Immunization against smallpox

DNA viruses Poxviruses Variola Vaccinia Large particles 200 x 250nm complex symmetry Variola is the smallpox virus. It produces a systemic infection with a characteristic vesicular rash affecting the face, arms and legs, and has a high mortality rate. Vaccinia has been derived from the cowpox virus and is used to immunize against smallpox... 

Evaluating a person s immunity against smallpox is difficult. In the past, a process called re-challenging was the only way... 

Smallpox vaccine is a viral vaccine. Introduction of infectious vaccinia virus into superficial layers of the skin results in viral multiplication, immunity and cellular hypersensitivity. It is used in immunization against smallpox disease. 

Lublin-Tannenbaum T, Katzenelson E, El-ad B, Katz E. Correlation between cutaneous reaction in vaccinees immunized against smallpox and antibody titer determined by plaque neutralization test and ELISA. Viral Immunology. 1990 3 (1) 19-25. 

The first successful active immunization is ascribed to Edward Jenner, an English country physician who in the I790 s tested a belief common among local dairymaids—that prior exposure to a mild cowpox infection of the udder on a cow provided immunization against smallpox. Beginning in 1796, Jenner carried out tests in which he intentionally infected people by applying cowpox lymph obtained from a lesion to small slits cut in the arms of volunteers. During a subsequent epidemic, none of the inoculated individuals developed smallpox. Jenner called the practice vaccination, from vacca, Latin for cow. 

A person who contracts smallpox may die, as a result of the damage done to his body by the smallpox virus multiplying in his cells. If he survives he has immunity against smallpox for the rest of his life but this immunity does not extend to other viral diseases. The immunity results from the induced manufacture of specific protein molecules, called antibodies the molecules (in this case the smallpox virus particles) that induce antibody formation are called antigens. 

Signs and Symptoms Clinical symptoms in humans similar to that seen in smallpox although often milder. Symptoms include extreme fatigue, fever, muscular, and back pain, with evolution of discolored spots (maculas) progressing successively to elevated bumps (papules), blisters (vesicles), pus filled pimples (pustules), and finally scabs. In addition, infected persons experience enlarged neck and groin lymph nodes. Vaccination with the smallpox vaccine immunizes against monkeypox. 

Not necessarily. Routine vaccination against smallpox ended in 1972. The level of immunity, if any, among persons who were vaccinated before 1972 is uncertain therefore, these persons are assumed to be susceptible. For those who were vaccinated, it is not known how long immunity lasts. Most estimates suggest immunity from the vaccination lasts 3 to 5 years. This means that nearly the entire U.S. population has partial immunity at best. Immunity can be boosted effectively with a single revaccination. Prior infection with the disease grants lifelong immunity. 

No, smallpox vaccine does not contain smallpox virus but another live virus called vaccinia virus. Since this virus is related to smallpox virus, vaccination with vaccina provides immunity against infection from smallpox virus. 

The vaccine against smallpox is made with a virus related to smallpox virus called vaccinia virus. It is not made with smallpox virus called variola. The vaccine is a highly effective immunizing agent against smallpox infection. It was successfully used to eradicate smallpox from the human population. 

Smallpox is a very ancient disease that has been mentioned in medical writing dating back to the third century AD. It originated in Egypt or India and became endemic in both of these countries. In the seventeenth and eighteenth centuries, it is estimated to have killed almost half a million people every year in Europe. The Spanish conquerors (conquistadors) of Mexico and Peru took smallpox with them. It is estimated to have killed over three million Aztec Indians, who had no immunity against this disease because, until then, it was unknown in the New World. 

In 1798 Edward Tenner published the classc memoir, An Inquiry into the Causes and Effect of the Variolae Vacciniae, documenting how inoculation with cowpox protected humans against smallpox infection [1]. Louis Pasteur s formulation of the germ theory extended the understanding of this kind of protection against infection [1,2]. About 100 years later, isolation of the diphtheria bacihus and description of a protective substance (antitoxin) by Roux and Yersin demonstrated that the protective substance found in the serum of immunized animals can be transferred to susceptible animals and thereby confer passive immunity [4]. The antitoxin or... 

Every adult, whether traveling or not, should be immunized with tetanus toxoid and should also be fully immunized against poliomyelitis, measles (for those bom after 1956), and diphtheria. In addition, every traveler must fulfill the immunization requirements of the health authorities of the countries to be visited. These are listed in Health Information for International Travel, available from the Superintendent of Documents, United States Government Printing Office, Washington, DC 20402. A useful website is http //www.cdc. gov/travel/vaccinat.htm. The Medical Letter on Drugs and Therapeutics also offers periodically updated recommendations for international travelers (see issue of April 15, 2002). Immunizations received in preparation for travel should be recorded on the International Certificate of Immunization. Note Smallpox vaccination is not recommended or required for travel in any country. 

The threat of a bioterrorist attack with smallpox is especially disturbing since the eradication of smallpox remains one of the great achievements in human history. Unfortunately, since routine vaccination against smallpox was discontinued in 1978, few people retain immunity today. Although there are only two official repositories of the smallpox virus today, it is still possible that terrorists will be able to obtain the virus. Thus, the government has had to stockpile supplies of the vaccine, and there is some debate about whether to resume routine smallpox vaccinations. Although the smallpox vaccine was discovered by accident, the story of how Louis Pasteur developed the first anthrax vaccine and his use of unvaccinated animals as controls remain as excellent lessons about the process of science (Trachtman 2002). 

Members of the poxvirus, herpesvirus and retrovirus families produce homologues that mimic RCA proteins and are thus able to escape complement action.20 The smallpox virus Variola major causes a serious, virulent infection in humans, while the virus that is used for vaccination against smallpox, vaccinia virus, usually causes only a very mild or even unapparent infection, at least in individuals with an intact immune system. 

D. Vaccine/Prophylaxis. Smallpox vaccine (vaccinia virus) is a licensed live poxvirus vaccine that induces strong cross-protection against smallpox. Reliable data are sparse as to efficacy and durability of protection. The duration vaccinia induced immunity is at least 3 years. Vaccine immunity may prevent or modify illness. Fully immune individuals exposed to the virus by the respiratory route may develop fever, sore throat, and conjunctivitis ("contact fever") lasting several days. The vaccine is administered by dermal scarification or intradermal jet injection. The appearance of a vesicle or pustule within several days indicates that the vaccine will be effective. Other available countermeasures include the postexposure use of Vaccinia immune globulin or primary vaccination within 3-4 days of exposure yields some protection. 

As a concluding statement, the fact that a treatment works for some, at least some of the time, is an indication that it should be perfected rather than rejected. Nor is it always necessary to understand how a treatment works, for what we are most interested in are results. For example, we may never know exactly how antibiotics work, other than that they are enzyme inhibitors. This, in spite of all the biochemical formnlas and equations, and the lengthy, technical, and encyclopedic treatises on the subject. For every answered question always leads to further questions. Ditto for the immunizations against various viral diseases, such as polio and smallpox — though we seem almost at a point that for some diseases the only new cases seem to be from the vaccination itself. Nevertheless, we are most grateful that antibiotics and immunizations most often do work, and we ll accept the same for any treatment of cancer. 

The historic objective of vaccination has been to induce long-lasting immunity against a disease for which the recipient is at risk. The most successful vaccination campaign eradicated smallpox as a public health problem. Particularly, vaccination against common infectious agents, including poliomyelitis, measles, mumps, and rubella, over the last 50 years has led to effective prevention of many diseases. 

Over the years, researchers have unraveled some of the mysteries of the immune system and have used its properties as a therapeutic aid. The first vaccine, that against smallpox, was developed about 200 years ago. Since that time it has been used so effectively as a preventive measure that smallpox has been eradicated. The action of vaccines of this sort depends on exposure to the infectious agent in a weakened form. The immune system mounts an attack, and the immune system retains memory of the exposure. In subsequent encounters with the same pathogen, the immune system can mount a quick and effective defense. This ability to retain memory is another major characteristic of the immune system. It is hoped that current research can be carried to the point of developing vaccines that can treat AIDS in people who are already infected. Other strategies are directed at finding treatments for autoimmune diseases. StiU others are attempting to use the immune system to attack and destroy cancer cells. 

---