Undernutrition can affect the invading microorganism

Selenium-Containing Polysaccharides—Structural Diversity, Biosynthesis, Chemical Modifications and Biological Activity

Selenosugars are a group of sugar derivatives of great structural diversity (e.g., molar masses, selenium oxidation state, and selenium binding), obtained as a result of biosynthesis, chemical modification of natural compounds, or chemical synthesis. Seleno-monosaccharides and disaccharides are known to be non-toxic products of the natural metabolism of selenium compounds in mammals. In the case of the selenium-containing polysaccharides of natural origin, their formation is also postulated as a form of detoxification of excess selenium in microorganisms, mushroom, and plants. The valency of selenium in selenium-containing polysaccharides can be: 0 (encapsulated nano-selenium), IV (selenites of polysaccharides), or II (selenoglycosides or selenium built into the sugar ring to replace oxygen). The great interest in Se-polysaccharides results from the expected synergy between selenium and polysaccharides. Several plant- and mushroom-derived polysaccharides are potent macromolecules with antitumor, immunomodulatory, antioxidant, and other biological properties. Selenium, a trace element of fundamental importance to human health, has been shown to possess several analogous functions. The mechanism by which selenium exerts anticancer and immunomodulatory activity differs from that of polysaccharide fractions, but a similar pharmacological effect suggests a possible synergy of these two agents. Various functions of Se-polysaccharides have been explored, including antitumor, immune-enhancement, antioxidant, antidiabetic, anti-inflammatory, hepatoprotective, and neuroprotective activities. Due to being non-toxic or much less toxic than inorganic selenium compounds, Se-polysaccharides are potential dietary supplements that could be used, e.g., in chemoprevention.

Is the infectiousness of dogs naturally infected with Trypanosoma cruzi associated with poly-parasitism?

Interactions among different species of parasites co-infecting the same host could be synergistic or antagonistic. These interactions may modify both the frequency of infected hosts and their infectiousness, and therefore impact on transmission dynamics. This study determined the infectiousness of Trypanosoma cruzi-seropositive dogs (using xenodiagnosis) and their parasite load (quantified by qPCR), and tested the association between both variables and the presence of concomitant endoparasites. A cross-sectional serosurvey conducted in eight rural villages from Pampa del Indio and neighboring municipalities (northeastern Argentina) detected 32 T. cruzi-seropositive dogs out of 217 individuals examined for infection. Both the infectiousness to the vector Triatoma infestans and parasite load of T. cruzi-seropositive dogs examined were heterogeneous. A statistically significant, nine-fold higher mean infectiousness was registered in T. cruzi-seropositive dogs co-infected with Ancylostoma caninum and a trematode than in T. cruzi-seropositive dogs without these infections. The median parasite load of T. cruzi was also significantly higher in dogs co-infected with these helminths. An opposite trend was observed in T. cruzi-seropositive dogs that were serologically positive to Toxoplasma gondii or Neospora caninum relative to dogs seronegative for these parasites. Using multiple logistic regression analysis with random effects, we found a positive and significant association between the infectiousness of T. cruzi-seropositive dogs and co-infections with A. caninum and a trematode. Our results suggest that co-infections may be a modifier of host infectiousness in dogs naturally infected with T. cruzi.

Determining the Provincial and National Burden of Influenza-Associated Severe Acute Respiratory Illness in South Africa Using a Rapid Assessment Methodology

Local disease burden data are necessary to set national influenza vaccination policy. In 2010 the population of South Africa was 50 million and the HIV prevalence was 11%. We used a previously developed methodology to determine severe influenza burden in South Africa.

Hospitalized severe acute respiratory illness (SARI) incidence was calculated, stratified by HIV status, for four age groups using data from population-based surveillance in one site situated in Gauteng Province for 2009–2011. These rates were adjusted for each of the remaining 8 provinces based on their prevalence of risk factors for pneumonia and healthcare-seeking behavior. We estimated non-hospitalized influenza-associated SARI from healthcare utilization surveys at two sites and used the percent of SARI cases positive for influenza from sentinel surveillance to derive the influenza-associated SARI rate. We applied rates of hospitalized and non-hospitalized influenza-associated SARI to census data to calculate the national number of cases. The percent of SARI cases that tested positive for influenza ranged from 7–17% depending on age group, year, province and HIV status. In 2010, there were an estimated 21,555 total severe influenza cases in HIV-uninfected individuals and 13,876 in HIV-infected individuals. In 2011, there were an estimated 29,892 total severe influenza cases in HIV-uninfected individuals and 17,289 in HIV-infected individuals. The incidence of influenza-associated SARI was highest in children <5 years and was higher in HIV-infected than HIV-uninfected persons in all age groups. Influenza virus was associated with a substantial amount of severe disease, especially in young children and HIV-infected populations in South Africa.

Dietary selenium in adjuvant therapy of viral and bacterial infections

Viral and bacterial infections are often associated with deficiencies in macronutrients and micronutrients, including the essential trace element selenium. In selenium deficiency, benign strains of Coxsackie and influenza viruses can mutate to highly pathogenic strains. Dietary supplementation to provide adequate or supranutritional selenium supply has been proposed to confer health benefits for patients suffering from some viral diseases, most notably with respect to HIV and influenza A virus (IAV) infections. In addition, selenium-containing multimicronutrient supplements improved several clinical and lifestyle variables in patients coinfected with HIV and Mycobacterium tuberculosis. Selenium status may affect the function of cells of both adaptive and innate immunity. Supranutritional selenium promotes proliferation and favors differentiation of naive CD4-positive T lymphocytes toward T helper 1 cells, thus supporting the acute cellular immune response, whereas excessive activation of the immune system and ensuing host tissue damage are counteracted through directing macrophages toward the M2 phenotype. This review provides an up-to-date overview on selenium in infectious diseases caused by viruses (e.g., HIV, IAV, hepatitis C virus, poliovirus, West Nile virus) and bacteria (e.g., M. tuberculosis, Helicobacter pylori). Data from epidemiologic studies and intervention trials, with selenium alone or in combination with other micronutrients, and animal experiments are discussed against the background of dietary selenium requirements to alter immune functions.

Effect of Giardia duodenalis in protein malnourished and renourished mice

The present study was designed to delineate the effect of Giardia duodenalis in malnourished and renourished BALB/c mice. Control and renourished mice were fed with a standard pellet diet while malnourished mice were fed with a low protein (4.3 %) diet both before and after being challenged orally with actively growing G. duodenalis trophozoites. It was observed that malnourished mice had a greater severity and longer duration of Giardia infection compared with renourished mice. These malnourished mice also had less body mass but higher cyst and trophozoite counts. Malnourished mice infected with Giardia had significantly decreased level of total serum proteins, albumin, globulins, hemoglobin, leukocyte, and differential leukocyte counts compared with renourished mice. From the data it is concluded that protein malnutrition profoundly affects the anthropometric and physiological parameters of the body indicating greater susceptibility and severity of the disease.

Nutrition and disease progression pre-highly active antiretroviral therapy (HAART) and post-HAART: can good nutrition delay time to HAART and affect response to HAART?

Several studies have investigated a variety of nutritional supplementation interventions in adults with HIV. In this narrative review, we summarize the evidence from 31 clinical trials that explore clinical benefits of macronutrient and micronutrient supplementation in this population while attempting to answer the question of whether good nutrition can delay the time to highly active antiretroviral therapy (HAART) initiation and response. We focused on trials published in English between 1990 and 2010 that reported on CD4 count, viral load, and disease progression or survival. Among 9 macronutrient and 22 micronutrient trials, we found that evidence for improved CD4 count and HIV viral load with nutritional supplementation was limited; only 11.1% and 36.8% of macronutrient and micronutrient supplementation trials, respectively, reported improved CD4 count; and 33.3% and 12.5% of macronutrient and micronutrient trials, respectively, reported decreased viral load. Given their utility as surrogate markers of HIV disease progression, this suggests limited evidence for nutritional interventions having an impact on delaying HAART initiation or on improving HAART response. However, there are challenges in evaluating the effects of nutritional supplementation on clinical disease in that comparisons are difficult due to heterogeneity in study design, patient population, nutrient doses and combinations, baseline levels of deficiency, and study endpoints, including lack of clarity in defining and reporting HAART status. Future studies need to adopt a more rigorous standard design with adequate power and follow-up and require a consensus on composition and dose of nutrient interventions to be tested to more specifically answer the question on the impact of nutritional interventions on HIV disease progression and HAART response.

Influence of body condition on influenza A virus infection in mallard ducks: experimental infection data

Migrating waterfowl are implicated in the global spread of influenza A viruses (IAVs), and mallards (Anas platyrhynchos) are considered a particularly important IAV reservoir. Prevalence of IAV infection in waterfowl peaks during autumn pre-migration staging and then declines as birds reach wintering areas. Migration is energetically costly and birds often experience declines in body condition that may suppress immune function. We assessed how body condition affects susceptibility to infection, viral shedding and antibody production in wild-caught and captive-bred juvenile mallards challenged with low pathogenic avian influenza virus (LPAIV) H5N9. Wild mallards (n = 30) were separated into three experimental groups; each manipulated through food availability to a different condition level (−20%, −10%, and normal ±5% original body condition), and captive-bred mallards (n = 10) were maintained at normal condition. We found that wild mallards in normal condition were more susceptible to LPAIV infection, shed higher peak viral loads and shed viral RNA more frequently compared to birds in poor condition. Antibody production did not differ according to condition. We found that wild mallards did not differ from captive-bred mallards in viral intensity and duration of infection, but they did exhibit lower antibody titers and greater variation in viral load. Our findings suggest that reduced body condition negatively influences waterfowl host competence to LPAIV infection. This observation is contradictory to the recently proposed condition-dependent hypothesis, according to which birds in reduced condition would be more susceptible to IAV infection. The mechanisms responsible for reducing host competency among birds in poor condition remain unknown. Our research indicates body condition may influence the maintenance and spread of LPAIV by migrating waterfowl.

Seasonal influenza epidemiology in sub-Saharan Africa: a systematic review

Acute respiratory infection (ARI) is a leading cause of mortality worldwide, of which influenza is an important cause that can be prevented with vaccination. We did a systematic review of research published from 1980 to 2009 on seasonal influenza epidemiology in sub-Saharan Africa to identify data strengths and weaknesses that might affect policy decisions, to assess the state of knowledge on influenza disease burden, and to ascertain unique features of influenza epidemiology in the region. We assessed 1203 papers, reviewed 104, and included 49 articles. 1-25% of outpatient ARI visits were caused by influenza (11 studies; mean 9·5%; median 10%), whereas 0·6-15·6% of children admitted to hospital for ARI had influenza identified (15 studies; mean 6·6%; median 6·3%). Influenza was highly seasonal in southern Africa. Other data were often absent, particularly direct measurement of influenza incidence rates for all ages, within different patient settings (outpatient, inpatient, community), and for all countries. Data from sub-Saharan Africa are insufficient to allow most countries to prioritise strategies for influenza prevention and control. Key data gaps include incidence and case-fatality ratios for all ages, the contribution of influenza towards admission of adults to hospital for ARI, representative seasonality data, economic burden, and the interaction of influenza with prevalent disorders in Africa, such as malaria, HIV, and malnutrition.

Role of nutrients in the development of neonatal immune response

Nutrients exert unique regulatory effects in the perinatal period that mold the developing immune system. The interactions of micronutrients and microbial and environmental antigens condition the post-birth maturation of the immune system, influencing reactions to allergens, fostering tolerance towards the emerging gastrointestinal flora and ingested antigens, and defining patterns of host defense against potential pathogens. The shared molecular structures that are present on microbes or certain plants, but not expressed by human cells, are recognized by neonatal innate immune receptors. Exposure to these activators in the environment through dietary intake in early life can modify the immune response to allergens and prime the adaptive immune response towards pathogens that express the corresponding molecular structures.

Host condition and individual risk of cowpox virus infection in natural animal populations: cause or effect?

Recent studies have provided evidence that endemic pathogens may affect dynamics in animals. However, such studies have not typically considered that infected individuals might have a preceding underlying poor condition. We examined whether individuals in poor condition are more likely to become infected by an endemic pathogen, using as a system the dynamics of cowpox virus in field voles. With data from monthly sampled vole populations, a nested case-control study evaluated whether susceptible individuals with poorer condition had higher probabilities of contracting cowpox. The influence of condition was found to be considerable, especially for males. At times when a susceptible male with good body condition had a relatively low probability of becoming infected, a susceptible male with poor body condition was twice as likely to contract cowpox; if this male was also anaemic, the chances were almost quadrupled. We discuss the care needed when interpreting the findings of wildlife disease studies.