L20: Schistosomiasis & Leprosy Flashcards by Ahmed Farag

Global Epidemeology of Schistosomiasis

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National Epidemeology of Schistosomiasis

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Schistosomiasis is endemic in Egypt since …..

Ancient Egypt (1250 B.C).

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The prevalence of S. mansoni was ….. and S. haematobium was …… in 1983 before the national control program

38.6%, 35%

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In 2014 the prevalence 0f S. mansoni was ….. and S. haematobium was …..

0.2%, 0.3%

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S. mansoni is endemic in ….. while
S. haematobium is endemic in …..

Delta, Upper Egypt

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Epidemic Threshold of Shistosomaisis

If the prevalence reaches 3% in a small population or 2% in schools.

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Suspected Case of Shistosomaisis

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Probable Case of Shistosomaisis

None

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Confirmed Case of Shistosomaisis

Presence of Schistosoma eggs in urine and stool

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CA of Shistosomaisis

the major species causing human disease
❶ Schistosoma haematobium
❷ S. manosni
❸ S. Japonicum

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Reservoir of Shistosomaisis

Man: Infected persons with S. haematobium or mansoni

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Intermediate Host of Shistosomaisis

❶ Bulinus Trancatus: for S.haematobium
❷ Biomphalaria alexandrina: for S.mansoni

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MOT of Shistosomaisis

contact infection (cercaria penetrate bare skin) .

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IP of Shistosomaisis

6-8 weeks

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Infectivity Period of Shistosomaisis

No man-to-man transmission but infected person can transmit infection by contaminating water up to 10 years.

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Susceptibility & resistance Shistosomaisis

Genetic Predisposition

❶ HLA class I & II antigens: more severe manifestations of
the disease.

❷ HLA-B16 & Cw2: S. haematobium associated bladder
cancer in Egypt.

❸ HLA-DR, DQ, DP: protection from hepatic fibrosis.

❹ 5q31-q35: Resistance to re-infection.

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Susceptibility & resistance Shistosomaisis

any age is susceptible, the peak at age 15-20y

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Susceptibility & resistance Shistosomaisis

more in males: more exposure (working in the field & swimming in canals).

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Susceptibility & resistance Shistosomaisis

education

educated may avoid polluting the environment & exposure to infection.

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Susceptibility & resistance Shistosomaisis

faculty Habits & Behaviours

Pollution of water by passing excreta in water channels.
Exposure to infection by water contact: bathing, ablution,
washing of clothes.

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Ecology of Schistosomiasis

(factors favoring endemicity)

Host Factors

(Previously described under susceptibility & resistance)

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Susceptibility & resistance Shistosomaisis

Occupation

famers, fishermen & workers of water channels clearance

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Ecology of Schistosomiasis

(factors favoring endemicity)

Host Factors
Agent Factors
Environmental Factors

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Ecology of Schistosomiasis (factors favoring endemicity) - Agent Factors

Ecology of Schistosomiasis (factors favoring endemicity) - Environmental Factors

Schistosomiasis may be introduced to the new reclamation areas in Toshki or Sinai through the previous factors .

...

General Prevention of **Shistosomaisis** - Environmental Sanitation

General Prevention of **Shistosomaisis** - Snail Control

Requirements of ideal Molluscicide

What is the Name of molluscicide of choice?

Niclosamide

General Prevention of **Shistosomaisis** - Health Education

General Prevention of **Shistosomaisis** - Protection of Man

Protective clothing unpractical by gloves & boots

Specific Prevention of **Shistosomaisis**

Vx: under trial.

Case Control Measures for **Shistosomaisis** - Early case Finding

Case Control Measures for **Shistosomaisis**

Case Control Measures for **Shistosomaisis** - Notification

Case Control Measures for **Shistosomaisis** - Isolation

not required

Case Control Measures for **Shistosomaisis** - TTT

Contact Control Measures for **Shistosomaisis**

Urine and stool analysis.

Outbreak (Community) Control Measures for **Shistosomaisis**

Mass treatment if the prevalence reaches the epidemic threshold .

Def of **Leprosy [Hansen’s disease]**

- is an infection caused by slow-growing bacteria called Mycobacterium leprae.

Previously feared as highly contagious & devastating disease but now we know it doesn’t spread easily and treatment is very effective

.....

Global Epidemeology of **Leprosy**

- There were 202,256 new leprosy cases registered globally in 2019, according to official figures from 161 countries from the 6 WHO Regions - The prevalence corresponds to 22.9 per million population

National Epidemeology of **Leprosy**

- Since 1994, Egypt has met WHO’s global leprosy elimination goal of reducing prevalence to less than 1 per 10 000 population ## Footnote Study Epidemic Threshold

Suspected Case of **Leprosy**

- Person showing one or more of the following features ❶ Hypopigmented or reddish skin lesions with definite loss of sensation ❷ Thickening of the peripheral nerves with loss of sensation

CC of **Leprosy**

Skin smear positive for acid-fast bacilli (M Leprae).

CA of **Leprosy**

Mycobacterium Leprae (acid fast bacilli)

Reservoir of **Leprosy**

Only human

Exit of **Leprosy**

Nasal discharge

MOT of **Leprosy**

The bacillus is likely transmitted via droplets, from the nose and mouth, during close and frequent contact with untreated cases

IP of **Leprosy**

on average, is 5 years. Symptoms may occur within 1 year but can also take as long as 20 years or even more.

Types of **Leprosy**

Susceptible Age of **Leprosy**

5-15 years is most susceptible

Susceptible Families of **Leprosy**

❶ Familial tendency (runs in families but the inheritance pattern is unknown) ❷ Genetic susceptibility

General Prevention of **Leprosy**

Specific Prevention of **Leprosy**

Specific Prevention of **Leprosy** - Active Immunization

❶ BCG vaccine offers a variable amount of protection against leprosy. ❷ Novel vaccine called LepVax entered clinical trials in 2017.

Specific Prevention of **Leprosy** - Chemoprophylaxis

Single dose rifampicin for close contact of newly diagnosed patient

Case Control measures of **Leprosy**

Case Control measures of **Leprosy** - Early Case Finding

the most important measure in control of leprosy

Case Control measures of **Leprosy** - Notification

local health office

Case Control measures of **Leprosy** - Isolation

no need for isolation, Patients are no longer infectious after the first monthly dose

Case Control measures of **Leprosy** - TTT

Case Control measures of **Leprosy** - rehab

for patient with deformities and disabilities

Contact Control Measures for **Leprosy**

❶ Enlistment by age, sex, vaccination history. ❷ Surveillance for early case finding annually for 5 years . ❸ Specific protection using BCG vaccine and single dose Rifampicin