Explains epidemiology of Amoebiasis and Ascariasis Target - UG students MBBS

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2. Dr. Mounica C
Assistant Professor
Dept of Community Medicine
Kamineni Institute of Medical Sciences
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3. AMOEBIASIS
 Introduction
 Problem statement
 Epidemiological
determinants
 Modes of transmission
 Incubation period
 Prevention & Control
ASCARIASIS
 Introduction
Geographical distribution &
prevalence
Epidemiological determinants
Modes of transmission
Incubation period
Symptoms
Prevention & Control
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Condition of harbouring protozoan parasite
Entamoeba histoltica with or without clinical
manifestations

5. • <10% of infection – symptomatic
• Intestinal & extra intestinal
• Intestinal Invasive
• Intestinal:
Mild abdominal discomfort & diarrhoea
Acute fulminating dysentery
• Extra intestinal: Involvement of liver, lungs, brain, spleen, skin
• Potentially lethal disease with substantial morbidity &
mortality
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6. World
• Common infection of GIT - Major Health Problem
• Invasive – 100,000 deaths
• Prevalence: 2% - 60%
• Endemic forms
o Transmission
o Re infection
India
• Prevalence: 15%(3.6 - 47.4)
• Large variations
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8. E.histolytica – 18 zymodemes
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9. Not
affected
by
chlorine
Killed if
dried,
heated
(>500C) or
frozen
Remain viable &
infective for several
days in faeces,
sewage & soil
(moisture & low
temperaure)
Infective
to man
Quadrinucleated
cysts
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Reservoir – Man
Immediate source of
infection - faeces
containing cysts

10. Household
infection
No sex
difference
Specific
ab
CMI – Control
recurrence of
invasive form
Any
age
No racial
difference
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11. Social disease
Higher during rains – cysts survive
Poor sanitation & SES
Sewage seepage into water supply
Epidemic outbreaks
Nightsoil for agriculture
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Vectors
Sexual
transmission
Faecal – oral
route
2 – 4 weeks or longer

13. Primary prevention
Water supply
Human excreta – safe disposal
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Sanitation
Food hygiene
Health education
Hand washing
Water filtration – sand filters
Water boiling

14. Secondary prevention
Treatment
Microscopy
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Early diagnosis
Serological tests
Symptomatic cases
Asymptomatic cases
Invasive Amoebiasis
•Indirect Heamagglutination
assay ( IHA )
•ELISA
•Counter Imunoelectrphoresis
(CIE)
Metronidazole
30 mg/kg/day in 3 divided doses
after meals for 8-10 days
•Endemic areas–No treatment needed except in
case of food handlers
•Non-endemic areas–Treated for 20 days with
Diiodohydroxyquin: 650mg TDS (adults)
30-40mg/kg (children)

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16. Group of parasitic diseases caused by intestinal
Most common infections
Tropical & subtropical areas
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17. • Infection of intestinal tract
• A.lumbricoides
• Vague symptoms of nausea, abdominal pain & cough
• Live worms – passed in stool or vomited
-- intestinal obstruction
-- migrate into peritoneal cavity
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18. • Most common human helminthic infection
• Worldwide distribution
• Highest prevalence in tropical & subtropical regions,
& areas with inadequate sanitation
• Heavy infection – common in children aged 3-8 years
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20. • Small intestine (mainly in jejunum & upper part of ileum)
Adult worms of A.lumbricoides
• Heavy egg production counterbalanced by heavy losses
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Reservoir – Man
Immediate source
of infection -
faeces containing
fertilised eggs

22. Adults – resistant
High degree of
host-parasite
tolerance
Compete for
vitamin A in
intestine
Malnutrition in
children who may
show growth
retardation
Infection rates
- High in
children
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Human habits –
OAD,
Contaminated
hands of children

23. Eggs remain viable for months/ years
Oxygen pressure
High vs low temperature
UV radiation from sunlight
Clay soils vs most porous soils
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18 days to several weeks
• Eggs passed in faeces of infected people
• Inadequate sanitation – eggs contaminate soil
Not carefully
cooked, washed or
peeled vegetables
Contaminated
water sources
Children – unwashed hands
Walking barefoot on contaminated soil –
active penetration of larvae

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• Related to no. of worms harbored
• Light infection – no symptoms
• Higher infection – diarrhoea, abdominal pain, general malaise,
weakness, impaired cognitive & physical development
• Larva migration – fever, cough, sputum, asthma, skin rash,
oesinophilia
• Adult worm aggregate masses - Volvulus, intestinal
obstruction or intessusception
• Wandering worms - Bowel perforation in ileococcal region,
blocking of common bile duct or may come out with vomit
Heavy infection: ≥ 50,000 eggs/gm of faeces

26. Primary prevention
Water supply
Human excreta – safe disposal
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Sanitation
Food hygiene
Health education
Hand washing
Water filtration – sand filters
Water boiling

27. Secondary prevention
Effective drugs - Treatment
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Albendazole
400 mg
single dose
Mebendazole
100 mg BD
3 days
Levamisole
2.5 mg/kg
single dose
Pyrantel
10 mg/kg
single dose
Treatment of complications
Anaemia – IFA
Hypoproteinaemia
Hypereosinophilia

28. Preventive Chemotherapy
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• Periodic treatment of at-risk people in endemic areas
o Preschool-aged children
o School-aged children
o Women of childbearing age (II & III Trimester pregnant
women & breast-feeding mothers)
o High-risk occupations: such as tea-pickers or miners
• Periodic deworming – integrated with other days or programs
Albendazole
400 mg
single dose
Mebendazole
500 mg
single dose

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30. • K Park. Textbook of Preventive and Social Medicine,
24th ed, Jabalpur Banarasidas Bhanot publication,
2016.
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