Pertussis
Whooping CoughEpidemiology
Is an acute, communicable infection of the respiratory tract caused by the gram-negative bacterium, Bordetella pertussis. Whooping cough is a disease of infants and pre-school children. The highest incidence found before the age of 5 years. Outbreaks occur periodically every 3-4 years. Marked decline has occurred in incidence & mortality rates during the last four decades in communities with active immunization program, good nutrition and good medical careSusceptibility & resistance
In non immunized susceptibility is universal. Highest incidence is in infants. School children are often act as a source of infection for younger siblings at home Incidence, mortality and morbidity are higher in females than males. There is no maternal immunity. One attack confers long immunity although second attacks can occasionally occur.Susceptibility & resistance
Cases in previously immunized adolescents and adults occur because of waning immunity. Protection produced by the vaccine is greater against severe disease & begins to wane after about 3 years Active immunization after exposure is not protective but it is not contraindicatedChain of events
Reservoir Human Mode of transmission Direct contact with respiratory discharge of infected person. Airborne Droplet Incubation period 6-20 daysPeriod of communicability Patient not treated with proper antibiotic onset of typical paroxysm Early in the 3weeks after Catarrhal stage In treated patient with erythromycin 5 days after the onset of therapy.
Clinical features
Catarrhal phase: is characterized by rhinorrhea, lacrimation, malaise, and cough that is mild and nonproductive. low-grade fever may also be present. This phase lasts between a few days and 1 week Paroxysmal phase : cough becomes more severe and frequent and eventually paroxysmal where five or more forceful coughs occur in a single episode; this phase usually lasts for 1-2 months or longer. Young infants partially vaccinated children, adolescents and adults often do not exhibit the whoop or cough paroxysm.Clinical features
Convalescent phase: The cough becomes less frequent and milder. This phase may last another 1-2 weeks or longer Complications Respiratory (bronchitis, otitis media ,bronchopneumonia,pneumothorax) Subcojuctival hemorrhage epistaxis CNS (convulsion, encephalitis)
Diagnosis
Laboratory methods currently available for the identification of B. pertussis include, Culture polymerase chain reaction (PCR), direct fluorescent antibody testing, and serologic antibody testing.Prevention and control
1.Public education Danger of the disease. Importance of immunization. Adherence to the immunization schedule 2.Immunization is recommended with 3 doses of vaccine consisting of a suspension of killed bacteria (wP or aP) with diphtheria & tetanus toxoids adsorbed on aluminum salts.Prevention
DPT whole cell vaccine DTaP a cellular preparation Iraq DPT 2 4 months 6 18 months first booster school entry second boosterPrevention
Side effects of vaccination Fever. Local redness and swelling at site of injection. Anaphylaxis ( first 24 hours) Collapse, shock like stat. Persistent crying >3 hours. Seizures. Encephalitis. Contraindication Progressive neurological disease Previous anaphylaxis or encephalopathy in same patient.Prevention
Family history of febrile seizure is not contra- indication. Mild illness. Well controlled seizure. Stable neurological disorders . Local reactions. 3. Protection of health workers who have been exposed to pertussis cases by using a 14 days course of erythromycin, azithromycin, clarithromycin.Control
Reporting obligatory Isolation Respiratory isolation for known cases Suspected cases should be removed from the presence of infants (especially unimmunized infants)& young children until: Patient have received at least 5 days of antibiotics. Those who do not receive antibiotics should be isolated for 3 weeks.Control
ContactsInadequately immunized household contacts <7 years should be excluded from Schools….etc for 21 days after exposure or until the case and contacts have received 5 days course of antibiotics.Verification of immunization status up to date.Passive immunization is not effective.Initiation of active immunization following recent exposure is not effective, but…..Close contacts <7 years who have not receive 4 DTP doses; or have not received a DTP dose within 3 years should be given a booster dose as soon after exposure as possible.Control
Antibiotic prophylaxis Initiation of postexposure prophylaxis in asymptomatic contacts within 21 days of the onset of cough in the index case can prevent the development of symptoms. Indications Close contacts. Individuals at high risk for severe or complicated pertussis. Regimins (Erythromycin for 14 days,Clarithromycin for 7 days,Azithromycin for 5 days)Persons at high risk for severe or complicated pertussis include
Infants particularly those younger than four months Persons with immunodeficiency Persons with underlying medical conditions (chronic lung disease, respiratory insufficiency, cystic fibrosis)Control
Specific treatment Treatment should be initiated within 21 days of start of symptoms The regimen for antimicrobial treatment is the same as that for prophylaxis Treatment shortens the period of communicability but does not affect symptomatology.Epidemic measures Look for unrecognized & unreported cases. Accelerated immunization : 1st dose 4-6 wk for age 4weeks 2nd dose 4weeks 3rd dose Immunization should be completed for those whose schedule is incomplete.
Diphtheria
EpidemiologyDiphtheria is an acute, communicable disease caused by the gram-positive bacillus Corynebacterium diphtheriae. Among non immunized populations, diphtheria most often occurs during fall and winter, although summer outbreaks have occurred. In tropical areas seasonality is less distinct. Inapparent , cutaneous & wound diphtheria infections are more common. Disease spreads more quickly and is more prevalent in poor socioeconomic conditions, where crowding occurs and immunization rates are low.
Epidemiology
Race No racial differences observed Sex No difference has been described for acute infections. Age Diphtheria affect children 1-5 years. In countries where wide spread immunization is practiced ,a shift in age incidence has been observed from preschool to school age.Chain of events
Reservoir Human Mode of transmission Direct contact with patients or carriers Indirect Articles Raw milk Incubation period 2-5 days
Chain of events
Period of communicability Unless treated, the period of communicability varies from 14-28 days from the onset of disease. Carriers may remain infective for longer periods. A case or carrier may be considered non-communicable when 2 cultures from the nose and throat ,24 hr apart, negative for diphtheria bacilli.Chain of events
Susceptibility & resistance There is maternal immunity which usually lost by age of 6 months.(for infants of immune mothers). Disease or inapparent infection usually,but not always lead to life long immunity Toxoid gives prolonged but not life long immunity which wanes with age.Clinical features
Respiratory tract form of diphtheria consist of pharyngotonsillar ,laryngotracheal ,nasal and combination of these forms. Pharyngotonsillar : sore throat, low grad fever, O/E mild pharyngeal erythema and localized exudate or grey-black adherent membrane Attempt to remove the membrane result in bleeding Laryngotracheal disease most often proceeded by pharyngotonsillar diphtheria, patient presented with hoarseness of voice and croupy cough. Non-respiratory mucosal surface may be a site of infection (conjunctiva ,genital tract)Diagnosis
Clinical findings Bacteriological examination Isolation of CoryneBacterium diphtheriae on cultures confirm the diagnosis. In all patients in whom diphtheria is suspected, obtain specimens from the nose and throat (i.e., nasopharyngeal and pharyngeal swab) for culture. Isolation of C .diphtheriae from close contacts may confirm the diagnosis, even if results of cultures on specimens taken from the patient are negative.Prevention Educational measures about the hazards of the disease and Importance of immunization Active immunization should be initiated in infancy (DTaP, DTP) Children <7 years of age (in Iraq) 2 months 1st dose 4 months 2nd dose 6 months 3rd dose 18 moths 1st booster dose 4-6 years 2nd booster dose This schedule does not need to be restarted because of delay in administering the scheduled dose . If pertusis component of DTP is contra-indicated DT
Prevention
Person age 7 years &older Adult (Td) is usually used (highly purified) for previously unimmunized. 3doses of Td is given, 1st,2nd doses at 4-8 weeks intervals. 3rd dose after 6 months - 1 years after the 2nd dose. Active protection is maintained by giving a dose of Td every 10 years.Prevention
Protection of highly risk group; They should be fully immunized and receive a booster dose every 10 years. HIV & immunocompromised children should be vaccinated. Use the same schedule