Contact Infectious Diseases
By
Dr. Sabry Ahmed Salem
Prof. of community medicine
Environ mental health &
occupational medicine
Contact diseases according to source of infection
I- from man
1- Intact skin & mucous membranes:
a- Infective skin diseases e.g. favus, ring worm
b- Infective eye diseases e.g. purulent and mucopurulent
conjunctivitis & trachoma
c- Infective eruptions: e.g. small pox, chicken pox
d- Leptospirosis
2- Diseases of injured skin & mucous membranes:
Wound infections.
Sexually transmitted diseases.
Animal bites e.g. rabies and rat-bite fever.
Tetanus and gas-gangrene
II- From animals
e.g. Rabies, rat- bite fever, cutaneous antrax, leptospirosis,
brucellosis, Dermato-phytoses.
III- Injection infection :
By contaminated syringes and blood transfusion e.g.
Pyogenic infections: staphylococi. mainly.
Infection from blood: syphilis, HCV, HBV, CMV, HIV
(AIDS) & malaria.
IV- Congenital infection:
In. utero infection transmitted from the mother to the
fetus before placenta formation, after placenta it is
called tranplacental infection”.
e.g.: AIDS, Mumps, Rubella, Varicella, HBV,
Toxoplasmosis, &, CMV
Rabies
* Causative agent: Rabies virus
2 types
-street virus (freshly isolated) -fixed virus
(successive passage in the brain & rabbit)
* Reservoir:
Dogs :Mainly, Cats, Fox & Wolf.
Rodents : Rarely.
Possibly: Man (Saliva), not reported.
Vampire bats: Not found in Egypt.
* Exit: Saliva of rabied animal.
* Mode of transmission:
1. Bite of rabied animals (mainly).
2. Lick of animals (abrasions in skin).
3. Possibility from man-to man by saliva spray (not reported).
* Incubation period: varies from 10 days to 6 months or
more depending on:
1- Site of bite.
3- Single or multiple bites.
2- Severity and extent of bite.
4- Skin: bare or covered.
5- Dose of injected virus.
6- Measures taken after bite.
* Clinical features:
I- In dogs:
1- Furious rabies (mad- dog syndrome)
Dies in 10 days.
Runs aimlessly attacks without stimulus.
Gasping respiration.
Salivation.
2- Dumb rabies : dies within 3 days, animal isolates it self
and dies in sleepness state.
III- In man:
Acute encephalomyelitis.
Hydrophobia.
Headache.
Malaise.
Mental depression.
Personality changes.
* Prevention:
I- For animals:
Destruction of stray dogs and cats.
Active immunization of dogs and cats using inactivated
vaccine: 2 doses, 2 week interval + booster dose yearly and
given licence.
Quarantine measures for imported dogs and cats.
II- For man:
1- Pre-exposure immunization for:
Veterinerians.
Night- guards.
zoo- workers.
Lab- workers.
Vaccine: Human diploid cell vaccine (HDCV)
1ml, IM in the deltoid region, 3 doses
1st , after1 week 2 nd, after 3 weeks 3 rd.
Booster dose: every 2 years.
2-Post- exposure management & immunization
a- Wound care: Free flushing with soap and water at once.
Cleaning.
No suturing of wounds.
Use chemical disinfectant.
b- Tetanus seropruphylaxis or booster dose of toxoid.
c- Chemoprophylaxis: by penicillin.
d- Specific protection by immunization
(vaccination & seroprophylaxis).
Immunization
Indications of post-exposure immunization
If the animal escaped start immunization at once.
If animal dies or killed and lab. examination of the
brain shows Negri bodies.
If the animal is present and dies within 2 days of
isolation.
Multiple bites or severe bites especially in the head
and neck : immunization should be started at once
Post- exposure immunization:
A- Without pre-exposure immunization(not immunized
before)
Those exposed to infection are immunized by vaccination
and seroprophylaxis if needed.
1- Vaccination:
a- Nerve tissue vaccine (NTV)
Doses: 2.5-5ml, sc at different sites of abdominal wall.
Severe exposure 21 doses + 2 doses and seroprophylaxis.
Mild or moderate: 14 doses.
sever exposure: seroprophylaxis + vaccination 21 doses /21
days + 1 dose after 10 days + 1 dose after 20 days from the
last dose
b-HDCV (Human diploid cell vaccine):
* Dose: 1ml IM/ deltoid region.
* Mild exposure: 3-4 dose/one week.
* Severe exposure: 5 doses over a period of one week
* Mild or moderate exposure 3 or 4 doses.
* No neurological or allergic complications.
2- Seroprophylaxis:
* Given with vaccination.
After severe exposure.
Without previous vaccination.
Nor post exposure vaccination within 2 years and the
available vaccine that will be given is NTV not HDCV.
* Dose: either:
Animal hyperimmune serum.
Or Human rabies immunoglobulin (HRIG): ½ dose around the
bite by infiltration in wound and the other ½ IM.
* Value:
Delay multiplication of the virus.
Give more time for diagnosis and for stimulation of immunity
to develop before the virus reaches CNS.
B- With previous vaccination (immunized before)
The exposed when re-exposed is given vaccination and
No seroprophylaxis.
If less than 2 years
1- HDCV
2 doses separated by 2 days, each of 1ml, IM, deltoid region.
2- NTV
* If HDCV is not available 5 doses / 5 days + 6th dose after 20
days.
If more than 2 years: as in post exposure without
immunization
Sexually – transmitted
Disease (STDs)
According to the cause or active agent they are
classified into:
A- Bacterial
Syphilis: treponema pallidum
Gonorrhea: Gonococci (N. gonorrhea)
Chancroid: Hemophilus ducreyi
Lymphogranuloma venerum: chlamydia trachomatis.
Non specific vaginitis: gardnerella vaginalis.
Non-specific urethritis: chlamydia trachomatis & Mycoplasma.
B- viral:
AIDS: HIV
Hepatitis B: HBV
Cytomegalovirus disease: CMV
Genital herpes: herpes simplex virus.
Genital warts: papilloma virus.
Molluscus contagiosum: pox virus.
C- Fungal
Candidiasis “ Vaginal thrush” : Candida albicans.
D- Protozoal
- Vaginitis & urethritis: trichomonas vaginalis.
E- Arthropodal:
Genital Scabies: Sarcoptes Scabii.
Pediculosis pubis: phthirus pubis.
Mode of transmission: Diseases are primarily
transmitted by sexual
contact: venereal diseases.
Other diseases: sexual and other modes of transmission.
Prevention of STDs:
I- Social and mental health
1. Socio-economic development: increases in come.
2. Social and religious guidance.
3. Mental health promotion of youth for sound morals and
psychological behaviour by:
-
Providing places and activities for youth.
-
Convient family life & supervision.
4. Marital and family welfare by:
-
Facilities for marriage of the youth.
-
Pre- marital counseling.
-
Social services - Scio economic support
-
Problem solving
II- Physical Health
1- Health education: for
- Mode of transmission.
- Manifestations.
- Value of seeking medical care.
2- Prevention of congenital infection by pre-marital & prenatal using
serological tests for diagnosis and treatment.
3- Specific prevention: by penicillin (chemoprophylaxis).
For syphilis: injection of 2-4 million units IM after exposure to cases.
For gonorrhea: oral penicillin 400,000 u.
For AIDs: trial to produce vaccine against HIV.
* Control of venereal diseases (STDs)
I- Case finding:
1- Comprehensive through medical examination :
- Pre-marital examination
- Pre-natal care.
- Examination of child
-Nurses, wet-nurses,
2- Survey studies: for
-prevalence
-ecological features of STDs
3- Clinical service
4- Screening:
- Pregnant females for congenital infections.
- Prisoner, army recruits.
•Screening of pregnant women for congenital
infection by:
Amniocentesis. Cord blood sampling of the fetus by
ultrasound.
Actions to diagnosed cases:
Case (measures):
Notification.
Treatment of cases by penicillin in big dose.
Health education of cases.
Psychological and social support.
Re-examination to confirm cure.
II- Contacts:
Examination of marital or sexual partner of diagnosed
case for case- finding.
III- Epidemiologic measures
Tracing the source of infection by investigations and
diagnosis of the case :
- Tracing (identification)
- Examination
- Treatment (if diseased)
- Health education
AIDS
AIDS
Acquired Immune Deficiency Syndrome
It is a serious life threatening disease that causes
progressive damage of the immune system and other organ
systems and is eventually fatal.
•Causative agent:
•HIV type I & II HIV human immunodeficiency virus DNA
retrovirus. Weak virus that affects T-helper cells which
stimulate B-lymphocytes to form antibodies.
•Reservoir: Man
- Case
- incubatory carrier with latent infection.
* Exit: blood, semen, vaginal secretions may be saliva and
tears (Rare).
* Period of infectivity:
From the onset of infection and throughout the life till death
* Mode of transmission:
-Sexual contact mainly
- Contact with infected blood
- Perinatal infection
-Kissing (saliva)
- Postnatal exposure of newborn to infected mother.
* Risk – groups:
- Male homosexual.
- I.v drug abuse.
- Sexual contact with infected person.
- Hemophilia cases treated with blood products.
- Recipients of blood transfusion.
-Haemodialysis.
*I.P: 6 ms 7 yrs. (Virus hide in WBCs).
* C/P:
Initial stage: influenza- like picture.
AIDS related complex (ARC):
- Low grade fever.
- Generalized L.Ns.
- Fatigue and weight loss.
- Diarrhea .
- Respiratory infection.
3- Secondary pathological conditions:
Due to immune dysfunctions e.g.
T.B.
-Neurological manifestations & Autoimmune disorders.
Malignancy: kaposi’s sarcoma & Lymphomas.
Prognosis of AIDS:
- Immune deficiency is irreversible
- Fatal within years from viral infections and malignancy.
* Diagnosis:
- Clinically: not diagnostic
- Blood testing becomes +ve 1-3 ms. After infection
1. Demonstration of HIV in blood sample by polymerase chain
reaction (PCR).
2. Isolation of the virus from lymphocytes, bone marrow &
plasma on tissue culture.
3. ELISA: detection of HIV antibodies (+ve)
4. Western Blot technique: To confirm diagnosis before
notification.
1- Factors related to marriage:
- Socioeconomic difficulties
- Marital disorders e.g divorce and separation
- Marital maladjustment
2- Faculty culture: religion and its impact on morals and
behavior.
3- Faulty lifestyle and concept of modernization: Alcoholism,
drug dependence , sexual promiscuity & lack of sublimitation &
uncontrolled personal instincts.
4- Prostitution is social problem related.
5- Inefficient and under utilization of health services.
Anthrax
* Causative agent:
Bacillus arthracis (Anthrax bacillus).
Aerobic spore-forming organism, remains viable for several
years in soil and materials such as wool, hair and hides.
* Reservoir:
Farm animals (cattle and sheep).
Bacteria exist in blood, intestine and organs of diseased
animal and sporulate on leaving the body.
* I.P: 1-7 days
* Mode of transmission:
1- Cutaneous anthrax
Occupational: farmers, veterinarians & butchers.
Non- occupational: using unsterilized shaving brushes.
2- Intestinal anthrax : Ingestion of meat and milk polluted
by the organism.
3- Respiratory anthrax :
Inhalation of contaminated dust with anthrax spores in the
sheds.
Inhalation of contaminated raw wool during the process of wool
sorting in industry causes wool sorter’s disease.
* C/P:
1. Cutaneous anthrax: skin lesion (malignant pustule).
2. Intestinal anthrax  splenomegaly & severe gastroenteritis
which may be fetal.
3. Respiratory antrax ( pneumonic authrax)  severe
hemoorhagic bronchopneumonia and septicemia  may
be fatal.
* Prevention of anthrax
I- In animals
a- Prevention
Environmental sanitation in shed & farm.
Veterinary care.
Vaccination
b- Control:
1. Isolation of the diseased animal.
2. Disinfection of animal discharges.
3. Burying carcasses of the diseased animals in deep pits and
covered with quick lime.
II- In man
a- Prevention:
1. Meat sanitation: in farms, during transport, abattoir.
2. Milk sanitation.
3. Measures for wool, hair & hides.
 Proper disinfection by formaline.
 Quarantine measures: certificate of disinfection.
1. Prevention of occupational infection
- Health education.
- Protective clothes.
- Washing facilities.
- Active immunization (cell – free vaccine).
b- Control:
i- Case :
- Case finding.
- Isolation.
- Notification.
-
Disinfection .
- Treatment :ciprofloxacin penicillin and tetracycline.
ii- Contact: In case of pneumonic anthrax: isolation of
contacts for 7 days.
iii- Epidemic measures: survey studies to trace source
and channel of infection.
Leprosy
Hanson’s disease
Chronic infectious skin disease may lead to disfigurement
of the face and Disability.
* Causative agent:
Mycobacterium leprae.
Acid fast bacilli.
Not cultured nor infect the experimental animals.
* Reservoir: Man: case as open case with ulcerated lesions
of skin and mucous membrane.
* Exit: Discharge of lesion
skin
Respiratory system
* Mode of transmission:
Prolonged contact with open case (common).
Inhalation (Rare).
* I.P: Several years.
* C/P: 3 types.
1- Lepromatous Leprosy:
1-Skin lesions.
2- Sensory loss.
3- Destruction of the nasal septum with collapse of the nose
leading to Disfugrement + Leonine facies.
2- Tuberculoid Leprosy:
1. Peripheral nerve affection causes Anaesthesia, muscle
weakness & paralysis.
2. Trophic changes of skin, muscles & bones.
3- Intermediate (Border- line) type:
Maculoanesthetic leprosy.
Prognosis: Untreated cases causes chronicity: chronic selflimited course with tendency to recovery.
Fatality: Rare, unless complicated by T.B or amyloid
nephrosis.
Complications:
Disfigurement  leonine facies.
Secondary infection.
Burns due to sensory loss.
Disability.
* Diagnosis: a- Clinical picture.
b- Laboratory:
Detection of acid-fast bacilli sample of lesions in skin and
respiratory discharges
Serologic tests of syphilis are +ve in lepromatous type.
Lepromin test: +ve in tuberculoid.
* Prevention
I- General
Socioeconomic development.
Health education.
II- Segregation: of the newborn from leprotic parents.
III- Specific:
Chemoprophylaxis (Sulfone): for at risk family contacts.
BCG to new borns and children is effective.
* Control:
I- Case:
1-Case- finding.
2-Notification.
3- Isolation: compulsory- segregation.
4-Disinfection.
5-Treatment: by
Multiple Drug Therapy (MDT).
6-Release: after becoming bacteriologically free.
II- Contacts
1. Periodic examination for case- finding.
2. Health education.
4-Special prevention by
3-Social assistance.
chemoprophylaxis
BCG immunization
N.B.: Leprosy, AIDS & Pulmonary T.B have long I.P.
Treatment of leprosy: by MDT: “Multi Drug therapy”
A simple and inexpensive course of treatment of leprosy
recommended by a WHO in 1981 advantages of MDT.
Well tolerated.
Accepted by patients.
Highly effective.
Easy to apply in the field.
Prevent development of drug resistance.
High cure rate.
Schedule:
A- Multibacillary type:
•Rifampicin.
•
•calfazimine
•Dapson.
600 mg.
300 mg
100mg
B- Paucibacillary type
-Rifampicin.
600 mg
-Dapson.
100 mg.
Tetanus
Lock – Jaw
* Causative agent: Clostridium tetani “ Tetanus bacillus”
* Anaerobic spore-forming bacteria."exotoxin"
* Reservoir: Animals (herbivorous animals, horses)
Man The organism lives in the intestine is excreted (exit)
with faeces and sporulates outside the body.
so No man- to- man spread.
* Mode of transmission Infection of wound, by spores
occurs in different methods:
1. Injury in polluted place.
2. Neonatal infection (tetanus neonatorum), umbilical stump
is contaminated * polluted instrument.
* Polluted dressing
3- Surgical tetranus (post- operative):
By
* unsterilized cat gut.
* Contaminated instruments & dressing
* Reactivation of dormant focus during surgery.
4- Puerperal infection:
Infection of uterus by non- sterile instruments with high risk after
septic abortion.
5-Otogenic infection: introduction of foreign body (F.B.) in the
air.
6- Idiopathic.
* I.P: 4-21 days
* Clinical picture:
Exotoxin invades blood producing toxemia: affect motor nerve
endings, AHC, of the spinal cord & Brain stem.
Tonic spasm of muscles
1.At first around the lesion.
2.Muscles: tonic spasm of muscles leads to lock jaw or trismus.
3.Facial muscles  Risus sardonicus i.e mixed expression of
smilling
4.Arched back.
5.Abdominal muscles- spasm
Untreated cases have high case- fatality rate due to heart
and respiratory failure.
* Prevention:
I- General prevention :
Sanitation of the environment: by
Animal shed away from human residence.
Animal carts replaced by mechanical vehicle.
2- Health education: for
- Mode of transmission.
- Complications.
- Protection.
3- Community development & clean environment
II- Specific prevention:
* Active immunization
* Seroprophylaxis
* Chemoprophylaxis
a- Active immunization : * Tetanus toxoid alone
* DPT * DT
i- Tetanus toxoid: For at- risk groups of adults, military forces
pregnant & gardeners.
Adults:
2 doses, 8 weeks interval + 3rd dose after 1y
Pregnants: 3 doses during pregnancy
1st  16-20 ws of pregnancy.
2nd  20- 24 ws of pregnancy
3rd  2 ws before delivery.
ii) DPT & DT: for infants and children
DPT: 0.5ml, IM, Never freezed, 2+4 +6 months and booster
dose at 18-24 ms.
DT:
booster dose at 5-6 years.
b- Seroprophylaxis: Human antitoxic immunoglob. (ATG)
Antitetanic serum (ATS)
i- Human Anti- tetanic immunoglobulin (ATG):
250-500 IU, IM gives protection for 10 days.
ii- Animal Antetetanic serum (ATS):
1500 IU, SC or IM, protection for 2 weeks given rapidly
after injury or bigger dose if delayed sensitivity is needed before
injection of the Anti titanic serum.
c- Chemoprophylaxis:
If the wound is managed properly  give penicillin (in place of
seroprophylaxis) penicillin sensitivity must be considered.
Care of the wound (wound management):
* cleaning
* Use of disinfectants
* Remove F.B. or necrotic tissue if present
d- Prevention of other forms of tetanus:
i- Tetanus neonatorum:
Aseptic cutting of the cord and dressing.
Training of midwives and giving them equipped kit.
Active immunization of mother during pregnancy.
ii- Puerperal tetanus:
Proper sterilization of instruments (during labour or abortion).
Active immunization during pregnancy.
Chemoprophylaxis after labour & abortion.
Trained midwives.
iii- Surgical tetanus:
Clean hospital environment.
Asepsis and sterilization during surgery.
Care and protection of wounds.
Use of sterilized cat gut.
* Control of tetanus :
1- Case:
- Case finding.
Notification, Isolation
- Treatment
Not needed.
* Treatment of tetanus:
i- Surgical care
ii- Specific therapy Serotherapy chemotherapy
serotherapy. ATS: 30000 to 200,000 IU
or ATG: 1500 IU (better) chemotherapy (rarely used)
Penicillin or tetracycline
2- Epidemic measures
For cases of hospital and neonatal infection specially
when repeatedly reported.
Gas Gangrene
* Causative agent: Clostridia group of bacteria which are
anaerobic spore forming bacteria and classified into Primary.
Secondary.
1- Primary bacteria from acid and gas
Saccharolytics  acid + gas
Toxigenic
Include Cl. Welchii (most important)
Cl. Edematiens
Cl. Septicum
2- Secondary bacteria
Protelolytics.
Facilitate growth and action of primary bacteria.
Include Cl. Histolyticum
Cl. Sporogenes
* Reservoir: Man and animals (small intestine)
* Exit: Stools contain organisms which sporulate under
anaerobic condition in the soil.
* Mode of transmission:
Contamination of deeply lacerated wounds (occupational &
war).
Surgical infection: non- sterilized instruments & dressings “
Postoperative”.
Puerperal infection: usually after septic abortion.
* C/P:
Locally: Myonecrosis, cellulitus with production of gas.
Myoneurosis (destruction of tissues & muscles).
Toxemia.
Case-fatality : very high.
* Prevention:
1. Surgical care of wounds.
 Removal of foreign body and necrotic tissues.
 Use of sterilized instruments & dressings.
 Chemoprophylaxis.
2- Prevention of surgical infection
- Surgical care of wound.
- Asepsis.
 Chemoprophylaxis.
 Pre operative preparation of skin obstetric care.
3- Prevention of puerperal infection :
 Family planning to avoid unwanted pregnancy.
 Chemoprophylaxis.
Specific prevention:
Seroprophylaxis by polyvalent antitoxin IM.
Chemoprophylaxis by penicillin.
* Control:
1- Case:
Case –finding.
Isolation: in special place.
Disinfection: of infected material.
Treatment : by
Chemotherapy  penicillin (Big dose).
Serotherapy  polyvalent antitoxin
2- Drastic measure
When a case is discovered in hospital ward, outpatient
clinic or operating theatre (i.e the case is introduced), the
following must be done.
Close the place.
Sterilization of any contaminated objects.
Sterilization of air by formaldehyde gas.
At- risk groups are protected by chemoprophylaxis and may be
seroprophylaxis.