NATIONAL INSTITUTE OF HYGIENE AND EPIDEMIOLOGY BUI VAN TUAN

1 MINISTRY OF EDUCATION AND TRAINING MINISTRY OF HEALTH NATIONAL INSTITUTE OF HYGIENE AND EPIDEMIOLOGY --------- BUI VAN TUAN SITUATION AND ASSOCIATED FACTORS OF TOXOCARA CANIS INFECTION IN MO DUC DISTRICT, QUANG NGAI PROVINCE IN 2016, AND EFFECTIVEENSS OF INTERVENTION MEASURES Major: Public Health Major code: 62 72 03 01 SUMMARY OF THE THESIS FOR THE DEGREE OF DOCTOR OF PUBLIC HEALTH Ha Noi - 2018

2 THIS THESIS IS ACCOMPLISHED AT THE NATIONAL INSTITUTE OF HYGIENE AND EPIDEMIOLOGY Scientific suervisors: 1. Assoc.Prof. Nguyen Van Chuong, Ph.D. 2. Prof. Vu Sinh Nam, Ph.D. Examiner 1:...... Examiner 2:...... Examiner 3:...... The thesis will be defended at the Board of Examiners of Institute at the National Institute of Hygiene and Eidemiology, at..., on......., 2018. More information of the thesis will be retrieved at: 1. National Library of Viet Nam 2. Library of the National Institute of Hygiene and Eidemiology

3 INTRODUCTION Toxocariasis is a zoonotic disease, which is transmitted to humans from swallowing larvae of the two secies Toxocara canis and Toxocara cati. The larvae can arasite on bodily organs such as brain, eyes, liver, and lungs ; and can cause serious symtoms such as eilesy, vision imairment or even blindness. Toxocariais is distributed from Southern hemishere to troical countries, with different revalence, from 0.7% in New Zealand to 93.0% in La Reunion (Africa). In Viet Nam, the increase in the infection of the disease in recent years has caused negative imact on the health of the community. However, little has been known of the studies on the current situation of toxocariasis, as well as the associated factors of the disease. In addition, no aroriate control measures have been in lace to be alied in to the community level. This study was conducted as a contribution to seek for the understanding of the distribution and associated factors of toxocariasis, and to roose timely and aroriate intervention measures, so as to hel reduce the incidence in the community. Objectives 1. To describe the current situation and associated factors of Toxocara canis on humans in Mo Duc district, Quang Ngai rovince in 2016. 2. To evaluate the effectiveness of some intervention measures alied to control human toxocariasis at studied sites (2016-2017).

4 New scientific ideas and significance of the study The thesis seeks to rovide a systematic research on the situation and associated factors of human Toxocara canis infections in Mo Duc district, Quang Ngai rovince in 2016, and to evaluate effectiveness of intervention measures alied to the community. This is the first study ever conducted in Viet Nam in terms of introducing intervention measures to human toxocariasis control, which indicates that the combined health education and deworming for dogs are effective measures to reduce the infections in the community and to imrove the knowledge, attitude and ractice of the high-risk oulation. The study is roven to be highly alicable, facilitating health care facilities at all levels to lan and imlement control activities of toxocariasis in the community. THESIS SRUCTURE The thesis is comosed of 117 ages (without references and aendices), which are divided into the Introduction (21 ages), background (34 ages), study objects and methodology (21 ages), study results (30 ages), discussions (27 ages), conclusions (2 ages), and recommendations (1 age). Chater 1. BACKGROUND 1.1. Current situation of toxocariasis infection 1.1.1. Case definition of toxocariasis According to the Case definition of infectious diseases, as attachment to the Decision Number 4283/QĐ-BYT, dated August 8, 2016 by the minister of Health:

5 - A susected case: A case is considered susected uon having the following symtoms: rurigo, urticarial, headache, abdominal ain, dysesia; muscle ain, fatigue, fever, wheezing; involvement of the enlargement of the liver, ulmonia, chronic abdominal ain, neurosychiatric symtoms, damage to the eye, vision imairment, endohthalmitis or aillitis, and distorted retina - A robable case: not alicable - A confirmed case: a susected case with the resence of the toxocara larvae, or the detection of the antibody of the larvae with ELISA technique, or detection a secific gene ortion of the larvae with molecular-biological technique. 1.1.2. Toxocara infections in the world Toxocariasis is resent in all over the world, but in troical countries, the disease is more revalent. The disease is distributed from the southern hemishere to Southern America, the Carriberian Sea, Africa, the Middle-East, South Asia and South-East Asia. In develoed countries, toxocara infections vary, including New Zealand (0.7%), Jaan (1.6%), Denmark (2.4%), Australia (7.5%), USA (14.0%), and Poland (15.0%). In troical coutries, the disease accounts for high incidence, including Nigeria (30.0%), Swaziland (45.0%), Indonesia (63.2%), Malaysia (58.0%), and Braxin (36.0%). 1.1.3. Toxocara infections in Viet Nam Since 2000, there have been several studies conducted on the infections of toxocariasis in the community, which indicated different incidences deeding on the regions. In the North, the infections ranged from 58.7-74.9%, while in the South, the infections were from 38.4-53.58%. In Central Vietnam, some studies were carried out, with the average infection rates being from 13.1-50.0%.

6 1.2. Associated factors of toxocara infections Much have been studied to described the risk factors of toxocara infections. These include sources of transmission, outer settings (soil, vegetable garden) contaminated with Toxocara embryonated eggs, favourite climate and weather facilating the develoment and survival of eggs in the environment, socioeconomic characteristics. In addition, human behaviours are considered risk factors such as free-ranged raising of dogs and cats, less frequent or no deworming of dogs and cats, carrying cats and dogs, eating raw vegetable, laying with soil, and no handwashing after laying with soil. 1.3. Control of toxocariasis All over the world, there ahve been a great deal of studies conducted on toxocariasis, but mainly focused on eidemiology, diagnosis, and treatment. However, less have been studied in the control of the disease, and just focussed on deworming for cats and dogs, management of ets, health education and introduction of laws on et management. In Viet Nam, there have not any studies on toxocariasis control, since it is considered as one of the neglected troical diseases. In recent years, increasing incidence of Toxocara infections has raised the necessity for the study of aroriate intervention measures for toxocariasis control, hence imroving the health of the eole. Chater 2. METHODOLOGY 2.1. Study objects - The samling frame is alied to select a erson aged from 2 to 70 years old in each selected household. Domestic dogs, soil, and vegetable areas of the house were also selected. - Public soil areas and vegerables sold at the local markets were selected.

7 2.2. Duration of study: From Aril, 2016 to December, 2017. 2.3. Study sites The study was conducted at two villages: Van Ha village of Duc Phong commune and Village 4 of Duc Chanh commune, Mo Duc district, Quang Ngai rovince. 2.4. Study methods. 2.4.1. Descritive cross-sectional design * Samle size: - The following formula was used to calculate the samle size for identifying the human toxocariasis incidence Z 2 (1 /2)..(1-) n = ---------------- x DE (Ɛ) 2 Z1-α/2: Z value (at 1.96 for 95% confidence level) : ercentage of estimating the community incidence. In this study, = 0.16 as referential rorotion by Bui Van Tuan in Bnih Dinh rovince. Ɛ: Effect size. In this study, Ɛ = 0,2. As this study involved two cluster samlings (first time at two villages, second time at household level), the DE was then calculated twice. With the design effect for each time at 1.5, so DE = 1.5 by 1.5 = 2.25, hence the samle size n = 1,147 eole. An additional 10% was added to the samle, resulting in the total samle of 1,280 eole for two villages, so there were 640 eole from each village. In each household, there were estimated 3 to 4 eole, so the total number of households in each village were 200. - Samle size for identifying the Toxocara infections in dogs:all dogs in 200 selected households - Samle size of soil: At households: 200 soil samles for each communes. At ublic laying laces: 10 soil samles/commune

8 - Samle size of vegetable: 200 samles of vegetable at each study site. - Samle size for KAP survey: One erson er household (200 household/commune). * Samling technique: - Samling for identifying the human toxocariasis incidence: 200 households er commune were selected by systematic ramdomization. - Samling for KAP survey: householder (ossible husband or wife of householder). - Samling for identifying toxocara infection in dogs: dosmetic dogs in the selected household - Samling for idetifying toxocara infection on vegetable: soil samles from 200 selected households. - Samling of vegetable: Five kinds of vegetable most ofen eaten raw by eole. 2.4.2. Community intervention design with control In this study, Duc Phong commune was selected as intervention commune and Duc Chanh as control commune. * Samle size for comaring the human Toxocara infections in two grous 2 z / 2 2 1 z 1 1 1 2 1 2 n While: 2 Z1-α/2: Z value (at 1.96 for 95% confidence level); Z1-β: = 0.84 when 1- = 80%; (, ) = 7.8; = 1-2 ; P = (1 + 2)/2. 1: estimated infection rate at the control commune after intervention (1=0.16). 2: estimated infection rate at the intervention commune after intervention (2 = 0.11) Calculated samles: n1 = n2 = 577 eole. An additional 10% was added to make u n1 = n2 = 635. Since the samle sizes for the intervention study was similar to those for cross-sectional study (n1 = n2 = 640), so the data from the cross-sectional study

9 was used as the re-intervention study. Similarly, data for the samle sizes for cross-sectional surveys on humans, dogs, soil, and vegetable were used as the re-intervention study. * Intervention measures - Case treatment: The measure was alied to both intervention and control communes. - Health education, deworming for dogs: This measure was alied to the intervention commune. 2.5. Ethics in research - This study was conducted with the roosal being aroved by the Board of bio-medical ethics, National Institute of Hygiene and Eidemiology. Chater 3. RESULTS 3.1. Current situation and associated factors of human Toxocara infections 3.1.1. Human Toxocara seroositivity Table 3.3. Human Toxocara seroositivity at studied sites Commune Blood samles for ELISA infected Duc Phong 662 119 17.9 Duc Chanh 665 111 16.7 Total 1,327 230 17.3 % >0.05 The overall seroositive rate of Toxocara canis was rather high in the two studied communes (17.3%), with the infection rates in Duc Phong and Duc Chanh communes being 17.9% and 16.7%, resectively. The infection rates in two communes were not significantly different.

10 Table 3.4. Toxocara infection by gender at study sites Commune Gender examined infected % Duc Male 318 53 16.7 >0.05 Phong Female 344 66 19.2 Duc Chanh Total Male 323 45 13.9 Female 342 66 19.3 Male 641 98 15.3 Female 686 132 19.2 >0.05 >0.05 Toxocara seroositive rates in men and women were 15.3% and 19.2%, which were not significantly different. Table 3.5. Toxocara infection by age grous Commune Age % grous examined infected > 15 435 90 20.7 2-15 227 29 12.8 <0.05 > 15 415 79 19.0 <0.05 2-15 250 32 12.8 > 15 850 169 19.9 <0.01 2-15 477 61 12.8 Significant differences were found between Toxocara Duc Phong Duc Chanh Total seroositive rates and age grous. 3.1.2. Human Toxocara infections Table 3.8. Human toxocara infections at studied sites Commune examined Seroositive (+) lus clinical symtoms Duc Phong 662 61 9.2 Duc Chanh 665 59 8.9 Total 1,327 120 9.0 Overall human Toxocara infection rate at study sites was 9.0%. %

11 3.1.3. Associated factors of Toxocara infections Table 3.11. Toxocara infections in dogs at studied sites Commune % examined infected Duc Phong 126 42 33.3 Duc Chanh 109 35 32.1 Total 235 77 32.8 >0.05 The overall Toxocara infection in dogs at studied sites was 32.8%, with that at Duc Phong commune of 33.3%; and Duc Chanh of 32.1%. Table 3.13. Proortion of soil samles contaminated with Location of soil At househol ds At ublic lacegro unds Commune Toxocara eggs examined contami nated Duc Phong 200 59 29.5 Duc Chanh 200 52 26.0 Total 400 111 27.8 Duc Phong 10 3 30.0 Duc Chanh 10 2 20.0 Total 20 5 25.0 % >0.05 >0.05 The roortion of soil samles contaminated with Toxocara eggs was 27.8% at households and 25.0% at ublic laygrounds.

Kinds of vegetable 12 Table 3.15. Toxocara eggs contamination on vegetable Duc Phong Duc Chanh Total contaminat contaminat contaminat examine examine examine ed ed ed d d d (%) (%) (%) mustard 2 1 3 40 40 80 greens (5.0) (2.5) (3.8) lettuce 40 5 4 9 40 80 (12.5) (10.0) (11.3) centella 40 1 2 3 40 80 (2.5) (5.0) (3.8) fish mint 40 3 4 7 40 80 (7.5) (10.0) (8.8) savory 3 2 5 40 40 80 leaves (7.5) (5.0) (6.3) Total 200 14 13 27 200 400 (7.0) (6.5) (6.8) The overall roortion of vegetable contaminated with Toxocara eggs was 6.8%; of which, the roortions of contaminated eggs was 11.3% on lettuce, 8.8% on fish mint, 6.3% on savory leaves, 3.8% on centella, and 3.8% on mustard green. Table 3.22. Association between dog raising and Toxocara infections Dog raising Infected Not infected Total OR (%) (%) (CI 95%) 49 169 218 Yes 1.2 (22.5) (77.5) (0.7-2.1) > 0.05 34 148 182 No (18.7) (81.3) No significant association was found between Toxocara infection in eole living in households with and without raising dogs (>0.05).

13 Table 3.23. Association between eating vegetable and Toxocara infections Regularly eating vegetable Infected (%) Not infected (%) 116 (77.9) 201 (80.1) Total OR (CI 95%) 33 149 Yes 1.1 (22.1) > 0.05 (0.6-1.9) 50 251 No (19.9) No significant association was found between the regularlity of eating vegetable and Toxocara infections (>0,05). Table 3.24. Association between living habits and Toxocara infections Living habits Infected (%) Not infected (%) Total OR (CI 95%) 24 24 48 Regularly Yes (50.0) (50.0) 4.9 < 0.01 carrying 59 293 352 (2.5-9.7) dogs No (16.8) (83.2) 63 167 230 Regularly Yes (27.4) (72.6) 2.8 laying with < 0.01 20 150 170 (2-7.0) soil No (11.8) (88.2) Handwashing after (33.0) (67.0) 38 77 115 Yes 2.6 (1.6-4.5) < 0.01 contacting 45 240 285 No soil (15.8) (84.2) Regularly 22 65 87 Yes washing (25.3) (74.7) 1.4 > 0.05 hands before 61 252 313 (0.8-1.9) No meals (19.5) (80.5) Significant associations were found between regularly contacting soil, carrying dogs, and not washing hand after contacting soil and Toxocara infection (<0.05).

14 3.2. Effectiveness of some intervention measures 3.2.1. Effectiveness of reducing seroositivity and infection rates of human toxocariasis 3.2.1.1. Changed seroositivity of human toxocariasis after intervention Table 3.25. Changed seroositivity of human toxocariasis Commune exam ined infect ed % Effective index % Interven tion effect % 2&4 Interve Before 662 119 17.9 44.7 ntion intervention (1) commu After 627 62 9.9 < 0.01 32.7 ne intervention (2) < 0.01 Contro Before 665 111 16.7 12.0 l intervention (3) commu After 632 93 14.7 > 0.05 ne intervention (4) After the intervention, the seroositivity reduced from 17.9% to 9.9% (<0.01) at the intervention commune and reduced from 16.7% to 14.7% (>0.05). The intervention effect was 32.7%. Table 3.26. Changed infection rates of toxocariasis after intervention Commune exa mine d infec ted % Effective index % Interventi on effect % 2&4 Interve Before 662 61 9.2 42.4 ntion intervention (1) commu After 627 33 5.3 < 0.01 34.5 ne intervention (2) < 0.05 Contro Before 665 59 8.9 7.9 l intervention (3) commu After 632 52 8.2 > 0.05 ne intervention (4) The infection rate of toxocariasis was reduced from 9.2% to 5.3% (<0.01) at the intervention commune, and from 8.9% to 8.2% (>0.05) at the control commune. The intervention effect was 34.5%.

15 3.2.1.2. Effectiveness of treatment with albendazol on Toxocariasis Table 3.27. Effectiveness of albedazol for the treatment of toxocariasis Commune Seroositivity (+) Confirmed cases Before (%) Intervention 61 (100.0) Control 59 (100.0) Total 120 (100.0) After (%) 5 (8.2) 11 (18.6) 16 (13.3) Effective index (%) Before (%) 91.8 61 (100.0) 81.4 59 (100.0) 86.7 120 (100.0) After (%) 3 (4.9) 8 (13.6) 11 (9.2) Effective index (%) 95.1 86.4 90.8 After one year, the seroositive and infection rates reduced by 86.7% and 90.8%, resectively. 3.2.2. Effectiveness of reducing the transmission sources in dogs and outer environment 3.2.2.1. Changed infection rates of Toxocara in dogs after intervention Table 3.30. Changed infection rates of Toxocara in dogs after intervention Examined dogs exa min ed infect ed % Effective index % Interventi on effect % 2&4 Interve n tion Before intervention (1) 126 42 33.0 80.9 commu After 111 7 6.3 <0.01 ne intervention (2) 64.4 Contro l commu ne Before intervention (3) After intervention (4) 109 35 32.1 16.5 97 26 26.8 >0.05 <0.01 The Toxocara infection rate in dogs at the intervention commune reduced by 80.9% (<0.01). The intervention effect was 64.4%.

16 Table 3.31. Chaged roortions of soil contaminated with Toxocara eggs Commune % Effectiv exami infe e index ned cted % Soil exami ned Interven tion effect % 2&4 Soil Interv Before 200 59 29.5 in entio intervention (1) 69.5 house n After 200 18 9.0 < 0.01 50.3 holds intervention (2) Contr Before 200 52 26.0 < 0.01 ol intervention (3) 19.2 After 200 42 21.0 > 0.05 intervention (4) Soil Interv Before 10 3 30.0 in entio intervention (1) 66.6 ubli n After 10 1 10.0 > 0.05 66.6 c intervention (2) layg Contr Before 10 2 20.0 > 0.05 round ol intervention (3) 0 After 10 2 20.0 > 0.05 intervention (4) The roortion of soil contaminated with Toxocara eggs in households of the intervention commune reduced from 29.5% to 9.0% (<0.01); while in the control commne, the roortion reduced from 26.0% to 21.0% (>0.05). The intervention effect was 50.3%. The roortion of soild contaminated with Toxocara eggs in ublic laygrounds of the intervention commune reduced from 30.0% to 10.0%, while no change in this roortion was found in the control commune. Table 3.32. Chaged roortions of vegetable contaminated with Toxocara eggs Vegetable examined examin ed infect ed % Effectiv e index % Interven tion effect % 2&4 Interve Before 200 14 7.0 ntion intervention (1) 71.4 commu After 200 4 2.0 < 0.05 71.4 ne intervention (2) Contro Before 200 13 6.5 <0.05 l intervention (3) 0 commu After 200 13 6.5 > 0.05 ne intervention (4) The roortions of vegetable samles contaminated with Toxocara eggs in the intervention commune reduced from 7.0% to 2.0% (<0.05), while no change in this roortion was found in the control commune. The intervention effect was 71.4%.

17 3.2.3. Effectiveness of health education in imroving the knowledge, attitude, and ractice of the community on toxocariasis control 3.2.3.1. Changed knowledge of toxocariasis Table 3.33. Changed knowledge on risks of Toxocara infection Intervention (n=200) Commune Correct answer % Effective index % Before (1) After (2) 95 137 47,5 68,5 44,2 < 0,01 Before (3) 87 43,5 19,5 After (4) 104 52,0 > 0,05 Interventio n effect % 2&4 24,7 < 0,01 Control (n=200) In the intervention commune, significant increase was found in the level of knowledge of the risks of infection (from 47.5% to 68.5%, <0.01), with the intervention effect of 24.7%. Table 3.34. Changed knowledge on symtoms of toxocariasis Commune Correct answer % Effective index % Intervention effect % 2&4 Intervention Before (1) 97 48.5 42.3 23.4 (n=200) After (2) 138 69.0 < 0.01 Control Before (3) 90 45.0 18.9 < 0.01 (n=200) After (4) 107 53.5 > 0.05 In the intervention commune, significant increase was found in the level of knowledge of the risks of infection (from 48.5% to 69.0%, <0.01), with the intervention effect of 23.4%. 3.2.3.1. Changed ractice on toxocariasis control Table 3.35. Changed ractice on toxocariasis control Commune Correct answer % Effective index % Intervention effect % 2&4 Intervention Before (1) 93 41.5 44.1 (n=200) After (2) 134 67.0 < 0.01 24.1 Control Before (3) 85 42.5 20.0 < 0.01 > 0.05 (n=200) After (4) 102 51.0 In the intervention commune, significant increase was found in the ractice on toxocariasis control activities (from 41.5% to 67.0%, <0.01), with the intervention effect of 24.1%.

18 Table 3.39. Changed ractice on carrying dogs and treatment of dogs feces Practice Commune Yes % Effectiv e index % Intervent ion effect % 2&4 Regularly carrying dogs Treatment of dog feces Intervention (n=200) Control (n=200) Intervention (n=200) Control (n=200) Before (1) 27 13.5 After (2) 9 4.5 Before (3) 21 10.5 After (4) 20 10.0 Before (1) 98 49.0 After (2) 129 64.5 Before (3) 84 42.0 After (4) 89 44.5 66.7 < 0.01 61.9 4.8 > 0.05 31.6 < 0.01 < 0.01 25.6 < 0.01 6.0 > 0.05 In the intervention commune, significant reduction was found in the ractice of carrying dogs (<0.01), and the intervention effect was 61.9%. In the same commune, the ractice of treating dogs feces increased significantly, with the intervention effect of 25.6%. Table 3.41. Changed habits of contacting soil and hand washing Habit Commune Yes % Effective index % Regularly contacting soil Washing hands after contacting soil Washing hands before meal Intervention (n=200) Control (n=200) Intervention (n=200) Control (n=200) Intervention (n=200) Control (n=200) Interventi on effect % 2&4 Before (1) 115 57.5 11.3 > 0.05 8.7 After (2) 102 51.5 > 0.05 Before (3) 115 57.5 2.6 After (4) 112 56.0 > 0.05 Before (1) 141 70.5 21.3 < 0.01 14.4 After (2) 171 85.5 < 0.05 Before (3) 144 72.0 6.9 After (4) 154 77.0 > 0.05 Before (1) 160 80.0 10.6 < 0.05 6.0 After (2) 177 88.5 < 0.05 Before (3) 153 76.5 4.6 After (4) 160 80.0 > 0.05

19 In the intervention commune, significant reduction was found in the habits of washing hands after contacting soil (from 70.5 to 85.5%, <0.01), and the intervention effect was 14.4%. Also, the habit of washing hands before meals increased from 80.0 to 88.5% (<0.05), but the intervention effect was just 6.0%. Chater 4. DISCUSSIONS 4.1. Current situation and associated factors of Toxocara infections in humans 4.1.1. Human Toxocara seroositivity The seroositivity of human toxocariasis was similar to the study conducted by Bui Van Tuan in Binh Dinh and Gia Lai rovinces (from 13.05-16.78%), but was lower than those in studies conducted in some countries of the South America, Africa, Asia, and Viet Nam. The differences might come from different test kits used for Toxocara diagnosis and different selection of ositive cut-offs. In addition, the differences might be of tyical conditions of each country, different timeframe of the studies, number of ets raised in the households, and tyical ractice of the eole raising and taking care of their ets. Therefore, there should be further in-deth studies to be conducted. The study indicated the seroositive rate in the age grou more than 15 years old was higher than the age grou from 2 to 15 years old. This result was in line with the study conducted by Nguyen Van Chuong in Dak Lak. Other studies conducted in Viet Nam, Taiwan, and Argentina showed no differences in seroositive rates among age grous. The differences might be due to the settings of the studies, either in urban or rural areas. In rural areas, most of the eole are farmers, contacting soil regularly and touching dogs more often, hence utting themselves at higher risk of infections.

20 4.1.2. Associated factors of Toxocara infections The overall roortion of Toxocara infection in dogs was 32.8%. This result was in agreement with other studies conducted in Nigeria from 2011-2012 with the infection rate of 34.6%; by Nguyen Van Chuong in Binh Dinh (22.8-32.4%) and in Dak Lak (35.8-37.0%); and by Bui Van Tuan in Binh Dinh and Gia Lai, with the infection rate of Toxocara canis in dogs being at 34.4-46.8%. The roortions of soil contaminated with Toxocara eggs in households and ublic laygrounds were 27.8% and 25.0%, resectively. These indicated high release of Toxocara larvae into the outer environment, esecially soil settings. Our study result was harmonized with that conducted by Santarem (2008) in rural areas of the Sao Paolo state (Brazil), indicating the roortion of 29.03%. In addition, similar results were also fund in the studies conducted by Nguyen Van Chuong in Binh Dinh (20.0-25.0%); in Dak Lak (36.7-38.3%), by Bui Van Tuan in Binh Dinh and Gia Lai (26.8%), and by Tran Xuan Mai (from 5.0-26.0%), deending on tyical geograhical chacracteristics. The roortion of vegetable contaminated with Toxocara eggs was 6.8%. Kinds of vegetable often consumed are mustard greens, lettuce, centella, fish mint, and savory leaves, which all were contaminated with Toxocara eggs, with lettuce having the highest contamination rate (11.3%). Our study indicated similar result with the study conductd by Nguyen Van Chuong on vegetable in Binh Dinh (4.0-8.0%) and Dak Lak (1.0-3.0%). These kinds of vegetable are lanted on ground, which are rone to dogs defecation. Our study also revealed the association between regularly carrying dogs, contacting soil, and not washing hands after contacting soil and Toxocara infection. The results were in line

21 with studies by Nguyen Van Chuong in Binh Dinh and Dak Lak, and by Bui Van Tuan in Binh Dinh and Gia Lai. 4.2. Efectiveness of some intervention measures 4.2.1. Effectiveness of reducing seroositivity and infection rates of human toxocariasis 4.2.1.1. Changed seroositivity and infection rates of human toxocariasis After one year of intervention in two communes, the seroositivity reduced from 17.9% to 9.9% (<0.01) at the intervention commune and reduced from 16.7% to 14.7% (>0.05); and The intervention effect was 32.7%. Regarding the human Toxocara infections, the infection rate of toxocariasis was reduced from 9.2% to 5.3% (<0.01) at the intervention commune, and from 8.9% to 8.2% (>0.05) at the control commune. The intervention effect was 34.5%. Our study was in line with the study conducted by Tran Minh Quy for fascioliasis control in Binh Dinh and Quang Ngai rovinces, with the reduction of the infection rates in the full-scale intervention commune from 8.8% to 4.2% (<0.05), in the artly intervention commune from 8.4% to 5.4%; but increase in the control commune (from 6.1% to 6.4%). Therefore, comared with the estimated reduction of 30.0% (from 16.0% to 11.0%), our study showed the intervention effects of reducing the seroositivity and infection rates of 32.7% and 34.5%, resectively. 4.2.1.2. Effectiveness of treatment with albendazol on Toxocariasis After one year, the seroositive and infection rates reduced by 86.7% and 90.8%, resectively. This result was in agreement with other studies conducted by Nguyen Van Chuong in Binh Dinh and Dak Lak, by Luong Truong Son in Ho Chi Minh City. This indicated that the treatment fo

22 albendazole for a 21-day course is very effective for Toxocariasis. 4.2.2. Effectiveness of reducing the transmission sources in dogs and outer environment After intervention, the Toxocara infection rate in dogs at the intervention commune reduced by 80.9% (<0.01). The intervention effect was 64.4%. Comared with the study by Bui Ngoc Thuy Linh on the effectiveness of deworming for dogs using injectable ivemectin, our study revealed lower effectiveness. This might be due to our alication of oral route, leaving less effectiveness. However in our study, the alication of oral medication made it eaiser for households when grinding it with dog meals. The roortion of soil and vegetable contaminated with Toxocara eggs reduced significantly. This indicated that the solution of deworming for dogs, couled with health education to change the ractice of environmental hygiene, treatment of dogs feces, would reduce the transmission source into the envinroment. The changed roortion of soil contaminated with Toxocara eggs was not significant, desite high effective index (66.0%). This might be due to small samle size (10 samles for 1 commune), which could lead to incorrect statistical calculations. 4.2.3. Effectiveness of health education in imroving the knowledge, attitude, and ractice of the community on toxocariasis control After intervention, significant increases were found in the level of knowledge of the risks of infection, symtoms, and control measures in the intervention commune ( < 0,01). Our result was in line with other studies conducted for fascioliasis control by Nguyen Van Chuong and Tran Minh Quy, but the intervention effect in our study was lower. This might be due to

23 the fact that much have ever been conducted on fascioliasis, which made the disease known to the community, hence better awareness and ractice. Meanwhile, taxocariasis as an newlyemerging troical disease is not focused in terms of control measures, which catches less attention from the eole. However, with the intervention effect from 23.4-24.7%, health education is considered the most effective measures for Toxocara control. Besides the changes relating to the habits of carrying dogs and washing hands after contacting soil following the intervention, the habit of regularly contacting soil was not changed in our study. This was due to our study was conducted in the rural areas, where eole are farmers, often contacting soil. Our study revealed good coordinations of health, veterinary health, education, local government, and other social organizations such as women s association and farmer association in toxocariasis control camaigns. Although this is the first study ever conducted to control toxocariasis in Viet Nam, its results revealed reduction of seroositivity in humans, decrease in transmission sources, and increase in level of knowledge, attitude, and ractice of the eole. The results of this study could eventually inform the initiatives for effective control measures of toxocariasis in the future. Health education is less exensive; however, it is easy to be imlemented, with significant effects of imroving the knowledge, attitude, and ractice of the community. In this study, the eole erceived dogs as the main source of infection, they rovided good ractice in controlling toxocariasis, which were translated in their more hygienic daily living activities, in better taking care of their dogs, and in regularly deworming for dogs. This roved our control measures were widely acceted

24 by the community, which would lay a foundation for a sustainable achieving further outcomes in the future. Chater 5. CONCLUSIONS 1. Current situation and associated factors of human Toxocara infections 1.1. Human Toxocara seroositivity and infection rates The overall seroositive rate of Toxocara canis was rather high in the two studied communes (17.3%), with the infection rates in Duc Phong and Duc Chanh communes being 17.9% and 16.7%, resectively. Toxocara seroositive rates in men and women were 15.3% and 19.2%, resectively; and eole aged more than 15 years old have higher seroositive rates than those aged from 2 to 15 years old. The overall human Toxocara infection rate at study sites was 9.0% (9.2% in Duc Phong, 8.9% in Duc Chanh communes). Main symtoms included urticarial (69.2%), headache (52.5%), abdominal ain (22.5%), and muscle ains (24.2%). 1.2. Associated factors of Toxocara infections The overall Toxocara infection rate in dogs in two communes was 32.8%, with that at Duc Phong commune of 33.3%; and Duc Chanh of 32.1%. The infection rate reduced by age. The roortion of soil samles contaminated with Toxocara eggs was 27.8% at households and 25.0% at ublic laygrounds. The roortion of vegetable contaminated with Toxocara eggs was 6.8%. Low levels of knowledge, attitude, and ractice of the community under study were found in the study communes, with less than 50% of the surveyed eole having correct answers. Toxocara infection was found to have close associations with regularly carrying dogs (OR= 4.9; CI 95%: 2.5-9.7);

25 regularly contacting soil (OR= 2.8; CI 95%: 2.0-70); not washing hands after contacting soil (OR= 2.6; CI 95%: 1.6-6.5). 2. Effectiveness of intervention measures in toxocariasis control 2.1. Effectiveness of reducing seroositivity and infection rates of human toxocariasis The seroositivity reduced from 17.9% to 9.9% at the intervention commune; with the intervention effect of 32.7%. The infection rate of toxocariasis was reduced from 9.2% to 5.3% at the intervention commune, with the intervention effect of 34.5%. 2.2. Effectiveness of reducing the transmission sources in dogs and outer environment The Toxocara infection rate in dogs at the intervention commune significantly reduced from 33.0% down to 6.3%., with the intervention effect of 64.4%. The roortion of soil contaminated with Toxocara eggs in households of the intervention commune reduced from 29.5% to 9.0%, with the intervention effect of 50.3%. The roortion of vegetable contaminated with Toxocara eggs reduced from 7.0% to 2.0%, with the intervention effect of 71.4%. 2.3. Effectiveness of health education in imroving the knowledge, attitude, and ractice of the community on toxocariasis control In the intervention commune, significant increase was found in the level of knowledge of the risks of infection, and better attitude of toxocara control, with the intervention effects from 23.4% to 24.7%. Also in the same commune, significant increases were found in the ractice of deworming for dogs (from 13.9% to 50.9%, intervention effect of 205.4%), treatment of dogs feces

26 (from 49.0% to 64.5%, intervention effect of 25.6%), washing hands after contacting soil (from 70.5% to 85.5%, intervention effect of 14.4%); meanwhile, reduction in the ractice of carrying dogs was found (from 13.5% to 4.5%, intervention effect of 61.9%). Chater 5. RECOMMENDATIONS 1. For the Ministry of health The national helmthiasis control rogram or roject should be established, with the helmthiniasis surveillance system being set u from central to grass-roots levels. 2. For the institutes of malariology, arasitology and entomology, and rovincial centers for disease control and revention Studies on situation and associated factors of toxocariasis in various eidemiological settings should be continued, esecially areas where dog and cat raising is oular. Intervention measures for toxocariasis control should be alied to rovinces, with focus on health education messages via social media, leaflets, osters. 3. For health facilities, related bodies, and the community Related bodies such as local government, social organizations, sectors of education and veterinary health should be involved in health education camaigns for toxocariasis control in the community. Messages of health education should be maintained on the broadcasting systems, couled with direct talks in schools or integrated in other health care rograms. Risks of infections and ractice of self rotection, environmental sanitation, and regular deworming for dogs should be racticed in a regular manner.

27 LIST OF PUBLISHED ARTICLES IN RELATION TO THE THESIS 1. Bui Van Tuan, Nguyen Van Chuong, Ly Chanh Ty, Tran Phuong Duyen, Vu Sinh Nam (2017), Seroositive rate of toxocariasis in human and associated factors in Mo Duc district, Quang Ngai rovince, 2016. Journal of Preventive Medicine; Vol. 27, 8-2017,. 572-578. 2. Bui Van Tuan, Nguyen Van Chuong, Vu Sinh Nam (2017), Infection rates of Toxocara s. in dogs and Toxocara eggs in soil and vegetables at some study sites of Mo Duc district, Quang Ngai rovince in 20166, Journal of Malaria and Parasite Diseases Control; Secial Issue (96) /2017,. 241-246. 3. Bui Van Tuan, Nguyen Van Chuong, Ly Chanh Ty, Vu Sinh Nam (2018), Effectiveness of some intervention measures for toxocariasis control in Mo Duc district, Quang Ngai rovince, Journal of Preventive Medicine, Vol. 28-2-2018,. 38-44.