Protozoan pathogens are a highly diverse group of unicellular organisms, several of which are significant human pathogens. One group of protozoan pathogens includes obligate intracellular parasites such as agents of malaria, leishmaniasis, babesiosis, and toxoplasmosis. The other group includes extracellular pathogens such as agents of giardiasis and amebiasis. An unfortunate unifying theme for...

Using polymerase chain reaction and sequencing, we investigated the prevalence of Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis in 841 body lice collected from various countries. We detected R. prowazekii in body lice from Burundi in 1997 and in lice from Burundi and Rwanda in 2001; B. quintana infections of body lice were widespread. We did not detect B. recurrentis in a...

Members of the genus Bartonella (formerly Rochalimaea) were virtually unknown to modern-day clinicians and microbiologists until they were associated with opportunistic infections in AIDS patients about 6 years ago. Since that time, Bartonella species have been associated with cat scratch disease, bacillary angiomatosis, and a variety of other disease syndromes. Clinical presentation of infecti...

1 Background – Infectious diseases are a major burden on human population, especially in lowand 2 middle-income countries. The increase in the rate of emergence of infectious outbreaks necessitates 3 a better understanding of the worldwide distribution of diseases through space and time. 4 Methods – We analyze 100 years of records of diseases occurrence worldwide. We use a graph-theoretical 5 a...

A consideration of available evidence for some known and well-characterized waterborne pathogens suggests that the diversity of pathogen virulence mechanisms and properties is too great to specifically predict the emergence and future human health impacts of new waterborne pathogens. However, some future emerging pathogens are existing microbes that will be discovered to cause disease. Some wil...

OBJECTIVES Human pathogen richness and prevalence vary widely across the globe, yet we know little about whether global patterns found in other taxa also predict diversity in this important group of organisms. This study (a) assesses the relative importance of temperature, precipitation, habitat diversity, and population density on the global distributions of human pathogens and (b) evaluates t...

Three defence mechanisms are responsible for the sterility of the normal tracheobronchial tree: the mucociliary escalator, which continuously traps inhaled micro-organisms; phagocytes; and the bronchial immune system. In the mucociliary system, the respiratory mucus which covers the respiratory mucosa is moved towards the pharnyx as a result of the beating of the cilia covering the airways epit...

Owing to their small size and paucity of phenotypic characters, progress in the evolutionary biology of microbes in general, and human pathogenic fungi in particular, has been linked to a series of advances in DNA sequencing over the past quarter century. Phylogenetics was the first area to benefit, with the achievement of a basic understanding of fungal phylogeny. Population genetics was the n...