Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to... Show morePreface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use immunosuppressants or who have chronic diseases. The clinic is closely connected to the department of Infectious Diseases at LUMC. The setting of a travel clinic within an academic medical hospital, provides unique circumstances for medical research, like an experienced team of nurses, expertise regarding immunization, a constant flux of travellers and the knowledge and infrastructure that is required for research into microbiology, virology and parasitology. Examples of research that stem from this clinic are projects on immunization against malaria, yellow fever, travellers' diarrhea, poliomyelitis and hepatitis B, vaccination of immunocompromised patients, and projects on travel related acquisition of extended spectrum ß-lactamase producing Enterobacteriacae and on the utility of post-travel screening of asymptomatic travellers for parasites. Show less
Insects are the most diverse group of animals on earth. They inhabit nearly all terrestrial habitats. One of the factors underlying this success is the ability of insect eggs to survive in adverse... Show moreInsects are the most diverse group of animals on earth. They inhabit nearly all terrestrial habitats. One of the factors underlying this success is the ability of insect eggs to survive in adverse conditions. For a long time the ability to survive these adverse conditions has been attributed to maternal investment in the form of a protective eggshell. In this thesis, I show that contrary to common belief, insect eggs are far from helpless. The insect egg itself develops a cellular layer around the egg called the serosa. This serosa protects the developing embryo from dehydration which enables it to survive in dry habitats. The serosa furthermore protects against infection, mounting an impressive immune response upon the entry of bacteria in the egg. The data presented in this thesis show the importance of the serosa in the survival of the insect egg. I propose that this multifunctional serosa contributed to the great success of insects. Show less
