Chapter 3. Sanitation and public health

How am I exposed?

What happens in me if I am exposed (different pathogens) Cases and participatory Approaches on different Community levels !

Can we manage the risks?

Which are the health Targets and guideline Procedures?

From where do pathogen come?

How can treatment and interventions minimize transmission?

Caroline Schönning, Swedish Institute for Infectious Disease Control (SMI), Sweden

3.1 Exposure and effects in humans

Learning objective :

To know and be familiar with pathogens of concern in water and sanitation systems, including the symptoms they cause and the effect on the individuals/population

DALYs – a general measure for health

The Global Burden of Disease (GBD)

Murray and Lopez, 1996

 Disability Adjusted Life Years (DALY)  morbidity: years lived with a disability  mortality: years lost  DALY (loss of healthy lived years) = n x t x S • • • n = number of affected persons t = the duration of the health effect S = measure of the severity of the health effect (mortality = 1)

Hypothetical example of DALYs

Quality of life Index 1.0

Remaining “disability”

0.8

0.4

0 20

Acute (infectious) illness

40 Age

Premature death by 65

60

Years lost

80

Leading DALYs in in the world 1990 & 2020

Disease/Injury Lower respiratory Diarrhoeal Perinatal period Depression Heart disease Tuberculosis Road accidents HIV Lung cancers Murray

et al.

(1996) Science 274:740-743 Rank 1 1990 2020 %DALYs Rank %DALYs 8.2

6 3.1

2 3 4 7.2

6.7

3.7

9 11

2

2.7

2.5

5.7

5 7 9 28 33 3.4

2.8

2.5

0.8

0.6

1

7

3

10 15

5.9

3.1

5.1

2.6

1.8

”The sanitary revolution” - the most important medical milestone since 1840 !? (BMJ, 2007)

DALYs attributable to risk factors

Water and sanitation causes a major part (9%) of GBD, that largely could be prevented. (WHO, 2008)

Diseases contributing to the water-, sanitation and hygiene-related disease burden

PEM: protein-energy malnutrition (Adapted from WHO, 2008)

Global risk factors for disease and premature deaths (% of DALYs)

Child underweigth for age Unsafe water, sanitation, hygiene Low fruit & vegetable intake Zinc deficiency Iron deficiency aaemia Vitamin A deficiency Child underweight ~7.9% Nutrition deficiencies ~7.4% Water & sanitation ~3.4%

Total targeted by ”Ecosan”: ~18.6%

in Sub-Saharan Africa ~7.6% 854 million chronically hungry 2 billion without food security FAO, 2006 Ref: Lopez et al. 2006. Global and regional burden of disease and risk factors; FAO, 2006

Infectious diseases

 Frequency of infection World ´s most common – karies Commonly existing diarrhoea and food poisoning Unusual opportunistic infections in immunocompromised individuals  Symptoms None (e.g. polio) Mild diarrhoea (e.g. Staphylococcus food poisoning) Life-threatening loss of water and salts (e.g. cholera)

The field of Epidemiology

 Definitions  (1) The study of the relationships of the various factors determining the frequency and distribution of diseases in a human community.

 (2) The field of medicine that attempts to determine the exact causes of localized outbreaks of disease. (Ologies & -Isms. Copyright 2008 The Gale Group, Inc)  The start in the middle of the 19th century  Cholera epidemics in London - consumption of water implied an increased risk for disease (John Snow)  Established that germs or bacteria cause infectious disease (Pasteur, 1857)

Occurrence of disease

 Prevalence  The number of cases in a defined population at a specified point in time  Incidence  The number of new cases arising in a given period in a specified population

Transmission of infectious agents

 Direct transmission  Touching  Kissing  Sexual intercourse  Other contact  Airborne, short distance via droplets, coughing, sneezing  Transfusion (blood)  Transplacental  Indirect transmission  Vehicle-borne (contaminated food, water, towels, farm tools etc.)  Vector-borne (insects, animals)  Airborne, long distance via dust and droplets  Parenteral (injections with contaminated syringes)

Consequences of exposure

Exposure No infection Infection Susceptible Immune Recovered No symptoms Symptoms of disease Death

Infectious dose

   Minimum infectious dose ID 50 Probability of infection  Dose-response curves  Severity of disease depending on  Ingested dose  The condition of the mechanical barrier  The stability of the normal enteric flora  Immunity  The nutritional status of the individual

Immunity – vulnerable groups

       More vulnerable groups in the society The old (elderly) Infants Pregnant women Immunocompromised Malnourished These groups comprise about 20% of the general population and are growing

Epidemiology - Definitions

Pandemic:

An epidemic (a sudden outbreak) that becomes very widespread and affects a whole region, a continent, or the world.

By contrast: An

epidemic

affects more than the expected number of cases of disease occurring in a community or region during a given period of time. An

endemic

is present in a community at all times but in low frequency. (http://www.medterms.com/script/main/art.asp?articlekey=4751)

Epidemic to endemic illnesses as detected by health surveillance

Outbreak detected Threshold for detection for an outbreak Endemic rate Undetected outbreak Hyperendemic Sporadic

Time

Diarrhoea and sanitation

    Causes ~1/5 of deaths in children <5 years (1.5 million) Has decreased, in 1980 ´s estimated 2/3 of deaths Less significant decrease in diarrhoeal disease in low income countries Infections related to water and sanitation     4.1% of the total DALY 88% of the burden attributable to unsafe water supply, sanitation and hygiene Improved sanitation can reduce diarrhoea by ~32% 391 million cases averted if MDG target met

Regional differences in average health burdens from diarrhoeal diseases

Source:

Our Planet Current annual diarrhea cases in SSA: 1.2 billion which lead to 769.000 dead children, mostly under 5 years

Treatment of diarrhoea

       Program in the 1980 ´s for rehydrating children – avoiding death Infromation, campaigns by WHO, UNICEF Did not give the expected success – less use than anticipated Symptoms are common Do not visit a medical doctor Start treatment late or not at all Want antibiotics or medicine that stops diarrhoea

Example: Ceará in Brasil

 Death from diarrhoea decreases   Decrease in incidence or better treatment?

General improvement of livelihood    e.g. water quality, sanitation, waste management, income, litearcy, health care, vaccination No single factor related to lower number of diarrhoea cases Continued studies of the real situation

Diarrhoeal diseases – Outbreaks related to water and sanitation

 Cholera  36 reported outbreaks from 2006-2009 (WHO)   Risk during flooding “Natural environmental” spread  Typhoid fever  Also endemic  Shigellosis

Cholera epidemic

   Acute watery diarrhoea, very deadly without rapid treatment Affects adults as much as children, especially informal caretakers High political profile : can be used as a political leverage   Characteristics for cholera outbreaks  high attack rate   low mortality economic and social burden Factors of spread  density of population    transportation facilities living conditions environmental reservoirs

Consequences of cholera outbreaks

Social Burden

Cholera Outbreak

Health impact

Health Care Facilities overwhelmed More supplies, more staff

Economic burden “Psychological” impact

Panic Media

Political impact

Who is responsible?

Classification of communicable diseases related to water and sanitation



Water-borne diseases:

caused by the ingestion of water

contaminated by human or animal faeces or urine

containing pathogenic bacteria or viruses or parasites; include cholera, typhoid, amoebic and bacillary dysentery and other diarrhoeal diseases.



Water-washed diseases:

caused by poor personal hygiene and skin or eye contact with contaminated water; include scabies, trachoma and flea, lice and tick-borne diseases.



Water-based diseases:

caused by parasites found in intermediate organisms living in water; include dracunculiasis, schistosomiasis and other helminths.



(Other) Water-related diseases:

caused by insect vectors which breed in water; include dengue, filariasis, malaria, onchocerciasis, trypanosomiasis and yellow fever. (WHO, 1996)

Waterborne pathogens

– important in water and sanitation system 

Bacteria

     The leading cause of gastrointestinal infections according to surveillance systems

Salmonella

,

Shigella

,

Campylobacter, E. coli (toxinprod.)

EHEC

Legionella

Opportunistic e.g.

Aeromonas hydrophila



Virus

 Probably the cause of many outbreaks, difficult to detect  Noroviruses (Calici-, Norwalk like), rotavirus, hepatitis A

Waterborne pathogens

– important in water and sanitation system 

Protozoa

 Complicated life cycles with resistent stages (chlorine)   

Giardia

,

Cryptosporidium, Entamoeba

Low infectious dose Milwaukee (USA) 1993, 400 000 individuals 

Helminths (worms)

   Varying transmission routes, e.g. soilborne

Ascaris, Trichuris, Schistosoma

(bilharzia), hookworm A large problem in many developing countries

Shigella

  

Salmonella infection – Salmonellosis and Typhiod fever

Salmonellosis

cramps – diarrhea, fever, and abdominal Caused by a variety of serotypes, e.g.

Salmonella

Typhimurium and

Salmonella

Enteridis Foods contaminated with animal feces   Animal origin (meat, poultry, eggs), vegetables Pets – handwashing important   

Paratyphoid and Typhoid fever

- fever and other symptoms, life-threatening Caused by

Salmonella

Typhi Contaminated food or water  More common in areas with low sanitary standard

Schistosoma

     Also known as bilharzia 200 million people are infected worldwide Variety of symptoms Freshwater contaminated by urine or faeces Life-cycle requires specific snail as host

Viral gastroenteritis

 What is viral gastroenteritis?  Inflammation of the stomach and small or large intestines   Caused by a variety of viruses that results in vomiting or diarrhea Often called ”stomach flu" (but not caused by the influenza viruses)  What causes viral gastroenteritis?   Many different viruses For example: rotaviruses, adenoviruses, caliciviruses, astroviruses, Norwalk virus, and a group of Norwalk-like viruses (later called calicivirus, norovirus)

Rotavirus

     Rotavirus is the most common cause of severe diarrhea among children Globally, rotavirus is estimated to cause 527,000 deaths in children annually Vomiting and watery diarrhea for 3 8 days, and fever and abdominal pain occur frequently Immunity after infection is incomplete Vaccination possible but not widespread (http://www.cdc.gov/rotavirus)

 

Previously called calicivirus or Norwalk (Like) viruses Transmission

   Perspn-to-person Food-borne Waterborne

Ascaris

Ascaris

  

Ascaris lumbricoides

is one of the largest and most common parasites found in humans It is estimated that 10% of the world's population is infected with this nematode The adult worms live in the small intestine and eggs are passed in the feces - a single female can produce up to 200,000 eggs each day

Ascaris lumbricoides

, fertilized egg. The egg is covered with a thick shell that appears lumpy approximate size = 65 µm in length. The adult worm. Adult females of this species can measure up to 18 inches long (males are generally shorter).

Ascaris

Cryptosporidium

   

Cryptosporidium

is a small parasite, about 3 5 µm.

It lives on the surface of the cells lining the small intestine and oocysts are passed in the feces.

Transmission of the infection occurs via the oocysts.

Many human infections have been traced to the contamination of drinking water with oocysts from agricultural "run-off" (i.e., drainage from pastures), so it is considered a zoonosis.

Cryptosporidium

Giardia

  

Giardia intestinalis Giardia duodenalis

(also known as

Giardia lamblia

or soil, food, or water that has been contaminated with feces Common in both developing and developed areas 

Giardia lamblia

trophozoites live in the small intestine of the host. Cysts, which are resistant to adverse environmental conditions, are passed in the feces of an infected host, and the next host is infected when it ingests cysts in food or water contaminated with feces.

 The trophozoites adhere closely to the lining of the small intestine, and in heavy infections much of the lining can be covered with trophozoites. The giardiasis symptoms range from none (in light infections) to severe, chronic diarrhea (in heavy infections).

Features of some gastrointestinal infections

Salmonella Campylobacter

EHEC Hepatitis A Rotavirus Norovirus Adenovirus

Cryptosporidium Giardia Ascaris

Morbidity (%)

6-80 25 76-89 70 50 70 54 39 20-40 15

Excretion (g -1 faeces)

10 4-8 10 6-9 10 2-3 10 4-6 10 7-11 10 5-9 10 11 10 7-8 10 5-8 10 4

Excretion time (days)

26-51 1-77 5-12 13-30 1-39 5-22 1-14 2-30 28-284 107-557

ID 50

23 600 900 1 120 30 6 10? 1.7 165 35 0.7 (Westrell, 2004)

Emerging pathogens

 Emerging diseases  Newly recognized or  Increasing importance  Zoonoses  Many emerging pathogens of zoonotic origin  Animal faeces contaminate water  Climate change  Increased risks related to water and sanitation  Affects food-production

Protozoa and helminths in faecal material

  Faecal samples from 120 urine-diverting latrines in KwaZulu-Natal, South Africa Varying features – water-filled to dry (normal)  Analysing for presence of:  parasitic protozoa

Giardia Cryptosporidium

and  helminths

Ascaris lumbricoides,

T

richuris trichiura

and

Taenia

spp (Trönnberg et al., 2010)

Protozoa and helminths in faecal material

      Parasites  54% positive for Giardia  21% positive for Cryptosporidium Helminths  59%

Ascaris lumbricoides

 48%

Trichuris trichiura

 18%

Taenia

spp In 73% of the 120 household toilets, one or several types of helminths were found Prevalence by family (at least one member infected) Supports theory of high prevalence in certain areas Treatment needed before use of faeces (Trönnberg et al., 2010)