smallpox

Smallpox: description

Smallpox (also called pox or variola) is a human-threatening, contagious viral infection. It is triggered by various subtypes of the variola virus (from the genus Orthopoxviruses). The symptoms range from a mild course to the often fatal “black smallpox”. The last cases of smallpox occurred in 1977, since then no new infections have been reported.

Smallpox is considered very infectious. They are transmitted as droplet and smear infection between humans. At first, smallpox-infected individuals complain of flu-like symptoms such as fever, body aches and fatigue. After that, the characteristic rash occurs, especially on the arms, legs and face.

Smallpox: Success story of vaccination

Due to the high risk of infection, the World Health Organization (WHO) started a smallpox eradication program in 1967. The core of the program was a worldwide smallpox vaccination. It had an effect: In Germany, the last smallpox case occurred in 1972. In 1980, the WHO officially declared the population free of pox.

Nevertheless, smallpox cases are not completely excluded in the future. Experts believe that, for example, smallpox could be released again through laboratory accidents. No unreasonable fear, because in the two research stations (Atlanta / USA, Kolzowo / Russia), which still keep smallpox viruses, there were already in the past smallpox diseases. The use as a biological weapon in terrorist attacks is conceivable. For this reason, industrialized countries such as the USA and Germany ordered large quantities of smallpox vaccine doses after the attacks of September 11, 2001, in order to protect the population in the event of a terrorist attack with smallpox.

Apart from these scenarios, researchers predict that various types of animal pox could change to pose a threat to humans. For already today a contagion with some animal pox kinds is possible. However, the symptoms are mild so far and then threatening for people with weak immune systems (such as HIV). It becomes particularly dangerous when smallpox causes severe progression through genetic modification. This is shown, for example, by an outbreak of monkey pox in Zaire in 1997, which was threatening in scale. For example, this smallpox form was more infectious than was known from monkey pox.

Smallpox: symptoms

Between the time of infection and the onset of the first symptoms (incubation period), leaves are about seven to 19 days old. Usually the first symptoms appear after about 14 days. There are various forms of smallpox, which differ in terms of symptoms and the severity of the complaints. The most important forms of smallpox are:

• Real smallpox (Variola major)
• White smallpox (Variola minor)
• Monkey pox and cowpox
• Hemorrhagic smallpox (“black leaves” or variola haemorrhagica)

Symptoms of true smallpox (Variola major)

In true smallpox, the disease usually begins insidiously. First of all, unspecific symptoms appear, as they also occur with a flu infection. These include, above all, high fever up to 40 ° C, head and body aches and a general inability to perform. These early symptoms last about four days in the case of true smallpox.

Then begins the typical smallpox rash (eruption stage) that lasts for about one to three weeks. First, the face and arms and legs form pale red patches that itch and slowly turn into small nodules. From these arise bubbles, which are first filled with a wound fluid, later with pus, and then called pustules. Over time, they dry and leave a hard crust on the skin. The pustules can cause disfiguring scars.

If the crust comes off, a strong itching again occurs. In addition, during this disease phase, a wave-shaped fever course in those affected. In addition, symptoms such as confusion, disorientation and delusions occur. One third of all those affected die from the true smallpox. Anyone who has survived the smallpox is immune to further infection with the true smallpox.

Symptoms of white smallpox (Variola minor)

The white smallpox (Variola minor) are significantly milder and shorter than the true smallpox. The complaints are less pronounced and the mortality rate is only about one percent. Anyone who suffers from white pox, however, has no protection against infection with the pathogen of true smallpox.

Symptoms of monkey pox and cowpox

In recent years, monkeys and cowpox have been reported more frequently in humans. These two smallpox species are not transmitted to humans primarily by monkeys or cows, but by pets such as cats or tame house rats. Monkeys and cowpox also show mild symptoms compared to the true smallpox. Those affected also suffer from flu-like symptoms. Even a skin rash occurs. However, only isolated, sharply defined pustules can be observed here.

Symptoms of Hemorrhagic Smallpox

As a black smallpox or variola haemorrhogica called a particularly dangerous form of the smallpox, which is caused by a subspecies of the variola virus. In this form of smallpox, the incubation period (= time from infection to the onset of symptoms) is shortened. Within a few days, there is extensive, heavy bleeding of the skin, mucous membranes and internal organs. The majority of patients die within the first week of illness, often during the first 48 hours.

Smallpox: causes and risk factors

The cause of smallpox is the variola virus, which belongs to the orthopoxviruses. Differences are mainly the two subspecies variola major (trigger of the true smallpox) and variola minor (trigger of white smallpox), which affect only humans. In addition, there are other smallpox species such as the monkey and cowpox, which can be transmitted from the animal to humans.

Smallpox: infection

Smallpox is transmitted from person to person, usually via saliva. For this, the smallest amounts of saliva, such as those arising from speech, sneezing or coughing, are sufficient (droplet infection). However, poxviruses can survive on surfaces for a certain amount of time. For example, they can also be spread over dishes, bed linen or hands (smear infection).

Immediately after transmission, the virus begins to multiply. First, it affects the place where it entered the body. This is usually the respiratory tract (respiratory tract), where the virus enters the mucous membrane and from there to the lymph nodes migrates. There it can continue to multiply and enter the spleen and bone marrow. From the bone marrow, it then passes through the bloodstream into the skin and mucous membranes. This leads to the typical skin changes of the skin (exanthema) and the mucous membranes (Enanthem).

At what stage of disease are smallpox contagious?

Since even small amounts of virus are sufficient and the infection also takes place over the smallest droplets, smallpox is considered very contagious. There is a risk of infection about two days before the rash occurs until the last infective crust falls off after about three weeks. In particular, the liquid-filled pustules so typical of smallpox are very contagious: when they burst, a great many viruses are released suddenly.

Transmission of monkey pox and cowpox

Cases of monkey pox have been isolated in the US in recent years. It is a mild form of expression compared to the true smallpox, which actually occurs mainly in monkeys. In the US, however, rodents and crescents were identified as transmitters.

Cases of cowpox occurred in Germany last in 2009. Also, cowpox is a comparatively harmless form of smallpox. The Robert Koch Institute (RKI) had identified as a carrier tame house rats and cats.

Smallpox: examinations and diagnosis

Basically, smallpox is currently considered eradicated. An actual smallpox disease is therefore currently extremely unlikely. However, infection with the milder monkey pox and cowpox is not excluded.

Since there are currently no cases of true smallpox and only a few cases of smallpox transmitted from animals, the knowledge of this disease in the medical profession is currently low. If you suspect smallpox (currently only monkey pox and cowpox) is therefore the right contact a specialized institution such as an institute for tropical medicine and infectious diseases, In principle, however, you can also inform the family doctor who, if there is a reasonable suspicion of a smallpox disease, will initiate further steps.

When you visit the doctor, this will first record the medical history (anamnesis). You should describe as accurately as possible, which symptoms have occurred with you. In addition, the doctor must try to determine the cause of the skin lesions. For this he can ask questions like:

• When and where was the last time you went abroad?
• Where do you work, or do you come into contact with potentially risky material (for example, in a test lab)?
• Have you noticed any other symptoms besides the rash?
• Do you have a cat or a rat as a pet? Did you notice any illness in your pet, for example a rash?

After the anamnesis, a physical examination takes place. In particular, the skin changes are considered. The true smallpox, monkey pox and cowpox show characteristic skin changes that can substantiate the suspicion. However, further investigations are necessary for the diagnosis of smallpox disease:

Further investigations

In order to exclude other skin diseases, the triggering virus must be directly detected. The simplest and fastest way to detect pox viruses is under the electron microscope. For this a sample (biopsy) of the pustules, the crust or some secretion is taken.

In addition, can be detected in a blood sample from the body formed antibodies (antibodies) against smallpox. In addition, to analyze the growth potential of the poxviruses, they can be grown. However, this is only possible in laboratories that meet a certain security level. To distinguish individual subspecies of the poxvirus, an electron microscope or a blood test is not enough. This requires special and very complicated procedures.

Smallpox: treatment

The cause of smallpox can not be treated directly. The following measures should be considered as theoretical instructions, as smallpox is officially considered eradicated. If a case of smallpox actually occurs again, only the symptoms can be alleviated. The most important medical measure is the isolation of the person concerned (quarantine). Sick people may no longer have any contact with the outside world and other people. The apartment, clothing and other items used or touched by the person concerned must be disinfected. In the first four days after infection, a smallpox vaccine can prevent or at least alleviate the disease.

Those affected should observe bed rest to protect the body. Also important are a high-energy diet and high hydration. For fever, antipyretic drugs can be taken. Whether special antiviral drugs (antivirals) can prevent the disease is not certain, as research on poxviruses has been banned for over 20 years.

Even against monkey pox and cowpox there is currently no special treatment. Although transmission of these two human-to-human diseases has not been observed so far, as a precaution the affected skin should be covered and gloves worn during wound care.

Smallpox: Disease course and prognosis

Pathogenesis and prognosis in smallpox depend primarily on the form of the disease, but also on the general health of the person affected. About one third of those affected die from the smallpox. The rare special form of hemorrhagic smallpox (black pox) is even more dangerous: it is deadly for almost all those affected.

Monkey and cowpox are usually much milder than the true smallpox. They usually heal within three to five weeks. However, monkey and cowpox can also be dangerous for people with weakened immune systems (such as HIV or prolonged cortisone therapy).

If the illness is over, consequential damage can still be left behind. Typical are, for example, the scars on the skin, which are visible after a disease with smallpox or a smallpox vaccine. In addition to this visual blemish, however, damage such as paralysis or deafness can actually be left behind – because the viruses also attack the central nervous system.

Prevention of smallpox: the smallpox vaccine

The most effective protection against smallpox is the smallpox vaccine. The smallpox vaccine is a live vaccine. This means that a healthy virus and no dead virus components are given. For vaccination the vaccinia virus is used. It is closely related to the variola virus, but far less dangerous. A vaccine against monkeypox and cowpox does not exist.

The smallpox vaccine is currently but not donebecause it can have potentially serious side effects and, moreover, there is currently no acute threat of smallpox. After the smallpox vaccination sometimes flu-like symptoms occur. Very rare are serious consequences such as a vaccine-induced encephalitis (“postvakzinale encephalitis”). Also, single fatal complications after vaccination have been reported.

Usually, the vaccine is injected into the upper arm. There a pustule forms. This pustule heals within a few days, leaving behind a scar (smallpox inoculation scar). In Germany, the smallpox vaccine was discontinued in 1975, worldwide in 1980. People who have been vaccinated against smallpox before this time, probably still have a residual protection against smallpox. For complete protection, the smallpox vaccine would have to be refreshed every five to ten years.

People with a weakened immune system should not be vaccinated against smallpox. The vaccine virus, which is safe for a healthy person, can also cause serious complications for you. Even after an organ transplant or a longer cortisone therapy no smallpox vaccination should be carried out, since the immune system is then too weak to fight the pathogen and build up a vaccine protection.

The smallpox vaccine also protects against the onset of the disease if it is given up to four days after the infection. Should it actually come again to an outbreak of smallpox, advises the WHO to an immediate smallpox vaccine. For this purpose, the German government keeps a large stock of vaccine doses in stock and trains personnel specially to carry out this vaccination. The supplies are only for the case of a stop. The danger that it will actually lead to a renewed outbreak of smallpox comes, but is currently classified as low.