesting a need for interventions to tackle their high death rate.