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Spatial characterization of colonies of the flying fox bat, a carrier of Nipah virus in Thailand.

Thanapongtharm W, Linard C, Wiriyarat W, Chinsorn P, Kanchanasaka B, Xiao X, Biradar C, Wallace RG, Gilbert M - BMC Vet. Res. (2015)

Bottom Line: While no evidence of infection in domestic pigs or people has been found to date, pig farming is an active agricultural sector in Thailand and therefore could be a potential pathway for zoonotic disease transmission from the bat reservoirs.Flying fox colonies are found mainly on Thailand's Central Plain, particularly in locations surrounded by bodies of water, vegetation, and safe havens such as Buddhist temples.Such proactive planning would help conserve flying fox colonies and should help prevent zoonotic transmission of Nipah and other pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Livestock Development (DLD), Bangkok, Thailand. weeraden@yahoo.com.

ABSTRACT

Background: A major reservoir of Nipah virus is believed to be the flying fox genus Pteropus, a fruit bat distributed across many of the world's tropical and sub-tropical areas. The emergence of the virus and its zoonotic transmission to livestock and humans have been linked to losses in the bat's habitat. Nipah has been identified in a number of indigenous flying fox populations in Thailand. While no evidence of infection in domestic pigs or people has been found to date, pig farming is an active agricultural sector in Thailand and therefore could be a potential pathway for zoonotic disease transmission from the bat reservoirs. The disease, then, represents a potential zoonotic risk. To characterize the spatial habitat of flying fox populations along Thailand's Central Plain, and to map potential contact zones between flying fox habitats, pig farms and human settlements, we conducted field observation, remote sensing, and ecological niche modeling to characterize flying fox colonies and their ecological neighborhoods. A Potential Surface Analysis was applied to map contact zones among local epizootic actors.

Results: Flying fox colonies are found mainly on Thailand's Central Plain, particularly in locations surrounded by bodies of water, vegetation, and safe havens such as Buddhist temples. High-risk areas for Nipah zoonosis in pigs include the agricultural ring around the Bangkok metropolitan region where the density of pig farms is high.

Conclusions: Passive and active surveillance programs should be prioritized around Bangkok, particularly on farms with low biosecurity, close to water, and/or on which orchards are concomitantly grown. Integration of human and animal health surveillance should be pursued in these same areas. Such proactive planning would help conserve flying fox colonies and should help prevent zoonotic transmission of Nipah and other pathogens.

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Risk area of NiV in the central plain of Thailand. Risk area of NiV produced by Potential Surface Analysis (PSA) based on i) flying fox distribution map, ii) distance to flying fox colonies, iii) house density and iv) pig farm density. The risk area of NiV for humans obtained from the first 3 factors (A), from all 4 factors (B), and the risk area of NiV for pigs produced by combining factors i, ii and iv (C). The yellow circles show different risk areas between B and C. Risk was low if the summation score was less than , moderate if the summation score was range between  and , and high if the summation score was more than .
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Fig7: Risk area of NiV in the central plain of Thailand. Risk area of NiV produced by Potential Surface Analysis (PSA) based on i) flying fox distribution map, ii) distance to flying fox colonies, iii) house density and iv) pig farm density. The risk area of NiV for humans obtained from the first 3 factors (A), from all 4 factors (B), and the risk area of NiV for pigs produced by combining factors i, ii and iv (C). The yellow circles show different risk areas between B and C. Risk was low if the summation score was less than , moderate if the summation score was range between and , and high if the summation score was more than .

Mentions: The overlay of potential surface maps corresponding to the first scenario under which humans are directly infected with NiV by bats show the higher-risk areas cover 6,199 km2 of 1,003 sub-districts, 159 districts, and 23 provinces and are mainly located to the north, northeast and east of Bangkok (Figures 6 and 7A). For the second scenario in which humans are infected via a pig reservoir, higher-risk areas cover 5,629 km2 of 653 sub-districts, 143 districts, and 23 provinces (Figure 7B). The higher-risk area of NiV in pigs cover 5,417 km2 of 607 sub-districts, 125 districts, and 23 provinces (Figure 7C). The two risk maps factoring in pig density looked very similar (Figure 7B & C). The higher-risk areas on both maps are located around the Bangkok metropolitan area, with environs to the west and north most affected. A slight difference in NiV risk levels between humans and pigs was observed in Bangkok, with greater risk for humans (Figure 7B) than for pigs (Figure 7C).Figure 6


Spatial characterization of colonies of the flying fox bat, a carrier of Nipah virus in Thailand.

Thanapongtharm W, Linard C, Wiriyarat W, Chinsorn P, Kanchanasaka B, Xiao X, Biradar C, Wallace RG, Gilbert M - BMC Vet. Res. (2015)

Risk area of NiV in the central plain of Thailand. Risk area of NiV produced by Potential Surface Analysis (PSA) based on i) flying fox distribution map, ii) distance to flying fox colonies, iii) house density and iv) pig farm density. The risk area of NiV for humans obtained from the first 3 factors (A), from all 4 factors (B), and the risk area of NiV for pigs produced by combining factors i, ii and iv (C). The yellow circles show different risk areas between B and C. Risk was low if the summation score was less than , moderate if the summation score was range between  and , and high if the summation score was more than .
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389713&req=5

Fig7: Risk area of NiV in the central plain of Thailand. Risk area of NiV produced by Potential Surface Analysis (PSA) based on i) flying fox distribution map, ii) distance to flying fox colonies, iii) house density and iv) pig farm density. The risk area of NiV for humans obtained from the first 3 factors (A), from all 4 factors (B), and the risk area of NiV for pigs produced by combining factors i, ii and iv (C). The yellow circles show different risk areas between B and C. Risk was low if the summation score was less than , moderate if the summation score was range between and , and high if the summation score was more than .
Mentions: The overlay of potential surface maps corresponding to the first scenario under which humans are directly infected with NiV by bats show the higher-risk areas cover 6,199 km2 of 1,003 sub-districts, 159 districts, and 23 provinces and are mainly located to the north, northeast and east of Bangkok (Figures 6 and 7A). For the second scenario in which humans are infected via a pig reservoir, higher-risk areas cover 5,629 km2 of 653 sub-districts, 143 districts, and 23 provinces (Figure 7B). The higher-risk area of NiV in pigs cover 5,417 km2 of 607 sub-districts, 125 districts, and 23 provinces (Figure 7C). The two risk maps factoring in pig density looked very similar (Figure 7B & C). The higher-risk areas on both maps are located around the Bangkok metropolitan area, with environs to the west and north most affected. A slight difference in NiV risk levels between humans and pigs was observed in Bangkok, with greater risk for humans (Figure 7B) than for pigs (Figure 7C).Figure 6

Bottom Line: While no evidence of infection in domestic pigs or people has been found to date, pig farming is an active agricultural sector in Thailand and therefore could be a potential pathway for zoonotic disease transmission from the bat reservoirs.Flying fox colonies are found mainly on Thailand's Central Plain, particularly in locations surrounded by bodies of water, vegetation, and safe havens such as Buddhist temples.Such proactive planning would help conserve flying fox colonies and should help prevent zoonotic transmission of Nipah and other pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Livestock Development (DLD), Bangkok, Thailand. weeraden@yahoo.com.

ABSTRACT

Background: A major reservoir of Nipah virus is believed to be the flying fox genus Pteropus, a fruit bat distributed across many of the world's tropical and sub-tropical areas. The emergence of the virus and its zoonotic transmission to livestock and humans have been linked to losses in the bat's habitat. Nipah has been identified in a number of indigenous flying fox populations in Thailand. While no evidence of infection in domestic pigs or people has been found to date, pig farming is an active agricultural sector in Thailand and therefore could be a potential pathway for zoonotic disease transmission from the bat reservoirs. The disease, then, represents a potential zoonotic risk. To characterize the spatial habitat of flying fox populations along Thailand's Central Plain, and to map potential contact zones between flying fox habitats, pig farms and human settlements, we conducted field observation, remote sensing, and ecological niche modeling to characterize flying fox colonies and their ecological neighborhoods. A Potential Surface Analysis was applied to map contact zones among local epizootic actors.

Results: Flying fox colonies are found mainly on Thailand's Central Plain, particularly in locations surrounded by bodies of water, vegetation, and safe havens such as Buddhist temples. High-risk areas for Nipah zoonosis in pigs include the agricultural ring around the Bangkok metropolitan region where the density of pig farms is high.

Conclusions: Passive and active surveillance programs should be prioritized around Bangkok, particularly on farms with low biosecurity, close to water, and/or on which orchards are concomitantly grown. Integration of human and animal health surveillance should be pursued in these same areas. Such proactive planning would help conserve flying fox colonies and should help prevent zoonotic transmission of Nipah and other pathogens.

Show MeSH
Related in: MedlinePlus