Download Endemic Diseases Involving Nervous System OBJECTIVES

Endemic Diseases Involving Nervous System
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OBJECTIVES
By the end of the lecture the student should be able to:
Definition of endemic disease.
Names of some diseases involving nervous system.
Discussion about some diseases.
ENDEMIC DISEASE
DEFINITION:
When the number of susceptible and immune persons are almost equal, the disease
or infectious agent constantly present in a community.
e.g. - Hepatitis A
- Typhoid fever
- Common cold
NAMES OF SOME ENDEMIC DISEASES INVOLVING NERVOUS SYSTEM
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Poliomyelitis.
Rabies.
Diphtheria.
Tetanus.
Cerebral Malaria.
Meningitis.
POLIOMYELITIS (INFANTILE PARALYSIS)
Poliomyelitis is an acute infectious disease caused by a specific (RNA) virus,
involving the nerve cells of the spinal cord and medulla.
CLINICAL FEATURES
Fever
Headache
Stiffness of neck
Stiffness of spine
Weakness of voluntary muscles
Flaccid paralysis of voluntary muscles, develops within the first few days.
EPIDEMIOLOGICAL DETERMINANTS
AGENT FACTORS.
(a) AGENT:
- The causative agent is the Poliovirus which has three serotypes: 1, 2, and 3.
- Most outbreaks of paralytic polio are due to type – 1 virus.
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(b) RESERVOIR OF INFECTION.
Man is only reservoir of infection.
(c) INFECTIOUS MATERIAL:
The virus is found in the faeces and oropharyngeal secretions of an infected person.
(d) PERIOD OF COMMUNICABILITY:
The cases are most infectious 7 – 10 days before and after onset of symptoms. In the
faeces, the virus is excreted commonly for 2 – 3 weeks.
EPIDEMIOLOGICAL DETERMINANTS
2. HOST FACTORS.
(a) AGE:
Poliomyelitis is chiefly encountered in children between the ages of 1 – 12 years.
(b) SEX:
Males to Female ratio is 3: 1
(c) RISK FACTORS:
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Fatigue.
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Trauma.
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Intramuscular injections.
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Operative procedures such as tonsillectomy .
(d) IMMUNITY:
Immunity following infection is fairly solid, although reinfection can occur.
EPIDEMIOLOGICAL DETERMINANTS
3. ENVIRONMENTAL FACTORS.
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Polio is more likely to occur during the rainy season.
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Highest incidence is in summer and early winter.
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The environmental sources of infection are contaminated water, food, flies, over
crowding, and poor sanitation.
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MODE OF TRANSMISSION
FAECAL – ORAL ROUTE:
- Infection may spread directly through contaminated fingers where hygiene is poor.
- Indirectly through contaminated water, milk, foods, flies and articles of daily use.
MODE OF TRANSMISSION
2. DROPLET INFECTION:
- This may occur in the acute
phase of disease when the
virus occurs in the throat.
- Close personal contact with an infected person facilitates droplet spread.
INCUBATION PERIOD
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7 – 12 days.
Commonly 12 days.
Range is 3 – 35 days.
METHODS OF CONTROL
1. PREVENTIVE ENVIRONMENTAL
CONTROL OF INFECTED PERSONS, CONTACTS AND ENVIRONMENT.
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NOTIFICATION: To local health authority.
ISOLATION:
- Patient is isolated for 6 weeks from the date of onset of the disease.
- Contacts are isolated for 3 weeks.
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CONCURRENT DISINFECTION: of oropharyngeal discharges, faeces and articles
soiled with them.
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TERMINAL DISINFECTION: None
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QUARANTINE:
- Infective.
- Quarantine of family contacts may be done for 3 weeks.
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IMMUNIZATION:
This is the sole effective means of controlling poliomyelitis. Two types of
vaccines are used.
1.Inactivated (Salk) polio vaccine
(IPV) {killed vaccine}
This vaccine contains all the 3 types of poliovirus, inactivated by formalin.
- 3 injections of 1 c.c. each are given, subcutaneously or intramuscularly.
- The first dose is given at the age of 6 weeks.
- The second injection is given 3 -5 weeks after the first injection.
- The third injection after 7 months of first injection.
- It is 80 – 97 % effective if 3 injections are given.
METHODS OF CONTROL
2.Oral (Sabin) Polio vaccine (OPV) {Live attenuated vaccine}
- It is given by mouth.
- The dose is 3 drops orally commencing at birth, at interval of 4 weeks for 3 months.
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TREATMENT:
- Use of respirators can be life saving if the respiratory mechanism is involved.
- Good orthopedic care is essential, to reduce musculoskeletal impairment.
- Rehabilitation of handicapped.
2. EPIDEMIC MEASURES.
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Isolation of all children with fever, till diagnosis is done.
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Education in bed nursing and disinfection of discharges and excreta.
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Mass immunization of vulnerable age groups.
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Postponement of nose and throat operations.
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Avoid violent exercise.
3. INTERNATIONAL MEASURE.
Telegraphic notification to WHO.
4. GLOBAL ERADICATION.
WHO has initiated a global program of polio eradication, in which children under 5
years are immunized. Some countries have achieved success in this effort.
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DIPHTHERIA
DEFINITION:
It is an acute infectious and communicable disease, characterized by involvement
usually of the respiratory tract (throat, nose, and larynx), the local production of
false membrane, and general symptoms, caused by absorption of exotoxin.
CLINICAL FEATURE
The bacilli multiply locally in the throat, and elaborate a powerful
exotoxin which is responsible for the
Formation of a grayish membrane over the tonsils, pharynx or larynx, with well –
defined edges.
Marked congestion oedema or local tissue destruction.
Enlargement of regional lymph nodes
Signs and symptoms of toxemia.
Toxemia gives rise to acute degenerative changes in the myocardium producing
myocarditis or even myocardial failure.
In 10 – 20 % diphtheria patients the CNS is involved, producing paralysis of
muscles of soft palate, extra ocular muscles, pharynx, diaphragm or limbs.
CLINICAL FEATURE
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RESPIRATORY TRACT FORMS OF DIPHTHERIA.
1.PHARYNGOTONSILLAR DIPH:
- Sore throat
- Difficulty in swallowing
- Low grade fever
- Mild erythema
- Localized exudate or a pseudo
membrane.
2.LARYNGOTRACHEAL DIPH:
- Fever
- Hoarseness of voice
- Croupy cough
3.NASAL DIPH: (mildest form)
- Usually is localized to the septum
turbinates of one side of nose.
- Occasionally a membrane may
extend into the pharynx.
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CLINICAL FEATURES
NON – RESPIRATORY MUCOSAL SURFACE.
Conjunctival diphtheria.
Genitals diphtheria.
Cutaneous diphtheria. (common in tropical areas).
EPIDEMIOLOGICAL DETERMINANTS
1. AGENT FACTORS.
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AGENT:
The causative agent is Corynebacterium Diphtheriae (Klebs Loeffler Bacillus), is a
gram – positive, non motile, club shaped organism. 4 types are distinguished
Gravis (more severe form), Mitis, Intermedius, & Belfanti (minimus).
(b) RESERVOIR OF INFECTION:
Reservoir is the infected person, may be patient or carriers, but the carriers are
common sources of infection, ratio is 95 : 5.
(c) INFECTIVE MATERIAL:
- Nasopharyngeal secretions.
- Discharges from skin lesions.
- Contaminated fomites.
- Infected dust.
(d) PERIOD OF INFECTIVITY:
14 – 28 days from the onset of the disease, but carriers may remain infective for much
longer period.
2. HOST FACTORS.
(a) AGE: frequent under 10 years of age.
(b) SEX: both sexes are affected.
(c) IMMUNITY:
- Infants born of immune mothers, are relatively immune until the first 6 months.
- Recovery after an attack is usually followed by immunity.
- Immunity is often acquired through un recognized infection.
3. ENVIRONMENTAL FACTORS.
- Occurs in all seasons, but common in autumn and winter months.
- It is prevalent throughout the world, but it occurs principally in the temperate zone.
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MODE OF TRANSMISSION
Man is only reservoir of infection.
The bacilli are spread by droplet from the upper respiratory tract.
Spread is favoured by crowding.
Dust and fomites are also mode of transmission, but their role is minimal.
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INCUBATION PERIOD
It is 2 – 5 days and often longer.
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DIAGNOSIS:
The diagnosis of diphtheria is mainly clinical.
A simple throat smear should be examined, if diphtheria like organism are found, a
culture should be obtained.
REMOTE EFFECTS OF DIPHTHERIA
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Heart
Kidneys
Liver
Adrenals
Peripheral nerves, are most often affected.
COMPLICATIONS
1.BACTERIAL COMPLICATIONS:
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Local bacterial infections.
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Bacterial pneumonia.
2.TOXIC COMPLICATIONS:
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Acute toxic myocarditis.
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Myocardial failure.
Toxic peripheral neuritis.
Local paralysis of VI and X cranial nerves.
TREATMENT
Diphtheria antiserum should be started as soon as possible.
1.IN MILD – MODERATE CASES:
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30,000 – 40,000 units are injected I.M.
2.IN SEVERE CASES:
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40,000 – 80,000 units, with at least half given I.V.
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Penicillin or erythromycin should also be used.
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PREVENTION & CONTROL
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PRIMARY MEASURES.
PRIMARY IMMUNIZATION:
- DPT vaccine include in EPI programme, given at 6 weeks, 10 weeks, & 14 weeks
interval by I.M. route.
- The booster dose of DPT given at 20 – 23 months.
1.CONTROL OF PATIENT, CONTACTS AND IMMEDIATE ENVIRONMENT.
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NOTIFICATION:
To local health authorities.
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ISOLATION:
Patient is isolated for 14 days from the date of onset of the disease.
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DISINFECTION:
- CONCURRENT DISINFECTION.
It is done of all articles in contact with the patient and all articles soiled with the nasal
or oral excretions of the patient.
- TERMINAL DISINFECTION.
It is done through fumigation of the room, with formaldehyde or with formalin spray.
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QUARANTINE OF CONTACTS:
Young children, if found to be carriers or suffering from nasal discharge or sore
throat, should be kept under surveillance and their throats cultured.
- Adult contacts, if they are carriers should not handle food or come in contact with
children, until shown not to be carriers by bacteriological tests.
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IMMUNIZATION OF CONTACTS:
- Child contacts, less than 10 yrs of age, and not previously immunized with toxoid,
may be given 1,000 units of antitoxin (50 units/kg) & at the same time a first dose
of toxoid should be given.
- Persons previously immunized, should have a reinforcing dose of toxoid.
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INVESTIGATION OF SOURCE OF INFECTIONS:
- Search for unreported & typical cases, carriers & contaminated milk, should be carried
out.
- 12% of convalescents are positive at the end of 2 months; 1% continue to be bacilli
carriers indefinitely.
- Discovered carriers should be restricted and treated accordingly.
2.EPIDEMIC MEASURES:
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Artificial immunization, by diphtheria toxoid, should be carried out to the largest
possible number of the population affected, with greatest emphasis on protection
of infants & pre – school children.
3. INTERNATIONAL MEASURES:
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Active immunization of susceptible infants and young children traveling to or
through countries, where diphtheria is a common disease, is necessary.
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A reinforcing dose of toxoid be given to those previously inoculated.
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Exchange of information between countries on current prevalence of diphtheria is
of great help.
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