Benjamin P Y-H Lee

Publications (7)22.47 Total impact

• Article: Influenza virus infection in nonhuman primates.

  Erik A Karlsson, Gregory A Engel, M M Feeroz, Sorn San, Aida Rompis, Benjamin P Y-H Lee, Eric Shaw, Gunwha Oh, Michael A Schillaci, Richard Grant, John Heidrich, Stacey Schultz-Cherry, Lisa Jones-Engel
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  ABSTRACT: To determine whether nonhuman primates are infected with influenza viruses in nature, we conducted serologic and swab studies among macaques from several parts of the world. Our detection of influenza virus and antibodies to influenza virus raises questions about the role of nonhuman primates in the ecology of influenza.
  Emerging Infectious Diseases 10/2012; 18(10):1672-5. · 6.79 Impact Factor
• Article: From the mouths of monkeys: detection of Mycobacterium tuberculosis complex DNA from buccal swabs of synanthropic macaques.

  Alicia K Wilbur, Gregory A Engel, Aida Rompis, I G A A Putra, Benjamin P Y-H Lee, Nantiya Aggimarangsee, Mukesh Chalise, Eric Shaw, Gunwha Oh, Michael A Schillaci, Lisa Jones-Engel
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  ABSTRACT: Although the Mycobacterium tuberculosis complex (MTBC) infects a third of all humans, little is known regarding the prevalence of mycobacterial infection in nonhuman primates (NHP). For more than a century, tuberculosis has been regarded as a serious infectious threat to NHP species. Advances in the detection of MTBC open new possibilities for investigating the effects of this poorly understood pathogen in diverse populations of NHP. Here, we report results of a cross-sectional study using well-described molecular methods to detect a nucleic acid sequence (IS6110) unique to the MTBC. Sample collection was focused on the oral cavity, the presumed route of transmission of MTBC. Buccal swabs were collected from 263 macaques representing 11 species in four Asian countries and Gibraltar. Contexts of contact with humans included free ranging, pets, performing monkeys, zoos, and monkey temples. Following DNA isolation from buccal swabs, the polymerase chain reaction (PCR) amplified IS6110 from 84 (31.9%) of the macaques. In general, prevalence of MTBC DNA was higher among NHP in countries where the World Health Organization reports higher prevalence of humans infected with MTBC. This is the first demonstration of MTBC DNA in the mouths of macaques. Further research is needed to establish the significance of this finding at both the individual and population levels. PCR of buccal samples holds promise as a method to elucidate the mycobacterial landscape among NHP, particularly macaques that thrive in areas of high human MTBC prevalence.
  American Journal of Primatology 07/2012; 74(7):676-86. · 2.22 Impact Factor
• Article: Status of the long-tailed macaque Macaca fascicularis in Singapore and implications for management

  John Chih Mun Sha, Michael D. Gumert, Benjamin P. Y.-H. Lee, Agustin Fuentes, Subaraj Rajathurai, Sharon Chan, Lisa Jones-Engel
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  ABSTRACT: The long-tailed macaque (Macaca fascicularis) population of the island-state of Singapore consists of ca. 1,218–1,454 individuals. About seventy percent of the population (ca. 1,027 individuals) is concentrated in both Bukit Timah and Central Catchment Nature Reserves, a system of reservoirs and forest reserves located in the center of Singapore. This core population resides mainly along perimeter forest areas of the reserve system, which is bordered by residential and recreational areas (e.g., parks and golf courses) and encircled by expressways. Periphery sub-populations (ca. 427 individuals) persist in forest fragments throughout Singapore mainland and on 5 offshore islands. Much of the Singaporean macaque population overlaps with human settlement and these commensal groups are mainly distributed close to roads, parks and residential areas. At least 70% of these groups are habituated to human presence and at least 50% to food provisioning. Moreover, commensal groups have more individuals and have higher infant:adult female ratios than non-commensal groups. The close association of habituated macaque groups living in human environments has led to increasing human-macaque conflict in Singapore. The overlap is also associated with human-induced population loss resulting from road accidents (2.4%); and trapping efforts (14%) aimed at ameliorating conflict issues. Consequently, it is important to better understand how humans are affecting macaque populations. In order to mitigate human-macaque conflict and at the same maintain a sustainable macaque population in Singapore, there is an urgent need for wildlife management strategies aimed at minimizing the extent of human–macaque conflict. Such strategies should include designing appropriate buffers around reserve areas, revised urban development plans, and managing the behavior of people interfacing with macaques.
  Biodiversity and Conservation 04/2012; 18(11):2909-2926. · 2.24 Impact Factor
• Article: Lead levels in long-tailed macaque (Macaca fascicularis) hair from Singapore.

  Michael A Schillaci, Benjamin P Y-H Lee, J Margaret Castellini, Michael J C Reid, Todd M O'Hara
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  ABSTRACT: Nonhuman primates are potentially good sentinels of environmental toxicants because they share a similar physiology and life history with humans. In this report we present the results of an analysis of lead concentrations in hair from long-tailed macaques in Singapore. We hypothesized that because Singapore is highly urbanized, its macaque population may be exposed to higher levels of lead. The results of our study indicated that Singapore's macaque population has not been exposed to high levels of environmental lead. Compared with previous studies of lead levels in human and nonhuman primate hair, the results of our analysis indicate a low level of exposure of monkeys to environmental lead (n = 27, arithmetic mean = 2.51 ppm, max = 6.45, min = 0.21 ppm). Hair lead concentrations varied both within social groups and by geographic location, with the highest concentrations observed in monkeys residing within an area containing a small-arms firing range and a manufacturing facility. Although lead exposure in this area seems to be low, additional monitoring and possible remediation may be warranted. Our study is among the first to illustrate how primates can serve as potential sentinels of environmental toxicants such as lead. Future research examining the efficacy of primates as sentinels of lead exposure should include monitoring of environmental lead levels, and comparison of hair lead levels with levels measured in blood samples.
  Primates 02/2011; 52(2):163-70. · 1.40 Impact Factor
• Article: Macaque-human interactions and the societal perceptions of macaques in Singapore.

  John Chih Mun Sha, Michael D Gumert, Benjamin P Y-H Lee, Lisa Jones-Engel, Sharon Chan, Agustín Fuentes
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  ABSTRACT: Humans and long-tailed macaques (Macaca fascicularis) interface in several locations in Singapore. We investigated six of these interface zones to assess the level of conflict between the two species. We observed macaque-to-human interactions and distributed questionnaires to residents and visitors of nature reserves. We observed an average of two macaque-to-human interactions per hour at the sites, which included affiliative or submissive behaviors (46.9%), aggression (19.1%), taking food and other items (18.5%) searching bins, cars, and houses (13.4%), and nonaggressive contact (2.1%). Two-thirds of interactions occurred when a human was carrying food or food cues, and one-quarter occurred when a human provoked macaques. Only 8% of interactions occurred without a clear human-triggered context. Our interview showed one-third of respondents experienced nuisance problems from macaques. They had items taken from them (50.5%) and received threats (31.9%). Residents reported more nuisance problems than visitors, and their perceptions toward macaques differed. Residents were more aware of the consequences of food provisioning and that there were regulations against feeding. Residents fed macaques less and held more negative sentiments toward macaques. Nearly half of the interviewed people held neutral attitudes toward macaques and only 26.2% of respondents thought conflict with macaques warranted urgent action. Nearly two-thirds of the respondents supported education programs to ameliorate human-macaque conflict, and less than 15% supported removing or eradicating macaques. 87.6% felt that it is importance to conserve and protect macaques. Our results show that human-macaque conflict exists in Singapore, but that it may not be severe. Human behavior is largely responsible for macaque-to-human interactions, and thus could be lessened with management of human behavior in interface zones (i.e. restrict food carrying and provocation). Moreover, our interviews shows people living in Singapore value macaques, do not wish them entirely removed, prefer education-based solutions, and consider conservation and protection of them important.
  American Journal of Primatology 06/2009; 71(10):825-39. · 2.22 Impact Factor
• Article: Morphology and somatometric growth of long‐tailed macaques (Macaca fascicularis fascicularis) in Singapore

  MICHAEL A. SCHILLACI, LISA JONES-ENGEL, BENJAMIN P. Y.-H. LEE, AGUSTIN FUENTES, NANTIYA AGGIMARANGSEE, GREGORY A. ENGEL, TULYAWAT SUTTHIPAT
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  ABSTRACT: Crab-eating, or long-tailed, macaques [Macaca fascicularis (Raffles, 1821)] have been studied extensively throughout their distribution in South and South-east Asia. Despite this extensive body of research, the island population of long-tailed macaques from Singapore remains virtually undescribed. In the present study, we compare the morphometric variability and patterns of growth observed in a population sample from Singapore with a composite sample from Thailand, north of the Isthmus of Kra. The results of our analyses indicate that there are statistically significant differences between the two populations in adult size and shape. For both males and females, the Singapore population is smaller than the Thai population. Relative to body length, the Singapore macaques exhibit significantly longer tails, and, relative to cranial length, they exhibit significantly more narrow faces than the Thai macaques. Although levels of sexual dimorphism for most morphometric traits are very similar, indicating similar levels of male–male competition for females, the Singapore males exhibit a significantly larger testicular volume relative to body weight, suggestive of an alternative male reproductive strategy. In addition to adult somatometric size and shape, comparisons of growth patterns relative to age and body size reveal significant differences between the two population samples. Combined, these results suggest either that statistically significant differences in adult morphology and patterns of growth can occur in presumably reproductively cohesive subspecies, or the Singapore macaques may be taxonomically distinct. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 675–694.
  Biological Journal of the Linnean Society 12/2007; 92(4):675 - 694. · 2.19 Impact Factor
• Article: Sensitive assays for simian foamy viruses reveal a high prevalence of infection in commensal, free-ranging Asian monkeys.

  Lisa Jones-Engel, Katherine A Steinkraus, Shannon M Murray, Gregory A Engel, Richard Grant, Nantiya Aggimarangsee, Benjamin P Y-H Lee, Cynthia May, Michael A Schillaci, Chaleamchat Somgird, Tulyawat Sutthipat, Lucia Vojtech, JianYuan Zhao, Maxine L Linial
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  ABSTRACT: Foamy viruses (FV) are retroviruses that naturally infect many hosts, including most nonhuman primates (NHPs). Zoonotic infection by primate FV has been documented in people in Asia who reported contact with free-ranging macaques. FV transmission in Asia is a concern, given abundant human-NHP contact, particularly at monkey temples and in urban settings. We have developed three assays capable of detecting the presence of FV in Asian NHP species that are commensal with humans: enzyme-linked immunosorbent assay (ELISA), Western blot assays using recombinant viral Gag protein, and an indicator cell line that can detect macaque FV. The recombinant ELISA correlates very well with the presence of FV sequences detected by PCR. We have used these assays to demonstrate both that FV is highly prevalent among free-ranging NHPs and that seroconversion occurs at a young age in these animals. These assays should also prove useful for large-scale analysis of the prevalence of FV infections in human populations in Asia that are commensal with free-ranging NHPs.
  Journal of Virology 08/2007; 81(14):7330-7. · 5.40 Impact Factor