waterborne pathogens in developing countries
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WATERBORNE PATHOGENS WATERBORNE PATHOGENS OF CONCERN IN OF CONCERN IN
DEVELOPING COUNTRIES:DEVELOPING COUNTRIES:
with Special Reference to Libyawith Special Reference to Libya
Prof. Khalifa Sifaw GhengheshProf. Khalifa Sifaw GhengheshDept. of Medical Microbiology, Dept. of Medical Microbiology,
Faculty of MedicineFaculty of MedicineTripoli - LibyaTripoli - Libya
INTRODUCTION
Drinking water is a major source of microbial pathogens in developing countries.
Waterborne disease cause more than 2 million deaths and 4 billion cases of diarrhea annually.
9 out of 10 deaths are in children and virtually all of the deaths are in develop-ing countries
WATERBORNE PATHOGENS INWATERBORNE PATHOGENS INDEVELOPING COUNTRIESDEVELOPING COUNTRIES
BACTERIA
Microorganism Major disease---------------------------------------------------------------------------Salmonella typhi Typhoid feverS. paratyphi Paratyphoid feverOther Salmonella SalmonellosisShigella spp. Bacillary dysentery
(Shigellosis)Vibrio cholerae CholeraDiarrheagenic E. coli GastroenteritisYersinia enterocolitica GastroenteritisCampylobacter jejuni GastroenteritisAeromonas spp. GastroenteritisVarious mycobacteria Pulmonary illness
ENTERIC VIRUSES
EnterovirusesPolio viruses PoliomyelitisCoxsackie A & B Aseptic meningitisOther enteroviruses Encephalitis
Rotavirus Gastroenteritis
Adenoviruses Upper respiratory and gastrointestinal illness
Hepatitis A & E viruses Infectious hepatitis
Norovirus Gastroenteritis
PROTOZOA & HELMINTHS
Balantidium coli Balantidosis (dysentery)
Cryptosporidium parvum Cryptosporidiosis
(gastroenteritis)
Entamoeba histolytica Amoebic dysentery
Giardia lamblia Giardiasis (gastroenteritis)
Ascaris lumbricoides Ascariosis
Causative Agents of Childhood Diarrhea in Libya
% positiveAgent Tripoli Benghazi Zliten--------------------------------------------------------------------------------------------------
-Single 41 35 44Multiple 19 6 12Rotavirus 32 24 27Salmonella 11 7 14Shigella 6 5 4Enteropathogenic E. coli 11 8 NDE. coli O157 7 ND NDCampylobacter 6 2 NDYersinia enterocolitica 0.6 0 NDAeromonas 15 0 6Cryptosporidium ND ND 13Giardia lamblia ND ND 1Entamoeba histolytica ND ND 12
Bacteriological Quality of Drinking Water in Libya
Type of No % positive for
Water tested E. coliAeromonas
----------------------------------------------------------------------
Well 1000 37 49
Fasghia 56 27 73
Majin 62 ND 60
From Mosques 50 14 18
Mineral 216 0 0
Outbreaks of waterborne disease in England and Wales from 1991 to 2000
Cause Number of Number Outbreaks of cases
----------------------------------------------------------------------------------------------------------
Public water supplies:Cryptosporidium 23 2837Campylobacter 1 281Gastroenteritis 1 229
Total 25 3347
Private water supplies:Campylobacter 8 178Mixed Campylobacter 1 43and CryptosporidiumCryptosporidium 3 74Gastroenteritis 2 81Giardia 1 31E. coli O157 1 14
Total 16 421
Recreational contact with surface waterViral gastroenteritis 1 7
Swimming pool contactCryptosporidium 23 337
----------------------------------------------------------------------------------------------------------
Overall total 65 4112
Outbreaks of waterborne disease in Tripoli1992-2004
Number of Number outbreaks of
cases
---------------------------------------------------------------------------------
Public water supplies:
Shigella sonnei 1 >1500
Private water supplies:
Shigella flexneri 1 6
Some Concerns Regarding Waterborne Pathogens
Efficacy of treatment (filtration and chlorination) and the use of E. coli as a fecal indicator: Chlorine-resistant parasitic protozoa
• Oocysts of Cryptosporidium parvum Various enteric viruses
Important to match the appropriate indicator for the group of pathogen(s) of interest.
Emerging Waterborne Issues
Rapid urbanization of humans in developing regions:
Places further stress on inadequate water supply and sanitation.
Climate change: A change in the distribution of rainfall
• Heavy rain fall• Flooding
Greater extremes in global weather patterns• Major waterborne outbreaks typically follow large storm
events in developing countries
Evolution of new pathogens
What We Should Do?
A combination of both monitoring of water quality and epidemiological surveillance.
A comprehensive public health surveillance strategy seems the most efficient approach to better understand and control the impact of water quality on gastrointestinal disease.
CONCLUSION
Despite our efforts, waterborne pathogens will
always be a major issue for human health, and
particularly so in developing countries
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