The first case was identified as a fatal wasting syndrome in the 1960s. It was then recognized as a transmissible spongiform encephalopathy in 1978. Surveillance studies showed the endemic of CWD in free-ranging deer and elk spread in northeastern Colorado, southeastern Wyoming and western Nebraska. It was also discovered that CWD may have been present in a proportion of free-ranging animals decades before the initial recognition. In the United States, the discovery of CWD raised concerns about the transmission of this prion disease to humans. Many apparent cases of CJD were suspected transmission of CWD, however the evidence was lacking and not convincing.In the 1980s and 1990s, bovine spongiform encephalopathy (BSE or "mad cow disease") spread in cattle at an epidemic rate. The total estimated number of cattle infected was approximately 750,000 between 1980 and 1996. This occurred because the cattle were fed processed remains of other cattle. Then human consumption of these infected cattle caused an outbreak of the human form CJD. There was a dramatic decline in BSE when feeding bans were put in place. On May 20, 2003, the first case of BSE was confirmed in North America. The source could not be clearly identified, but researchers suspect it came from imported BSE-infected cow meat. In the United States, the USDA created safeguards to minimize the risk of BSE exposure to humans.Variant Creutzfeldt-Jakob disease (vCJD) was discovered in 1996 in England. There is strong evidence to suggest that vCJD was caused by the same prion as bovine spongiform encephalopathy.
However, the female pelvis still must accommodate for bipedal locomotion which is what creates the challenges for obstructed labor. The brain size of humans has also increased as the species has evolved, resulting in a larger head of the fetus that must exit the womb. This requires human infants to be born less developed when compared to other species. The bones of the skull are not yet fused when a human infant is born in order to prevent the head from becoming too large to exit the womb. However, the head of the fetus is still large and poses the possibility for obstructed labor. Diagnosis
Obstructed labour is usually diagnosed based on physical examination. Ultrasound can be used to predict malpresentation of the fetus. In examination of the cervix once labor has begun, all examinations are compared to regular cervical assessments. The comparison between the average cervical assessment and the current state of the mother allows for a diagnosis of obstructed labor. An increasingly long time in labor also indicates a mechanical issue that is preventing the fetus from exiting the womb. Prevention
Access to proper health services can reduce the prevalence of obstructed labor. Less developed areas have inadequate health services to attend to obstructed labor, resulting in a higher prevalence among less developed area. Improving nutrition of female, both before and during pregnancy, is important for reducing the risk of obstructive labor.