Communicable Diseases Flashcards Preview

Preventive Medicine and Biostatistics > Communicable Diseases > Flashcards

Flashcards in Communicable Diseases Deck (30):

The infectivity of chicken pox lasts for
A. Till the last scab falls off
B. 6 days after onset of rash
C. 3 days after onset of rash
D. Till the fever subsides

Answer -B. 6 days after onset of rash

Period of communicability
Chicken pox - 1-2 days before to 4-5 days after appearance of rash.
Measles - 4 days before to 5 days after appearance of rash
Diphtheria - 14-28 days from disease onset
Poliomyelitis - 7-10 days before and after the onset of symptoms

Chicken pox
Also known as 'Varicella'
Causative agent - Varicella zoster virus [Human(alpha) Herpes virus-3]
Secondary attack rate - 90%
Incubation period - 14-16 days
Rash - dew drop on rose petal appearance, centripetal distribution pleomorphic rash
MC late complication of chickenpox - Shingles
Aspirin must not be given to children with chickenpox - Risk of Reye's syndrome
Strain of live attenuated chickenpox vaccine - OKA strain
Congenital varicella - Most threatening if transmitted in 1st trimester of pregnancy


Which of the following is not true of measles
A. High secondary attack rate
B. Only one strain causes infection
C. Not infectious in prodromal stage
D. Infection confers lifelong immunity

Answer- C. Not infectious in prodromal stage

Measles (Rubeola)
Period of communicability- 4 days before and 5 days after the onset of rash ( Rash - retroauricular origin)
Measles is highly infectious during prodromal period and during eruption. Period of communicability declines rapidly after appearance of rash. Measles has no second attacks (life long immunity is seen)

Note - WHO Measles elimination strategy - comprises 3-part Vaccination strategy ' Catch up, Keep up, Follow up'
- Catch up - One time nationwide, vaccination campaign targeting all children 9months -14 years of age, irrespective of h/o measles or vaccination status.
- Keep up - Routine services aimed at vaccinating more than 95% of each successive birth cohort.
- Follow up - Subsequent nationwide vaccination campaigns conducted every 2-4 years targeting usually all children born after the catch up campaign.

Accelerated Measles Mortality Reduction Strategy (WHO UNICEF) : Two doses of measles containing vaccine (MCV) to all children through routine and supplementary immunization activities.


To eradicate measles the percentage of infant population to be vaccinated is at least __________ %
A. 70
B. 80
C. 85
D. 95

Answer- D. 95%


Recommended vaccination strategy for rubella is to vaccinate first and foremost
A. Women 15-49yrs
B. Infants
C. Adolescent girls
D. Children 1-14 yrs

Answer- A. Women 15-49 yrs

Priority groups for rubella vaccination in India
1st priority- 15 -49 years reproductive age group females
2nd priority - All children 1-14 yrs of age
3rd priority - Routine universal immunisation of all children aged 1yr.


Which of the following is not true about influenza virus?
A. Influenza virus A is subject to frequent antigenic variations
B. Antigenic drift is a gradual antigenic change over a period of time
C. Antigenic shift is due to genetic recombination of virus
D. Major epidemics are due to antigenic drift

Answer -D. Major epidemics are due to antigenic drift

Antigenic variations in Influenza (MC in type A)
Antigenic shift occurs due to genetic recombination/ reassortment/ rearrangement, it occurs suddenly and may lead to epidemics/ pandemics whereas antigenic drift is due to point mutation and its occurs gradually/insidiously and may lead to sporadic cases.

Incubation period of Influenza - 18 - 72 hrs
Vaccines for influenza
A. Killed vaccines - 2 doses, 3-4 weeks apart, 0.5 ml, S.C., 70- 90% protective efficacy, duration - 3-6months and is rarely associated with GBS
B. Live attenuated vaccine - stimulate local as well as systemic immunity, antigenic variations presents difficulties in manufacture.
C. Newer vaccines -
1. Split virus vaccine- Sub-Virion vaccine', lower antigenicity and fewer side effects
2. Neuaraminidase specific vaccine - subunit vaccine
3. Recombinant vaccine


True about Diptheria are all except
A. Carriers are more common sources of infection than cases
B. Incubation period is 2-6 days
C. 25 Lf of Diptheria toxoid are present per ml in DPT vaccine
D. Diptheria is an endemic disease in India

Answer- C. 25 Lf of Diptheria toxoid are present per ml in DPT vaccine

DPT Vaccine
25 Lf of 25 Lf of Diptheria toxoid are present per 0.5 ml dose of DPT vaccine


The usual incubation period for pertussis is
A. 7-14days
B. 3-5 days
C. 21-25 days
D. Less than 3 days

Answer - A. 7-14 days

Incubation period is the time interval between invasion by an infectious agent and appearance of first sign or symptom of disease.


True about meningococcal meningitis is
A. Causative agent is a gram negative diplococci
B. Cases are the most important source of infection
C. Treatment with penicillin eradicates carrier state
D. Vaccine can be given in pregnancy

Answer - A. Causative agent is a gram negative diplococci

Case fatality rate (CFR) of meningococcal meningitis - 80%, with early diagnosis and treatment, CFR declines


A 2-yr old female child was brought to PHC with a history of cough and fever for 4 days with inability to drink for last 12 hrs. On examination, the child was having weight of 5 kg and respiratory rate of 45/min with fever. The child will be classified as suffering from
A. Very severe disease
B. Severe pneumonia
C. Pneumonia
D. No pneumonia

Answer - A. Very severe disease

Inability to feed and severe malnutrition (weight 5kg at 2 yrs age) makes the child as having very severe pneumonia


All of the following are targets of STOP TB STRATEGY partnership except-
A. Achieve a diagnosis rate >70% and cure rate >85% by 2005
B. Reduce prevalence to

Answer - C. Lower deaths to 70% and cure rate >85%
By 2010 - Reduce prevalence of and deaths due to TB by 50%
By 2015 - Eliminate TB as a public health problem ( less than 1 case/ million population)


Which type of sample can be used to isolate poliovirus earliest?
A. Stool
B. Blood
C. Throat

Answer- A. Stool

Stool examination
- Isolation of wild poliovirus from stool is the recommended method for laboratory confirmation of paralytic poliomyelitis
- Recommended in every case of AFP
- Virus usually can be found in feces from onset to up to > 8 weeks after paralysis, with the highest probability of detection during the first 2 weeks after paralytic onset.


Which of the following is not transmitted through sexual route
A. Hepatitis A
B. Hepatitis E
C. Both Hepatitis A and hepatitis E
D. Hepatitis D

Answer - B. Hepatitis E

Hepatitis E - caused by calcivirus with IC period 15-60days is transmitted via faeco-oral route.
Hepatitis A - caused by enterovirus 72 with IC period 15-45 days is transmitted via faces-oral, sexual route.
Hepatitis B- caused by hepadnavirus with IC period 30-180 days is transmitted via sexual route, perinatal, percutaneous and par enteral route.
Hepatitis C - caused by hepacivirus with IC period 15-160 days is transmitted via percutaneous route.
Hepatitis D - caused by viriods like with IC period 30-180 days is transmitted via sexual, perinatal and percutaneous route.


The freshly prepared ORS should not be used after
A. 6 hours
B. 12 hours
C. 18 hours
D. 24 hours

Answer- D. 24 hours.


All are true about Japanese encephalitis except
A. Man is incidental dead end host
B. Culicines and anophelines are vectors involved
C. Case fatality rate is over 90%
D. 85% of cases occur in children <15years age

Answer- C. Case fatality rate is over 90%

Case fatality rate of JE - 20-40% (may reach upto 58%)
Vectors of JE - Culicine mosquitoes and some anophelines
- Culex tritaeniorhynchus (most imp vector), Culex vishnui and Culex gelidus


Yellow fever vaccination starts protection after how many days of injection:
A. 5 days
B. 10 days
C. 15 days
D. 20 days

Answer- B. 10 days


The incubation period of yellow fever is
A. 3-6 days
B. 3-4 weeks
C. 1-2 weeks
D. 8-10 weeks

Answer- A. 3-6 days


JE virus life cycle in nature run between
A. Pigs - mosquitos
B. Cattle- birds
C. Pigs - humans
D. Birds - pigs

Answer- A. Pigs - Mosquito


The vector for KFD is
A. Aedes aegypti
B. Haemaphysalis
C. Culex
D. Xenopsylla

Answer- B. Haemaphysalis

Vectors of KFD in India - Hemophysalis spinigera(Hard tick)

Outside India - Soft tick


Maximum explosiveness of Plague is determined by
A. Total flea index
B. Cheopsis index
C. Burrow index
D. Specific percentage of fleas

Answer- B. Cheopsis index


In India "Rabies free" zone is
A. Goa
B. Lakshadweep
C. Sikkim
D. Nagaland

Answer - B. Lakshadweep


Endemic typhus is transmitted by
A. Flea
B. Tick
C. Mite
D. Mosquito

Answer- A. Flea


Epidemic typhus is transmitted by
A. Louse
B. Soft tick
C. Hard tick
D. Rat flea

Answer- A. Louse


Rickettsiae are transmitted by
A. Flea
B. Louse
C. Mosquito
D. Mite
E. Fly

Answer - A. Flea B. Louse and D. Mite


Scrub typhus is transmitted by
A. Flea
B. Mite
C. Tick
D. Mosquito

Answer- B. Mite


Plague is transmitted by
A. Hard tick
B. Soft tick
C. Rat flea
D. Louse

Answer-C. Rat flea


The highly infectious clinical form of plague is
A. Bubonic plague
B. Pneumonia plague
C. Septicaemic plague
D. All of the above

Answer- B. Pneumonia plague


False about leishmaniasis is
A. Coinfection with AIDS is now emerging
B. Indian leishmaniasis is a non-zoonotic infection with man as the sole reservoir
C. Aldehyde test of Napier is a good test for diagnosis
D. There are no drugs for personal prophylaxis

Answer- C. Aldehyde test of Napier is a good test for diagnosis

Aldehyde test of Napier - becomes positive after 2-3 months of disease onset and reverts to negative 6 months after cure.
It is a useful test for surveillance but not for diagnosis.

It is a nonspecific test, since it is positive in many chronic infections where albumin:globulin ratio is reversed

There are no drugs available for personal prophylaxis of kala azar.

Reservoir of infection- Dogs, jackals, foxes, rodents and other mammals

Indian kala Azar is a non-zoonotic infection - man as reservoir


Kala Azar is transmitted by
A. Phlebotomus sergenti
B. Phlebotomus papatasii
C. Phlebotomus argentipes
D. All of the above

Answer -C. Phlebotomus argentipes


Rash is absent in
A. Epidemic typhus
B. Endemic typhus
C. Scrub typhus
D. Q-fever

Answer- D. Q-fever


API is
A. Annual parasite index
B. Average parasitic index
C. Animal parasite index
D. Annual parasitic incidence

Answer- D. Annual parasitic incidence

API - Annual parasitic incidence is a sophisticated measure of malaria incidence in a community.

API = confirmed cases during one year/ population under surveillance X 100