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A survey of the dog population in rural Bangladesh
Preventive Veterinary Medicine 111 (2013) 134–138
Contents lists available at SciVerse ScienceDirect
Preventive Veterinary Medicine journal homepage: www.elsevier.com/locate/prevetmed
A survey of the dog population in rural Bangladesh Moazzem Hossain a,1 , Kamruddin Ahmed b,∗ , Aung Swi Prue Marma c , Sohrab Hossain d , Mohammad Azmat Ali e , Abul Khair Mohammad Shamsuzzaman f , Akira Nishizono g a
Disease Control, Directorate General of Health Services, Ministry of Health and Family Welfare, Dhaka, Bangladesh Research Promotion Institute, Oita University, Yufu, Japan Rabies Program, Directorate General of Health Services, Ministry of Health and Family Welfare, Dhaka, Bangladesh d Tongi Municipality, Tongi, Bangladesh e Dhaka City Corporation, Dhaka, Bangladesh f Department of Microbiology, Shahid Suhrawardy Medical College, Dhaka, Bangladesh g Department of Microbiology, Faculty of Medicine, Oita University, Japan b c
a r t i c l e
i n f o
Article history: Received 24 September 2012 Received in revised form 13 March 2013 Accepted 20 March 2013 Keywords: Dog population Bangladesh Rural area Census Rabies
a b s t r a c t Globally, Bangladesh ranks third in the number of human deaths from rabies. Although dogs are the principal known transmitters of rabies and knowledge of dog populations is essential for effective national control and proper planning, dog control programs are scarce in Bangladesh. Our objective was to count dogs in a rural area to understand the dog population of the country. For this purpose we selected six unions of Raipura upazila in Narsingdi district. Dog counting was done by direct observation following accepted guidelines. We determined the mean density of the dog population in Bangladesh to be 14 dog/km2 (95% CI 3.7, 24) and the human:dog ratio to be 120 (95% CI 55, 184). Our paper contribute to the literature which shows great variation in the human:dog ratio across regions of the developing world. The human:dog ratio depends on the area’s human (as well as dog) population, whereas dog density per unit area indicates the true number of dogs. We propose that extrapolating from the human:dog ratios of other regions not be relied upon for estimating dog populations, unless the ratios can be supplemented by actual counts of dogs within the target area. © 2013 Elsevier B.V. All rights reserved.
1. Introduction Every year an estimated 2100 people die of rabies in Bangladesh (Hossain et al., 2012). Dogs are the primary source and transmitters of rabies to humans and domestic animals in Bangladesh (Hossain et al., 2011, 2012). Our previous study showed that 54.2% of animal bite was caused by ownerless dogs and 43.0% by owned dogs (Hossain et al.,
∗ Corresponding author. Tel.: +81 97 586 5798; fax: +81 97 586 5719. E-mail address: [email protected] (K. Ahmed). 1 Institute of Allergy & Clinical Immunology of Bangladesh. 0167-5877/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.prevetmed.2013.03.008
2012). The relationship between human rabies cases and the ownership status of biting dogs is, however, unknown. Rabies epidemiology is highly responsive to humanand dog-population densities as well as to the cultural and socioeconomic environment in which the two populations interact (De Mattos et al., 1999). Although Bangladesh is ranked third highest in rabies-endemic countries for human deaths from rabies (Hossain et al., 2011), studies of dog populations in Bangladesh are scarce. This scarcity is an obstacle for the implementation of a national rabies control program. Estimation of the Bangladeshi dog population (Hossain et al., 2011) has been based on the human:dog ratio estimates for urban and rural Asia: 7.5 (95%CI 4.8, 10.1) and 14.3 (95%CI 0, 45.0), respectively
M. Hossain et al. / Preventive Veterinary Medicine 111 (2013) 134–138
(Knobel et al., 2005). Those estimates were from studies in the Philippines, Vietnam, Sri Lanka, India, China and Thailand. However, because those countries differ importantly by lifestyle, physical environment, culture, and population density from Bangladesh, it is possible that extrapolating a dog density for Bangladesh from the human:dog ratios of those countries is not appropriate. With an area of 147,470 km2 , Bangladesh is one of the densely populated on earth; the predominantly flat land of Bangladesh is crisscrossed by hundreds of rivers. At present, 76.5% of its population lives in rural areas. Dogs in the rural community are accepted as guards for poultry and as “garbage cleaners.” Dog ecology is a product of the cultural and socioeconomic conditions of the humans with whom these animals share their environment; the epidemiology of rabies is greatly influenced by those complex relationships (De Mattos et al., 1999). A little more than half of all dog bites of humans in Bangladesh are attributed to ownerless dogs, however the relationship between human rabies cases and the ownership status of biting dogs remains unknown (Hossain et al., 2012). A count of dogs will fill an important logistical gap in rabies control in Bangladesh. Because the greatest burden of rabies in Bangladesh is in rural areas (Hossain et al., 2012), we determined the number of dogs in a rural area of Bangladesh to measure both the dog density per unit area and the human:dog ratio. The study might be applicable to developing dog-control measures for effective rabies control, and for predicting the needs of dog-vaccination programs to prevent canine rabies. Also, comparing our counted dog population to the estimates based on human:dog ratios from other regions provides an evaluation of the appropriateness of that practice. 2. Materials and methods 2.1. Area Our study was conducted in six unions of Raipura upazila in the Narsingdi district (Fig. 1) (Anon., 2006). In Bangladesh, districts are divided into subdistricts (upazilas) and each upazila is divided into unions. Several villages constitute a union. For the present study, we selected a location that is totally isolated from the land mass by a large river. The unions in our study are located on an island in the Meghna River, one of the largest rivers in Bangladesh. Thus, they are completely isolated from mainland Raipura, with boat the only means of transport to the mainland. According to the 2001 national census, the total human population of Raipura was 454,546 (Anon., 2001). Between 2000 and 2009, the annual population growth rate in Bangladesh was 1.8% (Anon., 2003). Based on this growth rate, we estimated the population of Raipura in 2011 to be 536,356. The total area of Raipura upazila is 291.26 km2 and consists of 24 unions that include 231 villages (Anon., 2009). 2.2. Study design From October to December 2010, we conducted a pilot study on the prevention and control of rabies by animal
135
birth control (ABC). The study was undertaken by the Government of Bangladesh, the Institute of Allergy and Clinical Immunology of Bangladesh, and Bangladesh Anti Rabies Alliance. ABC activities commenced on the 29th October, 2010 and were carried out 2 days per week over the following 5 weeks. Determining the size of the dog population was part of the project. The three distinct seasons in Bangladesh are summer, rainy, and cool-dry. We believe that doing this study during the cool-dry season (as we did) was appropriate for several reasons. i. During the rainy season flood is common in the rural areas of Bangladesh (particularly in places surrounded by a big river like the Meghna). Even in the absence of flood, there is heavy rain which often causes breakdown of road links. Therefore, movements become difficult in the rainy season. ii. In the summer, the temperature is often high and uncomfortable for field workers. Moreover, occasional cyclones during this season add further difficulties for field studies. iii. During rainy or hot days, dogs take shelter in areas other than their dwelling places (and such areas are difficult to locate properly). Our study was done instead at the beginning of the cool-dry season. During this season, the temperature is comfortable and dogs pass their time in open places and are found in predictable locations. iv. A field study like ours needs good support from the local people. However, during rainy and hot seasons people are extremely disturbed by the weather conditions, busy with their own problems, and do not have the attitude to cooperate for a field study. v. The general consensus is that more puppies are seen during the cool-dry season than during other periods; however, because no study of litter “seasons” in dogs has been done for regions such as ours, we do not know whether the dog population is at the annual peak during this season. vi. Finally, we also argue that during the rainy or hot seasons, canine rabies-vaccination campaigns are unlikely to be mounted. Dog counting was done by direct observation following guidelines of the World Society for the Protection of Animals (Anon., 2008). These guidelines focus on estimating or monitoring simply the total number of roaming dogs in public areas. Counts made in selected regions are combined to estimate the total number of dogs roaming on public property at any one time. This number allows calculating statistics such as the density of roaming dogs per unit area. A successful rabies control project in Jaipur, India used this method to count the dog number (Reece and Chawla, 2006). This method is not the best way to count dogs but is suitable for resource-poor settings. Dog surveyors were recruited and given a half-day’s training in the counting-method and data recording. They were equipped with either digital cameras or mobile phones with in-built cameras and asked to photograph each dog during the survey to avoid double counting. Volunteers were also recruited from respective areas to assist
136
M. Hossain et al. / Preventive Veterinary Medicine 111 (2013) 134–138
Fig. 1. Inset showing the location of Narsingdi district of Bangladesh. Next to the map of Bangladesh is a map of Narsingdi district showing the location of Raipura upazila. Below is map of Raipura upazila showing the six study unions (Banshgari, Chandpur, Char Madhua, Mirzar Char, Paratali, and Sreenagar) which are completely surrounded by the Meghna River.
with the survey. Volunteers showed the survey team the dwelling places of street dogs or dog owners’ houses or identified community dogs. With their help, the team tried to assure that no dog was purposefully hidden. Dog owners confirmed their dogs. When someone claimed ownership of a dog, it was designated as dog with owner; otherwise the dog was designated as a ownerless. The street dogs were defined as the roaming dogs that are on public areas and not currently under direct control. The community dog was described as a pet dog not living in anybody’s house or living and eating particularly in one house but always free to move around – but under the control of people in the
community. Various office-holders of the sampled unions cooperated with the survey team by providing temporary lodging and meals. The total survey procedure was monitored and supervised by a veterinary surgeon (co-author S. Hossain).
2.3. Statistical analyses Mean and 95% confidence interval (CI) were determined by Prism 5 software (GraphPad Software Inc., La Jolla, CA, USA).
M. Hossain et al. / Preventive Veterinary Medicine 111 (2013) 134–138
3. Results As derived from the population census of 2001, the six unions in the study have a total human population of 97,900. Based on the growth rate of 1.8%, the estimated population of these unions for 2011 was 116,120 persons. The unions cover an area of 94.78 km2 . We found a total of 1143 dogs in this area. Of these, 570 (50%) were determined to be male, 290 (25%) to be female and 283 (25%) were of undetermined sex. Within this population, 682 (60%) dogs had an owner, 409 (36%) were ownerless street dogs, and 52 (4.5%) were community dogs. Based on the human population, land area, and dog population we determined the mean density of the dog population to be 14 (95% CI 3.7, 24.) dogs/km2 and the human:dog ratio to be 120 (95% CI 55, 184). 4. Discussion Animal-population estimates are useful to publichealth services in controlling rabies and other zoonotic infections (Serafini et al., 2008). Determining free-roaming dog populations is difficult where animal populations fluctuate due to migration (Serafini et al., 2008). Even in our study sites (situated in an ideal location for counting the dog population without immigration or emigration from the island), we found that the number of dogs varied among unions (data not shown). We took this variation as normal and that cannot be avoided in this type of research. The threshold density for rabies persistence is only 4.5 dogs/km2 (Brooks, 1990; Cleaveland and Dye, 1995; Kitala et al., 2002; Knobel et al., 2005). Rural Bangladesh has three times the dog population density to make rabies endemic. The dog-population density in rural Bangladesh matches that of some other areas of Asia (Knobel et al., 2005) and Kenya (Kitala et al., 2001). However, in the neighboring state of West Bengal in India, the dog population density is estimated to be 156–214 dogs/km2 (Pal, 2001). Studies in Sri Lanka and Nepal have also estimated comparatively high dog population densities of 108 dogs/km2 (Matter et al., 2000) and 2930 dogs/km2 (Kato et al., 2003), respectively. (It is likely that the high figure in Nepal is for Kathmandu and not the country as a whole.) The studies showing much higher dog-population densities compared with our Bangladesh study were carried out in urban areas where dog populations are high due to high carrying capacities. Although it would be appropriate to compare to studies done in rural areas of neighboring countries, only studies done in urban areas were available. High death rates due to frequent natural disaster and human invasion into dog habitats might also be responsible for the low dogpopulation density in Bangladesh. The human:dog ratio of 120 that we found is quite high compared with other studies showing a human:dog ratio between 3.40 to 48.30 in several countries (Anon., 2010). The human:dog ratio in rural Bangladesh could be affected by a number of factors. Because Bangladesh is one of the world’s most densely populated countries, a high human-population density relative to a low dogpopulation density makes the human:dog ratio seem so
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high. Outside of that relationship, the low carrying capacity of rural areas relative to urban centers, as well as cultural factors, could affect the ratio. For example, in the metropolis of Cairo with a predominantly Muslim population, the number of dog/100 people is only 0.09 (Jackman and Rowan, 2007), which is even-lower that we found (0.83 dogs/100 people), in our study given that Bangladesh is also a predominantly Muslim country. Similar to human:dog ratio, number of dogs/100 people is another way of expressing the relationship between number of humans and dogs. Therefore the human:dog ratio in Cairo is even higher than we found in our study. But possibly, religion predominance cannot fully explain these high human:dog ratios. For a counter example, the dog population in Indonesia (a predominantly Muslim country) is 6.25 dogs/100 people (Jackman and Rowan, 2007) comparable to the dog population in Black Urban area of South Africa (6.70 dogs/100 people) (Odendaal, 1994). In contrast, in urban Zambia it is only 2.2 dogs/100 people (DeBalogh et al., 1993). The human:dog ratio depends also on the human population of the area, whereas dog density per unit area indicates the actual number of dogs. Therefore, we propose that dog densities are needed (instead of relying only on estimated human:dog ratios from other settings) to estimate the number of dogs in areas where a dog count has not been previously conducted. In this study (similar to other studies), we counted more male than female dogs (Margawani and Robertson, 1995; Pal, 2001; Kongkaew et al., 2004). In rural areas of Bangladesh, dogs are used to guard livestock and property. There is a preference for male dogs as guard dogs, as well as for avoiding the need to manage the litters of bitches (Margawani and Robertson, 1995; Kitala et al., 2001). Although owned dogs were more frequent than ownerless or community dogs in our study, the Western notion of pet dogs is virtually absent in rural Bangladesh. The community dog implies loose ownership by more than one individual or household. Therefore, it must be noted that a proportion of apparently roaming dogs may in fact be owned by an individual or a community.
5. Conclusion The dog-population density in rural Bangladesh (14 dogs/km2 ) is comparable to other rural area in some – but not all other areas of Asia. However, we also found a very high human:dog ratio (of 120) which might be affected by the high human population density. The human:dog ratio varies considerably from one part of the developing world to another. We propose that in areas where the dog population has not been estimated directly, authorities should not extrapolate the dog-population density from human:dog ratios of other regions.
Conflict of interests The authors declare that they have no conflict of interest.
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Acknowledgements This study was supported in part by the Research Fund at the Discretion of the President, Oita University [610000N5010] to K. Ahmed. References Anon., 2001. Zila Profile. Bangladesh Bureau of Statistics, Available here: http://www.bbs.gov.bd/RptZillaProfile.aspx (accessed 03.12). Anon., 2003. Bangladesh, statistics. UNICEF, Available here: http://www. unicef.org/infobycountry/bangladesh bangladesh statistics.html (accessed 03.12). Anon., 2006. Raipura Upazila, Banglapedia, National Encyclopedia of Bangladesh, Available here: http://www.banglapedia.org/HT/ R 0054.HTM (accessed 03.13). Anon., 2008. Surveying roaming dog populations: guidelines on methodology. World Society for the Protection of Animals, Available here: http://www.icam211-coalition.org/downloads/Surveying %20roaming%20dog%20population%20-%20guidelines%20on %20methodology.pdf (accessed 04.12). Anon., 2009. National Statistics. Upazila Statistics, Available here: http://gramweb.net/regional search.php (accessed 03.12). Anon., 2010. Human:dog ratios. Rabiesblueprint, Available at: http://www.rabiesblueprint.com/IMG/pdf/Link46 HumanDogRatios. pdf (accessed 03.12). Brooks, R., 1990. Survey of the dog population of Zimbabwe and its level of rabies vaccination. Vet. Rec. 127 (24), 592–596. Cleaveland, S., Dye, C., 1995. Maintenance of a microparasite infecting several host species: rabies in the Serengeti. Parasitology 111 (Suppl.), S33–S47. De Mattos, C.C., De Mattos, C.A., Loza-Rubio, E., Aguilar-Setien, A., Molecular characterization of Orciari, L.A., Smith, J.S., 1999. rabies virus isolates from Mexico: implications for transmission dynamics and human risk. Am. J. Trop. Med. Hyg. 61 (4), 587– 597. DeBalogh, K., Wanderler, A., Meslin, F., 1993. A dog ecology study in urban and semi-rural areas of Zambia. Oderstepoort J. Vet. Res. 60 (4), 437–443. Hossain, M., Bulbul, T., Ahmed, K., Ahmed, Z., Salimuzzaman, M., Haque, M.S., Ali, A., Hossain, S., Yamada, K., Moji, K., Nishizono, A., 2011. Fiveyear (January 2004–December 2008) surveillance on animal bite and
rabies vaccine utilization in the Infectious Disease Hospital, Dhaka, Bangladesh. Vaccine 29 (5), 1036–1040. Hossain, M., Ahmed, K., Bulbul, T., Hossain, S., Rahman, A., Biswas, M.N., Nishizono, A., 2012. Human rabies in rural Bangladesh. Epidemiol. Infect. 140 (11), 1964–1971. Jackman, J., Rowan, A., 2007. Free-roaming dogs in developing countries: the benefits of capture, neuter and return programs. In: Salem, D.J., Rowan, A.N. (Eds.), The State of the Animals IV: 2007. Humane Society Press, Washington, pp. 55–78. Kato, M., Yamamoto, Y., Inukai, Y., Kira, S., 2003. Survey of the stray dog population and the health education program on the prevention of dog bites and dog-acquired infections: a comparative study in Nepal and Okayama Prefecture, Japan. Acta Medica Okayama 57 (5), 261–266. Kitala, P., McDermott, J., Kyule, M., Gathuma, J., Perry, B., Wandeler, A., 2001. Dog ecology and demography information to support the planning of rabies control in Machakos District, Kenya. Acta Trop. 78 (3), 217–230. Kitala, P.M., McDermott, J.J., Coleman, P.G., Dye, C., 2002. Comparison of vaccination strategies for the control of dog rabies in Machakos District, Kenya. Epidemiol. Infect. 129 (1), 215–222. Knobel, D.L., Cleaveland, S., Coleman, P.G., Fevre, E.M., Meltzer, M.I., Miranda, M.E., Shaw, A., Zinsstag, J., Meslin, F.X., 2005. Re-evaluating the burden of rabies in Africa and Asia. Bull. World Health Organ. 83 (5), 360–368. Kongkaew, W., Coleman, P., Pfeiffer, D.U., Antarasena, C., Thiptara, A., 2004. Vaccination coverage and epidemiological parameters of the owneddog population in Thungsong District, Thailand. Prev. Vet. Med. 65 (1/2), 105–115. Margawani, K.R., Robertson, I.D., 1995. A survey of urban pet ownership in Bali. Vet. Rec. 137 (19), 486–488. Matter, H.C., Wandeler, A.I., Neuenschwander, B.E., Harischandra, L.P., Meslin, F.X., 2000. Study of the dog population and the rabies control activities in the Mirigama area of Sri Lanka. Acta Trop. 75 (1), 95–108. Odendaal, J.S., 1994. Demographics of companion animals in South Africa. J. South African Vet. Assoc. 65 (2), 67–72. Pal, S.K., 2001. Population ecology of free-ranging urban dogs in West Bengal, India. Acta Theriol. 46 (1), 69–78. Reece, J.F., Chawla, S.K., 2006. Control of rabies in Jaipur, India, by the sterilisation and vaccination of neighbourhood dogs. Vet. Rec. 159 (12), 379–383. Serafini, C.A., Rosa, G.A., Guimaraes, A.M., De Morais, H.A., Biondo, A.W., 2008. Survey of owned feline and canine populations in apartments from a neighbourhood in Curitiba, Brazil. Zoonoses Public Health 55 (8–10), 402–405.
Contents lists available at SciVerse ScienceDirect
Preventive Veterinary Medicine journal homepage: www.elsevier.com/locate/prevetmed
A survey of the dog population in rural Bangladesh Moazzem Hossain a,1 , Kamruddin Ahmed b,∗ , Aung Swi Prue Marma c , Sohrab Hossain d , Mohammad Azmat Ali e , Abul Khair Mohammad Shamsuzzaman f , Akira Nishizono g a
Disease Control, Directorate General of Health Services, Ministry of Health and Family Welfare, Dhaka, Bangladesh Research Promotion Institute, Oita University, Yufu, Japan Rabies Program, Directorate General of Health Services, Ministry of Health and Family Welfare, Dhaka, Bangladesh d Tongi Municipality, Tongi, Bangladesh e Dhaka City Corporation, Dhaka, Bangladesh f Department of Microbiology, Shahid Suhrawardy Medical College, Dhaka, Bangladesh g Department of Microbiology, Faculty of Medicine, Oita University, Japan b c
a r t i c l e
i n f o
Article history: Received 24 September 2012 Received in revised form 13 March 2013 Accepted 20 March 2013 Keywords: Dog population Bangladesh Rural area Census Rabies
a b s t r a c t Globally, Bangladesh ranks third in the number of human deaths from rabies. Although dogs are the principal known transmitters of rabies and knowledge of dog populations is essential for effective national control and proper planning, dog control programs are scarce in Bangladesh. Our objective was to count dogs in a rural area to understand the dog population of the country. For this purpose we selected six unions of Raipura upazila in Narsingdi district. Dog counting was done by direct observation following accepted guidelines. We determined the mean density of the dog population in Bangladesh to be 14 dog/km2 (95% CI 3.7, 24) and the human:dog ratio to be 120 (95% CI 55, 184). Our paper contribute to the literature which shows great variation in the human:dog ratio across regions of the developing world. The human:dog ratio depends on the area’s human (as well as dog) population, whereas dog density per unit area indicates the true number of dogs. We propose that extrapolating from the human:dog ratios of other regions not be relied upon for estimating dog populations, unless the ratios can be supplemented by actual counts of dogs within the target area. © 2013 Elsevier B.V. All rights reserved.
1. Introduction Every year an estimated 2100 people die of rabies in Bangladesh (Hossain et al., 2012). Dogs are the primary source and transmitters of rabies to humans and domestic animals in Bangladesh (Hossain et al., 2011, 2012). Our previous study showed that 54.2% of animal bite was caused by ownerless dogs and 43.0% by owned dogs (Hossain et al.,
∗ Corresponding author. Tel.: +81 97 586 5798; fax: +81 97 586 5719. E-mail address: [email protected] (K. Ahmed). 1 Institute of Allergy & Clinical Immunology of Bangladesh. 0167-5877/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.prevetmed.2013.03.008
2012). The relationship between human rabies cases and the ownership status of biting dogs is, however, unknown. Rabies epidemiology is highly responsive to humanand dog-population densities as well as to the cultural and socioeconomic environment in which the two populations interact (De Mattos et al., 1999). Although Bangladesh is ranked third highest in rabies-endemic countries for human deaths from rabies (Hossain et al., 2011), studies of dog populations in Bangladesh are scarce. This scarcity is an obstacle for the implementation of a national rabies control program. Estimation of the Bangladeshi dog population (Hossain et al., 2011) has been based on the human:dog ratio estimates for urban and rural Asia: 7.5 (95%CI 4.8, 10.1) and 14.3 (95%CI 0, 45.0), respectively
M. Hossain et al. / Preventive Veterinary Medicine 111 (2013) 134–138
(Knobel et al., 2005). Those estimates were from studies in the Philippines, Vietnam, Sri Lanka, India, China and Thailand. However, because those countries differ importantly by lifestyle, physical environment, culture, and population density from Bangladesh, it is possible that extrapolating a dog density for Bangladesh from the human:dog ratios of those countries is not appropriate. With an area of 147,470 km2 , Bangladesh is one of the densely populated on earth; the predominantly flat land of Bangladesh is crisscrossed by hundreds of rivers. At present, 76.5% of its population lives in rural areas. Dogs in the rural community are accepted as guards for poultry and as “garbage cleaners.” Dog ecology is a product of the cultural and socioeconomic conditions of the humans with whom these animals share their environment; the epidemiology of rabies is greatly influenced by those complex relationships (De Mattos et al., 1999). A little more than half of all dog bites of humans in Bangladesh are attributed to ownerless dogs, however the relationship between human rabies cases and the ownership status of biting dogs remains unknown (Hossain et al., 2012). A count of dogs will fill an important logistical gap in rabies control in Bangladesh. Because the greatest burden of rabies in Bangladesh is in rural areas (Hossain et al., 2012), we determined the number of dogs in a rural area of Bangladesh to measure both the dog density per unit area and the human:dog ratio. The study might be applicable to developing dog-control measures for effective rabies control, and for predicting the needs of dog-vaccination programs to prevent canine rabies. Also, comparing our counted dog population to the estimates based on human:dog ratios from other regions provides an evaluation of the appropriateness of that practice. 2. Materials and methods 2.1. Area Our study was conducted in six unions of Raipura upazila in the Narsingdi district (Fig. 1) (Anon., 2006). In Bangladesh, districts are divided into subdistricts (upazilas) and each upazila is divided into unions. Several villages constitute a union. For the present study, we selected a location that is totally isolated from the land mass by a large river. The unions in our study are located on an island in the Meghna River, one of the largest rivers in Bangladesh. Thus, they are completely isolated from mainland Raipura, with boat the only means of transport to the mainland. According to the 2001 national census, the total human population of Raipura was 454,546 (Anon., 2001). Between 2000 and 2009, the annual population growth rate in Bangladesh was 1.8% (Anon., 2003). Based on this growth rate, we estimated the population of Raipura in 2011 to be 536,356. The total area of Raipura upazila is 291.26 km2 and consists of 24 unions that include 231 villages (Anon., 2009). 2.2. Study design From October to December 2010, we conducted a pilot study on the prevention and control of rabies by animal
135
birth control (ABC). The study was undertaken by the Government of Bangladesh, the Institute of Allergy and Clinical Immunology of Bangladesh, and Bangladesh Anti Rabies Alliance. ABC activities commenced on the 29th October, 2010 and were carried out 2 days per week over the following 5 weeks. Determining the size of the dog population was part of the project. The three distinct seasons in Bangladesh are summer, rainy, and cool-dry. We believe that doing this study during the cool-dry season (as we did) was appropriate for several reasons. i. During the rainy season flood is common in the rural areas of Bangladesh (particularly in places surrounded by a big river like the Meghna). Even in the absence of flood, there is heavy rain which often causes breakdown of road links. Therefore, movements become difficult in the rainy season. ii. In the summer, the temperature is often high and uncomfortable for field workers. Moreover, occasional cyclones during this season add further difficulties for field studies. iii. During rainy or hot days, dogs take shelter in areas other than their dwelling places (and such areas are difficult to locate properly). Our study was done instead at the beginning of the cool-dry season. During this season, the temperature is comfortable and dogs pass their time in open places and are found in predictable locations. iv. A field study like ours needs good support from the local people. However, during rainy and hot seasons people are extremely disturbed by the weather conditions, busy with their own problems, and do not have the attitude to cooperate for a field study. v. The general consensus is that more puppies are seen during the cool-dry season than during other periods; however, because no study of litter “seasons” in dogs has been done for regions such as ours, we do not know whether the dog population is at the annual peak during this season. vi. Finally, we also argue that during the rainy or hot seasons, canine rabies-vaccination campaigns are unlikely to be mounted. Dog counting was done by direct observation following guidelines of the World Society for the Protection of Animals (Anon., 2008). These guidelines focus on estimating or monitoring simply the total number of roaming dogs in public areas. Counts made in selected regions are combined to estimate the total number of dogs roaming on public property at any one time. This number allows calculating statistics such as the density of roaming dogs per unit area. A successful rabies control project in Jaipur, India used this method to count the dog number (Reece and Chawla, 2006). This method is not the best way to count dogs but is suitable for resource-poor settings. Dog surveyors were recruited and given a half-day’s training in the counting-method and data recording. They were equipped with either digital cameras or mobile phones with in-built cameras and asked to photograph each dog during the survey to avoid double counting. Volunteers were also recruited from respective areas to assist
136
M. Hossain et al. / Preventive Veterinary Medicine 111 (2013) 134–138
Fig. 1. Inset showing the location of Narsingdi district of Bangladesh. Next to the map of Bangladesh is a map of Narsingdi district showing the location of Raipura upazila. Below is map of Raipura upazila showing the six study unions (Banshgari, Chandpur, Char Madhua, Mirzar Char, Paratali, and Sreenagar) which are completely surrounded by the Meghna River.
with the survey. Volunteers showed the survey team the dwelling places of street dogs or dog owners’ houses or identified community dogs. With their help, the team tried to assure that no dog was purposefully hidden. Dog owners confirmed their dogs. When someone claimed ownership of a dog, it was designated as dog with owner; otherwise the dog was designated as a ownerless. The street dogs were defined as the roaming dogs that are on public areas and not currently under direct control. The community dog was described as a pet dog not living in anybody’s house or living and eating particularly in one house but always free to move around – but under the control of people in the
community. Various office-holders of the sampled unions cooperated with the survey team by providing temporary lodging and meals. The total survey procedure was monitored and supervised by a veterinary surgeon (co-author S. Hossain).
2.3. Statistical analyses Mean and 95% confidence interval (CI) were determined by Prism 5 software (GraphPad Software Inc., La Jolla, CA, USA).
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3. Results As derived from the population census of 2001, the six unions in the study have a total human population of 97,900. Based on the growth rate of 1.8%, the estimated population of these unions for 2011 was 116,120 persons. The unions cover an area of 94.78 km2 . We found a total of 1143 dogs in this area. Of these, 570 (50%) were determined to be male, 290 (25%) to be female and 283 (25%) were of undetermined sex. Within this population, 682 (60%) dogs had an owner, 409 (36%) were ownerless street dogs, and 52 (4.5%) were community dogs. Based on the human population, land area, and dog population we determined the mean density of the dog population to be 14 (95% CI 3.7, 24.) dogs/km2 and the human:dog ratio to be 120 (95% CI 55, 184). 4. Discussion Animal-population estimates are useful to publichealth services in controlling rabies and other zoonotic infections (Serafini et al., 2008). Determining free-roaming dog populations is difficult where animal populations fluctuate due to migration (Serafini et al., 2008). Even in our study sites (situated in an ideal location for counting the dog population without immigration or emigration from the island), we found that the number of dogs varied among unions (data not shown). We took this variation as normal and that cannot be avoided in this type of research. The threshold density for rabies persistence is only 4.5 dogs/km2 (Brooks, 1990; Cleaveland and Dye, 1995; Kitala et al., 2002; Knobel et al., 2005). Rural Bangladesh has three times the dog population density to make rabies endemic. The dog-population density in rural Bangladesh matches that of some other areas of Asia (Knobel et al., 2005) and Kenya (Kitala et al., 2001). However, in the neighboring state of West Bengal in India, the dog population density is estimated to be 156–214 dogs/km2 (Pal, 2001). Studies in Sri Lanka and Nepal have also estimated comparatively high dog population densities of 108 dogs/km2 (Matter et al., 2000) and 2930 dogs/km2 (Kato et al., 2003), respectively. (It is likely that the high figure in Nepal is for Kathmandu and not the country as a whole.) The studies showing much higher dog-population densities compared with our Bangladesh study were carried out in urban areas where dog populations are high due to high carrying capacities. Although it would be appropriate to compare to studies done in rural areas of neighboring countries, only studies done in urban areas were available. High death rates due to frequent natural disaster and human invasion into dog habitats might also be responsible for the low dogpopulation density in Bangladesh. The human:dog ratio of 120 that we found is quite high compared with other studies showing a human:dog ratio between 3.40 to 48.30 in several countries (Anon., 2010). The human:dog ratio in rural Bangladesh could be affected by a number of factors. Because Bangladesh is one of the world’s most densely populated countries, a high human-population density relative to a low dogpopulation density makes the human:dog ratio seem so
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high. Outside of that relationship, the low carrying capacity of rural areas relative to urban centers, as well as cultural factors, could affect the ratio. For example, in the metropolis of Cairo with a predominantly Muslim population, the number of dog/100 people is only 0.09 (Jackman and Rowan, 2007), which is even-lower that we found (0.83 dogs/100 people), in our study given that Bangladesh is also a predominantly Muslim country. Similar to human:dog ratio, number of dogs/100 people is another way of expressing the relationship between number of humans and dogs. Therefore the human:dog ratio in Cairo is even higher than we found in our study. But possibly, religion predominance cannot fully explain these high human:dog ratios. For a counter example, the dog population in Indonesia (a predominantly Muslim country) is 6.25 dogs/100 people (Jackman and Rowan, 2007) comparable to the dog population in Black Urban area of South Africa (6.70 dogs/100 people) (Odendaal, 1994). In contrast, in urban Zambia it is only 2.2 dogs/100 people (DeBalogh et al., 1993). The human:dog ratio depends also on the human population of the area, whereas dog density per unit area indicates the actual number of dogs. Therefore, we propose that dog densities are needed (instead of relying only on estimated human:dog ratios from other settings) to estimate the number of dogs in areas where a dog count has not been previously conducted. In this study (similar to other studies), we counted more male than female dogs (Margawani and Robertson, 1995; Pal, 2001; Kongkaew et al., 2004). In rural areas of Bangladesh, dogs are used to guard livestock and property. There is a preference for male dogs as guard dogs, as well as for avoiding the need to manage the litters of bitches (Margawani and Robertson, 1995; Kitala et al., 2001). Although owned dogs were more frequent than ownerless or community dogs in our study, the Western notion of pet dogs is virtually absent in rural Bangladesh. The community dog implies loose ownership by more than one individual or household. Therefore, it must be noted that a proportion of apparently roaming dogs may in fact be owned by an individual or a community.
5. Conclusion The dog-population density in rural Bangladesh (14 dogs/km2 ) is comparable to other rural area in some – but not all other areas of Asia. However, we also found a very high human:dog ratio (of 120) which might be affected by the high human population density. The human:dog ratio varies considerably from one part of the developing world to another. We propose that in areas where the dog population has not been estimated directly, authorities should not extrapolate the dog-population density from human:dog ratios of other regions.
Conflict of interests The authors declare that they have no conflict of interest.
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