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It is a disease caused by the exotoxin of Clostridium botulinum, a spore- forming, gm-positive anaerobe.
Human disease is usually caused by types A, B & E.
The incubation period ranges from a few hours to 10 days.
The disease usually follows the ingestion of contaminated preserved food-stuffs, but may develop from infected wounds or following gastrointestinal colonization in infants.
Symptoms arise from inhibition of acetyl choline- Mediated neuro-transmission and include descending weakness or paralysis, gastrointestinal symptoms, postural hypotension, dry mouth and dilated pupils.
Death usually occurs from respiratory arrest.
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It is an acute illness caused by infection of the intestine with the bacterium Vibrio cholera.
The incubation period is 1-3 days.
A person may get cholera by consumption of water or food contaminated with the cholera bacterium.
Ingestion of raw shell-fish has been reported as a source of cholera.
Infection is often mild or symptomless; however sometimes it can be severe. Approximately one in 20 infected persons suffers severe disease characterized by profuse watery diarrhea (rice water diarrhea), vomiting and leg cramps.
In these persons, rapid loss of body fluids & electrolytes leads to dehydration and shock. Without treatment, death may occur within hours.
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It is an infectious disease caused by herpesvirus, a member of the subfamily Alphaherpesvirinae.
The incubation period is 10 - 14 days.
The virus causes two distinct diseases, varicella (chicken-pox) and herpes Varicella is a highly contagious disease which is caused by air-borne spread of infectious virions released from skin or respiratory mucosa of patients.
There is usually a short or absent prodromal period, for 1 -2 days, of malaise and fever before the appearance of the characteristic rash.
The rash appears in crops and usually progresses rapidly from macules to papules, vesicles, pustules and finally crusts.
The rash has a central distribution mainly over the trunk, scalp and face.
Rare complications of varicella infection include pneumonia, cerebellar ataxia and encephalitis.
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It is an infectious disease caused by a potent exotoxin elaborated by Corynebacterium diphtheriae.
The incubation period is 7 days.
Diphtheria primarily affects the pharynx and in minor instances larynx, nasal lining, skin, conjunctiva or vagina.
The severe local and systemic manifestations are due to binding of the toxin with the cells interfering with enzymes necessary for protein synthesis leading to cell damage and death.
The disease results in acute inflammation, pseudomembrane formation and lymphadenopathy.
It may be associated with systemic toxicity, which may include myocarditis and neuritis.
Death may occur due to heart failure (Toxic myocarditis) or due to respiratory airway obstruction by the formed pseudomambrane.
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It is an infectious disease caused by anaerobic organisms mainly Clostridium perfringens, Clostridium septicum and Clostridium oedematiens.
The incubation period is from hours to 6 weeks.
Patients become infected through contamination of wounds with soil and dirt after trauma, operations or normal labor.
The disease is characterized by myonecrosis presented with pain and oedema in the region of the wound, with a serous or sero-sanginous exudate and a local crepitus sensation.
The draining lymph nodes enlarge markedly.
Associated systemic manifestations as toxemia, irregular feeble pulse, mild to moderate pyrexia, hypotension and collapse usually associate the local infection.
The disease usually terminates with death due to circulatory failure.
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It is an acute infectious disease caused by a single stranded RNA virus of the Picornaviridae family, genus Hepatavirus.
The incubation period is 2 - 6 weeks.
Man gets infection through consumption of contaminated food or drink.
The disease usually commences with a brief prodromal illness lasting for several days and characterized by fatigability, malaise, loss of appetite, nausea and vomiting.
In most patients the first objective sign of illness is darkening of urine, yellowing of sclera (jaundice), or passage of pale - colored stools.
Enlarged tender liver and elevated serum transaminases are always present. When disease does occur, it is usually mild and recovery is complete in 1-2 weeks. Occasionaly, the symptoms are severe and convalescence can take several months, rare deaths usually occur in the elderly.
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It is an infectious disease caused by a double stranded, enveloped DNA virus of the Hepadenaviridae family.
The incubation period ranges from 6 weeks to 6 months.
The development of clinical manifestations is highly age dependent; being more manifested in adults.
Clinical signs and symptoms of acute HBV infection include anorexia, nausea, malaise, vomiting, jaundice, dark urine, clay colored stool and abdominal pain.
Occasionally, extra-hepatic manifestations occur and include rash, arthralgia and arthritis. Fulminant hepatitis occurs in 1 - 2% of cases.
Chronic hepatitis develops in 6 - 10% of cases and causes liver cirrhosis.
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It is an infectious disease caused by members of the family Orthomyxoviridae that comprises three immunologically distinct types:
A, B and C.
The incubation period ranges from 1-3 days.
Influenza is characterized by abrupt onset of constitutional symptoms and signs as fever, myalgia, headache, severe malaise, non-productive cough, sore throat and rhinitis.
Pulmonary complications are the most common serious consequences.
The clinical picture is essentially the same for influenza A and influenza B whereas the clinical characteristics of influenza C are generally milder.
Epidemics of influenza occur during winter months nearly every year and are responsible for high rates of deaths and work absence days all over the world.
Rate of infection is highest among children and young adults, while rate of deaths is highest among old ages and high risk people with chronic diseases.
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It is an infectious disease caused by a member of Morbilivirus in the family of Paramyxovirus.
Incubation period is 10-12 days.
The virus is transmitted by droplet infection.
The prodromal stage is manifested by fever, malaise, conjunctivitis, coryza and tracheo-bronchitis that last for 2-4 days.
Koplik spots are pathognomonic for measles and appear 1-2 days before the onset of rash.
The rash is an erythematous maculopapular eruption that spreads all over the body within 3-4 days and is associated with a sudden rise of temperature up to 40ēC.
The most common complications of measles include otitis Media, pneumonia, diarrhea and encephalitis.
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It is an infectious disease caused by Neisseria meningitides a gram- negative kidney shaped cocci, commonly seen in pairs intra-cellularly.
The incubation period ranges from 7-9 days.
The organism spreads by droplet infection.
The most common manifestations of meningococcal meningitis are sudden onset of fever, malaise, myalgia and headache.
Seizures occur in 20% of cases together with vomiting and photophobia.
A macular eruption, which progresses to peticheal and ecchymotic rash, is present in the majority of cases.
The disease may be associated with myocarditis, endocarditis or pericarditis.
Septicemia may be fulminant and is associated with hypotension and extensive purpura.
Complications are mostly neurological including sensori-neural deafness and permanent disabilities.
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It is an infectious disease caused by a member of the genus Rubulavirus in the family Paramyxovirus.
The incubation period is 14-18 days.
The classic symptom of mumps is parotitis; however it may also affect the sub-mandibular and sub-lingual salivary glands.
It is associated with fever, headache, malaise, myalgia and anorexia.
Complications of mumps are more common in adults and include pancreatitis, meningo-encephalitis and orchitis/oophoritis that may result in infertility.
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It is an infectious disease caused by Streptococcus pneumoniae, a group anaerobic gram-positive organisms that grow as diplococcic, or in short chains.
The incubation period is 7 days.
The major clinical manifestations are otitis Media, sinusitis, tracheo-bronchitis, and pneumonia.
Pneumonia is manifested by high fever, chills and chest pain. Cough is dry in early stages and then becomes productive.
Cyanosis, sweating and increased respiratory rate may also occur.
Pneumococci may invade the blood stream resulting in meningitis and endocarditis.
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It is an infectious disease caused by poliovirus types I, II or III.
The incubation period is 7-14 days.
Infection primarily spreads by the feaco-oral route but may also spread by droplet transmission.
Approximately 90 -95% poliovirus infections are asymptomatic.
Non-specific illness with low-grade fever and sore throat (minor illness) occurs in 4 - 8% of infections.
Aseptic meningitis occurs in 1- 5% of patients few days after the minor illness has resolved.
Rapid onset of asymmetric acute flaccid paralysis occurs in 0.1- 0.2% of infections.
Lower limb muscles are the most common to be affected; however bulbar and respiratory muscles may also be involved.
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It is an infectious disease caused by rhabdovirus of the genus Lyssavirus.
The rabies virus is usually transmitted by the bite of an infected animal or contamination of broken skin by its saliva.
The incubation period varies from a few days to several months
(according to the site of the bite) usually 1-3 months.
Human rabies is a fatal disease once symptoms have appeared.
The disease is characterized by hyper-excitability and severe spasms of larynx and pharynx that may lead to hydrophobia.
Other manifestations include hyper- salivation, fever and convulsions.
The disease usually progresses to coma and death.
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It is an infectious disease caused by a member of the toga family.
The incubation period is 14-21 days.
The disease is transmitted by droplet infection.
It is usually mild and is characterized by lymphadenopathy (usually occipital & post-auricular) and maculopapular erythematous rash on the face and neck.
The rash spreads down and fades within 1- 3 days. Complications include arthritis, encephalitis, Guillian Barre syndrome and thrombocytopenia.
The most serious problem with rubella virus is on the developing fetus if a pregnant woman is exposed to infection during the first trimester.
It causes congenital rubella syndrome which is characterized by sensori-neural deafness, cataract, cardiovascular anomalies and mental retardation of the newborn.
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It is a disease caused by an exotoxin elaborated by Clostridium tetani.
The incubation period is 7-21 days.
Patient can get infection through wound contamination by C. tetani spores that are widely distributed in soil, intestine and feaces of horses, sheep and cattle.
The disease is manifested primarily by neuromuscular dysfunction in the form of convulsions and severe muscular spasm.
The muscle spasm usually involves the jaw (lock jaw) and neck and then becomes generalized.
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It is an infectious disease that is caused by an acid-fast bacillus known as Mycobacterium tuberculosis.
Mode of infection and incubation period vary according to the site of the disease as it may involve any part of the body.
Survey studies in Egypt showed that around 90 % of cases are pulmonary and 10 % are extra-pulmonary.
Cases of active pulmonary tuberculosis show constitutional and local chest manifestations that vary according to stage and severity of the disease.
Manifestations are non specific, but only suggestive, e.g. night low-grade fever, night sweats, anorexia, mild loss of weight.
Haemoptysis may occur in advanced stages.
Cases usually become chronic and may show exacerbations and remissions.
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It is an infectious disease caused by Salmonella typhi.
The incubation period is 10-14 days.
Infection results from the consumption of food or water contaminated by excreta of an acute case or a carrier. S.typhi can invade the human intestinal mucosa ultimately leading to bacteraemia.
The patient starts to develop symptoms such as: fever, myalgia, anorexia, abdominal discomfort ,headache and rose spots on the trunk.
Diarrhea in young children and constipation in older children are common manifestations. Less common and most severe complications are intestinal perforation, hemorrhage and death. Infection of gall bladder can lead to chronic carrier state in 2-4 % of acute cases.
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It is an infectious disease caused by a gram negative cocco-bacillus Bordetella pertussis.
The incubation period ranges from 7-10 days.
The disease is highly communicable and is transmitted by direct contact with airborne discharges from the respiratory mucous membranes of infected persons.
It manifested by episodes of forceful repetitive cough followed by a sudden massive inspiratory effort, which produces the characteristic whoop.
It is often accompanied with cyanosis and vomiting. In young infants the cough may be absent and the disease may manifest with spells of apnea.
Major complications include pneumonia, encephalitis and malnutrition (due to repeated vomiting).
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It is an infectious disease caused by single stranded RNA virus, a prototype member of the family flaviviridae.
The incubation period ranges from 3-6 days.
It is transmitted to man by mosquito or ticks.
The disease resembles many other arbo-viral infections and is characterized by fever, headache, malaise and myalgia.
It progresses to result in hepatic, renal and myocardial injuries, hmorrhage and death.
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