Cowpox - Origin

Origin

In the years 1770 till 1790 at least six people who had contact with a cow had tested independently the possibility of using the cowpox vaccine as an immunization for smallpox in humans for the first time; among them the English farmer Benjamin Jesty, in Dorset, in 1774 and the German teacher Peter Plett in 1791. Jesty inoculated his wife and two young sons and thus spared them probable death by smallpox which was raging in the area in which they lived. His patients who had contracted and recovered from the similar but milder cowpox (mainly milkmaids), seemed to be immune not only to further cases of cowpox, but also to smallpox. By scratching the fluid from cowpox lesions into the skin of healthy individuals, he was able to immunize those people against smallpox. It was reported that farmers and people working regularly with cows and horses were often spared during smallpox outbreaks. More and more an investigation conducted towards 1790 by the British Army showed that horse-mounted troops were less infected by smallpox than infantry, and this due to a major exposure to the similar horse pox virus (Variola equina). By the early 19th century, more than 100,000 persons in Great Britain had been vaccinated. The arm-to-arm method was also used to distribute Jenner's vaccine throughout the Spanish Empire. Spanish king Charles IV's daughter had been stricken with smallpox in 1798, and after she recovered, he arranged for the rest of his family to be vaccinated. In 1803, the king, convinced of the benefits of the vaccine, ordered his personal physician Francis Xavier de Balmis, to deliver it to the Spanish dominions in North and South America. To maintain the vaccine in an available state during the voyage, the physician recruited from the orphanages of Spain twenty-two young boys, age three to nine years, who have never had cowpox or smallpox before. During the trip across the Atlantic, de Balmis vaccinated the orphans in a living chain. Two children were vaccinated immediately before departure, and when cowpox pustules had appeared on their arms, material from these lesions was used to vaccinate two more children.

Jesty did not publicise his findings, however, credit was assumed by Jenner who performed his first inoculation, twenty-two years later and publicised his findings. It is said that Jenner made this discovery by himself possibly without knowing previous accounts twenty years earlier. Although Jesty could have been the first to discover it, Jenner let everyone know and understand it, thus taking credit for it.

The virus is found in Europe, and mainly in the UK. Human cases today are very rare and most often contracted from domestic cats. The virus is not commonly found in cows; the reservoir hosts for the virus are woodland rodents, particularly voles. It is from these rodents that domestic cats contract the virus. Symptoms in cats include lesions on the face, neck, forelimbs, and paws, and less commonly upper respiratory tract infection. Symptoms of infection with cowpox virus in humans are localized, pustular lesions generally found on the hands and limited to the site of introduction. The incubation period is nine to ten days. The virus is prevalent in late summer and autumn.