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Health and Sanitation Gwatt-Zentrum Tuesday, 23 August 2011 Peter - - PowerPoint PPT Presentation

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Epidemiology and Public Health Ecosystem Health Unit Sanitation Course SDC / HA Health and Sanitation Gwatt-Zentrum Tuesday, 23 August 2011 Peter Odermatt, PhD MPH Excreta-related infections Viral diseases Poliomyelitis Direct

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Epidemiology and Public Health Ecosystem Health Unit

Sanitation Course SDC / HA

Health and Sanitation

Gwatt-Zentrum Tuesday, 23 August 2011

Peter Odermatt, PhD MPH

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Excreta-related infections

Viral diseases

  • Poliomyelitis
  • Hepatitis A
  • viral diarrhoea

Bacterial diseases

  • Cholera
  • Typhoid
  • Shigellosis
  • Bacterial diarrhoea

Protozoal diseases

  • Amoebiasis
  • Giardiasis
  • Balantidiasis
  • Cryptosporidiasis

Helminth diseases

  • Ascariasis, Hookworm,
  • Trichiurasis, Strongyloidiasis
  • Schistosomiasis
  • Taeniasis
  • Clonochiasis / Opisthorchiasis

Direct transmission: Excreta Man (finger, water, foodstuff,

kitchenware, flies, cockroaches, soil)

Indirect transmission: Excreta inter. host man

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Virus

Capsid, protein spikes, genetic material (DNA, RNA)

Bacteria –

Capsule (sticky, biofilm), Pili (attach), DNA, flagellum (moving); prokaryote Most bacteria beneficial (intestinal flora, degradation nutrients), spore forming, some pathogens

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Corynebacterium

  • sp. (Gram +)

Staphylococcus aureus Micrococcus

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Parasite:

Protozoa (one cell), Helminths (worms), Ectoparasite (lice, flees, lice…), Giardia lamblia Malaria (Plasmodium sp.) Schistosomiasis Hookworm

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Preventive measures:

  • sanitation
  • water  hygiene

person, food … Context:

  • behaviour
  • environment
  • education
  • sociological and
  • economic status
  • health service

(WHO, 1995)

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  • I. Excreta related diseases
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Factors Affecting Transmission

  • General state of health,
  • Nutrition
  • Immunity ...
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6 Excreta related transmission routes

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Excreta related infections

  • I. Faecal-oral disease (non-

bacterial): non-latent, low infection dose

  • Virus: hepatitis A
  • Protozoa: Entamoeba histolytica, Giardia

lamblia, Cryptospridium sp.

  • Helminths (worms): Enterobiasis,

Hymenolepiase

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Trophozoite Entamoeba histolytica

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Cysts Entamoeba histolytica

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In colon:

  • A. Non-invasive infection
  • B. Intestinal disease
  • C. Extra-intestinal disease

Amoebiase

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Intestinal abscess due to Entamoeba histolytica

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Liver abscess due to Entamoeba histolytica

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Entamoeba histolytica

  • protozoan dysenteria (diarrhoea with blood)
  • ± 10% global population infected (without

symptoms)

  • ± 50 Mio sick & reach 100’000 deaths/year
  • Diagnosis
  • Examination of stool sample
  • Serodiagnostic and PCR (DNA search in stool)
  • Prophylaxis
  • Transmission fecal-oral
  • Food – and water-hygiene
  • Personal hygiene → sanitation
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  • II. Faecal-oral bacterial diseases:

non-latent, medium infection dose, moderately persistent, multiplication

  • diarrhoeas/dysenteries: Salmonellosis,

Shighellosis, Campylobacter, Cholera, Escherichia coli diarrhoea

Excreta related infections

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Cholera – Vibrio cholerae

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Vibrio spp. in shellfish, Abidjan

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Prevalence of Vibrio spp. infection in shellfish, Abidjan

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Vibrio species in shellfish, Abidjan

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  • III. Soil Transmitted helminths:

latent, persistent, no intermediate host

  • e.g. roundworm (Ascariasis), hookworm, …

Excreta related infections

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Ascaris life cycle

  • latency
  • 200’000

eggs/day

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Hookworm

life cycle

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Hookworm

  • Affected group: children
  • « bloodsuckers » → anaemia,

malnutrition

  • Latency
  • maturation in environment (moisture required)
  • Active penetration skin
  • protection (shoes …)
  • Treatment
  • efficient, cheap, safe (mass-treatment)
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  • IV. Beef and pork tapeworm:

latent, persistent, cow/pig intermediate host

  • Tapeworm (Taeniasis) - Cysticercosis

Excreta related infections

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Cysticercus (= larval stage) in intermediate host Head (Scolex) Egg Segmented body Proglottide

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Taenia solium Taenia saginata

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  • Progrottid von

Taenia saginata

  • > 15 Uterusästen
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Proglottiden

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Ei: Taenia sp. : 31 – 43 µm; gelb-braun

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Finnen (= Cysticercus) in Schweinefleisch

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Cysticercus von Taenia solium

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Cysticercose

Finne (Cysticercus)

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Garcia et al. Lancet, 2003

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  • Utilisation of human

excreta

  • Proximity with pigs
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  • V. Water based helminths

(worms): latent, persistent, aquatic intermediate hosts

– Schistosomiasis (Bilharzia) – Other flukes: liver fluke, intestinal flukes, lung fluke

Excreta related infections

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By J. Dick Maclean

Flukes (Trematodes)

  • adult worms
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Prevalence of O. viverrini in schoolchildren in Lao PDR (2003)

Vietnam Cambodia Thailand China

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Opisthorchis viverrini

Life cycle

Metacercaria

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Opisthorchis viverrini:

  • Adult
  • billiary tract,

Length: < 10 mm Cyproid fish:

  • length: 5-10 cm

Metacercaria in fish

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Schistosomiassis - Life Cycle

Cercariae Adult parasite Egg Fresh-water snail

urine stool

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snail : Neotricula aperta Rocky areas of Mekong river

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Reservoir host: Dog, porc, buffalo …

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Control measures

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Global distribution of schistosoma infections

From: Gryseels et al. Human schistosomiasis. Lancet 2006; 368: 1106–18

High transmission Low transmission (pre-elimination)

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  • VI. Excreta related insect vectors:

– Culex sp.- mosquito: Filariasis – Flies, cockroaches: transmission of I & II

Excreta related infections

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Eye infection: Trachoma

  • Chronic infection (conjunctiva &

cornea) caused by Chlamydia trachomatis (bacteria) Blindness

  • Transmission: person-person

direct or indirect (flies, hand, towel,…)

  • Prevention: regularly face +

sanitation

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6 Excreta related transmission routes

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Water transmitted infectious disease

  • I. Water-

borne Pathogens carried by water Faecal-oral transmission

  • II. Water-washed

(Water- scarce) water quantity problem

  • III. Water-

based Pathogen depends

  • n water animal/

plant

  • IV. Water-

related Pathogen transmitted close/ near water Mosquito-borne

Water related diseases

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Water related infections

  • I. Water-borne route:

– Faecal-oral route of transmission (faecal contamination of water):

  • Person to person, animal to person, direct - indirect

(water, food, towels …)

– Intestinal tract disease:

  • Virus (Hepatitis A, Poliomyelitis), Bacteria

(Cholera, Shigellosis, …), Protozoa (Crytosporidiosis, Amoebiasis, Giadiasis, …)

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  • II. Water washed – water scarce:

– Transmission due to low water quantity (washable infection) – A. Water washed: intestinal tract infection

  • Increase water availability: decrease faecal-oral

transmission, e.g. cholera, bacillary dysentery, … – B. Water washed: skin infection / eye disease

  • bacterial skin diseases (scabies, …), eye infection

(trachoma)

  • Transmission: not faecal-oral, not water-borne

– C: Water washed: insect-borne

  • Louse-borne: typhus outbreak (Rickettsia provazekii)
  • Louse-borne relapsing fever (Borrelia recurrentis)

Water related infections

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  • III. Water-based route

– Pathogens depend on water animals/plants (intermediate host) for transmission:

  • snails, fish, …

– e.g. schistosomiasis, flukes, …

Water related infections

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  • IV. Water related route of transmission

– Spread by/near water – insect (mosquito)-borne disease – Development of insect bound to water: requirement of mosquito (ecology) defines distribution – Malaria: Anopheles sp. – Dengue haemorrhagic fever (DHF): Aedes aegypti

Water related infections

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50-200 eggs 2-3 days

Development of Anopheles mosquito

Larve in clean water (parallel to surface) egg → adult: 10-14 days biting position pupe 3-5 days 3-5 days adult

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Malaria life cycle

Mosquito Liver Blood

Livercell Red cell Gametocyte

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Malaria

  • Parasite: number 1 killer
  • 4 parasites: Plasmodium falciparum deadly (no

reservoir)

  • Disease: from symptomless to acute disease & death

(semi-immunity possible)

  • Treatment exists but: expensive, diagnosis not easy,

under medical supervision, costly, … no vaccine

  • 42% of world population at risk
  • Ca. 500 million cases/year; ca 2 million death/year
  • Huge economic burden (hospital admission, disease

periods, death, …)

  • Mosquito: Anopheles sp., large number of species
  • Ecology of Anopheles sp. varies: Urban / rural; Plains,

forest, mountains, …; Small – large water sites; Look closely at local condition

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Malaria endemic countries (WHO, 2005)

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DHF : external bleeding

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Dengue (hemorrhagic) fever

  • Emerging disease in tropical and subtropical areas
  • Virus infection: Arbovirose n°1 for human infection/

disease

  • No treatment, no vaccine available
  • Transmission by mosquito: Aedes aegypti

Epidemics by intervals (3 -5 years)

  • Urban disease, today invasion in rural areas
  • 2.5-3 millions pop. At risk (1/2 global population)
  • 50-100 million cases/ year
  • 0,5 million de DHF hospitalised ( 90% children <

15 years)

  • Imported cases frequent
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Tourniquet test positive: spots = skin bleeding

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Aedes aegypti Mosquito

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Geographical distribution de Aedes aegypti

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Outbreak in Cuba 1981 : morbidity - mortality

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Larvicide:

  • Abbate
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  • I. Water borne

– Cryptosporidiosis

  • II. Water-washed

– Skin, eye disease

  • III. Water-based

– Schistosomiasis – Flukes

  • IV. Water-related

– DHF – Malaria

  • Improve quality of drinking water (prevent use of

unprotected sources)

  • Increase use of water quantity (availability,

reliability, acceptance); personal & domestic hygiene

  • Sanitation (prevent contamination); reduce water

contacts (infested water); control intermediate hosts; prevent man-made disease

  • Surface water management (water bodies: small–

large); destroy breeding site (cleaning up activities); reduce exposure to water sites; mosquito control (impregnated nets etc); man- made disease

Water: transmission and preventive strategies

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Thank you for your attention!