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Disease and epidemiology |
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Pneumococcal disease is an infection caused by a bacterium called Streptococcus pneumoniae (S. pneumoniae) or the pneumococcus. Infection can be invasive and result in pneumococcal pneumonia, pneumococcal bacteremia (bacterial infection of the blood), or pneumococcal meningitis. Other common non invasive diseases are otitis media (middle-ear infection) and sinusitis.
Pneumococcal diseases mainly affect infants and children under five years of age with the highest prevalence among children under two years of age. Elderly over 65 years of age, individuals with underlying medical condition, weakened immune systems, cerebrospinal fluid (CSF) leak or tobacco smokers are at increased risk of infection.
The bacterium spreads from person-to-person via respiratory droplets through coughing or sneezing. The disease is spread from person to person by droplets in the air. The pneumococci bacteria are common inhabitants of the human respiratory tract. Pneumococcal diseases are more common during the winter and in early spring when respiratory diseases are more prevalent.
The pneumococcus is the most common cause of serious bacterial pneumonia among children. Pneumococcal pneumonia is also common bacterial complication of influenza and measles. Complications of pneumococcal pneumonia include empyema (infection of the pleural space), pericarditis (inflammation of the sac surrounding the heart), and endobronchial obstruction with atelectasis and lung abscess formation.
Pneumococcal bacteremia is a common clinical presentation among children younger than age two years and younger. It occurs in about 25%–30% of patients with pneumococcal pneumonia. Symptoms include fever and chills, and possibly sleepiness and loss of appetite.
It is also a main cause of bacterial meningitis specially among children younger than age of one year. The disease has high fatality rate. Neurologic sequels are common among survivors of pneumococcal meningitis.
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Disease and epidemiology |
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Rotavirus gastroenteritis is caused by rotavirus that infects the stomach and bowel. Rotavirus gastroenteritis is common in infants and young children. Children under five years of age, especially those between 6 months and two years are most vulnerable to the disease.
Rotavirus is highly contagious among children. Repeat infections with different viral strains are possible, and most children have several episodes of rotavirus infection in the first years of life. The first infection tends to be the most severe as the body builds up immunity (resistance) to the virus afterwards. This is why rotavirus infections are extremely rare in adults.
The incubation period for a rotavirus lasts approximately two days. Infants and children with rotavirus infection have diarrhoea, vomiting, fever and often followed by abdominal pain and dehydration. Children - particularly those under the age of two- are at higher risk of dehydration and may require hospital treatment.
Infected people pass the virus before and after they have symptoms of the illness. Infection results from ingestion of infected foods or drinks. Touching a surface contaminated with rotavirus and then touching the mouth area can result in infection.
The virus is highly resistant in the environment and can survive for months in stools at room temperature. The virus is widespread in developing and developed countries.
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Disease and epidemiology |
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Tetanus is an infectious disease caused by anaerobic bacteria, Clostridium tetani, the spores of which are widespread in the environment.
Under favorable anaerobic conditions, such as in dirty, necrotic wounds or in the umbilical cord if it is cut with a non-sterile instrument, this bacillus may produce tetanospasmin, an extremely potent neurotoxin. This toxin blocks inhibitory neurotransmitters in the central nervous system and causes the muscular stiffness and spasms typical of generalized tetanus which is often manifested as lock jaw. Restlessness, headache, and irritability are common associated symptoms.
The incubation period between exposure to the bacteria and development of the initial symptoms of tetanus ranges from two days to two months, but it's commonly within 14 days of injury.
The disease may affect any age group. As the disease progresses, mild stimuli may trigger generalized tetanic seizure-like activity, which contributes to serious complications and eventually death unless supportive treatment is given. Case-fatality rates are high even where modern intensive care is available. |
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Disease and epidemiology |
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Rubella is contagious infectious disease caused by the rubella virus. The infection is usually mild sub-clinical. Possible presenting symptoms are fever, red rash blotchy and swollen lymph glands. The infection is transmitted by respiratory droplets from the nose or throat mucous secretions of infected individual.
The incubation period for rubella ranges between 14 and 21 days. Childhood infection is often mild and resolves without complication. But when infection is contracted by women in early pregnancy, the virus passes through the pregnant woman's bloodstream to infect her unborn child. That may present serious fetus complications, fetal death or birth defects which is called congenital rubella syndrome (CRS).
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