This document discusses the epidemiology of various common microbial agents that cause infections in children. It covers viral infections like measles, chickenpox, mononucleosis, hand foot and mouth disease, hepatitis A-C, dengue, Zika, influenza, HIV, and Ebola. It also discusses common bacterial infections like streptococcal, pneumococcal, diphtheria, pertussis, enteric fever, tetanus and tuberculosis. Finally, it covers the protozoal infections of malaria, leishmaniasis and amebiasis, providing details on the causative agents, modes of transmission, incubation periods and other epidemiological aspects of each disease.

1. MICROBIAL AGENTS AND THEIR
EPIDIMIOLOGY
BY DR SHIVANANDA
MODERATRATOR DR PALANIVEL RAJAN

2. EPIDIMIOLOGY
• Branch of medicine which deals with the
incidence , distribution , possible control of
diseases and other factors relating to health

4. MOST COMMON MICROBIAL AGENTS
IN CHILDREN
VIRAL INFECTIONS
• MEASLES
• VARICELLA(CHICKEN POX)
• INFECTIOUS MONONUCLEOSIS
• ERYTHEMA INFECTIOSUM
• MUMPS
• POLIOMYELITIS
• DENGUE

5. Contd...
• HAND FOOT AND MOUTH DISEASE
• HEPATITIS A
• HEPATITIS B
• HEPATITIS C
• CHIKUNGUNYA
• INFLUENZA
• HIV INFECTION
• ZIKA VIRUS
• EBOLA VIRUS

6. COMMON BACTERIAL INFECTIONS
• STAPHYLOCOCCAL INFECTIONS
• PNEUMOCOCCAL INFECTIONS
• DIPHTHERIA
• PERTUSSIS(WHOOPING COUGH)
• ENTERIC FEVER
• TETANUS
• TUBERCULOSIS

7. PROTOZOAL INFECTIONS
• MALARIA
• LEISHMANIASIS
• AMEBIASIS

8. MEASLES EPIDEMIOLOGY
• It is common and serious childhood exanthematous
illness
• Estimated to cause 140000 (2015) child hood deaths of
which 50% occured in india
• Caused by rubeola virus a RNA virus belongs to
paramyxovirus family
• Transmission – droplet spread respiratory air borne
• communicability - 4 days before and 4 days after the
rash
• Secondary attack rate 90%
• IP 10 DAYS
• PORT OF ENTRY – RESPIRATORY TRACT

9. VARICELLA (CHICKEN POX)
EPIDEMIOLOGY
• Common childhood exathematous illness
• Usually self-limited ill ness
• Caused – varicella zozter a DNA VIRUS of Herpes virus
family
• Transmission – air borne or direct contact
• Virus present in skin lesions and respiratory secretions
• IP 10 to 21 days
• Communicability- 2 days before the vesicles
appearence up to all the vesicles crusted
• Secondary attack rate 80%
• Herpes zoster – reactivation of virus

10. INFECTIOUS MONONUCLEOSIS
EPIDYMIOLOGY
• Caused by EB virus DNA Virus virus herpes family
• IM is uncommonly seen or reported in india
• Transmitted- by oral secretions
• In developed countries mostly seen in infancy
and early childhood
• EBV establishes life long latency with frequent
asyptamatic reactivations
• It is acute self limiting infection of RE system
• Ip 4 to 7 weeks

11. ERYTHEMA IFECTIOSUM
EPIDYMIOLOGY
• FIFTH DISEASE
• Caused by parvo virus B19 A DNA virus
• Peak age between 5 to 15 years
• Transmission-by droplets through respiratory
route
• IP- 4 to 28 days mean 16 to 17 days
• This should be differentiated from
measles,rubella, drug rash
• Asymptamatic infection is common
• Mildly contagious

12. MUMPS EPIDIMIOLOGY
• It is a acute viral infection charectorized by
painful enlargement of salivary glands mainly
parotid gland
• Caused by RNA virus of paramyxovirus
• Most common age 5 to 15
• Due to meternal antibodies infants are rarely
affected
• Man is only reservoir and no carrier state

13. Continued....
• Incidence high in winter and spring season
• Transmission- by direct contact, air borne,and
fomites contaminated by saliva and urine
• Communicability-6 days before and9 days
after appearence of salivary gland swelling
• Secondary attack rate 40 to 80%
• Infection or immunization give life long
immunity

14. POLIOMYELITIS EPIDEMIOLOGY
• Caused by polio virus
• 3 types exists Type 1, P1(most common cause of
epidemics)
Type2, P2
Type3,P3(a/w VAPP)
• Man is only reservoir and no carrier state exists
• Communicability-2to3 weeks
• IP – 7 to 14 days
• Route – oral

15. Continued.....
• For every clinical case there are 1000 sub
clinical cases in children and 75 in adults
• Risk of polio virus increased by tonsillectomy,
adenoidectomy, tooth extraction, sternous
physical exercise, fatigue and cortisone
administration
• Last polio case from india reported on
13/01/2011

16. Continued....
• WHO South east asia region certified polio
free from 27/03/2014
• No wild polio cases but VAPP &VDPV who has
launched ‘POLIO ERADICATION AND END
GAME STRATEGIC PLAN 2013 TO 2019’ WHICH
Entails shift from Trivalent to Bivalent polio
vaccine and introduction of inactivated polio
vaccine in national immunization shedule

17. HEPATITIS A EPIDEMIOLOGY
• Caused by non envoloped RNA virus
• Spreads via feco oral routethrough
contaminated food and water and person to
person under poor sanitory conditions
• The seviarity of infection increases with the
age
• Classic hepatitis is seen in older children,
adolscents and adults

18. Continued.....
• So in children under 5 , infection is
asymptomatic or presents as an
undifferentiated febril illness
• HAV infection induse life long protection
against reinfection
• So in developing countries where most are
infected in childhood symptomatic disease in
less and out breaks are less

19. Continued....
• Ip – 15 to 45 days ( mean 30 days)
• Onset usually abrupt, disease mild, self
limiting
• No chronic infection & not a/w cancer
• Vaccine: immunoglobulins and inactivated
vaccine available
• Prognosis excellent

20. HEPATITIS B EPIDEMIOLOGY(serum
hepatitis)
• HBV is not transmitted by breast feeding
• Caused by ds DNA of family Hepadna viride
• Contains DNA polymarase with reverse
transcripatase activity and HBV –X protein and
play role in hepatocellular carcinoma
• 25 crores people are living with HBV infection
world wide
• Approx 8 lakh 80 thosands deaths from
cirrhosis and hepatocellular carcinoma

21. Continued......
• Transmission-Parenteral(mc), sexual or vertical
transmission
• IP- 30 to 180 days(mean 30 to 60days)
• Carrier rates in india 2to3%
• Transmission mainly due to perinatal
transmission
• Less commonly due to contact with infected
child during first 5 years of age
• Vaccines available:HBIG, Recombinant vaccine
• Prognosis worse with age

22. HEPATITIS C EPIDEMIOLOGY
• POST TRANSFUSION HEPATITIS
• PARENTERALLY TRANSMITTED NON A NON B
HEPATITIS VIRUS
• CAUSED BY ss RNA of Flaviviridae
• Transmission – parenteral(mc),vertical or
sexual transmission(+/-)
• World wide prevalence of HCV is 3% (1.7
crores)

23. Continued....
• HCV not transmitted by breast feeding
• Unlike HBV,HCV not transmitted to household
contacts and sexual transmission is infrequent
• Acute disease is uaually subclinical
• Vaccines: no
• IP – 15 to 160 days
• Maximum chance of chronic hepatitis and
carrier state

24. Chickengunya epidemiology
• An acute disease with fever, arthritis, and skin
rash
• Caused by envoloped RNA Virus
• Rural cycle involve Aedes africans, A. Fancifer
and wild primates
• Urban cycle involve A.aegypti and humans
• Out breaks occur during rainy season
• After an epidemic disease vanes for years
because large portion of people are immune

25. INFLUNZA EPIDEMIOLOGY
• INFLUNZA VIRUS is capable of causing disease
in humans, birds and animals
• The Influenza virus is an RNA virus of the
orthomyxoviridae family
• INFLUNZA A is further classified in to 2
subtypes Hemeagglutinin(H) and
Neuraminidase(N)
• INFLUENZA B classified into two distinct
lineages yamagata and victoriya but not into
sub types

26. Continued.....
• Influnza genome prone to frequent mutations
and reassortments
• This leads to antigenic shifts and drifts
• The currently circulating influnza strains are
H3N2, PANDEMIC H1N1 and influenza B
• Avian H5N1 commonly reffered as bird flu is
highly pathogenic

27. Continued.....
• Transmission-droplets or direct contact
• Port of entry-respiratory tract
• IP-1 to 3 days
• Period of infectivity-7 days after illness
• Attack rate high inchildren and young adults
• In india it occurs throughout the year with
peak during mansoons

28. HIV EPIDEMIOLOGY
• Morethan 36 million persons worldwide were
living with hiv infection(2016)
• Of them 2.1 million were children under 15
years of age
• >90% living in developing countries
• With out access to antiretroviral therapy 20%
of vertically infected children will progress to
AIDS or death in their 1st year of life and >50%
will die before 5 th birthday

29. Continued.....
• Caused by HIV1 &HIV2 of the Retroviridae
family
• Transmission of HIV occurs via sexual contact,
parenteral exposure to blood, vertical
transmission from mother to child
• The primary route of infection in pediatric
population is vertical transmission

30. Continued.....
• Vertical transmission of HIV can occur during
intrauterine or intrapartum periods or through
Breast feeding
• Upto 30% are infected in utero, heighest % in
intrapartum
• Risk factors for vertical transmission include
preterm delivary(<34 weeks), low meternal
antenatal CD4 count, Birth weight <2400gm,
>4hrs of ruptured membranes, illicit drugs during
pregnancy

31. ZIKA VIRUS EDIDIMIOLOGY
• Caused by RNA flavivirus closely related to
chikungunya and dengue viruses
• It causes microcephaly in new born
• No cases have been reported in india as yet,
but due to presence of Aedes aegypti
mosquito, India is at high risk for introduction
of virus
• Primarily transmitted by mosquito bite
• Others –vertical transmission from mother to
child, sexual and through blood transfusion

32. DENGUE EPIDEMIOLOGY
• GLOBAL PREVALENCE of dengue has increased
• Disease endemic in more than 100 countries
• South east asia and westren pacific are most
seriously affecting regions
• Approximately 50 million annual cases of
dengue across the world
• 5 lakh cases require hospitalization due to
severe dengue infection
• Among them 2.5 % die

33. Continued...
• Case fatality rate in severe dengue infection is >20%
• Secondary attack rate is 40 to 50%
• Caused by any of the 4 serotypes DENV-1, DENV-2,
DENV-3, DENV-4, Arboviruses of flaviviridae family
RNA VIRUSES
• TRANSMISSION- through the bites of infected
female aedes mosquito
• IP- 2 to 3 days
• AMPLIFYING HOST- HUMANS
• Virus circulate in blood for 2to7 days at
approximately same time as fever

34. EBOLA VIRUS EPIDEMIOLOGY
• EBOLA VIRUS is a RNA virus belonging to the
family Filoviridae
• Several out breaks of haemorrhagic fever have
been reported with high mortality
• Natural reservoir- old world fruit bat
• Transmission- through direct contact with bats
or consumption of products contaminated
with bat feces or body fluids

35. Continued....
• Humans can also be infected by direct contact
with infected animals or eating meat of
infected animals
• Human to human transmission to family
members, caretakers, and health care workers
can occur through close contact or handling
the fluids of infected patients

36. STAPHYLOCOCCAL INFECTIONS
EPIDEMIOLOGY
• Staphylococci are ubiquitous.All the persons have
coagulase negitive staphylococci on their skin
• Moist skin folds are colonize with S.aureus
• Colonization of the umbilical stump, skin and
perineal areabof the neonates with S. Aureus is
common
• Because of staphylococci are found on skin and in
nasopharynx, shedding of bacteria common, and
is responsible for many hospital acquired
infections

37. PNEUMOCOCCAL EPIDEMIOLOGY
• Most commn bacterial cause of pediatric
infections perticularly pneumonia
• Pneumococci colonize the nasopharynx, in
children it is more
• Serotypes 1,3,4,5,6,9,14,18,19 and 23 usually
causes disease in humans and are
incorporated in vaccine
• Dissemination is facilitated by over crowding

38. DIPHTHERIA EPIDEMIOLOGY
• CAUSED BY Corynebacterium diphtheriae
• Transmitted by contact or via droplets of
secretion
• Port of entry – commonly respiratory tract
• Age- pre school age children
• Communikability upto 7weeks with out
antibiotics
• Vaccine is given along with Pertussis& Tetanus

39. PERTUSSIS EPIDEMIOLOGY
• CAUSED BY Bordetella pertussis
• Also called whoophing cough
• It is disease of infants and pre school children
• The heighest incidence found before age of 5
years
• Vaccination is given along with Diphtheria and
Tetanus
• IP- 7 to 14 days
• Transmission – aerosal droplets

40. TETANUS EPIDEMIOLOGY
• CAUSED BY Clostridium tetani a spore forming
gram positive bacteria
• These spores are wide spread in environment
• Can be prevent entirely by immunization
• Tetanus occur worldwide but is more common
in hot, damp climates
• IP- 8 days

41. NEONATAL TETANUS
• Major cause of mortality in developing
countries
• Infection results from unhygienic birth
practices, most commonly when the umbilical
cord is contaminated at the time of cutting
• Can be prevented by vaccination to the
mother

42. ENTERIC FEVER EPIDEMIOLOGY
• CAUSED BY Salmanella species
• Transmitted by feco-oral route
• Burden is more in places where water supply and
sanitory conditions are poor
• Enteric fever is commonest cause of fever lasting
for more than 7 days
• IP – 7 to 14 days
• Effective method of prevention is improving
hygine and sanitation

43. TUBERCULOSIS EPIDEMIOLOGY
• CAUSED BY Mycobacterium tuberculosis
• More than 90% cases occuring in developing
countries
• Most children acquire the organism from
adults so epidemiology of childhood TB
follows that in adults
• Reservoir of infection- open or infective cases
• Mode of infection- inhalation of droplets of
infected secretions

44. Continued...
• Adolscents , especially girls more prone to
develope disease
• Undernourished children more prone to
develope disease
• Malnourished child who does not respond to
dietary therapy should be investigated for TB
• Increased risk of infection seen in institutional
settings

45. MALERIA EPIDEMIOLOGY
• Most important protozoal disease
• Caused by plasmodium genus
• There are 4 species pathogenic to man p.vivax,
P.faciparum, P.maleriae, P. Ovale
• First 2 occurs in india
• Most deaths due to P.falciparum

46. Continued...
• Mainly occurs in tropical climate
• Infectious stage is SPOROZITE
• Transmitted by female anapheles mosquito
• Destroying the breeding sites of mosquitoes is
important for planning control measures by
insecticide spraying
• Use of insecticide treated nets

47. LEISHMANIASIS
• CAUSED BY Leishmania donovani
• Transmitted by bites of female sandflies
• In india more cases reported from bihar and up
• Humans are cheif reservoirs
• Children aged 1 to 4 years are more susceptible
to the disease
• As the sandflies are endophilic spraying house
with insecticide is effective

48. AMEBIOSIS EPIDEMIOLOGY
• CAUSED BY Entameba histolytica
• It is less common in children and responcible
for <3% cases of diarrhoea in <5 children
• Infective form is cyst
• About 90% cases are asymptomatic
• Poor sanitation and sewage contamination
main source of infection

49. Communicable diseases
• By food and water
Viruses : Polio, hepatitis A,E, viral diarrhoeas
such as rota virus and adenovirus
Bacterial: thyphoid , parathyphoid , cholera,
bacillary dysentery, e coli, campylobacter
Protozoa: amebiasis
• Prevention – good personal hygiene & hand
washing, safe water supply , protection of
public water supply from contamination

50. Droplet transmission
• Mumps
• Rubella
• Pertussis
• Diphtheria
• Influenza
• Pneumococcus

51. Air borne spread
• Chicken pox
• Measles

52. THANK YOU