Morphology diseases and laboratory diagnosis

2. • Paramyxoviridae contains a group of viruses; which are
transmitted via the respiratory route following which :
• They may cause localized respiratory infections in children
e.g. respiratory syncytial virus & the parainfluenza viruses)
or
• They may disseminate throughout the body to cause highly
contagious diseases of childhood such as mumps (parotid
enlargement) & measles(rashes).

3. • Parainfluenza viruses
resemble Orthomyxoviruses
in morphology but are larger
& pleomorphic.
• Size : 100 – 300 nm, rarely
800nm, Rarely large
filaments & giant forms
seen.
• Symmetry : Helical
• Nucleocapsid : 18nm
• Genome : Negative sense,
linear, single stranded , non
– segmented RNA

4. • Six structural Proteins :
Which form capsid,
polymerase, matrix protein
( underlies the envelop),&
envelop glycoproteins.
• Envelop : Nucleocapsid is
surrounded by a host
derived lipid envelop in
which the following virus
coded peplomers
(glycoproteins ) are
inserted.

5. • F – Glycoprotein : Present in all myxoviruses. Mediate
membrane fusion. Also have hemolysin activity ( except
in pneumoviruses).
• Larger Glycoproteins – Help in attachment to the host
cells. May be either H or HN or G type –
1. HN Glycoproteins – Have both haemagglutinin &
neuraminidase activities e.g. in parainfluenza & mumps
viruses
2. H Glycoproteins – Have only haemagglutinin activity
e.g. in measles.
3. G Glycoproteins – No haemagglutinin & neuraminidase
activities. Help in attachment e.g. in respiratory syncytial
virus.

6. • Paramyxoviridae family - Divided into two subfamilies -
Paramyxovirinae & Pneumovirinae.
Subfamilies Paramyxovirinae Pneumovirinae
Genera Respirovirus Rubulavirus Morbillivirus Henipavirus Pneumovirus Metapneumovirus
Human
Viruses
Parainfluenza
1, 3
Mumps
Parainfluenza
2, 4a, 4b
Measles Hendra
Nipah
(Zoonotic)
Respiratory
Syncytial
virus
Human
metapneumovirus

7. • Human parainfluenza viruses – one of the major causes of
lower respiratory tract infections in young children. Has 5
serotypes.
• Type 1 and 3 – Genus Respirovirus.
• Type 2, 4a, 4b – Genus Rubulavirus.

8. • Transmission by respiratory route ( By direct salivary contact or
by large – droplet aerosols).
• Incubation Period – 5 to 6 days.
• Virus multiplies locally and cause various respiratory
manifestations.
• Mild common cold syndrome like rhinitis, pharyngitis.
• Laryngotracheobronchitis ( croup) – with type 1 & 2 viruses.
• Bronchitis & Pneumonia
• Reinfection.

9. • Worldwide in distribution
• Type 3 – Most prevalent serotype & exists as endemic
throughout the year with annual epidemics during spring.
• Type 1 & Type 2 – Less common. Tend to cause epidemics
during rainfall or winter.
• Type 4a & 4b cause milder illness and are most difficult to
isolate.
• Parainfluenza viruses – Important cause of outbreaks in
pediatric wards, day care centers & in schools.

10. • Antigen detection : Viral antigens in the infected exfoliated
epithelial cells of nasopharynx – Detected by direct
immunofluorescence by using specific monoclonal antibodies. It
is rapid but less sensitive.
• Viral isolation :
1. Specimens – Nasal washes, bronchoalveolar lavage fluid, lung
tissue. Specimens to be inoculated as early as possible.
2. Tissue culture – Primary monkey kidney cell line – most
sensitive. Other cell lines used – LLC – MK2.
3. Produce little or no cytopathic effects
4. Viral growth detected by performing haemadsorption using
guinea pig erythrocytes or Ag detection by direct IF.

11. •Serum antibodies : Can be measured by neutralization test,
haemagglutination inhibition test or ELISA. Presence of IgM or
fourfold rise of IgG titer – Indicative of active infection.
• Reverse transcriptase PCR : Highly specific & sensitive. But
available only in limited settings.

12. • Most common cause of parotid gland enlargement in children. In
severe cases, it can also cause orchitis & aseptic meningitis.
• PATHOGENESIS :
 Transmission – Through respiratory route via droplets, saliva, &
fomites.
 Primary replication – Occurs in the nasal mucosa or upper
respiratory mucosa → infects mononuclear cells & regional lymph
nodes→ spills over to blood stream resulting in viremia →
dissemination.
 Target sites – Mumps virus has special affinity for glandular
epithelium. Classic sites – salivary glands, testes, pancreas,
ovaries, mammary glands, & central nervous system.

13. • CLINICAL MANIFESTATIONS :
• Incubation period – 7 – 23 days (Average 19 days).
• Inapparent infection – Half of the infected persons are either
asymptomatic or present with non specific symptoms such as
fever, myalgia, & anorexia( more common in adults).
• Bilateral parotitis – Acute non – suppurative parotid gland
enlargement, present in 70 – 90% cases. Rarely may be unilateral.
• Epididymo – orchitis – Next most common presentation. 15 – 30
% cases.
• Aseptic meningitis – Occurs in < 10% cases with a male
predominance , self limiting
• Oophoritis – In about 5% of females
• Atypical mumps – Absent parotitis, directly presents as aseptic
meningitis.

14. • EPIDEMIOLOGY –
• Endemic worldwide. Peak in winter & spring.
• Period of communicability – Pts are infectious from 1 wk. before
to 1 wk. after the onset of symptoms. It is shed in saliva,
respiratory droplets, & urine.
• Source – Clinical & subclinical cases. No carrier state.
• Reservoir – Humans are the only reservoir of infection.
• Incidence – 100 – 1000 cases per 10000.
• Age – 5 – 9 years. No age spared.
• Immunity – One attack – lifelong immunity.

15. • LABORATORY DIAGNOSIS –
• Specimens – Buccal or oral swab, CSF, Saliva, urine
• Antigen detection – By direct IF test
• Viral isolation – 1. Primary monkey kidney cells, 2. Shell viral
technique. Cytopathic effect – cell rounding & giant cell formation.
• Serum Abs – By ELISA, neutralization test, haemagglutination
inhibition test.
• RT – PCR – Detects viral RNA.
• TREATMENT –
• No specific antiviral drug. T/t – mostly symptomatic

16. • PROPHYLAXIS –
• LIVE ATTENUATED VACCINE – From Jeryl Lynn or RIT 4385, or
Urabe strain. It is prepared in chick embryo cell line.
• MUMPS VACCINE IS AVAILABLE AS – 1. Trivalent MMR vaccine
(Live attenuated Measles – Mumps – Rubella vaccine) or 2.
Quadrivalent MMR – V vaccine ( contains additional live
attenuated varicella vaccine) or 3. Monovalent mumps vaccine (
not commonly used)
• Schedule – 2 doses of MMR is given by IM route at 1 yr. & 4 – 6
yr.(before starting school)
• Efficacy – 90% after second dose.

17. • Measles is an acute, highly contagious childhood disease,
characterized by fever, respiratory symptoms, followed by typical
maculopapular rash.
• PATHOGENESIS –
 Transmission – Via respiratory route through droplet inhalation &
aerosols.
 Spread – Virus multiplies locally in the respiratory tract →Then
spreads to regional lymph nodes → enters the blood stream in
infected monocytes (primary viremia)→ further multiplies in
reticuloendothelial system → spill over into blood ( secondary
viremia)→ disseminates to various sites.
 Target sites – Predominantly the virus is seeded in the epithelial
surfaces of the body, including skin, respiratory tract &
conjunctiva.

18. • CLINICAL MANIFESTATIONS –
• Incubation period – 10 days to 3 wks.
1. PRODROMAL STAGE – lasts for 4 days.
Characterized by – Fever – On day 1
i.e. 10th day of inf.
• Koplik’s spots - are pathognomic of
measles, appear on 12th day of inf. – 1
mm white to bluish spot surrounded by
an erythema on buccal mucosa near 2nd
lower molar. Rapidly spread to entire
buccal mucosa & fades away on onset of
rash.
• Non specific symptoms – Cough, coryza,
nasal discharge, redness of eye, diarrhea
or vomiting.

19. • CLINICAL MANIFESTATIONS –
2. Eruptive stage –
• Maculopapular dusky red rashes after 4
days of fever ( i.e. 14th day of infection).
Typically appear first behind the ears→
spread to face, arm, trunk & legs→ then
fade in the same order after 4 days of
onset.
3. Post Measles Stage –
• Characterized by weight loss, weakness
,disorientation , chronic illness.

20. • COMPLICATIONS –
• Secondary bacterial infections – Otitis media,
Bronchopneumonia.
• Recurrence of fever or failure of fever to subside with rash.
• Giant cell pneumonitis ( Hecht’s pneumonia) in
Immunocompromised pts. Acute Laryngotracheobronchitis &
diarrhoea.
• CNS complications –
1. Post measles encephalomyelitis
2. Measles inclusion body encephalitis
3. Subacute sclerosing panencephelitis

21. • LABORATORY DIAGNOSIS :
• Specimen – Nasopharyngeal swab
• Antigen detection by using anti –
nucleoprotein antibodies.
• Virus isolation –
1. Monkey or human kidney cells or Vero /
hSLAM cell line – produces CPE as
multinucleated giant cells ( Warthin – Finkeledy
cells.
2. Shell viral culture
• Antibody detection – Against nucleoprotein Ag
by ELISA or neutralization tests.
• Reverse – transcriptase PCR – detects viral
RNA.

22. • PROPHYLAXIS –
• Live attenuated vaccine – Strains used –
Edmonston strain, Schwartz strain ,
Edmonston - Zagreb strain , Moraten strain.
• Vaccine is prepared in chick embryo cell
line.
• Vaccine available in lyophilized form & has
to be reconstituted with distilled water & to
be used within 4 hours. Stored at -200 C
• Dose – One dose (0.5ml) containing > 100
infective viral units & is administered
subcutaneously.

23. • PROPHYLAXIS –
• Combined vaccines – MMR or MMR – V
vaccines
• Contacts – Measles immunoglobulin –
0.25 mg / kg/body wt.

24. • EPIDEMIOLOGY –
• Source – Cases are only source of infection.
• Reservoir – Humans only
• Infective material – Virus shed in secretions of nose, throat, &
respiratory tract of cases of measles.
• Period of communicability - Pts. Are infectious from 4 days
before to 4 days after the onset of rash.
• Secondary attack rate – high
• Age – Children 6 months to 3 years in developing countries &
older children > 5 yrs. In developed countries.

25. • RSV is a major respiratory pathogen of young children & is the
most common cause of LRTI ( Bronchiolitis & pneumonia) in
infants.
• PATHOGENESIS –
• Transmission – Direct contact( contaminated fingers, fomites, self
inoculation onto conjunctiva or anterior nares or by large
droplets.
• Spread – It replicates locally in the epithelial cells of nasopharynx
 spread to LRT  cause bronchiolitis & pneumonia
• Pathology – Peribronchiolar infiltration by lymphocytes.
Submucosal edema, Necrosis of bronchiolar epithelium &
formation of plugs consisting of mucus, cellular debris & fibrin
which occlude the smaller bronchioles.

26. • CLINICAL MANIFESTATIONS –
• I.P. – 3 – 5 days . Most common cause of LRTI in infants < 1 yr.
• Symptoms – Running nose, fever, accompanied by cough,
wheezing, & dyspnoea.
• In Adults – RSV produces influenza like URTI. Occasionally can
cause LRTI
• Recurrent infection – Common both in children & adults.

27. • LABORATORY DIAGNOSIS –
• Ag Detection – Direct IF test detecting virus on exfoliated cells &
ELISA detecting Ag in nasopharyngeal secretions.
• Virus Isolation – HeLa & HEp – 2 cell lines for RSV isolation .
Characteristic CPE – Syncytium formation.
• Antibody Detection – IF, neutralization tests, ELISA.
• Reverse Transcriptase PCR – Viral RNA.

28. • Not a myxovirus . Also c/a German measles.
• MORPHOLOGY - Belongs to Togaviridae family & is the only
member under genus Rubivirus. It is enveloped, SS RNA virus
measuring 50 – 70 nm. Envelop contains two types of spike – like
glycoproteins E1 & E2. Only one serotype. Humans only reservoir.
• Types of infections – Post natal or congenital
• Transmission – spreads from person to person by respiratory
droplets via upper respiratory mucosa.
• Spread – Replicates locally in nasopharynx  L.N.  viremia after
7 – 9 days  Rash

29. • CLINICAL FEATURES –
• I.P. – 14 days . Infection subclinical in 20%
• Rash – generalized & maculopapular in nature.
• Lymphadenopathy
• Forchheimer spots – Pin head sized petechie on soft palate &
uvula.
• Complications – Arthralgia and Arthritis.

30. • LABORATORY DIAGNOSIS –
• Specimens – Nasopharyngeal & Throat swab.
• Virus Isolation – In monkey or rabbit origin cell lines & then
growth detected by viral interference. Shell viral technique.
• Antibody Detection – By HAI or ELISA
• CONGENITAL RUBELLA SYNDROME – Has teratogenic effect.
Transmission to fetus if mother is infected during first trimester .
• Causes ear defect, ocular defect, cardiac defect & CNS defects.

31. • VACCINATION –
• RA 27/3 is live attenuated vaccine for rubella prepared from
human diploid fibroblast cell line. Available singly or in
combination of mumps & measles – MMR.
• Schedule – Single dose (0.5 ml) of vaccine is administered
subcutaneously.