دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
1
|
ا ل ص ف ح ة
Chicke pox
herpes zoster
• Clinical features
Varicella (chickenpox): Chickenpox generally presents with a low-grade
fever, malaise and a rash. The rash is firstly maculopapular then
becomes vesicular (blistered) and progresses to crusted lesions over
about five days.
They are most numerous on the trunk and on the face, scalp, limbs and
mucous membranes of the mouth. Some cases (about 5%) are
subclinical or mild in nature. Adults tend to suffer with more severe
disease than children. Newborns and immunosuppressed patients are at
greatly increased risk of severe chickenpox.
The case fatality rate is lower for children than for adults . One out
every 100000 children with varicella , compared with 1 out of every
5000 adults . Prior to the availability of effective viral therapies , the
fatality rate was up to 30% , but it is likely lower now .
Complications:
*pneumonia ( viral and bacterial )
* secondary bacterial infections
*hemorrhagic complications
* encephalitis
*Infection early in pregnancy may be associated with congenital
varicella syndrome
Herpes zoster (shingles):
• Herpes zoster or shingles is characterized by a predominantly
unilateral vesicular eruption within a dermatome. It is often
associated with severe pain that may precede lesions by 48–72
hours. The rash lasts up to several weeks depending on severity.
The rash is often more widespread and persistent in
immunosuppressed patients. Patients must be carefully evaluated
to ensure that there is no eye involvement when the rash involves
the ophthalmic area of the face. Specialist treatment is mandatory
in this case as blindness can result.
• Incidence increases with age and
• children under 12 are rarely affected unless immunosuppressed.
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
2
|
ا ل ص ف ح ة
• complication of herpes zoster in many (especially elderly) patients
is prolonged pain (post-herpetic neuralgia) which may persist for
months after resolution of the skin lesions.
• Lesions may appear in croups in irregular fashion along nerve
pathways , are usually unilateral, deeper seated and more closely
aggregated than those of chickenpox .
Sever pain and parasthesia are common
Method of diagnosis
Confirmation of the diagnosis is generally only required when the
clinical picture is atypical. It is made by:
- isolation of the virus in cell cultures
- visualization by electron microscopy
- serological tests for antibodies
- immunofluorescence on lesion swab or fluid
- nucleic acid testing or PCR.
Infectious agent
• Human herpes virus 3 (alpha) or varicella
• zoster virus (VZV).
Reservoir : Humans are the only reservoir of the virus, and disease
occurs only in humans.
Occurrence
• Chickenpox is a highly contagious but generally mild disease and is
endemic in the population. It becomes epidemic among
susceptible individuals mainly during winter and early spring.
More than 90% of cases are children under 15 years of age.
• Herpes zoster (shingles) occurs in 20% of people, mostly when
they are elderly due to the reactivation of latent virus from the
dorsal root ganglia.
Mode of transmission
• -person to person by direct contact
• - airborne spread of vesicle fluid or secretions of the respiratory
tract of chickenpox cases or of vesicle fluid of patient with HZ ,
indirectly through articles freshly soiled by discharges from
vesicles of mucous membranes of infected people .
• Incubation period : The incubation period is from two to three
weeks, usually 14-16 days.
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
3
|
ا ل ص ف ح ة
Period of communicability
• Usually communicable for one to two days (up to five days) before
the onset of the rash, continuing until all lesions are crusted.
Communicability may be prolonged in patients with altered
immunity. Those with zoster are considered infectious for a week
after lesions appear.
Susceptibility & resistance
• Susceptibility to chickenpox is universal among those not
previously infected. Over 80% of non-immune household contacts
of a case of chickenpox will become infected.
• Patients who are at high risk of severe disease/complications if
they do not have immunity include: infants less than one month
old, pregnant women and immunosuppressed individuals
including those with hematological malignancies, on
chemotherapy, high dose steroids or with HIV infection.
Methods of control
A- preventive measures :
• Symptomatic management of cases: Tepid bathing or cool
compresses may help to reduce itching.
• Children with chickenpox should be excluded for at least five days
after the rash appears. A few remaining scabs are not a reason for
continued exclusion.
Children with shingles can attend school if the lesions can be covered
adequately however exclusion from swimming and contact sports
should be advised for seven days after the rash appears.
-Advise adults to stay away from work for the same period
• -Avoid contact with high risk susceptible persons.
• -Aspirin should never be given to children with varicella due to a
strong association with the development of Reye’s syndrome.
• -If chickenpox develops in pregnancy, refer within 24 hours of rash
onset.
- live attenuated varicella virus vaccin .
A single 0.5 ml Sc dose is recommended for routine immunization of
children up 12 yr of age who have not had varicella .
Varicella vaccine is recommended for susceptible persons.
Priority groups for adult immunization include :
-Person who have close contact with persons at high risk for serious
complications .
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
4
|
ا ل ص ف ح ة
Persons who live or work in environments where transmission of VZV
is likely
(Teachers of young children , day care employees & residents & staff
members in institutional setting)
- persons who live & work in environments where transmission can
occur ( college students , military personnel )
**Persons more than 13 yr old require 2 dose of vaccine 4-8 weeks
apart .
***Mild varicella- like rash at the site of injection or at distant sites
occur in about 2%-4% of children & about 5% of adults.
**The duration of immunity is unknown , but antibodies have persisted
for at least 10 yr .
2- protect high risk individuals who cannot be immunized , such as
nonimmune neonates & immunodeficient, from exposure by
immunizing household or other close contacts .
3- Varicella- zoster immune globulin (VZIG ) , is effective in modifying
or preventing disease if given withen 96 hours after exposure.
B-control of patient
contacts & the immediate environment :
- isolation : exclude children from school or public places until vesicle
become dry, usually after 5 days , exclude infected adults from
workplace& avoid contact with susceptible .
- concurrent disinfection : articles soild by discharge from nose &
throat.
-Quarantine : usually none . However, in a hospital where susceptible
children with known recent exposure may justify quarantine for a period
of at least 10-21 days after exposure ( up to 28 days if VZIG has been
given )
- protection of contacts :
vaccine is recommended for use in susceptible persons exposure to
varicella .
-VZIG given within 96 hours of exposure may prevent or modify
disease in susceptible close contacts of cases .
- antiviral drugs such as acyclovir, a dose of 80 mg/kg/day in 4 divided
doses is given within a week of exposure . –
investigation of contacts & source of infection : a source of infection
may be a case of varicella or herpes zoster
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
5
|
ا ل ص ف ح ة
Management of the disease
• Primary varicella infection in the healthy child is a rather benign
disease that requires symptomatic therapy only. Oral acyclovir
should be considered for healthy persons at increased risk of
severe varicella infections.
• Adults and immunocompromised persons with chickenpox have a
more complicated course than that occurring in children, and
therefore, the condition necessitates a more aggressive
pharmacotherapeutic approach. Intravenous acyclovir therapy is
recommended for patients who are immunosuppressed or
immunocompromised.
• Varicella-zoster immune globulin (VZIG) is indicated for use in
highly susceptible, VZV-exposed immunocompromised or
immunosuppressed populations.
epidemic measures :
• Outbreaks of varicella are common in school, day care &
institutional setting which may associated with complications .
• infectious cases should be isolated & susceptible contacts
immunized immediately to control an outbreak.
• Or VZIG should be evaluated immediately for consideration if
vaccine is contra indication .
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
6
|
ا ل ص ف ح ة
Typhoid and Paratyphoid fever
• A systemic bacterial disease with insidious onset of sustained
fever, severe headache, malaise, anorexia, relative bradycardia,
nonproductive cough in early stage of illness, rose spots on the
trunk and constipation more often than diarrhea in adults.
• Intestinal hemorrhage or perforation can occur in 1% of cases.
Case fatality rate is 10%-20% without antibiotic therapy and 1%
with antibiotic use. Relapse may occur in 15%-20% of patients, but
with milder form.
• Paratyphoid fever presents a similar clinical picture, but tends to
be milder, and the case-fatality rate is much lower.
Case classification
• Suspected case: Any case having the following features: sustained,
non-sweating fever of 38 oC or more, for 3 days or more, abdominal
discomfort (abdominal pain, diarrhea or constipation). With 2 or
more of the following symptoms: dry non-productive cough, relative
bradycardia, anorexia, severe headache.
Confirmed Case: A suspect or probable case with detection of S.
typhi or S. paratyphi through positive culture of blood, stool, urine or
bone marrow (laboratory investigation: culture of blood early in the
disease; stool and urine after the first week; or bone marrow culture
which provide the best bacteriologic confirmation (90%-95%
recovery) even in patients who have already received antimicrobials.
Because of its limited sensitivity and specificity, serologic tests (widal
test) are generally of little diagnostic value.)
Carrier: any person discharging bacilli in stool or urine for more than a
year following infection.
Infectious agent:
• For typhoid fever: Salmonella typhi
• For paratyphoid fever: Salmonella paratyphi A
Occurrence:
Worldwide, mostly endemic in many developing countries, especially
in the Middle East.
It occurs throughout the year with seasonal increase in summer
months.
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
7
|
ا ل ص ف ح ة
Reservoir:
Humans, rarely domestic animals for paratyphoid.
Mode of transmission
Ingestion of food and water contaminated by feces and urine of
patients and carriers.
Incubation period:
Depends on inoculum size and host factors; from 3 days to over 60
days (range 8-14 days). For paratyphoid is 1-10 days.
Period of communicability:
As long as bacilli appear in excreta, from first week throughout
convalescence (1-2 weeks for paratyphoid).
Susceptibility and resistance
• General and is increased in individuals with gastric achlorhydria
and possibly in those who are HIV- positive. Relative specific
immunity follows recovery from clinical disease, inapparent
infection and active immunization. In endemic areas, typhoid
fever is most common in preschool children and children ages 5-
19 years old.
Methods of control
Preventive measures
1-Educate the community about the importance of hand washing.
2-Dispose human feces in a sanitary manner.
3-Protect, purify and chlorinate public water supply.
4-Control fly by screening, spraying with insecticides; control fly
breeding by frequent collection and disposal of garbage.
5-Clean preparation and handling of food.
6-Pasteurize or boil all milk and dairy products.
7-Good personal hygiene of patient, convalescent and carriers.
8-Encourage breast-feeding throughout infancy; boil all milk and
water used for infant feeding.
9-Periodic examination of the food handlers and exclusion of chronic
carriers from work until three consecutive negative stool cultures are
obtained at least one month apart (for acute cases 24 hour apart).
10-Immunization of the high risk group.
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
8
|
ا ل ص ف ح ة
typhoid fever : immunization
• for occupational exposure, travel to endemic area, living in area of
high endemisity & household member of documented S . typhi
carrier and
• microbiology laboratory personnel who frequently work with S .
typhi .
• An oral live vaccine using salmonella typhi strain Ty 21a , live
attenuated S . typhi (requiring 1 capsule by the mouth , 4 doses,
2 days apart)
• .. Time immunization should be completed by (before possible
exposure) by 1 week.
• Minimum Age For Vaccination is 6 years. & older & adults
• Booster Needed Every 5 years for people who remain at risk
• A paranteral vaccine containing the polysaccharide Vi antigen
(single dose). It not give for children younger than 2 year .
• Time immunization should be completed by (before possible
exposure) is 1 weeks.
• Minimum Age For Vaccination is 2 years.
• Booster Needed Every 2 years.
• PTF : oral typhoid vaccine (Ty 21a) conferred partial protection
against paratyphoid
Control measures
1-Suspected cases should be reported from all health care facilities to
higher level.
2-Confirmed cases should be investigated using case investigation
form; enteric precautions for acute cases and should be supervised
until 3 consecutive negative cultures of feces at least 24 hours apart
and at least 48 hours after any antimicrobials, and not earlier than 1
month after onset. If any of these is positive, repeat cultures at
monthly intervals during the 12 months following onset until at least
3 consecutive negative cultures are obtained.
3-Search for unreported cases, carriers or contaminated food, water,
milk or shellfish.
4- Household and close contacts should not be employed in
sensitive occupations (food handlers) until at least 2 negative feces
cultures, taken at least 24 hours apart, have been obtained.
دكتوره هديل
طب مجتمع
) ( الفصل الثاني
lec : 9
9
|
ا ل ص ف ح ة
Epidemic measures:
1- search for the case or carrier who is the source of infection & for
the vehicle (water or food) by which infection was transmitted.
2- eliminate suspected contaminated food.
3- pasteurize or boil milk, or exclude milk supplies & other foods
suspected on epidemiological evidence until safety is ensure.
4- chlorinate suspected water supplies adequately under competent
supervision or avoid use. All drinking water must be chlorinated,
treated with iodine or boiled before use.
5- routine use of vaccine is not recommended.