Epidemiology of Schistosoma Hematobium Flashcards

1
Q

What is epidemiology?

A

the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is schistosomiasis?

A

An acute and chronic, parasitic disease caused by blood flukes/trematode worms of the genus Schistosoma.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Infections causing illness in humans are with?

A
  1. Schistosoma mansoni,
  2. S. haematobium,
  3. S. japonicum,
  4. S. guineensis
  5. S. mekongi and S. intercalatum
    • less commonly can cause disease.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which species causes intestinal schistosomiasis?

A

S. mansoni

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which species causes urogenital schistosomiasis?

A

S. haematobium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the signs and symptoms in the early phase of infection of schistosomiasis?

A
  1. Rash or itchy skin within days after infection
  2. Fever, chills, cough, and muscle aches can begin within 1-2 months of infection.
    - Most people have no symptoms at this stage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the signs and symptoms in the late phase of infection of schistosomiasis?

A

Symptoms are caused by body’s reaction to the eggs produced by worms

  1. Eggs from adult worms travel to the intestine, liver or bladder, causing inflammation or scarring
  2. Damage to the liver, intestine, lungs, and bladder.
  3. Rarely, eggs are found in the brain or spinal cord and can cause seizures, paralysis, or spinal cord inflammation.
  4. Female genital schistosomiasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Children who are repeatedly infected by schistosomiasis can develop?

A
  1. anemia
  2. malnutrition
  3. learning difficulties
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the signs and symptoms of S. haemotobium?

A

include urogenital symptoms & signs:

  1. Cystitis
  2. Ureteritis with hematuria,
  3. Bladder cancer
  4. Glomerulonephritis and
  5. Central nervous system lesions e.g. transverse myelitis with flaccid paraplegia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do you diagnose SH?

A

Use samples of urine
1. Color – blood urine
2. Examined for the presence of eggs
– using the filtration technique for SH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the global burden and distribution of SH?

A
  • Schistosomiasis transmission reported in 78 countries
  • Only 51 countries with moderate-to-high transmission require large scale treatment in communities
  • Affects 240 million people worldwide
  • At least 206 million people were infected or required treatment in 2018
  • At least 91.4% of those requiring treatment for schistosomiasis live in Africa
  • WHO estimates the annual death rate at 200 000 globally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the geographical distribution of S. mansoni?

A

parts of South America (Brazil and Venezuela) and the Caribbean, Africa, and the Middle East

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the global geographical distribution of S. haemotobium?

A

Africa and the Middle East and Corsica (France)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the global geographical distribution of S. japonicum?

A

Far East

China, Indonesia, the Philippines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the global geographical distribution of S. mekongi?

A

Southeast Asia and Several districts of Cambodia and the Lao People’s Democratic Republic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the global geographical distribution of S. intercalatum?

A

Central West Africa

17
Q

Describe the transmission and prevalence of SH?

A
  • Transmission in Malawi is highly focal, with considerable variation in space and time
  • National prevalence of S. haematobium
    ~6.9% (95% CI 1.9 - 11.9%)
  • prevalence rates of up to 94.9% for Schistosoma haematobium in some communities
18
Q

Seasonality of transmission of SH varies by?

A

geographical, environmental, biological and behavioural factors.

19
Q

How are people infected by SH?

A

during routine agricultural, domestic, occupational, and recreational activities, which expose them to infested water

20
Q

Describe the determinants and risk factors of SH with regards to populations and the environment?

A

Populations in frequent contact with infected sources
1. Mostly affects poor and rural communities
2. Agricultural and fishing populations
– E.g along the Lake Malawi or rivers
3. Women doing domestic chores in infested water
4. Children (SAC) vulnerable to infection
– frequent contact with infested waters
5. Migration to urban areas /population
movements introduce disease to new areas
6. Development schemes , dams
7. Tourists to infected areas

21
Q

What are the public health interventions for prevention and control of SH?

A
  1. Large-scale treatment of at-risk population groups (preventive chemotherapy)
  2. Access to safe water
  3. Improved sanitation
  4. Hygiene education
  5. Snail control
22
Q

Describe the large scale treatment of at risk population groups (preventative chemotherapy)?

A

– Repeated over a number of years in a
community, will reduce and prevent morbidity.
– Targets all who are at-risk
– WHO strategy for control focuses on reducing disease morbidity through periodic, targeted treatment with praziquantel.

23
Q

Describe the epidemiology of large scale treatment of at risk population groups?

A
In 2019
- at least 236.6 million people 
required preventive treatment for 
schistosomiasis 
- more than 105.4 million people were reported to have been treated
24
Q

The groups targeted for treatment of SH are?

A
  1. School-aged children in endemic areas.
  2. Adults considered to be at risk in endemic areas
  3. people with occupations involving contact with infested water, such as fishermen, farmers, irrigation workers
  4. women whose domestic tasks bring them in contact with infested water.
  5. Entire communities living in highly endemic areas
25
Q

Which drug is used to treat SH?

A

Praziquantel is the recommended treatment
against all forms of schistosomiasis.
• It is effective, safe, and low-cost

26
Q

What are the public health interventions for prevention and control of SH?

A
  1. Access to safe water
  2. Improved sanitation
  3. Hygiene education
  4. Snail control
  5. Praziquantel
27
Q

Describe some of the challenges for SH control?

A
  1. Need for integrated approach to the
    control, other aspects not adequately done
    - Poverty
    - Access to safe water / Improved sanitation
  2. Inadequate behavioural change
  3. Lack of praziquantel in other countries
  4. Lack of better methods for snail control