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Common infectious diseases

Common infectious diseases. Objectives 1-These infections are common and can cause serious complications so should know the features for early diagnosis, early treatment and prevent these complications. 2- to give early and correct treatment so reduce morbidity and mortality.

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Common infectious diseases

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  1. Common infectious diseases

  2. Objectives 1-These infections are common and can cause serious complications so should know the features for early diagnosis, early treatment and prevent these complications. 2- to give early and correct treatment so reduce morbidity and mortality. 3- to know the risk of these infections during pregnancy and how reduce this risk. 3- to know the preventive measures and encourage them.

  3. Pertussis (whooping cough) it is an acute respiratory tract infection caused by Bordetella pertussis. Bordetella parapertussis is an occasional cause of sporadic pertussis . EPIDEMIOLOGY: - It is extremely contagious, with attack rates 100% in close contacts. - Neither natural disease nor vaccination provides complete or lifelong immunity against reinfection or disease. - Transmission is by droplets released during intense coughing especially in the catarrhal stage. CLINICAL MANIFESTATIONS: Incubation period 3–12 days. Pertussis divided into 3 stages:

  4. 1- The catarrhal stage (1–2 wk) : congestion and rhinorrhea, low-grade fever, sneezing, lacrimation, conjunctivitis, & mild dry cough . 2- paroxysmal stage(2-6wk.): The cough begins as a dry, intermittent, irritative and progress into the inexorable paroxysms. During attack of paroxysm, tongue protruding maximally, eyes bulging and watering, face purple, until coughing ceases and a loud whoop(forcefull inspiratory gasp) follows. Post-tussive emesis is common. Infants <3 mo of age do not showing classical stages.The catarrhal phase lasts only a few days.After that, young infant begins to choke, gasp, with face reddened. Cough may not be prominent & Whoop infrequently occurs. Apnea may be the only symptom .

  5. 3- convalescent stage (≥2 wk) : the number, severity, and duration of episodes diminish. Chronic cough may persist for several months. - Findings on physical examination generally are uninformative. Conjunctival hemorrhages and petechiae on the upper body are common. DIAGNOSIS : Pertussis should be suspected in any individual who has pure or predominant complaint of cough, especially if the following are absent: fever, exanthem or enanthem, sore throat, hoarseness, tachypnea, wheezes, and crackles. 1- typical clinical presentation. 2- Leukocytosis (15,000–100,000 cells/mm3) with absolute lymphocytosis .

  6. 2- Chest x-ray: perihilar infiltrate or atelectasis. 3- Isolation of B. pertussis in culture of specimen obtained by deep nasopharyngeal aspiration . 4-Direct fluorescent antibody (DFA) testing of nasopharyngeal secretions. 5- polymerase chain reaction. 6- serologic tests for detection of antibody to B. pertussis antigen in acute & convalescent samples. DIFFERENTIAL DIAGNOSIS : 1-adenovirus infection. 2- mycoplasma & chlamydia pneumonia . 3- respiratory syncytial virus infection . COMPLICATIONS : 1- Apnea especially in infants < 3mo. of age .

  7. 2- Secondary bacterial infections (otitis media and pneumonia) . 3- Bronchiectasis . 4- conjunctival and scleral hemorrhages, epistaxis, hemorrhage in the central nervous system (CNS) and retina. 5- pneumothorax and subcutaneous emphysema . 6- umbilical and inguinal hernias . 7- Seizures due to hypoxemia, intracranial hemorrhage or hyponatremia from excessive secretion of antidiuretic hormone during pneumonia can occur. 8- Laceration of the lingual frenulum.

  8. TREATMENT : Indications for hospitalisation : *infants < 3mo. of age are admitted to hospital almost without exception. *Those between 3–6 mo if paroxysms are severe *Those of any age if significant complications occur. 1-Supportive care: - avoid provoking factors for cough like smoke, excessive stimulation . - Good hydration, adequate nutrition & avoid large volume feeding . - For excessive secretion, frequent suction to clean airway & prevent aspiration .

  9. 2- Antibiotics: - Azithromycin :it is drug of choice in neonets, 10mg/kg/day for 5days . Alternatives drugs are: - Erythromycin40 -50mg/kg/day in 4 divided doses for 14 days. Or Clarithromycin, Trimethoprim-sulphamethoxazole(TMP-SMZ) . 3- respiratory isolation of patient immediately & until 5days after initiation of macrolide therapy . 4- macrolide agents should be given to all close & household contacts regardless of age, history of immunization or symptoms.

  10. PREVENTION : DPT vaccine. Varicella-Zoster Virus(VZV) It is human herpesvirus , enveloped with double-stranded DNA genomes. It causes primary infection which is varicella (chickenpox). This infection result in lifelong latent infection of sensory ganglion neurons. Reactivation of this latent infection causes herpes zoster (shingles). EPIDEMIOLOGY : - Patients with varicella are contagious from 24 to 48 hr before the rash appears and until vesicles are crusted, usually 3–7 days after onset of rash. - Transmission by respiratory secretions and the fluid of skin lesions.

  11. Clinical manifestations of chickenpox : -Incubation period 10 to 21 days. - Prodromal symptoms: Fever, malaise, anorexia, headache, and mild abdominal pain occur 24–48 hr before the rash appears. - Varicella rash appear first on the scalp, face, or trunk. Initially consists of intensely pruritic erythematous macules that evolve through the papular stage to form clear, fluid-filled vesicles. While the initial lesions are crusting, new crops form on the trunk and then the extremities.The distribution of the rash is centripetal.

  12. Progressive Varicella : Inimmunocompromised children, varicella can progress to cause visceral organinvolvement, coagulopathy, severe hemorrhage, and continued hemorrhagic vesicle development . Neonatal Chickenpox : Infants whose mothers develop varicella in the period from 5 days before to 2 days after delivery are at high risk for severe varicella, because the mother has not yet developed a significant antibody response. Those newborn given human V-Z Ig & if develop disease give acyclovir . If the mother develops varicella more than 5 days prior to delivery, infection is attenuated due to transmission of maternal antibody across the placenta.

  13. Congenital Varicella Syndrome (CVS): When pregnant women develop chickenpox early in pregnancy(1st 20 wk of pregnancy) , 2% of fetuses demonstrate CVS . Stigmata of CVS: - Cicatrix (a zigzag scarring, in a dermatomal distribution). - Microphthalmia, Cataracts ,Chorioretinitis &optic atrophy. - Microcephaly, Hydrocephaly,Calcifications & Aplasia of brain . - Hypoplasia of an extremity, Motor and sensory deficits , Anal/urinary sphincter dysfunction. Diagnosis of CVS : 1- History of gestational chickenpox with stigmata in the fetus . 2- PCR to detected viral DNA in tissue samples . 3- VZV IgM antibody detected in the cord blood sample. TREATMENT: No specific treatment for CVS.

  14. Differential diagnosis of varicella : 1-vesicular rashes caused by other infectious agents, such as herpes simplex virus, enterovirus, or S. aureus . 2- drug reactions . 3-contact dermatitis . 4-insect bites. DIAGNOSIS : 1- Clinically 2- Leukopenia with relative lymphocytosis . 3-Direct fluorescence assay to identify the virus from the cutaneous vesicular lesions . 4- PCR . 5- 4-folds rise in VZV-IgG antibodies .

  15. COMPLICATIONS : 1- Secondary bacterial infections. 2- Encephalitis and Cerebellar Ataxia. 3- Reye syndrome: can associated with varicella especially if aspirin use as antipyretic . 4- Transverse mylitis & Gullian barre syndrom . 5-Pneumonia. 6- others rare complications: hepatitis, nephritis, nephrotic syndrome, hemolytic-uremic syndrome, myocarditis, pericarditis, pancreatitis, and orchitis, thrombocytopenia, purpura, hemorrhagic vesicles, hematuria, and gastrointestinal bleeding .

  16. TREATMENT : 1- Aspirin should not be used as antipyretic in varicella . 2- calamine lotion for soothing pruritis, or use antihistamine . 3- Acyclovir : indicated for sever disease & in immunocompromised patients, I.V 10mg/kg/dose every 8hr. - Oral Acyclovir used for herpes zoster in children .

  17. PREVENTION : 1-Varicella vaccine . 2- Postexposure Prophylaxis : varicella-zoster immune globulin (VZIG) given within 96hr. of exposure, indicated in : 1- immunocompromised patients . 2- pregnant woman . 3- Newborns whose mothers develop varicella 5 days before to 2 days after delivery . 4- premature infants <28 wk of gestation . 5- high-risk patient in close contacts with patient have herpes zoster .

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