assoc. prof. dr. yvonne lim ai lian department of parasitology, faculty of medicine, university of...
TRANSCRIPT
Assoc. Prof. Dr. Yvonne Lim Ai Lian
Department of Parasitology, Faculty of Medicine,
University of Malaya, 50603 Kuala Lumpur, Malaysia.
Water Safety Conference 2010
Aim - Halving by 2015 the proportion of people without sustainable access to safe drinking water and proper sanitation.
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Declared as the International Decade for
Action – Water for Life
2005-2015
Every year, unsafe water, coupled with a lack of basic sanitation, kills at least 1.6 million children under the age of five years especially from diarrheal diseases.
(Source: WHO and UNICEF 2006)
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
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Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
Cryptosporidium Giardia Entamoeba Blastocystis
CyclosporaToxoplasma Isospora Acanthamoeba
Parasites that can cause diarrheal diseases
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Parasite Number of outbreak(s)Crytosporidium 165Giardia 132Entamoeba 9Cyclospora 6Toxoplasma 3Isospora 3Blastocystis 2Balantidium 1Microsporidium 1Acanthamoeba 1Naegleria 1Source: Karanis et al., 2007. Waterborne transmission of protozoan parasites: a worldwide review of outbreaks and lessons learnt. Journal of Water and Health 5: 1-38.
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
In 2005 – WHO included both Giardia and Cryptosporidium in the ‘Neglected Diseases Initiative’ (Savioli et al., 2006).
In 2006 - WHO has recognised Cryptosporidium as a ‘reference’ for water quality (Medema et al., 2006).
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World Health Organization
Global recognition
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
Discovered by Antonie Van Leeuwenhoek in 1681
Common intestinal parasite (especially in children)
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How does Giardia get into human body?
In healthy people (immunocompetent) - self-limiting
Main symptom – diarrhoea (initially frequent and watery but later becomes bulky, sometimes frothy, greasy and offensive)
In acute cases - flatulence, sulphurous belching, abdominal distension with cramps
In chronic cases - malaise, weight loss & vitamins A, B12 malabsorption, disaccharidase (lactase) deficiencies
Young children “failure to thrive”
In healthy people (immunocompetent) - self-limiting
Main symptom – diarrhoea (initially frequent and watery but later becomes bulky, sometimes frothy, greasy and offensive)
In acute cases - flatulence, sulphurous belching, abdominal distension with cramps
In chronic cases - malaise, weight loss & vitamins A, B12 malabsorption, disaccharidase (lactase) deficiencies
Young children “failure to thrive”
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Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
Nitroimidazole drugs (i.e. metronidazole, tinidazole and ornidazole) - highly effective
Quinacrine - excellent efficacy but poorly tolerated in children
Furazolidone - effective alternative but must be administered four times a day for 7 to 10 days
Paromomycin - used during early pregnancy, because it is not systematically absorbed, but it is not always effective
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Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
Important pathogen in immunocompromised people (e.g., HIV/AIDS) – opportunistic parasite
May cause an acute gastrointestinal disease that can lead to death in these individuals
Oocysts (infective stage) ◦ extremely hardy to environmental
pressures◦ easily spread via water◦ difficult to inactivate (by chlorination) or
to remove from water intended for consumption without the use of filtration
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Cryptosporidium
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
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How does Cryptosporidium get into human body?
In immunocompetent people - self-limiting Main symptom – non-bloody watery diarrhea
without fever
Other symptoms – low grade fever, nausea & vomiting, abdominal pain
In immunocompetent people - self-limiting Main symptom – non-bloody watery diarrhea
without fever
Other symptoms – low grade fever, nausea & vomiting, abdominal pain
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What are the symptoms of Cryptosporidium infections?
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
In immunocompromised patients (e.g., HIV/AIDS)
Diarrhea – up to 17 litres a day Bowel-movement frequency – 6-25 per day Fluid losses of 3-6 litres per day is common Abdominal cramping and pain Low grade fever Nausea Vomiting Tiredness Profound weight loss – especially in chronic cases
In immunocompromised patients (e.g., HIV/AIDS)
Diarrhea – up to 17 litres a day Bowel-movement frequency – 6-25 per day Fluid losses of 3-6 litres per day is common Abdominal cramping and pain Low grade fever Nausea Vomiting Tiredness Profound weight loss – especially in chronic cases
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What are the symptoms of Cryptosporidium infections in HIV/AIDS patients?
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
Currently, there is no drug of choice.
Symptomatic treatment.
In HIV patients, cryptosporidiosis treatment of choice is immune reconstitution using HAART.
This acts prophylacticly.
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Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
HUMAN
Elderly Children
Immuno-compromised
WATER
Oceans
StreamsRivers
ANIMAL
Cattle
DogsChicken
Goat
Cats
Sewage
DrinkingWater
Web of interactions between human, animal and the environment
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
High excretion rate for prolonged period by infected hosts◦ Infected calf - up to 105 cysts g-1 faeces◦ Infected human - up to 106 cysts g-1 faeces◦ For several days and weeks
Low infectious dose◦ eg. 10-100 (oo)cysts
Robustness of the transmission stages (i.e., cysts and oocysts) ◦ enables them to survive some water treatment processes
Wide host range - humans and animals◦ increases the potential for environmental spread and
contamination
Small size –4-10m◦ aid their penetration through sand filters
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Why are Cryptosporidium and Giardia easily transmitted via water?
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
In Malaysia
Petronas Twin Towers
Journal of Water and Health, 2008
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Key:
Human population
Animal population
Water samples
Prevalence of Giardia – 2.6 – 25%◦ Out of every 100 people, at least 3-25 have
Giardia infection.
Prevalence of Cryptosporidium – 0.9 – 23% Out of every 100 people, at least 1-23 have
Cryptosporidium infection.
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Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia
Occurrence of Giardia and Cryptosporidium in domestic and wild animals in Malaysia (4.1-36%)
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Water type Numbers examined
Giardia Cryptosporidium
% positive Range of cysts/L
% positive Range of oocysts/L
Environmental water
Rivers 183 38.8% 0.1 – 12,780 10.9% 0.4 - 246
Well 28 17.9% 0-0.25 7.1% 0-0.75
Drinking water treatment plants
Dam 28 0 0 0 0
Raw 92 48% 0.03-120.0 8.7% 0.05 – 3.0
Treated 91 0 0 0 0
Backwash water 2 100% 1600 - 2400 100% 1200 - 1600
Household water
Kitchen tap 10 0 0 0 0
Household storage containers
20 100% 0.4 – 2.0 0 0
Sewage water treatment plants
Influent 30 100% 18-8480 40% 1-80
Effluent 30 83.3% 1-1462 20% 20-80
Occurrence of Giardia and Cryptosporidium (oo)cysts in Malaysian water
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Human populations Giardia duodenalis assemblage A Giardia duodenalis assemblage B Cryptosporidium hominis Cryptosporidium hominis
IaA14R1, IbA10G2R2, IdA15R2, IeA11G2T3R1, IfA11G1R2
Cryptosporidium parvum IIdA15G2R1
Cryptosporidium meleagridis Cryptosporidium felis
Bird and cattle Cryptosporidium parvum
Goat Giardia duodenalis assemblage A and E
Zoological watershed Giardia duodenalis assemblage A and B
Recreational water Giardia duodenalis assemblage A
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Monis et al. 2009
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Giardia sp. Genotype Major host
G. duodenalis Assemblage A Humans and other primates, dogs, cats, livestock, rodents and other wild mammals
Assemblage B Humans and other primates, dogs, some species of wild mammals
Assemblage C, D Dogs
Assemblage E Cattle, other hoofed livestock
Assemblage F Cats
Assemblage G Rats
G. agilis Amphibians
G. muris Rodents
G. microti Muskrats, voles
G. psittaci Birds
G. ardeae Birds
Which species of Giardia is dangerous to humans?
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Which species of Cryptosporidium are dangerous to humans?
Species Major Hosts
Cryptosporidium parvum* Human, mouse, cattle, pig, sheep, horse, goat
Cryptosporidium hominis* Human
Cryptosporidium meleagridis* Human , turkey
Cryptosporidium felis* Human , cat
Cryptosporidium canis* Human , dog
Cryptosporidium muris* Human , mouse
Cryptosporidium suis* Human, pig
Cryptosporidium andersoni CattleCryptosporidium baileyi ChickenCryptosporidium bovis CattleCryptosporidium fayeri KangarooCryptosporidium fragile Black-spined toadCryptosporidium galli ChickenCryptosporidium macropodum KangarooCryptosporidium molnari FishCryptosporidium ryanae CattleCryptosporidium saurophilum LizardCryptosporidium scopthalmi FishCryptosporidium serpentis Snake, lizardsCryptosporidium varanii LizardCryptosporidium wairi Pig
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Detection of these organisms have been sporadic, uncoordinated and not systematic.
Making these data less useful for effective and accurate interpretation.
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The need for regulatory procedures in Malaysia.
Putting in place mechanisms of monitoring and surveillance.
Event-driven monitoring of source water for Cryptosporidium and Giardia contamination
Site-specific risk assessment Site-specific monitoring
programme
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Development of a risk assessment model for Cryptosporidium and Giardia in Malaysia
Extensive application of the risk assessment in all catchment areas in Malaysia
Utilisation of predictive model such as Geographical Information System (GIS) to map out the areas with
various risk levels
Comprehensive determination of occurrence, density, viability and molecular characterisation of
Cryptosporidium and Giardia isolated from samples of high risk areas.
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REGULATEDMONITORING
AND SURVEILLANC
E SYSTEM
The late Prof. Rohani Ahmad (National University of Malaysia, UKM)
The late Prof. Huw Smith (Director, Scottish Parasite Diagnostic Laboratory, Glasgow)
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Division of Engineering Services, Ministry of Health Malaysia
National University of Malaysia (UKM)
Universiti Putra Malayasia (UPM)
Universiti Malaysia Terengganu
Scottish Parasite Diagnostic Laboratory
Drinking Water and Wastewater Treatment Plant Operators in various parts of Malaysia
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Thank youPromoting clean and safe water supply
Yvonne Lim Ai Lian
Water Safety ConferenceNovember 2-4 2010, Kuching, Malaysia