No abstract

Scabies, a mite infestation frequently sexually transmitted, dates back to antiquity but remains a challenging parasite for study in clinical practice and community settings. Its history is one of centuries of slow progress to recognize the mite and to finally establish its nexus to the clinical syndrome of pruritis with several protean manifestations and different epidemiological patterns. Contemporary methods of management are briefly reviewed, with the future promise of improved evolutionary knowledge associated with the advent of molecular and genetic technology. Current information indicates that humans and earlier protohumans were most likely the source of animal scabies, first of dogs, and later of other species with subsequent spread to wildlife. Morphologically identical variants of Sarcoptes scabiei are nonetheless host specific, as determined by recent DNA studies, and invite future investigations into the dynamics of this troublesome sexually transmissible agent, with the goal of improved recognition and control.

The objective of this review is to provide an integrated historical account of the complex, often convoluted events impacting milk hygiene and its resultant effect on infant mortality from 1875 to 1925. Heat pasteurization of cow's milk is necessary for rendering this important nutrient source safe for humans—particularly infants. Developed by Louis Pasteur in 1864, pasteurization evolved from the commercially important parboiling of wine and beer when the Industrial Revolution was effecting rapid societal change in Western societies. In European and American societies of the early and mid-19th century, infant mortality rates were 30- to 60-fold higher than the current rates of five or six deaths per 1,000 live births per year. With proof of the germ theory of disease came convincing evidence of the role of microbes in the transmission of infections, which led to the discovery that microbial pathogens were transmissible via milk. Diseases caused by milkborne pathogens include human and bovine tuberculosis, brucellosis, salmonellosis, streptococcal infections, diphtheria, and “summer diarrhea.” With pasteurization of milk, infectious diseases with their high infant mortality rates decreased by only half by the early 20th century, despite concurrent medical and dairy hygiene advances. To further mitigate unacceptably high infant mortality rates, social support providers—including public health nurses and midwives—encouraged breastfeeding, especially among socioeconomically disadvantaged mothers. Improvements in pulsating vacuum milking machines also favorably impacted food safety by providing a clean, enclosed environment. Currently, bottle feeding still competes with breastfeeding as the preferred method, and the sale of raw, unpasteurized milk remains a contentious issue. Informed and responsible food safety professionals, physicians, and public health officials currently view breastfeeding as the preferred feeding method and milk pasteurization as the safer and more prudent alternative.

The following series of concise summaries addresses the evolution of infectious agents in relation to sex in animals and humans from the perspective of three specific questions: (1) what have we learned about the likely origin and phylogeny, up to the establishment of the infectious agent in the genital econiche, including the relative frequency of its sexual transmission; (2) what further research is needed to provide additional knowledge on some of these evolutionary aspects; and (3) what evolutionary considerations might aid in providing novel approaches to the more practical clinical and public health issues facing us currently and in the future?