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Valuing Health and Economic Costs of Water Pollution in Thailand

By

Siripen Supakankunti

Pirus Pradithavanij

Tanawat Likitkererat

The Centre for Health Economics Faculty of Economics, Chulalongkorn University

Bangkok, Thailand

July 2001

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Table of Contents Page 1. Introduction 2 2. Natural History of Selected Water-borne Diseases 2 2.1 Diarrhea 3 2.2 Dysentery 4

2.3 Cholera 5 2.4 Typhoid 5 3. Method of Valuing Health Impact and Economic Costs 6 3.1 Health Impacts in term of Burden of Water-borne Diseases 6 3.2 Economic Cost of Water-borne Diseases: 6 4. Study Results 7 4.1 Calculation of Disability Adjusted Life Years (DALYs) 7

4.2 Direct and Indirect Cost 12 5. Summary 14

5.1 Diarrhea 14 5.2 Dysentery 14 5.3 Typhoid 15

Annex 16 Reference 26

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List of Tables Page Table 1 Causes of acute diarrhea 3 Table 2 Life Table 7 Table 3 Years of Life Lost 8 Table 4 Years Lived with Disability 8 Table 5 Disability Adjusted Life Years 8 Table 6 DALYs, YLLs, and YLDs of the 3 Specific Diseases Classified by

Selected Provinces Based on Classification of Water Quality in

Table Source of Drinking Water

Table Cost of Out-Patient Care by Specific Disease

Table Sensitivity Analysis of Out-Patient Cost

Table Hospitalization cost of In-Patient Care classified by specific diseases 13 Table 11 Length of Stay and Wage Lost due to Hospitalization of Thai People

Aged More Than 14 years old 13 Table 12 Income Forgone from Premature Death Caused byWater-borne diseases 13 Table 13 Direct and Indirect Cost classified by 3 specific diseases 14 Table 14 Quality Standard of Water in the Ground Reservoir 16

Classification of ground water reservoir Table 15 Income forgone from premature death caused by Diarrhea & Food Poisoning 18 Table 16 Income forgone from premature death caused by Dysentery 20 Table 17 Income forgone from premature death caused by Enteric Fever 23

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Valuing Health and Economic Costs of Water Pollution in Thailand Siripen Supakankunti1, Ph.D. Pirus Pradithavanij2, M.D., M.P.H.

Tanawat Likitkererat3, M.Sc. 1. Introduction

Thailand is a tropical country. River and water reservoirs are essential for living and considered life of Thai people. Water quality is one of the serious environmental problems facing Thailand. The purpose of this paper is to make rough estimates of the health and economic costs associated with water pollution in Thailand, excluding the estimate of production impacts. Earlier studies conducted by the World Bank indicated that the health benefits of providing universal access to clean water and sanitation to the Thai people would be significant (World Bank, 1997). The results of this study are intended to raise awareness of policy makers about the importance of water quality issues, to contribute to the setting of priorities for action, and to improve the quality and management of water resources in the country. However, this analysis is only limited to the estimation of public health impacts of water pollution and measured in terms of the burden of water-borne diseases, including diarrhea, dysentery, cholera and typhoid on the population. In valuing the economic costs of these four diseases, two types of costs are considered: (i) direct costs; and (ii) indirect costs. 2. Natural History of Selected Water-borne Diseases4, 5

Water borne diseases refer to illnesses caused by contaminated water. Very often

contaminated water is mixed with food, so the characteristics of a food borne diseases are rather similar to those water borne diseases. Contamination may be both by biological agents and chemical agents. This study, nonetheless, emphasizes only on biological agents. Diseases or abnormal conditions usually present themselves with gastrointestinal symptoms, because pathogens contact directly and firstly with gastrointestinal tract.

In pathogenesis, there needs to have an imbalance in three main factors, host, agent, and environment. All the factors are interdependent. The host is vulnerable when exposed to environment contaminated with virulent agents, by drinking or eating unclean water or food. An immuno-compromised person is more susceptible to disease. A minimum quantity of agents is also required to cause the disease. Many pathogens can survive in natural water after passing from patients or asymptomatic carriers to environment via secretion such as stool. A coliform bacterium is therefore a standard indicator to demonstrate whether suspected water is unpurified with feces or not. There may be vectors such as flies or other insects, which carry pathogens from one place to another place. In an area where sanitation and public water is poor or does not exist, pathogens such as cholera can spread very quickly and widely.

1 Director, the Centre for Health Economics, Faculty of Economics, Chulalongkorn University. 2 Assistant Director, Bangkok Pattaya Hospital, Chonburi. 3 Academic Staff, The College of Public Health, Chulalongkorn University. 4 Grendell JH, McQuaid HR, and Friedman SL. Current Diagnosis & Treatment in Gastroenterology. International edition. LANGE medical book. 1996. 5 Jaroonvej N. Tropical Diseases . 2nd edition.

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Besides, socio-economic status and education are important host factors. High socio-economic status will generally prevent host from exposure to hazardous environment. Sufficiently educated people will know how to protect themselves and how to take care primarily of themselves, if afflicted, better than uneducated people. For these reasons, the prognosis and outcome of treatment, if any, are predictably good in more educated patients. 2.1 Diarrhea

Diarrhea is a common condition with severity varying from acute to chronic and from self-limited symptom to severe life threatening condition. The causes of diarrhea are numerous for both acute and chronic. It is helpful in clinical practice to differentiate acute from chronic diarrhea as to which the proper management of such cases can be administered. Acute diarrhea is basically infectious diseases, whereas chronic diarrhea is fundamentally patho-physiological abnormalities. This study will, therefore, focus on acute diarrhea as a contagious disease associated with water.

Exposure to unpurified water and contaminated food is one of the common causes of acute diarrhea that may lead to ingestion of either infectious agents or their toxins that are summarized in Table 1.

Table 1. Causes of acute diarrhea4

Noninflammatory Diarrhea Inflammatory Diarrhea Viral

Norwalk virus Rotavirus

Protozoa

Giardia lamblia Crytosporidium

Bacterial 1. Preformed enterotoxin Staphylococcus aureus Bacillus cereus Clostridium perfringens 2. Intra-intestinal enterotoxin

production E coli (Enterotoxigenic) Vibrio cholerae

New medications Fecal impaction

Viral Cytomegalovirus

Bacterial

1. Cytotoxin production E coli O157:H7 (Enterohemorrhagic) Vibrio parahaemolyticus Clostridium difficile 2. Mucosal invasion Shigella Salmonella sp. Enteroinvasive E coli Aeromonal Yersinia enterocolytica Plesimonal 3. Bacterial proctitis Chlamydia N gonorrhoeae

Protozoal

Entamoeba histolytica

Intestinal ischemia Inflammatory bowel disease Radiation colitis

Thanks to the breakthrough in molecular biochemistry, advance laboratory investigation in acute diarrhea can reveal pathogenic microorganisms up to 60-80% of the cases. It is, however, costly and unnecessary, particularly in mild cases. Such investigation

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will therefore be useful in epidemiological studies and biomedical research rather than the routine management of disease or daily medical practices. More useful investigation in clinical practice is a microscopic examination of the stool. This method can help distinguish noninflammatory (enterotoxigenic) and inflammatory (enteroinvasive) diarrhea as their therapies are quite dissimilar.

Most prevalent diarrhea is acute in onset and usually persists for less than 3 weeks. More than 90% of acute diarrhea is mild and self-limited and responds within 5 days to simple rehydration therapy or symptomatic antidiarrheal agents. The goal of initial intervention is to distinguish these patients from those with more serious conditions.

Food poisoning is another clinical form of acute diarrhea. Gastrointestinal symptoms usually include both upper and lower tracts. Nausea, vomiting, abdominal pain, and diarrhea with or without low-grade fever are commonly present in most cases within a short period of exposure. One of the major causes of food poisoning is bacteria and their toxins listed in Table 1. 2.2 Dysentery

Dysentery has two main types, bacillary dysentery (Shigellosis) and amoebic dysentery.

Bacillary dysentery is caused by a gram negative bacilli, namely Shigella. It can be divided into 4 subgroups according to their biochemical properties, Sh. dysenteriae, Sh. flexneri, Sh. boydei, and Sh. sonnei. In tropical areas, Sh. flexneri is responsible for the majority of cases up to 78%, whereas in subtropical areas, Sh. sonnei is responsible for up to 85%. Shigella bacilli are passed within stool and can contaminate food and water by hand of infected persons or fly. Incubation period is approximately 1-7 days, but usually less than 3 days. Classical case will present with severe bloody diarrhea, crampy abdominal pain, and fever. In early stage, watery diarrhea without gross blood can be found and bloody stool will follow 3-5 days later.

Severe case usually occurs in children, elderly, and unhealthy people and is caused by Sh. dysenterias the most. In such cases, gangrene of large bowel, circulatory collapse, and death can occur. Chronic shigellosis and chronic carrier may be developed in some cases. Extraintestinal complications may involve remote systems like respiratory system, neuromuscular system, and hematological system.

Epidemiologically, it can be found all around the world, where public utility and sanitation are not well established, where people live together in crowded places, and where personal hygiene is poor, especially in tropical areas. The incidence is approximately 10-15% of acute diarrhea cases in adult. This number is higher in children, particularly in the age under 8 years. The incidence may rise up to 15-25% and reach its peak in the age of 9-18 months.

Like bacillary dysentery, amoebic dysentery or amebiasis is an inflammatory diarrhea. However, it is caused by protozoa, namely E. histolytica. Clinical symptoms can vary from asymptomatic infected person or carrier to a full-blown dysentery with hepatic abscess. The patients can also be presented with both acute and chronic illness.

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Incubation period is approximately 8-10 days. Patients may suffer from lower abdominal pain, intermittent bloody mucoid stools, and fever. No or improper treatment may result in;

• Asymptomatic amoebiasis or carrier • Chronic amoebiasis • Amoebic granuloma or amoeboma • Serious complication such as intestinal perforation, widespread of disease with

abscess formation (hepatic abscess)

The prevalence has been estimated at 10% and up to 80% of population in endemic areas. Man and women are equally at risk in all age group especially after 20. The reservoir of protozoa is a person who could be either a carrier or a patient. An infective stage is a 4-nucleated cyst passing with stool. It can contaminate food and drinking water if the sanitation and personal hygiene is poor. 2.3 Cholera

Vibrio cholerae is a gram-negative, comma-shaped rod that can produce the most severe form of acute watery diarrhea (cholera gravis). The clinical spectrum is, however, ranging from nothing in immune person or asymptomatic carrier to profound volume and electrolyte depletion and death soon after first 2-3 hours of onset, although severe cases are less frequently found. The organism produces toxin, named cholera toxin. This toxin leads to sudden and severe fluid and electrolyte imbalance by promoting secretion and inhibiting absorption in small bowel.

Early onset may manifest with vomiting and abdominal distension followed by rapidly repeated passing of watery stool probably with incontinence. The characteristic of stool is large in volume and looks like a “rice water” with minimal content. Low grade fever may be presented. Serious complications may include pulmonary edema, acute renal failure, and severe electrolyte imbalance.

The organism has capability to spread very quickly, either sporadically or epidemically. It infests only in human beings. The prevalence is notably high in illegal immigrants near the border and some major industrial cities. Consequently, sporadic outbreak can be found in some specific areas where there are illegal immigrants. In endemic areas, adult is usually immune to the disease, whereas children are at great risk. One of major risk factors is sanitation and access to pure water, since water is major route of transmission. 2.4 Typhoid

The causative agent is Salmonella sp.. Salmonella can actually produce 2 major clinical syndromes, typhoid fever and gastroenteritis. Typhoid is a systemic illness that has few primary symptoms relating to gastrointestinal tract. Typhoid fever or enteric fever or paratyphoid fever are caused by S. typhi, S. paratyphi A, B, or C. It is characterized by a prolonged fever with other systemic manifestations. In classical case, incubation period is ranging from 7 to 21 days and symptoms involve a 4 week period.

The first week is characterized by fever with or without chill, headache, poor appetite, and weakness. The second week is characterized by high and sustains fever,

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dehydration, and drowsiness. Organomegaly can also be found. Patients usually come to see physician during this week. Pulse and temperature dissociation will support a diagnosis. Many patients still have normal bowel habits. The third week is characterized by intermittent fever, intestinal involvement, and systemic involvement. Intestinal hemorrhage and perforation, and acute cholecystitis are potential complications that might need surgery during this period. Other complications that need medical treatment include pneumonia, jaundice, anemia, dissiminated intravascular clotting (DIC), psychosis, and renal involvement. Clinical symptoms will be subsided in the fourth week even no antibiotics is treated. Recurrent case and chronic carrier can also be found, particularly in gallstone patients.

Incidence of typhoid is higher in children than in adult and highest in the age below 6 months. Salmonella can be found in animals such as birds, livestock, reptiles and household animals. It is estimated that the infected quantities are 102-106. The spread of disease can occur sporadically or epidemically from contaminated food and water. Chronic carrier can pass the pathogen into the stool for more than one year if left untreated. Vaccination is available in both oral and injected forms.

Again all diseases mentioned above are closely related with food and drinking water. In fact, the balance between immunity and infectivity is theoretically important to prevent the diseases individually and collectively. The improvement in public sanitation and personal hygiene, and access to clean water are however still main stays to protect a large scale of population from the diseases. 3. Method of Valuing Health Impact and Economic Costs 3.1 Health Impacts in term of Burden of Water-borne Diseases

This analysis is limited to the estimation of public health impacts of water pollution and measured in terms of the burden of water-borne diseases, including diarrhea, dysentery, cholera and typhoid on the Thai population. Health impact valuation includes the estimation of DALYs, Disability-Adjusted Life Years, which includes year of life disability (YLDs) and years of life lost (YLLs). DALY was developed as the measurement unit for the Global Burden of Disease Study (Murray 1994), which was an attempt to quantify the burden of disease and injury on human populations. This quantification also requires a unit of time-based measures of health status that incorporate non-fatal health outcomes. 3.2 Economic Cost of Water-borne Diseases:

Economic cost can be estimated in term of direct and indirect economic cost. In this study, the direct economic cost includes the cost directly incurred by the patient such as cost of medical expenses as an outpatient or inpatient. Indirect economic cost refers to the cost that is indirectly incurred by the patient such as wage lost. Lost wages in fact should include both lost wages from disability and death. In this study, lost wage includes those that are the results of hospitalization as an inpatient and income forgone due to premature death.

Income forgone due to premature death of Thai population caused by water borne

diseases and quality of water can be classified into two categories. One is for productivity lost due to illness but can continue working and the other is due to premature death or

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productivity becomes zero. This approach is one among three approaches of estimations of human capital. Income forgone here is calculated based on premature death only but does not account for income loss due to illness (reduced productivity) because of insufficient data.

Where n = number of productive years lost due to premature death d = age of death r = discount rate (8.00%) g = increasing growth rate of income per capita per year (5.00%) Assumption: Working age is 14 to 60 years old.

4. Study Results 4.1 Calculation of Disability Adjusted Life Years (DALYs)

In calculating DALYs for the 3 selected diseases, 3 steps of calculation were performed which are 1) Life table calculation, 2) Year of Life Lost (YLL) calculation and 3) Years Lived with Disability (YLD) calculation.

To calculate life table, mid-year population and number of deaths from the birth-death registration system of the Ministry of Interior of the year 1998 has been used. Taken into account that registered population and death of infant and aging people is distorted. The distribution of the population must be adjusted. The calculated life table is as shown in table 2.

Table 2: Life Table

Life Expectancy Age Group Male Female

<1 70 - - - - - - -

For YLL and YLD calculation, as being communicable disease specific mortality and morbidity data from 1998 Annual Epidemiology Surveillance Report have been used. According to the nature of the 3 selected diseases, once the disease occurred, there are 2 possible ways, which are normal health, or death. There is no disability after patients have

∑=

= ++

=d-60n

0nn

n

r)(1g)(1 * capitaper GNP

Loss Forgone Income

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been treated. Thus, the data from DRGs payment system that composed of more than one million cases together with mid-year population have been used to figure out remission rate, incident rate and case fatality rate.

The results of YLL and YLD calculation are shown in tables 3-6. The numbers in

the bracket are parameters input to the calculation. The first parameter is discount rate and the second is age-weighting modulation factors. For discount rate, 0 means that there is no discount rate used in the calculation and the figure 3 demonstrates that the discount rate of 3% has been used. For the second parameter, the value could be 0 and 1, which indicates that age-weighting modulation factor is used in the calculation, or not. The discount rate was applied in this study because the result of the DALYs calculation must reflect lost in the future and must be calculated at present value. But for the age-weighting, we decided to apply uniform age-weighing on the assumption that lost of ability to work for various age groups is equal.

Table 3: Years of Life Lost

Diseases YLLs (0,0) YLLs (3,0) Male Female Total Male Female Total Diarrhea 7,399.90 6,890.28 14,290.18 3,758.00 3,468.04 7,226.04 Dysentery 242.88 240.79 Typhoid - - Total , , , , , ,

We reported only 3 diseases since there is no report on Cholera cases found. It is likely that Cholera cases were already reported as severe diarrhea. For all 3 types of diseases, there is no great difference between males and female. Diarrhea cases are found to be the greatest in numbers, compared to the other 2 diseases. This evidence showed that Thailand is faced with more serious case of Diarrhea than the other two types of water borne diseases.

Table 4: Years Lived with Disability

Diseases YLDs (0,0) YLDs , Male Female Total Male Female Total Diarrhea , , , , , , Dysentery , , , , , , Typhoid Total , , , , , ,

From calculated YLL and YLD, as a result of summation of those parameters

DALYs of the specific diseases are illustrated in table 5.

Table 5: Disability Adjusted Life Years

Diseases DALYs (0,0) DALYs (3,0) Male Female Total Male Female Total Diarrhea 62,749.36 64,079.20 126,828.57 58,303.78 59,831.76 118,135.54 Dysentery 2, , , , , , Typhoid Total , , , , , ,

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The health value or outcomes of calculation above are DALYs of the diseases for the whole country in the year For this study, DALYs of the diseases by selected provinces were calculated Provinces were selected by their quality of natural water across the country. The data were surveyed and reported annually by Bureau of Environmental Health, Department of Health , the Ministry of Public Health.

Unfortunately, the Annual Epidemiology Surveillance Report of the Epidemiology

Division, Office of the Permanent Secretary for Public Health, does not provide data segregated by age group and province at the same time. From the report, data separated by age group do not reflect provincial perspective. And data segregated by province were not segregated by age group. To solve the problem, we assume that distribution of cases over age group is the same in every province. Calculation of YLL/death and YLD/case have been performed. The YLL of the selected provinces caused by the 3 diseases by multiply number of death of the province by YLL/death were also computed. The YLD can be calculated by multiplying number of case by YLD/case. Finally, DALYs caused by the 3 diseases of the selected provinces can be done by summation of the YLL and YLD. The final results are as displayed in table 5.

Table 6. DALYs, YLLs, and YLDs of the 3 Specific Diseases Classified by Selected Provinces Based on Classification of Water Quality in 1999

Diarrhea

Province No. of Case

Incidence rate (/1000)

No. of Death

CFR (/

YLLs YLLs death YLDs YLDs case DALYs

Class

Nan , , ,

Roi-et , , ,

Class

Chai Nat ,

Nakorn Sawan , , ,

Ang Thong ,

Ayutthaya , , ,

Class

Sakol Nakorn , , ,

Nakorn Rajsrima

, , ,

Nonburi , , ,

Nationwide , , , ,

Dysentery

Province No of Case

Incidence rate

No of Death

CFR YLLs YLLs death YLDs YLDs case DALYs

Class

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Nan - - - -

Roi-et , - - - -

Class

Chai Nat - - - -

Nakorn Sawan - - - -

Ang Thong - - - -

Ayutthaya - - - -

Class

Sakol Nakorn - - - -

Nakorn Rajsrima

, - - - -

Nonburi - - - -

Nationwide , , ,

Typhoid

Province No of Case

Incidence rate

No of Death

CFR YLLs YLLs death YLDs YLDs case DALYs

Class

Nan - - - -

Roi-et - - - -

Class

Chai Nat - - - -

Nakorn Sawan - - - -

Ang Thong - - - -

Ayutthaya - - - -

Class

Sakol Nakorn - - - -

Nakorn Rajsrima

- - - -

Nonburi - - - -

Nationwide ,

Note CFR �case fatality rate Classification of water quality is illustrated in an annex. Basically class 2 is better than class 3 and 4 and class 3 is better than class 4.

Table 6 shows that the quantity or the number of cases is greatest in diarrhea, dysentery, and typhoid respectively. After adjusting for population in each province, the incidence rate remains highest in diarrhea, dysentery, and typhoid respectively. There is no

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relationship or association between either the number of cases or the incidence rate and water quality, as class of water quality increases from class 2 to class 4 for all 3 selected diseases. The quality of the severity of the cases may be estimated from CFR, YLL/death, and YLD/case. Unfortunately YLL/death, and YLD/case cannot be directly estimated for each specific province due to the limit of the existing data as already mentioned. YLL/death, and YLD/case of the nation are used instead to find the YLL and YLD for each specific province. YLD/case of all three diseases seem to be almost the same, varying between 0.08-0.10. YLL/death is particularly low in diarrhea (22.37), whereas those of the other two diseases are differentially high (25.53-26.79). CFR, however, is highest in diarrhea (0.279) and quite the same for the rest (0.134-0.135). All severity indicators of all diseases are again not related to water quality, as class of water quality increases. The greatest burden or DALY can be found in diarrhea (118,135.54), since the total number of cases is greatest, up to 1.16 million cases. The second and the third burden are from dysentery and typhoid respectively. The relationship between burden of these selected diseases and the water quality cannot be quantified. The data on sources of drinking water from the Report of National Statistical Office shows that only 0.8% of households in Thailand consume water from River, Canal, Stream, Water Fall (Figure 1). Rather, most households drink water from safe sources. This helps explain why the outcomes of diseases, as mentioned above, do not relate to the quality of drinking water. Figure 1 Percentage of Sources of Drinking Water

Table 7 Source of Drinking Water

18.7

2.3

6.0

18.637.7

0.8

15.70.2-

Tap Water Inside

Tap Water Outside

Public Well

Private Well

Rain Water

River, Canel, Stream,Water FallBottle Drinking Water

Others

Unknown

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Source of Drinking Water Household Percentage

Tap Water Inside 2,806,011 18.7 Tap Water Outside ,Public Well ,Private Well , ,Rain Water , ,River, Canal, Stream, Water Fall ,Bottle Drinking Water , ,Others ,Unknown , -

Direct and Indirect Cost

For economic evaluation, direct economic costs were estimated from the cost of

medical services as an outpatient or inpatient case in Tables 8-10. Cost of medical expenses in OPD clinic was estimated to be 170 baht/visit using data from the pilot study for Health Insurance Project, Ministry of Public Health (S. Supakankunti and W. S. Janjaroen, 2000). There is no doubt that the cost is highest in diarrhea, because it causes the highest number of OPD visits. Once again dysentery is the second most and typhoid is the last. Sensitivity analysis shows not the ranking of the diseases by the OPD visit cost, but the possible range of number of OPD visit, as the cost per visit can vary in different settings and areas.

Table 8. Cost of Out-Patient Care by 3 Specific Diseases (Bahts)

Disease No. of case Cost Diarrhea 1,157,629 196,796,930 Dysentery 59,064 10,040,880 Typhoid 7,165 1,218,050 Total 208,056,030

Table 9. Sensitivity Analysis of Out-Patient Cost

Disease No.of case Cost at cost case �

Diarrhea , , , , , , , ,Dysentery , , , , , , ,Typhoid , , , , , ,Total , , , , , , Assumption Utilization rate of community and provincial hospital is the same Number of OPD cases also includes IPD cases The reason is that, for IPD case,

the patient has to visit OPD first then admit as an in-patient. So that we count IPD case as an OPD case as well.

For IPD cases, the hospitalization cost was estimated based on the data of DRGs from the Health Insurance Office, Ministry of Public Health in Table 10. The cost per case for each particular disease is different. Diarrhea has the lowest cost per case, while

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dysentery and typhoid are almost the same, which are higher in cost. This characteristic is similar to YLL/death in Table 7.

Table 10. Hospitalization cost of In-Patient Care classified by 3 specific diseases (Bahts)

Disease No.of case Cost/case Hospitalization Cost Diarrhea 94,199 1,019.59 96,044,424.35 Dysentery , , , ,Typhoid , , , ,Total , ,

Indirect economic cost firstly refers to wage lost due to absence from work as a result of hospitalization. The age of 14 was set to be the youngest age of the working group. The cost depends on the length of stay and the wage of patient or minimum wage/day. Wage lost from diarrhea is the highest, but the second highest is typhoid followed by dysentery. This is simply because the length of stay of typhoid is 2 times longer than that of dysentery (Table 11).

Table 11. Length of Stay and Wage Lost due to Hospitalization of Thai People Aged More Than 14 years old

(Bahts) Length of Stay

Disease No. of case Total Average

Wage Lost

Diarrhea , , , ,Dysentery , , , ,Typhoid , , , ,Total , , ,

Another indirect economic cost was calculated from income forgone due to

premature death as shown in Table Diarrhea can lead to life lost in all age groups of population Although diarrhea seems to be an uncomplicated disease and needs no special therapy, CFR is high as shown in Table 7. Its CFR is higher than those of the other two diseases. This is especially true in very young and very old persons. Accordingly, income forgone from premature death is highest in diarrhea. Income forgone is highest in the youngest age group (116 million DALYs), followed by dysentery and typhoid respectively. Table 12. Income forgone from premature death caused by water-borne diseases (Bahts)

Disease 0-4 5-1 - - - - - Total Diarrhea , , , , , , , , , , , , , , , ,Dysentery , , , , , , , , ,Enteric Fever , , , ,Total , , , , , , , , , , , , , , , ,

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Table Direct and Indirect Cost classified by specific diseases

bath

Cost

Disease Direct Indirect Total Diarrhea 292,841,354.35 303,947,614.87 596,788,969.22 Dysentery 19,280,057.64 11,212,773.57 30,492,831.21 Typhoid 6,965,617.55 3,839,864.17 10,805,481.72 Total 319,087,029.54 319,000,252.61 638,087,282.15 5. Summary

Water borne diseases refer to illnesses caused by contaminated water. Very often contaminated water is mixed with food, so the characteristics of a food borne diseases are rather similar to the water borne disease. Contamination may be both by biological agents and chemical agents. This study, nonetheless, emphasizes only on biological agents. Diseases or abnormal conditions usually present themselves with gastrointestinal symptoms, because pathogens contact directly and firstly with gastrointestinal tract. 5.1 Diarrhea

From natural history of selected water-borne diseases the exposure to unpurified

water and contaminated food may lead to ingestion of either infectious agents or their toxins that are already summarized in Table 1. Most prevalent diarrhea is acute in onset and usually persists for less than 3 weeks. More than 90% of acute diarrhea is mild and self-limited and responds within 5 days to simple rehydration therapy or symptomatic antidiarrheal agents. Food poisoning is another popular clinical form of acute diarrhea. Nonetheless, the exposure history is sometimes not obvious or mixed with other causes of acute diarrhea. The existing records may therefore include food poisoning with other acute diarrhea.

Diarrhea leads to wage lost the most among 3 selected diseases. This is not

surprising, since it produces the highest number of IPD cases. However, this does not mean that diarrhea produces more severe clinical cases than the other two diseases. It is simply because the incident cases of diarrhea are much higher than those of typhoid and dysentery. This number is probably underestimated.

5.2 Dysentery

Epidemiologically, it can be found all around the world, where public utility and

sanitation are not well established, where people live together in crowded places, and where personal hygiene is poor, especially in tropical areas. The incidence is approximately 10-15% of acute diarrhea cases in adult. This number is higher in children, particularly in the age under 8 years. The incidence may rise up to 15-25% and reach its peak in the age of 9-18 months.

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5.3 Typhoid

Incidence of typhoid is higher in children than in adult and highest in the age below 6 months. The spread of disease can occur sporadically or epidemically from contaminated food and water. Chronic carrier can pass the pathogen into the stool for more than one year if left untreated. Vaccination is available in both oral and injected forms.

In summary, the results from Table 3-11 showed that Diarrhea cases are found to be the greatest in numbers compared to the other 2 diseases. This evidence showed that Thailand is faced with more serious case of Diarrhea than the other two types of water borne diseases. In term of YLL and YLD, YLD/case of all three diseases seem to be almost the same, varying between 0.08-0.10. YLL/death is particularly low in diarrhea (22.37), whereas those of the other two diseases are differentially high (25.53-26.79). CFR, however, is highest in diarrhea (0.279) and quite the same for the rest (0.134-0.135). All severity indicators of all diseases are again not related to water quality, as class of water quality increases.

The greatest burden or DALY can be found in diarrhea (118,135.54), since the total number of cases is greatest, up to 1.16 million cases. The second and the third burden are from dysentery and typhoid respectively. The relationship between burden of these selected diseases and the water quality cannot be quantified.

For economic evaluation, direct economic costs were estimated from the cost of

medical services as an outpatient or inpatient case in Tables 8-10. There is no doubt that the cost is highest in diarrhea, because it causes the highest number of OPD visits. Once again dysentery is the second most and typhoid is the last. For IPD cases, the hospitalization cost was estimated in Table 10. The cost per case for each particular disease is different. Diarrhea has the lowest cost per case, while dysentery and typhoid are almost the same, which are higher in cost. This characteristic is similar to YLL/death in Table 7.

For indirect economic cost, firstly refers to wage lost due to absence from work as a

result of hospitalization. The age of 14 was set to be the youngest age of the working group. The cost depends on the length of stay and the wage of patient or minimum wage/day. Wage lost from diarrhea is the highest, but the second highest is typhoid followed by dysentery. This is simply because the length of stay of typhoid is 2 times longer than that of dysentery. Another form of indirect economic cost comes from income forgone due to premature death. The results showed that Diarrhea could lead to life lost in all age groups of population. Although diarrhea seems to be an uncomplicated disease and needs no special therapy, still its CFR is higher than those of the other two diseases. This is especially true in very young and very old persons. Accordingly, income forgone from premature death is highest in diarrhea. Income forgone is highest in the youngest age group (116 million DALYs), followed by dysentery and typhoid respectively.

Again all diseases mentioned above are closely related with food and drinking

water. In fact, the balance between immunity and infectivity is theoretically important to prevent the diseases individually and collectively. The improvement in public sanitation and personal hygiene, and access to clean water are however still main stays to protect people from afflicting the diseases.

18

Annex Table 14 Quality Standard of Water in the Ground Reservoir

Water Quality by Utility Item Quality Statistics Unit Class 1 Class 2 Class 3 Class 4 Class 5

1 Colour, odour and taste

- N N’ N’ N’ -

2 Temperature °c N N’ N’ N’ - 3 PH N 5-9 5-9 5-9 - 4 DO P20 mg/l N >6 >4 >2 - 5 BOD P80 ” N <1.5 <2 <4 - 6 Total coliform

bacteria P80 MPN/

dl N <5,000 <20,000 -

7 Fecal coliform bacteria

P80 ” N <1,000 <4,000 -

8 NO3 mg/l N <5 - 9 NH3 ” N <0.5 - 10 Phenols ” N <0.005 - 11 Cu ” N <0.1 - 12 Ni ” N <0.1 - 13 Mn ” N <1 - 14 Zn ” N <1 -

<0.005* - 15 Cd ” N <0.05**

16 Cr Hexavalent ” N <0.05 - 17 Pb ” N <0.05 - 18 Total Hg ” N <0.002 - 19 As ” N <0.01 - 20 Cyanide ” N <0.005 -

Radioactivity - Alpha

b/l

N

<0.1

-

21

- Beta ” N <1 22 Total

organochlorine pesticides

mg/l N <0.05 -

23 DDT µg/l N <1 - 24 Alpha-BHC ” N <0.02 - 25 Dieldrin ” N <0.1 - 26 Aldrin ” N <0.1 - 27 Heptachlor &

Heptachlor epoxide

” N <0.2 -

28 Endrin ” N Not found

-

Note: Announcement of National Environmental Committee, volume 8, 1994 N natural condition N’ water temperature does not higher 3 degree celcius than normal temperature in nature * CaCo3 < 100 mg/l ** CaCo3 > 100 mg/l > equal to or more than

< equal to or less than P20 percentile 20 P80 percentile 80 mg/l milligram/liter dl deciliter b/l becerel/liter

19

µg microliter MPN most probable number Classification of ground water reservoir Quality standard values will be set for only reservoir class 2-4. Values of reservoir class 1 represent a natural water condition while those of reservoir class 5 will not be determined Class 1: reservoir where quality of water is in natural condition without any wasted water from any activities. Water can be used for;

- consumption by passing a normal disinfecting process - natural reproduction of basic life unit - conservation

Class 2: reservoir where wasted water is drained from some activities. Water can be used for;

- consumption by passing a normal disinfecting process and general quality improvement process

- conservation of water animals - fishery - swimming and water sports

Class 3: reservoir where wasted water is drained from some activities. Water can be used for;

- consumption by passing a normal disinfecting process and general quality improvement process

- agricultural purpose Class 4: reservoir where wasted water is drained from some activities. Water can be used for;

- consumption by passing a normal disinfecting process and special quality improvement process

- industrial purpose Class 5: reservoir where wasted water is drained from some activities. Water can be used for only;

- transportation

20

Table 15 Income forgone from premature death caused by Diarrhea & Food Poisoning

Diarrhea & Food Poisoning Number of productive

years lost due to premature

death (n)

Calculated income foregone from premature death at each age interval based on GDP per capita 1999 (baht)

0-4 5-14 15-24 25-34 35-44 45-54 55-64

2.0 9.5 19.5 29.5 39.5 49.5 59.5

1 -

-

1,129,800.00

2,400,825.00 2,118,375.00 2,259,600.00

3,813,075.00

2 -

-

1,098,416.67

2,334,135.42 2,059,531.25 2,196,833.33

-

3 -

-

1,067,905.09

2,269,298.32 2,002,322.05 2,135,810.19

-

4 - 1,232,911.26

1,038,241.06

2,206,262.26 1,946,701.99 2,076,482.12

-

5 - 1,198,663.73

1,009,401.03

2,144,977.19 1,892,626.94 2,018,802.07

-

6 - 1,165,367.51

981,362.12

2,085,394.49 1,840,053.97 1,962,724.23

-

7 - 1,132,996.19

954,102.06

2,027,466.87 1,788,941.36 1,908,204.11

-

8 - 1,101,524.08

927,599.22

1,971,148.35 1,739,248.54 1,855,198.44

-

9 - 1,070,926.18

901,832.58

1,916,394.22 1,690,936.08 1,803,665.15

-

10 - 1,041,178.23

876,781.67

1,863,161.05 1,643,965.63 1,753,563.34

-

11 - 1,012,256.62

852,426.63

1,811,406.58 1,598,299.92 1,704,853.25

-

12 4,402,724.32 984,138.38 828,748.11

1,761,089.73 1,553,902.70

-

-

13 4,280,426.42 956,801.20 805,727.33

1,712,170.57 1,510,738.74

-

-

14 4,161,525.69 930,223.39 783,346.01

1,664,610.28 1,468,773.77

-

-

15 4,045,927.75 904,383.85 761,586.40

1,618,371.10 1,427,974.50

-

-

16 3,933,540.87 879,262.08 740,431.22

1,573,416.35 1,388,308.54

-

-

17 3,824,275.85 854,838.13 719,863.69

1,529,710.34 1,349,744.42

-

-

18 3,718,045.96 831,092.63 699,867.48

1,487,218.39 1,312,251.52

-

-

19 3,614,766.91 808,006.72 680,426.71

1,445,906.76 1,275,800.09

-

-

20 3,514,356.72 785,562.09 661,525.97

1,405,742.69 1,240,361.19

-

-

21 3,416,735.70 763,740.92 643,150.25

1,366,694.28 1,205,906.72

-

-

22 3,321,826.37 742,525.90 625,284.96

1,328,730.55

-

-

-

23 3,229,553.42 721,900.18 607,915.94

1,291,821.37

-

-

-

24 3,139,843.60 701,847.39 591,029.38

1,255,937.44

-

-

-

25 3,052,625.72 682,351.63 574,611.90

1,221,050.29

-

-

-

21

Number of productive


death (n)


26 2,967,830.56 663,397.42 558,650.46

1,187,132.23

-

-

-

27 2,885,390.83 644,969.71 543,132.39

1,154,156.33

-

-

-

28 2,805,241.08 627,053.89 528,045.38

1,122,096.43

-

-

-

29 2,727,317.72 609,635.73 513,377.45

1,090,927.09

-

-

-

30 2,651,558.89 592,701.40 499,116.97

1,060,623.56

-

-

-

31 2,577,904.48 576,237.47 485,252.61

1,031,161.79

-

-

-

32 2,506,296.02 560,230.88 471,773.37

-

-

-

-

33 2,436,676.69 544,668.91 458,668.55

-

-

-

-

34 2,368,991.22 529,539.21 445,927.76

-

-

-

-

35 2,303,185.91 514,829.79 433,540.88

-

-

-

-

36 2,239,208.52 500,528.96 421,498.08

-

-

-

-

37 2,177,008.29 486,625.38 409,789.80

-

-

-

-

38 2,116,535.84 473,108.01 398,406.75

-

-

-

-

39 2,057,743.17

459,966.12

387,339.89

-

-

-

-

40 2,000,583.64

447,189.28

376,580.45

-

-

-

-

41 1,945,011.87

434,767.36

366,119.88

-

-

-

-

42 1,890,983.77

422,690.49

-

-

-

-

-

43 1,838,456.44

410,949.09

-

-

-

-

-

44 1,787,388.20

399,533.83

-

-

-

-

-

45 1,737,738.53

388,435.67

-

-

-

-

-

46 1,689,468.02

377,645.79

-

-

-

-

-

47 1,642,538.35

367,155.63

-

-

-

-

-

48 1,596,912.28

356,956.86

-

-

-

-

-

49 1,552,553.61

347,041.40

-

-

-

-

-

50 1,509,427.12

337,401.36

-

-

-

-

-

51 1,467,498.59

328,029.10

-

-

-

-

-

52 1,426,734.74

-

-

-

-

-

-

53 1,387,103.22

-

-

-

-

-

-

22



death (n)


54 1,348,572.57

-

-

-

-

-

-

55 1,311,112.23

-

-

-

-

-

-

56 1,274,692.44

-

-

-

-

-

-

57 1,239,284.32

-

-

-

-

-

-

58 1,204,859.75

-

-

-

-

-

-

Total 116,327,984.24 32,903,787.03

27,858,604.13

50,339,037.31

34,054,764.91

21,675,736.24

1,906,537.50

Table 16 Income forgone from premature death caused by Dysentery

Dysentery



death (n)


0-4 5-14 15-24 25-34 35-44 45-54 55-64

2.0 9.5 19.5 29.5 39.5 49.5 59.5

1 0.0 0.0 0.0 0.0 141,225.0 70,612.5 0.0

2 0.0 0.0 0.0 0.0 137,302.1 68,651.0 0.0

3 0.0 0.0 0.0 0.0 133,488.1 66,744.1 0.0

4 0.0 32,445.0 0.0 0.0 129,780.1 64,890.1 0.0

5 0.0 63,087.6 0.0 0.0 126,175.1 63,087.6 0.0

6 0.0 61,335.1 0.0 0.0 122,670.3 61,335.1 0.0

7 0.0 59,631.4 0.0 0.0 119,262.8 59,631.4 0.0

8 0.0 57,975.0 0.0 0.0 115,949.9 57,975.0 0.0

9 0.0 56,364.5 0.0 0.0 112,729.1 56,364.5 0.0

10 0.0 54,798.9 0.0 0.0 109,597.7 54,798.9 0.0

11 0.0 53,276.7 0.0 0.0 106,553.3 53,276.7 0.0

12 207,187.0 51,796.8 0.0 0.0 103,593.5 0.0 0.0

13 201,431.8 50,358.0 0.0 0.0 100,715.9 0.0 0.0

23



death (n)


14 195,836.5 48,959.1 0.0 0.0 97,918.3 0.0 0.0

15 190,396.6 47,599.2 0.0 0.0 95,198.3 0.0 0.0

16 185,107.8 46,277.0 0.0 0.0 92,553.9 0.0 0.0

17 179,965.9 44,991.5 0.0 0.0 89,983.0 0.0 0.0

18 174,966.9 43,741.7 0.0 0.0 87,483.4 0.0 0.0

19 170,106.7 42,526.7 0.0 0.0 85,053.3 0.0 0.0

20 165,381.5 41,345.4 0.0 0.0 82,690.7 0.0 0.0

21 160,787.6 40,196.9 0.0 0.0 80,393.8 0.0 0.0

22 156,321.2 39,080.3 0.0 0.0 0.0 0.0 0.0

23 151,979.0 37,994.7 0.0 0.0 0.0 0.0 0.0

24 147,757.3 36,939.3 0.0 0.0 0.0 0.0 0.0

25 143,653.0 35,913.2 0.0 0.0 0.0 0.0 0.0

26 139,662.6 34,915.7 0.0 0.0 0.0 0.0 0.0

27 135,783.1 33,945.8 0.0 0.0 0.0 0.0 0.0

28 132,011.3 33,002.8 0.0 0.0 0.0 0.0 0.0

29 128,344.4 32,086.1 0.0 0.0 0.0 0.0 0.0

30 124,779.2 31,194.8 0.0 0.0 0.0 0.0 0.0

31 121,313.2 30,328.3 0.0 0.0 0.0 0.0 0.0

32 117,943.3 29,485.8 0.0 0.0 0.0 0.0 0.0

33 114,667.1 28,666.8 0.0 0.0 0.0 0.0 0.0

34 111,481.9 27,870.5 0.0 0.0 0.0 0.0 0.0

35 108,385.2 27,096.3 0.0 0.0 0.0 0.0 0.0

36 105,374.5 26,343.6 0.0 0.0 0.0 0.0 0.0

37 102,447.4 25,611.9 0.0 0.0 0.0 0.0 0.0

38 99,601.7 24,900.4 0.0 0.0 0.0 0.0 0.0

39 96,835.0 24,208.7 0.0 0.0 0.0 0.0 0.0

40 94,145.1 23,536.3 0.0 0.0 0.0 0.0 0.0

41 91,530.0 22,882.5 0.0 0.0 0.0 0.0 0.0

24



death (n)


42 88,987.5 22,246.9 0.0 0.0 0.0 0.0 0.0

43 86,515.6 21,628.9 0.0 0.0 0.0 0.0 0.0

44 84,112.4 21,028.1 0.0 0.0 0.0 0.0 0.0

45 81,775.9 20,444.0 0.0 0.0 0.0 0.0 0.0

46 79,504.4 19,876.1 0.0 0.0 0.0 0.0 0.0

47 77,295.9 19,324.0 0.0 0.0 0.0 0.0 0.0

48 75,148.8 18,787.2 0.0 0.0 0.0 0.0 0.0

49 73,061.3 18,265.3 0.0 0.0 0.0 0.0 0.0

50 71,031.9 17,758.0 0.0 0.0 0.0 0.0 0.0

51 69,058.8 17,264.7 0.0 0.0 0.0 0.0 0.0

52 67,140.5 0.0 0.0 0.0 0.0 0.0 0.0

53 65,275.4 0.0 0.0 0.0 0.0 0.0 0.0

54 63,462.2 0.0 0.0 0.0 0.0 0.0 0.0

55 61,699.4 0.0 0.0 0.0 0.0 0.0 0.0

56 59,985.5 0.0 0.0 0.0 0.0 0.0 0.0

57 58,319.3 0.0 0.0 0.0 0.0 0.0 0.0

58 56,699.3 0.0 0.0 0.0 0.0 0.0 0.0

Total 5,474,258.1 1,699,333.2 0.0 0.0 2,270,317.7 677,366.8 0.0

25

Table 17 Income forgone from premature death caused by Enteric Fever

Enteric Fever



death (n)


0-4 5-14 15-24 25-34 35-44 45-54 55-64

2.0 9.5 19.5 29.5 39.5 49.5 59.5

1 0.0 0.0 0.0 70,612.5 0.0 0.0 0.0

2 0.0 0.0 0.0 68,651.0 0.0 0.0 0.0

3 0.0 0.0 0.0 66,744.1 0.0 0.0 0.0

4 0.0 0.0 0.0 64,890.1 0.0 0.0 0.0

5 0.0 0.0 0.0 63,087.6 0.0 0.0 0.0

6 0.0 0.0 0.0 61,335.1 0.0 0.0 0.0

7 0.0 0.0 0.0 59,631.4 0.0 0.0 0.0

8 0.0 0.0 0.0 57,975.0 0.0 0.0 0.0

9 0.0 0.0 0.0 56,364.5 0.0 0.0 0.0

10 0.0 0.0 0.0 54,798.9 0.0 0.0 0.0

11 0.0 0.0 0.0 53,276.7 0.0 0.0 0.0

12 0.0 0.0 0.0 51,796.8 0.0 0.0 0.0

13 0.0 0.0 0.0 50,358.0 0.0 0.0 0.0

14 0.0 0.0 0.0 48,959.1 0.0 0.0 0.0

15 0.0 0.0 0.0 47,599.2 0.0 0.0 0.0

16 0.0 0.0 0.0 46,277.0 0.0 0.0 0.0

17 0.0 0.0 0.0 44,991.5 0.0 0.0 0.0

18 0.0 0.0 0.0 43,741.7 0.0 0.0 0.0

19 0.0 0.0 0.0 42,526.7 0.0 0.0 0.0

20 0.0 0.0 0.0 41,345.4 0.0 0.0 0.0

21 0.0 0.0 0.0 40,196.9 0.0 0.0 0.0

22 0.0 0.0 0.0 39,080.3 0.0 0.0 0.0

23 0.0 0.0 0.0 37,994.7 0.0 0.0 0.0

24 0.0 0.0 0.0 36,939.3 0.0 0.0 0.0

26



death (n)


25 0.0 0.0 0.0 35,913.2 0.0 0.0 0.0

26 0.0 0.0 0.0 34,915.7 0.0 0.0 0.0

27 0.0 0.0 0.0 33,945.8 0.0 0.0 0.0

28 0.0 0.0 0.0 33,002.8 0.0 0.0 0.0

29 0.0 0.0 0.0 32,086.1 0.0 0.0 0.0

30 0.0 0.0 0.0 31,194.8 0.0 0.0 0.0

31 0.0 0.0 0.0 30,328.3 0.0 0.0 0.0

32 0.0 0.0 0.0 0.0 0.0 0.0 0.0

33 0.0 0.0 0.0 0.0 0.0 0.0 0.0

34 0.0 0.0 0.0 0.0 0.0 0.0 0.0

35 0.0 0.0 0.0 0.0 0.0 0.0 0.0

36 0.0 0.0 0.0 0.0 0.0 0.0 0.0

37 0.0 0.0 0.0 0.0 0.0 0.0 0.0

38 0.0 0.0 0.0 0.0 0.0 0.0 0.0

39 0.0 0.0 0.0 0.0 0.0 0.0 0.0

40 0.0 0.0 0.0 0.0 0.0 0.0 0.0

41 0.0 0.0 0.0 0.0 0.0 0.0 0.0

42 0.0 0.0 0.0 0.0 0.0 0.0 0.0

43 0.0 0.0 0.0 0.0 0.0 0.0 0.0

44 0.0 0.0 0.0 0.0 0.0 0.0 0.0

45 0.0 0.0 0.0 0.0 0.0 0.0 0.0

46 0.0 0.0 0.0 0.0 0.0 0.0 0.0

47 0.0 0.0 0.0 0.0 0.0 0.0 0.0

48 0.0 0.0 0.0 0.0 0.0 0.0 0.0

49 0.0 0.0 0.0 0.0 0.0 0.0 0.0

50 0.0 0.0 0.0 0.0 0.0 0.0 0.0

51 0.0 0.0 0.0 0.0 0.0 0.0 0.0

52 0.0 0.0 0.0 0.0 0.0 0.0 0.0

27



death (n)


53 0.0 0.0 0.0 0.0 0.0 0.0 0.0

54 0.0 0.0 0.0 0.0 0.0 0.0 0.0

55 0.0 0.0 0.0 0.0 0.0 0.0 0.0

56 0.0 0.0 0.0 0.0 0.0 0.0 0.0

57 0.0 0.0 0.0 0.0 0.0 0.0 0.0

58 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Total 0.0 0.0 0.0 1,480,559.9 0.0 0.0 0.0

28

Reference

Bureau of Environmental Health, Department of Health., Annual Report on Situation of Quality of Water in Thaiuland, 1997-2000.

Epidemiology Division, Office of the Permanent Secretary for Public Health, Summary

Report on Disease Surveillance, 1998, Ministry of Health, 1999. Grendell JH, McQuaid HR, and Friedman SL. Current Diagnosis & Treatment in

Gastroenterology. International edition. LANGE medical book. 1996. Jaroonvej N. Tropical Diseases. 2nd edition. Murray, Christopher J.L., and Alan D. Lopez, eds. The Global Burden of Disease:A

Comprehensive Assessment of Mortality and Disability from Diseases, Injuries, and Risk Factors in 1990 and Projected to 2020 (Global Burden of Disease and Injury Series, Volume I). Cambridge, Mass.:Harvard School of Public Health on behalf of the World Health Organization and the World Bank.

National Statistical Office, Report on Health and Welfare Survey 1996. Bangkok Aksom

Thai Press, 1997. National Statistical Office, Report on Household’s Economic and Social Status Survey

1996, Bangkok Aksom Thai Press, 1998. Siripen Supakankunti and Wattana S. Janjaroen “Economic Analysis of Health Card Project

in Thailand: Case of Chiang Mai Province”, 2000.

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