Patients with Argentine haemorrhagic fever have mainly central nervous system involvement and haemorrhagic manifestations, with leucopenia and thrombocytopenia. Activation of blood coagulation, fibrinolysis, the complement system and cytokines was observed in the acute phase of the disease.
In the twenty years since its description, Lyme disease has evolved from being a curiosity in three small communities on the east bank of the Connecticut River to the most common vector-borne disease in the U.S. and Germany, and a worldwide concern. In this short time, the aetiologic agent has been identified and grown, the clinical syndromes due to this agent have been delineated, seroconfirmatory tests developed, effective therapeutic regimens determined, a vaccine found safe and effective, and the epidemiology and ecology understood sufficiently to establish avoidance and prevention strategies, However, the mechanisms whereby the aetiologic agent, Borrelia burgdorferi sensu late actually causes tissue damage/dysfunction remain to be defined. The following represents a review of some proposed immunopathogenic mechanisms with a focus on possible autoimmunity.
Human immunodeficiency virus type 1 reverse transcriptase (HIV1 RT) is essential for virus replication. After cell infection, RT catalyses the synthesis of the proviral genome, which is then integrated into the host cell genome. The present understanding of the origin of viral genetic information variations following provirus synthesis is summarized here. During reverse transcription, the structures of the primer-template nucleic acid duplex (A, A-like and B forms), and the local helix bends, modulate RT DNA polymerizing activity by acting on kinetic parameters of nucleotide incorporation and on enzyme processivity. Moreover, the cellular microenvironment, such as dNTP pool imbalance, is involved in mutation fixation by directly influencing RT activity and viral mutation rates. In addition to genome variations linked to RT activity, other parameters, like permanent viral replication and compartmentalization, contribute to HIV1 variability. The implications of these findings on therapy directed against HIV1 infection are discussed.
An explosive cholera outbreak with Vibrio cholerae O1, Inaba, El Tor began in Peru in January 1991 and extended to all the Latin American countries except Uruguay and the Caribbean. The number of cases diminished from 396,363 in 1991 to 17,260 in 1997, while the fatality rate remained around 1%. The source and features of the epidemic and the prospects for the eradication of cholera in Latin America are discussed.
beta-Lactams are the most prescribed antibacterials for the treatment of bacterial infections. Bacteria have developed mechanisms to resist the action of beta-lactam drugs, of which the catalytic function of beta-lactamase is the most important, These enzymes catalyse hydrolysis of beta-lactam antibiotics, whereby the drug is destroyed. This review offers a perspective on the function of these enzymes and their clinical implications.
In this review we show how the application of molecular biology has improved our understanding of the epidemiology of candidiasis and the role of certain virulence factors in the pathogenesis of this important infection, opening up new approaches to prevention and treatment.
As a result of the intensive agricultural practices in the humid pampas of Argentina, a "new" arenaviral haemorrhagic fever emerged more than 50 years ago. With the aim of contributing to a better understanding of rodent-borne diseases, the epidemiology and ecology of Junin virus and the public health experience with Argentina haemorrhagic fever are reviewed here.
β-Lactams are the most prescribed antibacterials for the treatment of bacterial infections. Bacteria have developed mechanisms to resist the action of β-lactam drugs, of which the catalytic function of β-lactamase is the most important. These enzymes catalyse hydrolysis of β-lactam antibiotics, whereby the drug is destroyed. This review offers a perspective on the function of these enzymes and their clinical implications.
Helicobacter pylori is the world's commonest infection, but the modes of transmission are largely unknown. Under laboratory conditions, houseflies can carry viable H. pylori on their external surfaces and in their alimentary tracts. More recently, H. pylori DNA has been demonstrated in wild flies in the USA and in Poland, by polymerase chain reaction. Flies can acquire H. pylori from the environment and could therefore function as a significant reservoir and vector in the transmission of H. pylori.
A subacute encephalitis, termed AIDS dementia complex (ADC), which involves the infection of the central nervous system and afflicts up to 50% of adult HIV-infected individuals, can culminate in dementia, paralysis and death. Although a number of possible mechanisms for ADC have been proposed, the actual reasons for the pathogenesis of ADC in adults and progressive encephalopathy in infants and children still remain poorly understood. The aim of the present review is to shed some light on the most recent developments which may provide insights into plausible molecular and biological mechanisms involved in neuropathogenesis caused by HIV.
The oral cavity comprises a vast number of different bacterial populations which constitute a perfect example of microbial ecology. Bacterial species present in the various oral sites normally coexist harmoniously. However, under specific conditions which favour some species with pathogenic potential over the other members of the community, periodontal diseases are initiated. On the one hand, bacterial interactions both positive (mutualism, commensalism and synergism) and negative (competition and antagonism) may play a significant role in these mixed infections by ultimately favouring the periodontopathogenic species. On the other hand, certain types of bacterial interactions may help maintain a healthy state by preventing colonization of subgingival sites by pathogenic species. This review will focus on positive and negative bacterial interactions involving the principal periodontopathogens : Porphyromonas gingivalis, Treponema denticola, Bacteroides forsythus and Actinobacillus actinomycetemcomitans.
High ammonia levels in mammalian tissues, especially blood (as well as in urine), are toxic, causing severe metabolic disorders. The underlying pathogenic principles are for the most part poorly understood. In this review we discuss 1) possible mechanisms of ammonia toxicity, 2) general mechanisms of bacterial ammonia production and 3) Klebsiella virulence. Special reference is made to possible effects of nitrogen fixation, ureolysis, proteolysis and amino acid ammonification.
There are more than 300 million carriers of hepatitis B virus (HBV) worldwide at high risk for the development of hepatitis, cirrhosis and hepatocellular carcinoma. Although the pathogenesis of chronic infection is essentially immune-mediated, its variability and underlying mechanisms remain major obstacles to the development of effective treatments, This review outlines some of the aspects of HBV-associated chronic liver diseases in the hope that the knowledge obtained will be central to the development of new therapeutic approaches.
Distinct strains of transmissible spongiform encephalopathy agents differ with respect to both their biological and physicochemical properties. These strain differences may be due to variability in the conformation of the disease-specific isoform of the prion protein.
There is a resurgence of interest in the clinical epidemiology of malaria among African children. This renewed interest follows fifty years of failure to eradicate infection in Africa and redirected efforts toward disease control and prevention. We have a poor understanding of the mechanisms by which clinical immunity is acquired; however, several recent studies have provided new insights into how fast clinical protection is acquired under the varied transmission intensities common to Africa. What is clear is that the frequency with which individuals encounter infection from birth will determine the speed with which they become clinically immune and the patterns of severe pathology they are likely to experience. There remains doubt and concerns over the long-term consequences of reducing natural parasite exposure in several areas of Africa. New field studies are urgently required to tackle these issues so that control may be guided by an improved understanding of malaria as a disease that can lead to death.
The small GTPase rho has been shown to act as an important switch that links signalling cascades initiated by cellular receptors to the cytoskeleton. While the important role of rho for major functions of probably all eukaryotic cells has long been established, this review looks at this small GTPase as a regulator of cytoskeletal rearrangements during invasion of epithelial cells by Shigella.
The epidemiology of foodborne diseases has changed rapidly in the last two decades. Emergence of newly recognized foodborne pathogens has significantly contributed to this change. Several pathogens have newly emerged as, or have the potential to be, important foodborne pathogens, including Escherichia coli O157:H7 and other enterohaemorrhagic E. coli, Salmonella typhimurium Definitive Type 104, Cryptosporidium parvum, Cyclospora cayetanensis, Arcobacter butzleri and Helicobacter pylori. Others such as Campylobacter jejuni and Listeria monocytogenes have been recognized pathogens for many years but have only in the past two decades been determined to be predominantly foodborne. Although approaches such as hazard analysis critical control point (HACCP) programs will significantly improve safety of our food supply, changes in food processing, products, and practices, and human behaviour will influence the emergence of foodborne pathogens into the next century.
Large population displacements are always associated with a high rate of mortality due to infectious diseases. Measles immunization, the provision of clean water and sanitation and the effective management of malaria, diarrhoea and pneumonia cases are the main measures for preventing excess mortality at the initial phase of a refugee influx. During the postemergency phase, public health activities also target specific issues such as tuberculosis and reproductive health.
Probiotic bacteria provide a variety of health benefits to immunocompetent hosts; however, their use in immunodeficient patients may pose problems. Some probiotics are closely related to bacteria that are opportunistic pathogens and can transfer antibiotic resistance genes. Intestinal bacteria have recently been associated with inflammatory and autoimmune diseases in immunodeficient hosts; similar problems may arise if probiotics are fed to immunodeficient patients. The safety, efficacy, benefits and costs of feeding probiotic bacteria to immunodeficient patients needs to be carefully considered and fully researched to assure they will not cause infectious, inflammatory or autoimmune diseases in these susceptible hosts.
