Bordetella pertussis: Clinical manifestations and diagnosis

Ans. is ‘d’ i.e., Flagillary hemagglutinin, pertussis toxin, fimbrial 

.       Acellular pertussis vaccines currently available from different manufactures should be considered as different and unique products because of the presence of one or more different components which are:

– Chemically or genetically detoxified pertussis toxin (PT toxoid).

–       Filamentous hemagglutinin

–       69k Da outer membrane protein ( also known as pertactin).

–       Fimbrial-2 and fimbrial-3 antigens.

Ans. is ‘a’ i.e., B. pertusis 

• Whooping cough (also called pertussis) is caused by Bordetella pertussis.

Ans. is ‘b’ i.e., < 5 

o In prevaccine era, and in countries where immunization is limited the peak incidence of pertussis is in children 1-5 years of age, infant accounts for < 15% of cases.

o In recent years, where vaccination is employed, approximately one half of cases have occuured in infants younger than 1 year of age and one fourth in adolescent and adults.

Ans. is ‘b’ i.e., Cerebellar ataxia

• Paraplegia                                   
• Ataxia

o Gasro Intestinal manifestation —> Hernia & Rectal Prolapse

o Hemorrhagic —> Subconjuctival hemorrhage, Intracranial hemorrhage

o Severe malnutrition

o Although ataxia is seen in Pertusis, it is not of cerebellar origin. There is no involveoment of cerebellum in Pertusis (can you find any signs of cerebellar involvement in this pt. ie. Hypotonia, Intentional tremors. Nystagmus, scanning speech)

o It is sensory ataxia.

Ans. is ‘a’ i.e., Nasopharyngeal swab 
“Culture of nasopharyngeal secretion remains the gold stadard for diagnosis of whooping cough”

Ans is ‘a’ i.e., Nasopharyngeal swab 

o Presence of recurrent bouts of severe cough followed by an audible whoop suggests a diagnosis of pertusis (Whooping cough).

o Nasopharyngeal Swab is the single best specimen to isolate the organism from the options provided.

Ans. is ‘c’ i.e., Erythromycin 
Treatment of pertussis

DOC                   —->      Macrolides (Erythromycin, Azithromycin, Clarithromycin)

Alternative            —->        Cotrimoxazole

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”.

Ans. is ‘a’ i.e., Maternal antibody provides protection in infants 

o Infants are susceptible to infection from birth because maternal antibody does not give them protection.

o Mode of transmission —> Whooping cough is spread mainly by droplet infection and direct contact. Each time the patient coughs, sneezes or talks, the bacilli are sprayed into the air. Most children contract infection from their playmates who are in the early stages of the disease. The role of fomites in the spread of infection appears to be very small, unless they are freshly contaminated.

Ans. is ‘c’ i.e., Case 
o B. Pertussis infects only man.

o The source of infection is a case of pertussis.

Ans. is ‘a’ i.e., 7-14 days 

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.

Ans. is ‘a’ i.e., Incubation period is 7-14 days, ‘c’ i.e., Can affect any age 

o Incubation period of Pertussis is 7-14 days.

o Source of infection is only a case of pertussis.

o Pertussis is primarily a disease of infants and preschool children. However it can also affect, though less commonly, older children, adolescents and adults.

o SAR in unimmunized household contacts is 90%.

o More cases occur during winter and spring month, due to overcrowding.

Ans. is ‘a’ i.e., Infectivity is highest in paroxysmal state 

o Infectivity is maximum in catarrhal stage (not in paroxysmal stage).

Option b require some explanation here :‑

o Most of the cases of whooping cough is caused by B. pertussis.

o In a small percentage of cases (< 5%), it is caused by B. parapertussis.

o There is no cross immunity of B. pertussis with B. parapertussis —> antibodies against B. Pertussis do not protect against B. parapertussis.

Ans. is ‘a’ i.e., Erythromycin 

Control of whooping cough

o Control of whooping cough requires :‑

1)       Management of cases and contacts

2)       Prevention by active immunization

Cases: Erythromycin is the DOC. Alternatives are ampicillin, tetracyclin & septran.

Contacts : Those who are exposed —> 10 days erythromycin

Ans. is ‘c’ i.e., Erythromycin prevents spread of disease between children

o Efficacy of Pertusis Vaccine – reported to be from 70-90%

o Risk of acute encephalopathy – is 1 in 40, 000 cases following DTP vaccine.

o Pertusis toxin produces Lymphocytosis & not polymorphonuclear Leukoctyosis.

Leukocytosis due to absolute lymphocytosis is characteristic in late catarrhal or paraoxysmal stage.

o Prophylactic erythromycin prevents infecting bacteria to become established – prevents spread of disease – Park

Ans. is ‘c’ i.e., Pertussis
In may 1974, the WHO officially launched a global immunization programme, known as expanded programme of immunization (EPI) to protect all children of the word against six vaccine-preventable diseases by the year 2000.

The answer is A, Bordetella pertussis infection. Bordetella pertussis infection is one of only two infectious diseases (the other is infectious lymphocytosis) that manifests in the blood as a mature lymphocytosis. A “mature” lymphocytosis is one in which the cells appear relatively small, with condensed chromatin, and no unusual “reactive” changes – basically, they look like regular old mature lymphocytes.
In Bordetella, the lymphocytes often have a weird “clefted” appearance” as shown in the photomicrograph below. 

Ans. is ‘d’ i.e., All of the above
Pertussis vaccine

• Available as whole cell and acellular as DTPw and DTPa
• Primary immunisation at 6, 10, 14 weeks followed by booster dose 1’/2 year and 5 year.
• Whole cell causes more side effect than acellular
• Side effect-local pain, redness, fever, irritability, excessive cry because of cortical irritation.

Contraindication

1. Progressive neurological disease (Relative)
2. Immediate anaphylasix
3. Encephalopathy
4. Persistent Inconsable cry
5. Hypotensive – hyporesponsive episode

Ans. is ‘c’ i.e., 90% 
Herd immunity

• It is the level of resistance of a community or group of people to a particular disease.
• It occurs when the vaccination of a portion of the population (or herd) provides protection to unprotected (non‑ vaccinated) individuals.
• Advantage of herd immunity
• It is not necessary to achieve 100% immunization to control a disease by providing herd immunity.
• When a certain percentage of population, is vaccinated, the spread of disease is effectively stopped.
• This critical percentage is referred to as herd immunity threshold.

Disease                Herd immunity threshod

Diphtheria      →      85%

Measles          →      83-94%

Mumps           →      75-86%

Pertussis        →      92-94%

Polio              →      80-86%

Rubella          →      80-85%

Small pox      →      83-85%

Ans. is ‘d’ i.e., 90%

SAR of some important infectious diseases