Historically, malignant smallpox accounted for 5%–10% of cases, and the majority (72%) was in children. Malignant smallpox is accompanied by a severe prodromal phase that lasts 3–4 days, prolonged high fever, and severe symptoms of toxemia. The rash on the tongue and palate is usually extensive.

The skin lesions mature very slowly and by the seventh or eighth day the lesions are flat and appear to be buried in the skin. Unlike ordinary-type smallpox, the vesicles contain very little fluid, are soft and velvety to the touch, and may contain hemorrhages. Malignant smallpox is nearly always fatal.

There is usually no fever during evolution of the rash. The skin lesions tend to be fewer and evolve more quickly, are more superficial, and may not show the uniform characteristic of more typical smallpox. Modified smallpox is rarely, if ever, fatal. This form of variola major is more easily confused with chickenpox.

Ordinary Smallpox

Ninety percent or more of smallpox cases among unvaccinated persons are of the ordinary type. In this form of the disease, by the second day of the rash, the macules become raised papules. By the third or fourth day the papules fill with an opalescent fluid to become vesicles. This fluid becomes opaque and turbid within 24–48 hours, giving them the appearance of pustules; however, the so-called pustules are filled with tissue debris, not pus.

By the sixth or seventh day, all the skin lesions have become pustules. Between 7 and 10 days the pustules mature and reach their maximum size. The pustules are sharply raised, typically round, tense, and firm to the touch. The pustules are deeply embedded in the dermis, giving them the feel of a small bead in the skin. Fluid slowly leaks from the pustules, and by the end of the second week the pustules deflate, and start to dry up, forming crusts (or scabs). By day 16-20 scabs have formed over all the lesions, which have started to flake off, leaving de-pigmented scars.
Ordinary smallpox generally produces a discrete rash, in which the pustules stand out on the skin separately. The distribution of the rash is densest on the face; denser on the extremities than on the trunk; and on the extremities, denser on the distal parts than on the proximal. The palms of the hands and soles of the feet are involved in the majority of cases. In some cases, the blisters merge together into sheets, forming a confluent rash, which begin to detach the outer layers of skin from the underlying flesh. Patients with confluent smallpox often remain ill even after scabs have formed over all the lesions. In one case series, the case-fatality rate in confluent smallpox was 62%.

The lifecycle of poxviruses is complicated by having multiple infectious forms, with differing mechanisms of cell entry. Poxviruses are unique among DNA viruses in that they replicate in the cytoplasm of the cell rather than in the nucleus. In order to replicate, poxviruses produce a variety of specialized proteins not produced by other DNA viruses. The most important of which is a viral-associated DNA- dependent RNA polymerase.

Four orthopoxviruses cause infection in humans: variola, vaccinia, cowpox, and monkeypox. Variola virus infects only humans in nature, although primates and other animals have been infected in a laboratory setting. Vaccinia, cowpox, and monkeypox viruses can infect both humans and other animals in nature.

Smallpox localizes in small blood vessels of the skin and in the mouth and throat. In the skin, this results in a characteristic maculopapular rash, and later, raised fluid-filled blisters. Variola  major produces a more serious disease and has an overall mortality rate of 30–35%. Variola minor causes a milder form of disease (also known as alastrim, cottonpox, milkpox, whitepox, and Cuban itch) which kills about 1% of its victims.
Long-term complications of V. major infection include characteristic scars, commonly on the face, which occur in 65–85% of survivors. Blindness resulting from  corneal ulceration and scarring, and limb deformities due to arthritis and osteomyelitis are less common complications, seen in about 2–5% of cases.

Testing pregnant women for Group B Streptococcus and Chlamydia trachomotic, and then giving antibiotic treatment if needed, reduces pneumonia in infants. Suctioning the mouth and throat of infants with meconium –stained amniotic fluid decreases the rate of aspiration pneumonia.
Vaccination is important for preventing pneumonia in both children and adults. Vaccinations against Haemophilus influenzae and Streptococcus pneumoniae in the first year of life have greatly reduced their role in pneumonia in children. Vaccinating children against Streptococcus pneumoniae has also led to a decreased incidence of these infections in adults because many adults acquire infections from children.
A vaccine against Streptococcus pneumoniae is also available for adults. In the U.S., it is currently recommended for all healthy individuals older than 65 and any adults with emphysema, congestive heart failure, diabetes mellitus, and cirrhosis of the liver, alcoholism, cerebrospinal fluid leaks, or those who do not have a spleen. A repeat vaccination may also be required after five or ten years.
Influenza vaccines should be given yearly to the same individuals who receive vaccination against Streptococcus pneumoniae. In addition, health care workers, nursing home residents, and pregnant women should receive the vaccine.

Diagnosing pneumonia can be difficult in some people, especially those who have other illnesses. Occasionally a chest CT scan or other tests may be needed to distinguish pneumonia from other illnesses.

Depending on any underlying conditions they may have any type of organism causing the infection:

Bacteria.
Many types of bacteria can cause pneumonia. Bacterial pneumonia can occur on its own, at the same time as viral pneumonia, or you may develop it after you’ve had a viral upper respiratory infection such as influenza. Signs and symptoms, which are likely to come on suddenly, include shaking chills, a high fever, sweating, shortness of breath, chest pain, and a cough that produces thick, greenish or yellow phlegm

Viruses.
About half of pneumonias are caused by viruses. Viral pneumonia tends to begin with flu-like signs and symptoms. It usually starts with a dry (nonproductive) cough, headache, fever, muscle pain and fatigue. As the disease progresses, you may become breathless and develop a cough that produces just small quantities of phlegm that may be clear or white. When you have viral pneumonia, you run the risk of also developing a secondary bacterial pneumonia

Mycoplasma
pneumonia spreads easily in situations where people congregate and is common among schoolchildren and young adults. Mycoplasma pneumonia responds well to treatment with the appropriate antibiotics, although you may continue to have a dry, nagging cough and continue to feel weak during your convalescence.

Fungi.
Certain types of fungus also can cause pneumonia, although these types of pneumonia are much less common. Most people experience few if any symptoms after inhaling these fungi, but some develop symptoms of acute pneumonia, and still others may develop a chronic pneumonia that persists for months.

Bacterial pneumonia is often confined to just one area (lobe) of the lung. This is called lobar pneumonia.

This disease is very common in the babies. Pneumonia is a lung infection which is caused due to bacteria, fungi and virus. The babies can easily get pneumonia and have symptoms like cough, fever and even breathing problems. Sometimes it can be treated at home and if it is serious the baby can be hospitalized too. Pneumonia occurs suddenly in babies and can last for about one week to ten days.

Why Pneumonia causes in babies ?

There are many causes of pneumonia which are caused by various micro-organisms like bacteria, viruses and any other organism. They are:-
Bacteria – The babies are affected by pneumonia due to bacteria which includes the symptoms like rust or green colored phlegm.
Mycoplasma – It is a kind of bacteria in which babies get mild fever and the recovery requires a long time. The symptoms which cause pneumonia due to this micro-organism are nausea and vomiting, white phlegm etc.
Viruses - About fifty percent of pneumonia cases are reported in babies who are caused by viral infections. The symptoms look similar like flu.

Neonatal tetanus

Neonatal tetanus is a form of generalized tetanus that occurs in newborn infants. It occurs in infants who have not acquired passive immunity because the mother has never been immunized. It usually occurs through infection of the unhealed umbilical stump, particularly when the stump is cut with a non-sterile instrument. Neonatal tetanus is common in many developing countries and is responsible for about 14% (215,000) of all neonatal deaths, but is very rare in developed countries.

Local tetanus

Local tetanus is an uncommon form of the disease, in which patients have persistent contraction of muscles in the same anatomic area as the injury. The contractions may persist for many weeks before gradually subsiding. Local tetanus is generally milder; only about 1% of cases are fatal, but it may precede the onset of generalized tetanus.

Generalized tetanus

General tetanus is the most common type of tetanus, representing about 80% of cases. The generalized form usually presents with a descending pattern. The first sign is trismus, or lockjaw, and the facial spasms called risus sardonicus, followed by stiffness of the neck, difficulty in swallowing, and rigidity of pectoral and calf muscles. Other symptoms include elevated temperature, sweating, elevated blood pressure, and episodic rapid heart rate. Spasms may occur frequently and last for several minutes with the body shaped into a characteristic form called opisthotonos. Spasms continue for 3–4 weeks, and complete recovery may take months.

Cephalic tetanus

Cephalic tetanus is a rare form of the disease, occasionally occurring with otitis media which means ear infections in which C. tetani is present in the flora of the middle ear, or following injuries to the head. There is involvement of the cranial nerves, especially in the facial area.