Incubation period

Incubation period

Q. 1

Shortest incubation period is seen in:

 A

Hepatitis A

 B

Hepatitis B

 C

Rubella

 D

Influenza

Q. 1

Shortest incubation period is seen in:

 A

Hepatitis A

 B

Hepatitis B

 C

Rubella

 D

Influenza

Ans. D

Explanation:

Influenza [Ref: Park 20/e, p 143,139,185, 189 (19/e chapter 5 p123)]

Incubation period is the time elapsed between exposure to the pathogenic organism and when symptoms and signs are first apparent.

Incubation period of some pathogens are:

  • Varicella (Chickenpox) – usually 14 to 16 days
  • Measles (Rubeola) – usually 10 days from exposure to onset of fever, and 14 days to appearance of rash
  • Rubella (German Measles) – 2 to 3 weeks; usually 18 days
  • Mumps – 2 to 3 weeks; usually 18 days
  • Influenza – 18 to 72 hours
  • Diphtheria – 2 to 6 days
  • Pertussis – usually 7 to 14 days, but not more than 3 weeks
  • Meningiococcal Meningitis – usually 3 to 4 days. but may vary from 2 to 10 days
  • Tuberculosis – the time from receipt of infection to the development of a positive tuberculin test ranges from 3 to 6 weeks, and thereafter, the development of disease depends upon the closeness of contact, extent of the disease and sputum positivity of the source case and host parasite relationship. Thus the incubation period of tuberculosis varies from weeks, months or years.
  • Polio – usually 7 to 14 days
  • Hepatitis A – 15 to 45 days (usually 25 to 30 days)
  • Hepatitis B – 45 to 180 days
  • Hepatitis C – 40 to 120 days
  • Cholera – from few hours up to 5 days, but commonly 1- 2 days
  • Typhoid – usually 10 – 14 days, but it may be as short as 3 days or as long as 3 weeks depending on the dose of bacilli ingested.
  • Amoebiasis – 2 to 4 weeks
  • Ascariasis – about 2 months
  • Filariasis – 8 to 16 months
  • Rabies – highly variable from 4 days to many years but usually 3- 8 weeks
  • Yellow fever – 3 to 6 days (6 days recognized under International Health Regulations)

Q. 2 Shortest incubation period is for which food poisoning:
 A Staphylococcus aureus
 B Bacillus cereus
 C Salmonellosis
 D Vibrio cholera
Q. 2 Shortest incubation period is for which food poisoning:
 A Staphylococcus aureus
 B Bacillus cereus
 C Salmonellosis
 D Vibrio cholera
Ans. B

Explanation:

Bacillus cereus


Q. 3 Shortest incubation period is seen in:
 A Hepatitis A
 B Hepatitis B
 C Rubella
 D Influenza
Q. 3 Shortest incubation period is seen in:
 A Hepatitis A
 B Hepatitis B
 C Rubella
 D Influenza
Ans. D

Explanation:

Influenza


Q. 4 All of the following are used as proxy measures for incubation period, except:
 A Latent period
 B Period of communicability
 C Serial interval
 D Generation time
Q. 4 All of the following are used as proxy measures for incubation period, except:
 A Latent period
 B Period of communicability
 C Serial interval
 D Generation time
Ans. B

Explanation:

Period of communicability


Q. 5 Incubation period of plasmodium vivax is:
 A 5 – 7 days
 B 7 – 10 days
 C 10 – 14 days
 D 15 – 30 days 
Q. 5 Incubation period of plasmodium vivax is:
 A 5 – 7 days
 B 7 – 10 days
 C 10 – 14 days
 D 15 – 30 days 
Ans. C

Explanation:

10 – 14 days


Q. 6

The limitation of movement of well persons or animals exposed to communicable diseases for a period usually not longer than the longest incubation period is known as:

 A

Quarantine

 B

Segregation

 C

Modified quarantine

 D

Isolation

Q. 6

The limitation of movement of well persons or animals exposed to communicable diseases for a period usually not longer than the longest incubation period is known as:

 A

Quarantine

 B

Segregation

 C

Modified quarantine

 D

Isolation

Ans. A

Explanation:

Isolation: Separation for the period of communicability of infected persons in such places or under such conditions as prevent transmission of infectious agent to the susceptible.

Quarantine: It is the limitation of movement of such well persons or animals exposed to communicable diseases for a period usually not longer than the longest incubation period of the disease to prevent effective contact with those not exposed.
Segregation: It is the separation for special consideration, control of or observation of some part of a group of persons from others to facilitate control of communicable disease.
Ref: Park 21st edition, page 110-111.

Q. 7

Incubation period of chancroid is:

 A

< 7 days

 B

10-14 days

 C

2-3 weeks

 D

3-4 weeks

Q. 7

Incubation period of chancroid is:

 A

< 7 days

 B

10-14 days

 C

2-3 weeks

 D

3-4 weeks

Ans. A

Explanation:

Chancroid: caused by Hemophilus  ducreyi

  • Incubation period is 4 to 7 days
  • Azithromycin  is drug of choice
 
Ref: Park 21st edition, page 305.

Q. 8

Which of the following is not a proxy measure of the incubation period of a disease?

 A

Communicable Period

 B

Latent Period

 C

Serial Interval

 D

Generation Time

Q. 8

Which of the following is not a proxy measure of the incubation period of a disease?

 A

Communicable Period

 B

Latent Period

 C

Serial Interval

 D

Generation Time

Ans. A

Explanation:

Communicable period is defined as the time during which an infectious agent may be transferred from an infected person or animal to another person or animal.

As a rule, infectious diseases are not communicable during the incubation period, with a few exceptions.

Latent period is equivalent to incubation period in non-infectious diseases.

Serial interval and generation time are roughly equal to the incubation period.

Ref: Park’s Textbook Of Preventive And Social Medicine, By K. Park, 19th Edition, Page 93, 94.


Q. 9

True about Diptheria –

 A

Caused by Gram negative bacilli

 B

Incubation period 2-5 days

 C

Chemoprophylaxis is done with rifampicin

 D

All

Q. 9

True about Diptheria –

 A

Caused by Gram negative bacilli

 B

Incubation period 2-5 days

 C

Chemoprophylaxis is done with rifampicin

 D

All

Ans. B

Explanation:

Ans. is ‘b’ i.e.,Incubation period 2-5 days

.  Diptheria is caused by Gram positive bacilli, Corynebacterium diphtheriae

.   Incubation period of most common form of diphtheria ( faucial/ tonsiliopharyngeal diphtheria) is 2-5 days.

. For chemoprophylaxis erythromycin or penicillin are used.

Previously immunized asymptomatic household contact should receive booster dose of diphtheria toxoid. Those not fully immunized but asymptomatic contacts should receive immunization for their age”.—0.P. Ghai 7th/221 “Lifelong immunity is usually, but not always, acquired after disease or inapparent infection”—health.vic.gov.au> IDAES home > blue book

. So, child recovered from illness is already is immune. No active immunization is required.


Q. 10

Incubation period for B. cereus –

 A

1-6 hrs

 B

8-16 hrs

 C

24 hrs

 D

a and b

Q. 10

Incubation period for B. cereus –

 A

1-6 hrs

 B

8-16 hrs

 C

24 hrs

 D

a and b

Ans. D

Explanation:

Ans. is. ‘a’ i.e., 1-6 hrs & ‘b’ i.e., 8-16 hrs 

.                              Incubation period of emetic type of food poisoning                —>    1-5 hours

.                              Incubation period of diarrheal type of food poisoning            —> 8-16 hours


Q. 11

Incubation period of gas gangrene is – 

 A

1-3 days

 B

4-6 days

 C

7-10 days

 D

a and b

Q. 11

Incubation period of gas gangrene is – 

 A

1-3 days

 B

4-6 days

 C

7-10 days

 D

a and b

Ans. D

Explanation:

Ans. is ‘a’ i.e., 1-3 days; ‘b’ i.e., 4-6 days 

.   The incubation period of gas gangrene depends upon the causative organism :

Cl. perfringens —›                 10 – 48 hrs (1 to 2 days)

Cl. septicum           —>          2 – 3 days

Cl. novyi                 —>          5 – 6 days

If you will have to choose one option, go ahead with 10 – 48 hrs, as 80% of the gas gangrene cases are caused by Cl. perfringens. (Cl. welchii) 


Q. 12

All of the following statements rearding Clostridium tetani are true, except –

 A

Spores are resistant to heat

 B

Primary immunization consists of three doses

 C

Incubation period is 6-10 days

 D

None

Q. 12

All of the following statements rearding Clostridium tetani are true, except –

 A

Spores are resistant to heat

 B

Primary immunization consists of three doses

 C

Incubation period is 6-10 days

 D

None

Ans. D

Explanation:

Ans. is None 

All of the above statements regarding tetanus and Clostridium tetani are true.

Tetanus spores are highly resistant to a number of injurious agents including boiling and autoclaving for 15 minutes at 120 ( Heat) ‘ —

‘ The incubation period is usually 6-10 days ‘-

Tetanus is not transmitted from person to person ‘—-

‘ The primary series ( of active immunization) for adults consists of three doses. The first and second dose are given 4-8 weeks apart and the third dose is given 6-12 months after the second. Thereafter a booster dose is requires every 10 years’— 


Q. 13

Incubation period of salmonella typhi –

 A

2-5 days

 B

3-21 days

 C

14-25 days

 D

0-60 days

Q. 13

Incubation period of salmonella typhi –

 A

2-5 days

 B

3-21 days

 C

14-25 days

 D

0-60 days

Ans. B

Explanation:

Ans. is ‘b’ i.e., 3-21 days 

Enteric fever

.   The term enteric fever includes typhoid fever caused by S.typhi and paratyphoid fever caused by S. paratyphi A, B and C.

.  The ability to resist intracellular killing and to multiply with in these cells is a measure of virulence of salmonella.

.  The incubation period for S. typhi ranges from 3 to 21 days.

.  Most prominant symptom of this systemic infection is prolonged fever. (Step-ladder pyrexia).

.  Early physical findings are —> Rash (rose spot), Relative bradycardia, Hepatosplenomegaly, Epistaxis.

Complications occur in 3′ and41  weeks –> Intestinal perforation and GI hemorrhage are the two most common complications. 


Q. 14

The usual incubation period of pertusis is ‑

 A

7-14 days

 B

3-5 days

 C

21-25 days

 D

Less than 3 days

Q. 14

The usual incubation period of pertusis is ‑

 A

7-14 days

 B

3-5 days

 C

21-25 days

 D

Less than 3 days

Ans. A

Explanation:

Ans. is ‘a’ i.e., 7-14 days 

Whooping cough (pertussis)

After an incubation period of about 1-2 weeks, the disease takes a protracted course comprising three stages– the catarrhal, paroxysmal and convalescent – each lasting approximately two weeks.


Q. 15

Incubation period of syphilis

 A

1 hour – 5 hour

 B

24 hour – 48 hour

 C

1 days – 10 days

 D

10 days – 90 days

Q. 15

Incubation period of syphilis

 A

1 hour – 5 hour

 B

24 hour – 48 hour

 C

1 days – 10 days

 D

10 days – 90 days

Ans. D

Explanation:

Ans. is ‘d’ i.e., 10 days – 90 days 


Q. 16

Incubation period of gonorrhoea is – 

 A

Less than 24 hrs

 B

1 to 2 days

 C

2 to 15 days

 D

12 to 25 days

Q. 16

Incubation period of gonorrhoea is – 

 A

Less than 24 hrs

 B

1 to 2 days

 C

2 to 15 days

 D

12 to 25 days

Ans. C

Explanation:

Ans. is ‘c’ i.e., 2 to 15 days 

  • Incubation period of gonorrhea is 2 – 8 days.

Q. 17

Incubation period of Diptheria is – 

 A

2 – 6 days

 B

2 – 6 hrs

 C

2 – 6 weeks

 D

2 – 6 months

Q. 17

Incubation period of Diptheria is – 

 A

2 – 6 days

 B

2 – 6 hrs

 C

2 – 6 weeks

 D

2 – 6 months

Ans. A

Explanation:

. Ans. is `a’ i.e., 2 – 6 days 

–  The incubation period of diphtheria is commonly 3-4 days.


Q. 18

Consider the following statements –                    

  1. In leptospirosis, the incubation period ranges from 2 to 20 days.
  2. In leptospirosis, urine may show microscopic haematuria

Which of the statements given above is are correct ?

 A

1 only

 B

2 only

 C

Both 1 and 2

 D

Neither 1 nor 2

Q. 18

Consider the following statements –                    

  1. In leptospirosis, the incubation period ranges from 2 to 20 days.
  2. In leptospirosis, urine may show microscopic haematuria

Which of the statements given above is are correct ?

 A

1 only

 B

2 only

 C

Both 1 and 2

 D

Neither 1 nor 2

Ans. C

Explanation:

Ans. is ‘c’ i.e., Both 1 and 2 


Q. 19

Regarding Rabies, true is –

 A

Incubation period depends on the site of bite

 B

Diagnosis is by eosinophilic intranuclear inclusion

 C

It is a RNA virus

 D

Caused only by dogs

Q. 19

Regarding Rabies, true is –

 A

Incubation period depends on the site of bite

 B

Diagnosis is by eosinophilic intranuclear inclusion

 C

It is a RNA virus

 D

Caused only by dogs

Ans. A

Explanation:

Ans. is ‘a’ Incubation period depends on the site of bite

Variability of incubation period

.    Incubation period of rabies depends on :

– The site of bite                                                            – Severity of bite

– Number of wounds                                                    – Amount of virus injected

– Species of biting animal                                            – Protection provided by clothing and treatment undertaken

.  Incubation period is shorter in :

– Severe exposures

–   Bites on face, head, neck and upper extremities

–  Bites by wild animals

About other options

. Pathognomonic Negri bodies are intracytoplasmic (not intranuclear) eosinophilic inclusion bodies

. Rabies virus is a RNA virus

. It can be caused by many wild animals (not only by dogs).


Q. 20

Incubation period of HBV is ‑

 A

45 to 180 days

 B

6 to 60 days

 C

10 days

 D

10 hrs

Q. 20

Incubation period of HBV is ‑

 A

45 to 180 days

 B

6 to 60 days

 C

10 days

 D

10 hrs

Ans. A

Explanation:

Ans. is ‘a’ i.e., 45 to 180 days


Q. 21

Which of following is correct about Prions ‑

 A

Long incubation period

 B

Destroyed by autoclaving at 121°C

 C

Nucleic acid present

 D

Immunogenic

Q. 21

Which of following is correct about Prions ‑

 A

Long incubation period

 B

Destroyed by autoclaving at 121°C

 C

Nucleic acid present

 D

Immunogenic

Ans. A

Explanation:

Ans. is ‘a’ i.e., Long incubation period 

  • There is long incubation period in prion disease.
  • Prions are not destroyed by autoclaving at 121°C.

“Autoclaving at 134°C for 5 hrs or treatment with 2 N NaOH for several hours is recommended for sterilization ofprions”.                                                  

  • Prions lack nucleic acid.
  • They are not immunogenic.

Q. 22

Incubation period of pertussis is –

 A

7 days

 B

7-14 days

 C

14-28 days

 D

28 days

Q. 22

Incubation period of pertussis is –

 A

7 days

 B

7-14 days

 C

14-28 days

 D

28 days

Ans. B

Explanation:

Ans. is ‘b’ i.e., 7-14 days 

Pertussis

After an incubation period of about 1-2 weeks, the disease takes a protracted course comprising three stages, – the catarrhal, paroxysmal and Convalescent – each lasting approximately two weeks.

Remember

o Catarrhal stage is the stage of maximum infectivity.

o Maximum complications occur in Paroxysmal stage.


Q. 23

Incubation period of scabies is: 

 A

7 days

 B

2 weeks

 C

4 weeks

 D

2-3 days

Q. 23

Incubation period of scabies is: 

 A

7 days

 B

2 weeks

 C

4 weeks

 D

2-3 days

Ans. C

Explanation:

C. i.e. 4 weeks


Q. 24

Time interval between invasion of the infection agent and appearance of first sign or symptom ‑

 A

Serial interval

 B

Incubation period

 C

Quarantine

 D

Period of infectivety

Q. 24

Time interval between invasion of the infection agent and appearance of first sign or symptom ‑

 A

Serial interval

 B

Incubation period

 C

Quarantine

 D

Period of infectivety

Ans. B

Explanation:

Ans. is `b’ i.e., Incubation period 

Incubation period

o Clinical symptoms of an infectious disease are not produced immediatly after invasion of infectious agent into the host.

o First infectious agent multiplies and produces some cellular/tissue response which results in clinical manifestations.

  • So there is an interval between invasion of infectious agent and onset of clinical manifestations which is known as incubation period i.e., “the time interval between invasion by an inectious agent and appearance of the first sign and symptom of the disease in question”.

o The length of incubation period is characteristic of each disease.

o There is minimum incubation period for each disease before which no illness can occur.

  • Incubation period varies for different infection and also from person to person with same disease.
  • It is so because incubation depends upon many factors : –

i)   Generation time of pathogen          iii) Portal of entery

ii)  Infective dose                               iv) Individual susceptibility

Median incubation period

  • It is the time required for 50% of cases to occur following exposure.

Q. 25

All of the following are used as proxy measure for incubation period except –

 A

Latent period

 B

Period of communicability

 C

Serial interval

 D

Generation time

Q. 25

All of the following are used as proxy measure for incubation period except –

 A

Latent period

 B

Period of communicability

 C

Serial interval

 D

Generation time

Ans. B

Explanation:

Ans. is ‘b’ i.e., Period of communicability 

  • Latent period, serial interval and generation time, all are approximate measure of incubation period, i.e., these period can give some idea about incubation period.

Latentperiod

  • The period from disease initiation to disease detection.
  • It is used in non-infectious disease as the equivalent of incubation period in infectious disease.

Serial interval

  • The gap time between onset of primary case and secondary case.

o By collecting information about a whole series of such onset, we get a distribution of secondary cases from which we can guess the incubation period.

Generation time

o Interval between receipt of infecton by host and maximal infectivity of the host.

o Generation time is roughly equal to the incubation period.

About option ‘b’

Communicable period

  • The time during which an infectious agent may be transferred directly or indirectly from an infected person to another person.

o The period of communicability has no relation with incubation period, it merely reflects the duration when the infectious agent may be transferred. This may occur during incubation period, during actual illness or during convalsescence.

o Generally communicable diseaes are not communicable in incubation period except – measles, Chicken pox, Pertussis hepatitis A, i.e., these diseases are communicable during their late incubation period.


Q. 26

Incubation period helps in determining all except‑

 A

Period of isolation

 B

Period of quarantine

 C

Identification of source of infection

 D

Immunization

Q. 26

Incubation period helps in determining all except‑

 A

Period of isolation

 B

Period of quarantine

 C

Identification of source of infection

 D

Immunization

Ans. A

Explanation:

Ans. is ‘a’ i.e., Period of isolation 

Incubation period is useful for : –

i)    Tracing the source of infection and contacts.

ii)     Period of surveillance or quarantine

iii)   Immunization

iv)     Identification of point source or propagated epidemics

v)    Estimating the prognosis of a disease.


Q. 27

Application of Incubation period is all except ‑

 A

To differentiate co-primary cases from secondary cases

 B

To find out time for isolation

 C

To find out time for Quarantine

 D

To prevent infection to the contacts of the infected person

Q. 27

Application of Incubation period is all except ‑

 A

To differentiate co-primary cases from secondary cases

 B

To find out time for isolation

 C

To find out time for Quarantine

 D

To prevent infection to the contacts of the infected person

Ans. B

Explanation:

Ans is ‘b’ i.e. To find out time for isolation 

“The duration of isolation is determined by the duration of communicability of the disease and the effect of chemotherapy on infectivity.”- Park


Q. 28

Disease highly transmitted during incubation period is –

 A

Pertussis

 B

Cholera

 C

Measles

 D

a and c

Q. 28

Disease highly transmitted during incubation period is –

 A

Pertussis

 B

Cholera

 C

Measles

 D

a and c

Ans. D

Explanation:

Ans. is ‘a’ i.e., Pertussis; ‘c’ i.e., Measles

“As a rule, infectious diseases are not communicable during the incubation period, but there are exceptions, for example, measles, chickenpox, whooping cough (pertusis) and hepatitis A are communicable during the later part of incubation period”.


Q. 29

Serial interval is a measure of ‑

 A

Sensitivity

 B

Specificity

 C

Incubation period

 D

Positive predictive value

Q. 29

Serial interval is a measure of ‑

 A

Sensitivity

 B

Specificity

 C

Incubation period

 D

Positive predictive value

Ans. C

Explanation:

Ans. is ‘c’ i.e., Incubation period 

“In actual pracatice we seldom know precisely the incubation period of a disease. But we know, when an outbreak of a disease occur, say in a family which is the smallest group and also a closed group, there is an initial primary case. The primary case is followed by two or three secondary cases with in a short time. The gap in time between the onset primary case and the secondary case is called “serial interval”. By collecting information about the whole series of such onset, we get a distribution of secondary case from which we can guess the incubation period of disease”


Q. 30

Epidemiological studies is carried for a period of –

 A

Incubation period

 B

Twice the incubation period

 C

Four times the incubation period

 D

Half the incubation period

Q. 30

Epidemiological studies is carried for a period of –

 A

Incubation period

 B

Twice the incubation period

 C

Four times the incubation period

 D

Half the incubation period

Ans. B

Explanation:

Ans. is ‘b’ i.e., Twice the incubation period 


Q. 31

Which of the following is a characteristic of a point source epidemic ?

 A

Herd immunity regulates spread of cases

 B

Person to person transmission is seen

 C

Secondary wave of cases is always seen

 D

All cases develop within one incubation period

Q. 31

Which of the following is a characteristic of a point source epidemic ?

 A

Herd immunity regulates spread of cases

 B

Person to person transmission is seen

 C

Secondary wave of cases is always seen

 D

All cases develop within one incubation period

Ans. D

Explanation:

Ans. is ‘d’ i.e., All cases develop within one incubation period 


Q. 32

Serial interval measures –

 A

Incubation period of disease

 B

Sensitivity

 C

Specificity

 D

Positive predictive value

Q. 32

Serial interval measures –

 A

Incubation period of disease

 B

Sensitivity

 C

Specificity

 D

Positive predictive value

Ans. A

Explanation:

Ans. is ‘a’ i.e., Incubation period of disease 


Q. 33

Prognosis of a disease can be given by- 

 A

Secondary attack rate

 B

Incubation period

 C

Latency

 D

Serial interval

Q. 33

Prognosis of a disease can be given by- 

 A

Secondary attack rate

 B

Incubation period

 C

Latency

 D

Serial interval

Ans. B

Explanation:

Ans. is ‘b’ i.e., Incubation period 


Q. 34

In control of communicable diseases, the period of quarantine in respect of a disease is determined by-

 A

Incubation period

 B

Infectivity period

 C

Duration of illness 

 D

Carrier state

Q. 34

In control of communicable diseases, the period of quarantine in respect of a disease is determined by-

 A

Incubation period

 B

Infectivity period

 C

Duration of illness 

 D

Carrier state

Ans. A

Explanation:

Ans. is ‘a’ i.e., Incubation period 


Q. 35

Confidence limit includes –

 A

Range & standard deviation

 B

Median and standard error

 C

Mean and standard error

 D

Mode and standard deviation

Q. 35

Confidence limit includes –

 A

Range & standard deviation

 B

Median and standard error

 C

Mean and standard error

 D

Mode and standard deviation

Ans. C

Explanation:

Ans. is ‘c’ i.e., Mean and standard error 

Confidence limit

  • Estimate of mean varies from sample to sample.

o Therefore, instead of single estimate of mean, a confidence interval generates a lower and upper limit of mean. o This interval from lower to upper limit is called confidence limit.

o Confidence limit is distributed on either side of mean and the deviation from the mean is determined by standard deviation.

  • For example 95% confidence limit (area under 2 standard deviation) means that 95% of the values in the distribution will be included in this limit (95% confidence limit —> 2 SD).
  • 95% (2 standard deviation) is the most commonly used confidence limit.

None – in option ‘c’, standard error is there instead of standard deviation.

“Standard error of a statistic is the standard deviation of the sampling distribution of the statistics”. — Handbook


Q. 36

Incubation period of influenza

 A

18 – 72 hrs

 B

1 – 6 hrs

 C

5 – 10 days

 D

< 1 hrs

Q. 36

Incubation period of influenza

 A

18 – 72 hrs

 B

1 – 6 hrs

 C

5 – 10 days

 D

< 1 hrs

Ans. A

Explanation:

Ans. is ‘a’ i.e., 18 – 72 hrs


Q. 37

Shortest incubation period is seen in‑

 A

Influenza

 B

Hepatitis B 

 C

Hepatitis A

 D

Rubella

Q. 37

Shortest incubation period is seen in‑

 A

Influenza

 B

Hepatitis B 

 C

Hepatitis A

 D

Rubella

Ans. A

Explanation:

Ans. is ‘a’ i.e., Influenza 

o Mumps                              16 – 18 days

o Influenza                           2 – 3 days

o Hepatitis A                        > 15 – 90 days

o Hepatitis B                        6 wk to 6 months


Q. 38

Incubation period of rubella is –

 A

18-72 hours

 B

2-3 weeks

 C

1-3 months

 D

>1 year

Q. 38

Incubation period of rubella is –

 A

18-72 hours

 B

2-3 weeks

 C

1-3 months

 D

>1 year

Ans. B

Explanation:

Ans. is ‘b’ i.e. 2-3 weeks.

Rubella

  • Rubella virus belongs to togavirus family —> enveloped RNA virus .

o Only one antigenic type of virus exists.

  • Source of infection      clinical or sub-clinical case.

o A large number of rubella infections are sub-clinical, this represents one of the major differences between measles and rubella.

  • There is no known carrier state in postnatally acquired rubella, but infants born with congenital rubella may shed virus for many months.

o Infective period —> A week before the onset of symptoms to about a week after rash appears.

o Rubella is much less communicable than measles because of absence of coughing in rubella.

o Age group —> 3-10 years.

o Transmission —            1) Droplet infection by respiratory route.

2) Vertical transmission from mother to fetus.

o Incubation period — 2-3 weeks.

o Clinical manifestations

a)  Prodromal

o Low grade fever, sore throat, coryza.

b)  Lymphadenopathy

  • Posterior auricular, cervical and sub-occipital.

c)Rash

  • Begins on the face and spreads down the body.

o A petechial exanthem on the soft palate – Forschheimer spots.

Complications

o Arthralgia

o Encephalitis

o Thrombocytopenic purpura


Q. 39

Incubation period of swine flu –

 A

1-3 days

 B

2-3 weeks

 C

10-15 days

 D

5 weeks

Q. 39

Incubation period of swine flu –

 A

1-3 days

 B

2-3 weeks

 C

10-15 days

 D

5 weeks

Ans. A

Explanation:

Ans. is ‘a’ i.e., 1-3 days 

Swine flu

o Swine flu, also called swine influenza, or pig influenza, is caused by influenza virus.

o It is mainly occurs in swines (pigs) and occasionally transmitted to human.

o It is usually caused by influenza virus type A (H1-N1).

o Incubation period is about 1-3 days and the symptoms of swine flu in humans are similar to most influenza infections, e.g. fever, cough, rhinorrhea, fatigue and headache.


Q. 40

Incubation period of typhoid –

 A

3-20 days

 B

14-45 days

 C

5-10 days

 D

15-60 days

Q. 40

Incubation period of typhoid –

 A

3-20 days

 B

14-45 days

 C

5-10 days

 D

15-60 days

Ans. A

Explanation:

Ans. is ‘a’ i.e., 3-20 days

o This question is somewhat tricky one for PGI Chandigarh, because more than one options can be correct.

“Usually incubation period is 10-14 days. But it may be short as 3 days or as long as three weeks depending upon the dose of the bacilli ingested”  – Park

o So, for PGI Chandigarh more than one options may be correct as in this question.

           Option ‘a’ —>                 3 days to 3 weeks (20 days)

   


Q. 41

Incubation period of plasmodium vivax is- 

 A

5-7 days

 B

7-10 days

 C

10-14 days

 D

15-30 days

Q. 41

Incubation period of plasmodium vivax is- 

 A

5-7 days

 B

7-10 days

 C

10-14 days

 D

15-30 days

Ans. C

Explanation:

Ans. is ‘c’ i.e., 10-14 days 


Q. 42

The incubation period of yellow fever is –

 A

3 to 6 days

 B

3-4 weeks

 C

1 to 2 weeks

 D

8-10 weeks

Q. 42

The incubation period of yellow fever is –

 A

3 to 6 days

 B

3-4 weeks

 C

1 to 2 weeks

 D

8-10 weeks

Ans. A

Explanation:

Ans. is ‘a’ i.e., 3 to 6 days 

o Incubation period of yellow fever is 3-6 days (6 days recognized under international health regulation).


Q. 43

Incubation period of gonococcal ophthalmia neonatorum is:

 A

24 hours

 B

5-7 days

 C

7-10 days

 D

None of the above

Q. 43

Incubation period of gonococcal ophthalmia neonatorum is:

 A

24 hours

 B

5-7 days

 C

7-10 days

 D

None of the above

Ans. D

Explanation:

Ans. None of the above


Q. 44

Incubation period of Hepatitis A is:          

March 2013

 A

2-4 weeks

 B

4-6 weeks

 C

6-8 weeks

 D

8-10 weeks

Q. 44

Incubation period of Hepatitis A is:          

March 2013

 A

2-4 weeks

 B

4-6 weeks

 C

6-8 weeks

 D

8-10 weeks

Ans. A

Explanation:

Ans. A i.e. 2-4 weeks

Hepatitis A

  • It is a liver disease caused by the hepatitis A virus.
  • The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the faeces of an infected person.
  • The disease is closely associated with a lack of safe water, inadequate sanitation and poor personal hygiene.
  • Unlike hepatitis B and C, hepatitis A infection does not cause chronic liver disease and is rarely fatal
  • It can cause debilitating symptoms and fulminant hepatitis (acute liver failure), which is associated with high mortality.
  • The incubation period of hepatitis A is usually 14-28 days.

Q. 45

Incubation period of staphylococcus aurues food poi­soning:          

March 2013

 A

1-6 hours

 B

7-12 hours

 C

13-18 hours

 D

19-24 hours

Q. 45

Incubation period of staphylococcus aurues food poi­soning:          

March 2013

 A

1-6 hours

 B

7-12 hours

 C

13-18 hours

 D

19-24 hours

Ans. A

Explanation:

Ans. A i.e. 1-6 hours

Classification of Food Poisoning:

Based on symptoms and duration of onset

Nausea and vomiting within six hours (Staphylococcus aureus, Bacillus cereus)

– Abdominal cramps and diarrhoea within 8-16 hours (Clostridium perfringens, Bacillus cereus)

– Fever, abdominal cramps and diarrhoea within 16-48 hours (Salmonella, Shigella, Vibrio parahemolyticus, Enteroinvasive E.coli, Campylobacter jejuni)

– Abdominal cramps and watery diarrhoea within 16-72 hours (Enterotoxigenic E.coli, Vibrio cholera 01, 0139, Vibrio parahemolyticus, NAG vibrios, Norwalk virus)

– Fever and abdominal cramps within 16-48 hours (Yersinia enterocolitica)

– Bloody diarrhoea without fever within 72-120 hours (Enterohemorrhagic E.coli 0157:H7)

– Nausea, vomiting, diarrhoea and paralysis within 18-36 hours (Clostridium botulinum)

Based on pathogenesis

 good intoxications resulting from the ingestion of preformed bacterial toxins. (Staphylococcus aureus, Bacillus cereus, Clostridium botulinum, Clostridium perfringens)

Food intoxications caused by noninvasive bacteria that secrete toxins while adhering to the intestinal wall (Enterotoxigenic E.coli, Vibrio cholerae, Campylobacter jejuni)

– Food intoxications that follow an intracellular invasion of the intestinal epithelial cells. (Shigella, Salmonella)

– Diseases caused by bacteria that enter the blood stream via the intestinal tract. (Salmonella typhi, Listeria monocytogenes)


Q. 46

Food poisoning with incubation period of 1-6 hours is most probably caused by:    

March 2013

 A

Streptococcus viridans

 B

Staphylococcus aureus

 C

Salmonella typhi

 D

H. pylori

Q. 46

Food poisoning with incubation period of 1-6 hours is most probably caused by:    

March 2013

 A

Streptococcus viridans

 B

Staphylococcus aureus

 C

Salmonella typhi

 D

H. pylori

Ans. B

Explanation:

Ans. B i.e. Staphylococus aureus


Q. 47

Which has an incubation period of less than a week:

March 2010

 A

Cholera

 B

Measles

 C

Filaria

 D

Kala-azar

Q. 47

Which has an incubation period of less than a week:

March 2010

 A

Cholera

 B

Measles

 C

Filaria

 D

Kala-azar

Ans. A

Explanation:

Ans. A: Cholera

Cholera is an acute diarrhoeal infection caused by ingestion of the bacterium Vibrio cholerae. Transmission occurs through direct faecal-oral contamination or through ingestion of contaminated water and food.

The disease is characterized in its most severe form by a sudden onset of acute watery diarrhoea that can lead to death by severe dehydration and kidney failure.

The extremely short incubation period – two hours to five days – enhances the potentially explosive pattern of outbreaks, as the number of cases can rise very quickly.

About 75% of people infected with cholera do not develop any symptoms.

However, the pathogens stay in their faeces for 7 to 14 days and are shed back into the environment, potentially infecting other individuals.

Cholera is an extremely virulent disease that affects both children and adults.


Q. 48

Incubation period knowledge helps in all of the following except:         

September 2007

 A

Isolation

 B

Quarantine

 C

Detecting source of infection

 D

Vaccination

Q. 48

Incubation period knowledge helps in all of the following except:         

September 2007

 A

Isolation

 B

Quarantine

 C

Detecting source of infection

 D

Vaccination

Ans. A

Explanation:

Ans. A: Isolation

Quarantine applies to those who have been exposed to a contagious disease but who may or may not become ill. Isolation applies to persons who are known to be ill with a contagious disease.

Epidemiological importance of knowledge of incubation period:

  • Tracing the source of infection and contacts
  • Period of surveillance/quarantine
  • Immunization
  • Identification of point source or propagated epidemics
  • Prognosis

Q. 49

Which of the following disease has an incubation period of less than 1 week:      

March 2010

 A

Measles

 B

Cholera

 C

Mumps

 D

Pertussis

Q. 49

Which of the following disease has an incubation period of less than 1 week:      

March 2010

 A

Measles

 B

Cholera

 C

Mumps

 D

Pertussis

Ans. B

Explanation:

Ans. B: Cholera

Measles- 10 days from the onset of fever and 14 days to appearance of rash.

Cholera: few hours upto 5 days, but commonly 1-2 days Mumps: 2-3 weeks (usually 18 days)

Pertussis: usually 7-14 days, but not more than 3 weeks


Q. 50

Incubation period of Rabies depends on:

September 2010

 A

Number of bites

 B

Site of bite

 C

Animal species

 D

All of the above

Q. 50

Incubation period of Rabies depends on:

September 2010

 A

Number of bites

 B

Site of bite

 C

Animal species

 D

All of the above

Ans. D

Explanation:

Ans. D: All of the above

The incubation period for rabies is very variable, generally several weeks but varying from a week to a year or longer, depending on the virus strain, host species and the site of inoculation.

In humans, periods from less than 10 days to as long as six years have been recorded, but more than half of cases show an incubation period of one to three months.

Bites to the head or neck are generally associated with shorter incubation while bites to the extremities produce longer incubation periods.


Q. 51

Incubation period of measles is:

September 2011

 A

5 days

 B

10 days

 C

15 days

 D

20 days

Q. 51

Incubation period of measles is:

September 2011

 A

5 days

 B

10 days

 C

15 days

 D

20 days

Ans. B

Explanation:

Ans. B: 10 days

For measles, time period from exposure and development of first symptom (onset of fever) is 10 days

Measles/ Rube°la/ Morbilli

  • It is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus.
  • Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses.
  • Symptoms include fever, cough, runny nose, red eyes and a generalized, maculopapular, erythematous rash.
  • Measles (also sometimes known as English Measles) is spread through respiration (contact with fluids from an infected person’s nose and mouth, either directly or through aerosol transmission), and is highly contagious — 90% of people without immunity sharing living space with an infected person will catch it.
  • An asymptomatic incubation period occurs nine to twelve days from initial exposure and infectivity lasts from two to four days prior, until two to five days following the onset of the rash (i.e. four to nine days infectivity in total).
  • An alternative name for measles in English-speaking countries is rubeola, which is sometimes confused with rubella (German measles); the diseases are unrelated
  • The classical symptoms of measles include four-day fevers and the three Cs — cough, coryza (head cold) and conjunctivitis (red eyes).
  • The fever may reach up to 40 °C (104 °F).
  • Koplik’s spots seen inside the mouth are pathognomonic (diagnostic) for measles, but are not often seen, even in real cases of measles, because they are transient and may disappear within a day of arising.
  • The characteristic measles rash is classically described as a generalized, maculopapular, erythematous rash that begins several days after the fever starts.
  • It starts on the head before spreading to cover most of the body, often causing itching.
  • The rash is said to “stain”, changing color from red to dark brown, before disappearing.
  • The measles rash appears two to four days after initial symptoms, and lasts for up to eight days.

Complications

  • Complications with measles are relatively common, ranging from relatively mild and less serious diarrhea, to pneumonia, Otitis media and acute encephalitis (and rarely subacute sclerosing panencephalitis); corneal ulceration leading to corneal scarring.
  • Complications are usually more severe in adults who catch the virus.

Q. 52

Average incubation period of AIDS is:     

March 2011

 A

1 year

 B

3 years

 C

5 years

 D

10 years

Q. 52

Average incubation period of AIDS is:     

March 2011

 A

1 year

 B

3 years

 C

5 years

 D

10 years

Ans. D

Explanation:

Ans. D : 10 years

The median interval from infection to the development of symptoms is around 7-10 years, although subgroups of patients exhibit ‘fast’ or ‘slow’ rates of progression.


Q. 53

Incubation period of measles is:    

September 2011

 A

10 days

 B

14 days

 C

21 days

 D

45 days

Q. 53

Incubation period of measles is:    

September 2011

 A

10 days

 B

14 days

 C

21 days

 D

45 days

Ans. A

Explanation:

Ans. A: 10 days

The incubation period of measles is around 10 days


Q. 54

Incubation period of syphilis is:

September 2006

 A

10-14 days

 B

30-60 days

 C

9-90 days

 D

3-6 months

Q. 54

Incubation period of syphilis is:

September 2006

 A

10-14 days

 B

30-60 days

 C

9-90 days

 D

3-6 months

Ans. C

Explanation:

Ans. C: 9-90 days

Acquired syphilis:

–        Primary syphilis: incubation period 2-3 weeks (range 9-90 days): local infection

–        Secondary syphilis: incubation period 6-12 weeks (range 1-6 months): generalised infection

–        Early latent syphilis: asymptomatic syphilis of less than 2 years duration

–        Late latent syphilis: asymptomatic syphilis of 2 years or longer duration

–        Late symptomatic syphilis (tertiary syphilis): cardiovascular syphilis, neurosyphilis, gummatous syphilis

Congenital syphilis:

–        Early congenital syphilis occurs within the first 2 years of life.

–        Late congenital syphilis emerges in children older than 2 years.


Q. 55

Incubation period of cholera is ‑

 A

1-2 days

 B

7-10 day

 C

10-14 days

 D

3-5 weeks

Q. 55

Incubation period of cholera is ‑

 A

1-2 days

 B

7-10 day

 C

10-14 days

 D

3-5 weeks

Ans. A

Explanation:

Ans. is ‘a’ i.e., 1-2 days


Q. 56

Incubation period of new disease determined by‑

 A

Lead time

 B

Generation time

 C

Serial interval

 D

Latent period

Q. 56

Incubation period of new disease determined by‑

 A

Lead time

 B

Generation time

 C

Serial interval

 D

Latent period

Ans. B

Explanation:

Ans. is ‘b’ i.e., Generation time

Generation time

  • Interval between receipt of infecton by host and maximal infectivity of the host.
  • Generation time is roughly equal to the incubation period.

Q. 57

Incubation period of measles –

 A

14 days

 B

1 Month

 C

3 Month

 D

5 Month

Q. 57

Incubation period of measles –

 A

14 days

 B

1 Month

 C

3 Month

 D

5 Month

Ans. A

Explanation:

Ans. is ‘a’ i.e., 14 days


Q. 58

Incubation period of HiN, influenza ‑

 A

3 days

 B

2 weeks

 C

3 weeks

 D

4 weeks

Q. 58

Incubation period of HiN, influenza ‑

 A

3 days

 B

2 weeks

 C

3 weeks

 D

4 weeks

Ans. A

Explanation:

Ans. is ‘a’ i.e., 3 days

  • The incubation period of pandemic influenza A (H1N1) is 2-3 days, but could range upto 7 days (1 week). 
  • On 26th september 2011 WHO has adapted a new nomenclature as Influenza A (HINI) pdm 09.
  • Case difinitions : ‑
  1. Suspected case : – A person with acute febrile respiratory illness (fever  38°C) with onset : (1) Within 7 days of close contact to confirmed case of influenza A (F111\11) 2009; or within 7 days of travel to areas where there are confirmed cases; or (3) Resides in a community where there are confirmed cases.
  2. Probable case : – A person with acute febrile respiratory illness who : (1) is positive for influenza A, but unsubtypable for H1 and H3 by influenza RT-PCR or reagents used to detect seasonal influenza virus infection; or (2) is positive for influenza A by influenza rapid test or IFA and meets criteria for suspected case; or (3) who died of an enexplained acute respiratory illness who is considered to be epidemiologically linked to a probable or confirmed case.
  3. Confirmed case : – A person with acute febrile respiratory illness with laboratory confirmed influenza A (H1N1) 2009 by one or more of following : (i) Real time PCR; (ii) viral culture; (iii) four-fold rise in virus specific neutrilizing antibodies.

Q. 59

Leprosy is not targeted for global eradication because

 A

No effective vaccine

 B

Highly infectious but low pathogenicity

 C

Only humans are reservoir

 D

Long incubation period

Q. 59

Leprosy is not targeted for global eradication because

 A

No effective vaccine

 B

Highly infectious but low pathogenicity

 C

Only humans are reservoir

 D

Long incubation period

Ans. D

Explanation:

Ans. d. Long incubation period


Q. 60

Which of the following is not true for incubation period

 A

To differentiate between secondary attacked and co­incident primary cases

 B

To determine the period of isolation of cases

 C

To determine the period of quarantine

 D

To prevent disease in contacts

Q. 60

Which of the following is not true for incubation period

 A

To differentiate between secondary attacked and co­incident primary cases

 B

To determine the period of isolation of cases

 C

To determine the period of quarantine

 D

To prevent disease in contacts

Ans. B

Explanation:

Ans. b. To determine the period of isolation of cases


Q. 61

Shortest incubation period is of which infection ‑

 A

Chicken pox

 B

Measles

 C

Rubella

 D

Influenza

Q. 61

Shortest incubation period is of which infection ‑

 A

Chicken pox

 B

Measles

 C

Rubella

 D

Influenza

Ans. D

Explanation:

Ans. is ‘d’  i.e., Influenza



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