smallpox

Smallpox : 

Smallpox

: 

Smallpox is a serious, contagious and sometimes fatal disease. There is no specific treatment for smallpox, and the only prevention is vaccination. The name smallpox is derived from the latin word “spotted” and refers to the raised bumps that appear on the face and body of an infected person. Smallpox is in the Orthopoxvirus genus of viruses. “subfamily that cause generalized infections with a rash in mammals” Smallpox

Origin of Smallpox : 

Origin of Smallpox The name Variola was first used in the 6th century. Derived from the Latin word varius (spotted) or varus (pimple). Anglo-Saxons in the 10th century used the word poc or pocca (bag or pouch) to describe an exanthemous “skin rash” disease, possibly smallpox. In the 15th century, the English used the prefix small to distinguish variola the smallpox from syphilis, the great pox.

First Case of Smallpox : 

First Case of Smallpox There is no animal reservoir, and no human carriers. First certain evidence comes from the mummified remains of Ramses. (1157 B.C.) Written descriptions did not appear until the 10th century in Southwestern Asia.

Smallpox Travel : 

Smallpox Travel Smallpox was likely carried from Egyptian traders to India during the millennium B.C. where it became established as an endemic “local” infection. From Asia and Africa smallpox spread with increasing frequency into less populous areas, and then into Europe. Epidemics of the disease can be found in the bible, and in ancient Greek and Roman literature.

Smallpox in the Ancient World : 

Smallpox in the Ancient World Peloponnesian Wars (430 B.C.) “between Athens & Sparta” . A person aboard a ship from North Africa came to Athens infected with smallpox. Thucydides “ancient Greek historian remembered for his history of the Peloponnesian War” , recorded smallpox symptoms. Described as violent heats, unnatural, putrid odors, stomach distress, and the body covered with small pustules and ulcers. Also noted that those who survived became immune.

Smallpox in the New World : 

Smallpox in the New World In the early 16th century smallpox began to imported into the western hemisphere. The Spanish inadvertently owe success in conquering the Aztec and Incas in Mexico to smallpox. Smallpox arrived in North America via Canada, and Mexico. 1616-19 A Smallpox Plague killed 90% of the population of the Indians in the area of Massachusetts. 1666 Smallpox epidemic in England.

Smallpox as Biological Warfare : 

Smallpox as Biological Warfare Lord Jeffrey Amherst, Commanding General of British Forces in North America during the French and Indian War. (1754-1763) Used blankets (smallpox blankets) coated with smallpox dust as germ warfare to wipe out the Native American population. More than half the population were killed with the epidemic.

History of Variolation and Vaccine : 

History of Variolation and Vaccine Known that survivors became immune to the disease. As a result, physicians intentionally infected healthy persons with smallpox organisms. Variolation is the act of taking samples (pus from pustules or ground scabs) from patients whose disease had been benign, and introducing it into others through the nose or skin.

Survival Rates with Variolation : 

Survival Rates with Variolation Two to Three percent of variolated persons died of smallpox, became the source of a new epidemic, or developed other illnesses from the lymph of the donor such as tuberculosis or syphilis. The case fatality rates were still ten times lower in those that were variolated compared to those with naturally occurring smallpox. Side effects of variolation were the appearance of smallpox itself, but it would disappear after a week or so.

Edward Jenner : first vaccine : 

Edward Jenner : first vaccine Jenner spent his time supplying cowpox material to others around the world. In recognition of his work the British government awarded Jenner ten thousand pounds in 1802, and twenty thousand pounds in 1807. Jenner was honored for his technique, and vaccine became the universally used term to indicate introducing material under the skin to produce a protection against disease.

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In this time smallpox was greatly feared, as one in three of those who contracted the disease died, and those who survived were often badly disfigured. Voltaire recorded that 60% of people caught smallpox, with 20% of the population dying of it. Noting the common observation that milkmaids did not generally get smallpox, Jenner theorized that the pus in the blisters which milkmaids received from cowpox(a disease similar to smallpox, but much less virulent) protected the milkmaids from smallpox.

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On 14 May 1796, Jenner tested his theory by inoculating James Phipps, a young boy of 8 years, with material from the cowpox blisters of the hand of Sarah Nelmes, a milkmaid who had caught cowpox from a cow called Blossom. Jenner inoculated Phipps with cowpox pus in both arms on the same day. The inoculation was accomplished by scraping the pus from Nelmes' blisters onto a piece of wood then transferring this to Phipps' arms. This produced a fever and some uneasiness but no great illness.

Vaccination : 

Vaccination The smallpox vaccine is actual live vaccinia virus, unlike other vaccines which use dead virus; for this reason the vaccination site must be cared for to prevent spread . Smallpox vaccine is administered using a bifurcated needle, not an injection, unlike any other vaccine The bifurcated needle is dipped into the vaccine and then used to prick the skin 15 times in about 3 seconds in a 5mm radius area It is administered into the superficial layer of the skin

4 Main Complications of Vaccination : 

4 Main Complications of Vaccination Ecxema vaccinatum Occurred in vaccinated persons or unvaccinated contacts who were suffering from or had a history of eczema Progressive vaccinia (vaccinia necrosum) Occurred in persons who suffered from an immune deficiency or with humoral or immune globulin deficiencies Local lesion at the vaccination site failed to heal; all lesions spread progressively until the patient died, usu. 2-5 months later Occurred in 11 person, with 4 deaths Generalized vaccinia Occurred in otherwise healthy individuals Characterized by development, from 6-9 days after vaccination, of a generalized rash, sometimes covering whole body Prognosis good Occurred in 143 persons with no deaths Postvaccinial encephalitis Most serious complication Occurred in 16 persons with 4 deaths

Eradication : 

Eradication In 1801 Jenner said, “The annihilation of the smallpox, the most dreadful scourge of the human species, must be the final result of this practice.” Compulsory vaccinations began in the following years: 1807 in Bavaria 1810 in Denmark 1835 in Prussia 1853 in Britain

Eradication : 

Eradication Even after vaccination outbreaks still continued because the virus was imported by travelers where there were still endemics. Not until after WWI did most of Europe become smallpox free, and not until after WWII was transmission stopped throughout Europe and North America. In less developed countries smallpox continued largely unabated until the middle of the 20th century.

Eradication : 

Eradication 1940s: large scale preparations of a stable freeze dried vaccine was perfected by Collier. 1950: Pan American Sanitary Organization decided to undertake a hemisphere wide eradication program. 1958: Union of Soviet Socialist Republics proposed to the WHO that a global smallpox eradication program be undertaken.

Eradication : 

Eradication The campaign was based on a two fold strategy. 1) Mass vaccination campaigns in each country using a vaccine of ensured potency and stability that would reach at least 80% of the population. 2)Development of a system to detect and contain cases and outbreaks.

Eradication : 

Eradication 26 October 1977 the last naturally occurring case of smallpox was recorded in Merka Somalia. In 1978 two cases were reported. These were both from people working in labs with smallpox in England.

Eradication : 

Eradication 1980: WHO formally declared that smallpox was dead. The eradication of smallpox was one of the most important branches of modern medicine. Jenner has been acknowledged as the father of immunology,

Slide 25: 

Feel like a break?!

Transmission of Smallpox : 

Transmission of Smallpox Humans are the only natural host of smallpox and it is not known to be transmitted by insects or animals (no animal reservoir) Transmission generally occurs from direct and fairly prolonged face-to-face contact (in order for infected spit particles to pass from one person to another) Smallpox can also be spread through direct contact with infected bodily fluids or contaminated objects (ie. Bedding and clothing) . In rare instances, smallpox can spread through the air of an enclosed area. Variola major renders infected people bedridden so spreading to the community is reduced In variola minor, however, the symptoms are so mild that patients remain ambulatory during the infection phase and can spread the virus more widely

Ways smallpox could spread. : 

Ways smallpox could spread. By Touch if Infected By Touching someone through physical contact

Clinical forms : : 

Clinical forms : There are 2 clinical forms of Smallpox: Variola Major and Variola Minor Variola major is severe and the most common form with more extensive rash and higher fever with a death rate of about 30% Variola minor has less common presentation and much less severe with death rate of 1% or less

Stages of Smallpox : 

Stages of Smallpox Incubation Period Lasts on average 12-14 days but can range from 7-17 days Person is not contagious and exhibits no symptoms Prodrome Phase This is when initial symptoms develop and is also called the pre-eruptive stage. Begins abruptly with fever, malaise, headache, head and body aches, prostration, and often nausea and vomiting Body Temperature rises to at least 101F and is often higher Note that this severe febrile prodrome right before the onset of the rash is characteristic of smallpox and can be used to differentiate it from other rash illnesses This phase lasts 2-4 days and is sometimes contagious

Stages of Smallpox: Rash Phase : 

Stages of Smallpox: Rash Phase When the first visible lesions appear the fever may start to go down. This is the most contagious period (the time when the saliva has the most virus in it) Lasts 4 days. Rash emerges as small red spots on tongue and in mouth (about 24 hours before the appearance of rash on the skin) Lesions in the mouth and pharynx enlarge and ulcerate quickly, releasing large amount of virus into the saliva. These spots develop into sores that break open and spread large amounts of virus into mouth and throat. The rash starts on the face as a few macules, known as herald spots, and spreads to the arms and the legs then to the hands and feet The rash usually spreads to all parts of the body in just 24 hours By the 3rd day of the rash the rash becomes raised bumps or papules By the 4th day the bumps become vesicular, fill with a thick, opaque fluid and often have depression in center that looks like a bellybutton (this umbilication is a major distinguishing characteristic of smallpox especially from chickenpox)

Stages of Smallpox: Rash Phase : 

Stages of Smallpox: Rash Phase The fever will rise again By the 6th or 7th day the lesions have become pustules B/w 7 and 10 days the pustules mature and reach their max size At around 10 days of the rash the pustules begin to form a crust. At about 14 days most of the lesions scab over and some begin to separate. About 3 weeks after the onset scabs have separates and the site of each lesion is depigmented and eventually becomes pitted scars because of deeper skin layer involvement

Stages of Smallpox: Rash Phase : 

Stages of Smallpox: Rash Phase The rash of smallpox has a centrifugal distribution, meaning it is most dense on the face, and more dense on the extremities than on the truck These characteristics are important in differentiating smallpox from other causes of rash illness Another differentiating characteristic of smallpox is that the lesions are all in the same stage of development on that part of the body (unlike chickenpox) these stages of development are: macules, papules, vesicles, and crusted lesions

Treatment of Smallpox : 

Treatment of Smallpox Vaccine is administered up to 4 days after exposure to the virus and before the rash appears, provides protective immunity and can prevent infection or ameliorate the severity of the disease There is really no effective treatment, other than the management of the symptoms Adequate fluid intake (difficult) Alleviation of pain and fever Keeping skin lesions clean to prevent bacterial infection Some compounds, such as Cidofovir, are under investigation as chemotherapeutic agents

Gracias : 

Gracias