During the outbreak of Nipah virus encephalitis involving pigs and humans in peninsular Malaysia in 1998/1999, a conventional approach was initially undertaken to collect specimens from fruit bats by mist-netting and shooting, as an integral part of wildlife surveillance of the natural reservoir host of Nipah virus. This study describes a novel method of collecting fruit bats' urine samples using plastic sheets for isolation of Nipah virus. This novel approach resulted in the isolation of several other known and unidentified infectious agents besides Nipah virus.
Nearly 75% of all emerging infectious diseases (EIDs) that impact or threaten human health are zoonotic. The majority have spilled from wildlife reservoirs, either directly to humans or via domestic animals. The emergence of many can be attributed to predisposing factors such as global travel, trade, agricultural expansion, deforestation/habitat fragmentation, and urbanization; such factors increase the interface and/or the rate of contact between human, domestic animal, and wildlife populations, thereby creating increased opportunities for spillover events to occur. Infectious disease emergence can be regarded as primarily an ecological process. The epidemiological investigation of EIDs associated with wildlife requires a trans-disciplinary approach that includes an understanding of the ecology of the wildlife species, and an understanding of human behaviours that increase risk of exposure. Investigations of the emergence of Nipah virus in Malaysia in 1999 and severe acute respiratory syndrome (SARS) in China in 2003 provide useful case studies. The emergence of Nipah virus was associated with the increased size and density of commercial pig farms and their encroachment into forested areas. The movement of pigs for sale and slaughter in turn led to the rapid spread of infection to southern peninsular Malaysia, where the high-density, largely urban pig populations facilitated transmission to humans. Identifying the factors associated with the emergence of SARS in southern China requires an understanding of the ecology of infection both in the natural reservoir and in secondary market reservoir species. A necessary extension of understanding the ecology of the reservoir is an understanding of the trade, and of the social and cultural context of wildlife consumption. Emerging infectious diseases originating from wildlife populations will continue to threaten public health. Mitigating and managing the risk requires an appreciation of the connectedness between human, livestock and wildlife health, and of the factors and processes that disrupt the balance.
Nipah encephalitis is a particular dangerous disease that affects animals and man. Fatal cases of the disease have been identified in the persons looking after pigs in the villages of Malaysia. The causative agent is presumably referred to as morbilliviruses of the Paramixoviridae family. Two hundred persons died among the ill patients with the signs of encephalitis. The principal hosts of the virus were fox-bats (Megaschiroptera) inhabiting in the surrounding forests. The present paper descries the epidemiological features of the disease, its clinical manifestations, abnormal anatomic changes, diagnosis, and implemented controlling measures.
Two related, novel, zoonotic paramyxoviruses have been described recently. Hendra virus was first reported in horses and thence humans in Australia in 1994; Nipah virus was first reported in pigs and thence humans in Malaysia in 1998. Human cases of Nipah virus infection, apparently unassociated with infection in livestock, have been reported in Bangladesh since 2001. Species of fruit bats (genus Pteropus) have been identified as natural hosts of both agents. Anthropogenic changes (habitat loss, hunting) that have impacted the population dynamics of Pteropus species across much of their range are hypothesised to have facilitated emergence. Current strategies for the management of henipaviruses are directed at minimising contact with the natural hosts, monitoring identified intermediate hosts, improving biosecurity on farms, and better disease recognition and diagnosis. Investigation of the emergence and ecology of henipaviruses warrants a broad, cross-disciplinary ecosystem health approach that recognises the critical linkages between human activity, ecological change, and livestock and human health.
This study evaluated rabies epidemiology in Far EastAsia. Questionnaires were sent by the OIE to Far East Asian countries and eight questionnaires were returned. Data were collected from these returns, as well as from recent publications, to gather information regarding rabies epidemiology in these countries. More than 29,000 human deaths were reported in 2006 in Far East Asia, representing more than 50% of all human rabies cases around the globe. There are only a few countries or regions from which no human rabies was reported in 2006 such as Japan, Singapore, South Korea, Malaysia, Hong Kong, and Taiwan. In many of these rabies endemic countries, the number of human rabies cases has not changed much during the past decade. The only country with a steady decline is Thailand, where the number of cases has decreased from around 200 to about 20 cases per year. The most dramatic changes were observed in China. Human rabies cases declined from around 5,000 cases per year in the 1980s to about 160 in the mid-1990s. However, these trends have since been reversed. A steady increase has been reported over the past 10 years with more than 3,200 cases reported in 2006. Although there are many factors that contribute to the epidemic or endemic nature of rabies in these countries, the single most important factor is the failure to immunize domestic dogs, which transmit rabies to humans. Dog vaccination is at or below 5% in many of these countries, and cannot stop the transmission of rabies from dogs to dogs, thus to humans. It is thus most importantforthese countries to initiate mass vaccination campaigns in dog populations in order to stop the occurrence of human rabies in Far East Asia.
House shrews (Suncus murinus) and rats (Rattus rattus diardii), trapped during a survey period from July 1978 to December 1979 and thereafter on a random basis, from residences within and outside the Veterinary Research Institute, Ipoh, Malaysia campus, were bacteriologically examined for the presence of salmonellae. Of the 55 shrews and 8 rats examined, 39 (71%) shrews and 2 (25%) rats were found positive. There were 46 Salmonella isolates which included 5 dual infections. These were serotyped as S. weltevreden, S. bareilly, S. stanley, S. augustenborg, S. hvittingfoss, S. emek, S. paratyphi B, S. ohio and S. matopeni in order of frequency of isolation. The significance of these findings especially with regard to salmonellosis in man and animals is discussed.
West Nile virus (WNV) is a zoonotic single-strand RNA arbovirus (family Flaviviridae: Flavivirus), transmitted among avian hosts in enzootic cycles by a mosquito vector. The virus has a significant disease effect on humans and equines when it bridges into a cycle with various sequelae with epidemic potential. This study was carried out to identify the potential spectrum of WNV hosts in three geographic areas with climatologically distinct features: Malaysia, Qatar, and the United States of America (U.S.). Serum samples were collected from avian and mammal species suspected to be reservoirs for the virus at these areas in a cross-sectional epidemiologic study. The samples were tested for the presence of antibodies against the virus using an enzyme-linked immunosorbent assay. Data on putative risk factors were also collected and analyzed for significance of association with seropositivity using the logistic regression analysis. Among the tested avian and mammalian species, raccoons had the highest seroconversion rate (54%) followed by crows (30%), horses (27%), camels (10%), other avian species (7%), and canine species (3%). It was almost twice as likely to detect seroconversion among these mammalian and avian species in the fall in comparison to other seasons of the year. Only mammalian and avian species and seasons of the year were significantly associated with the likelihood of seroconversion to WNV when we controlled for other factors in the multivariate analysis. Our data from the U.S. showed that raccoons and camels are susceptible to infection by the virus and may play a role in the perpetuation of endemic foci for the disease.
The objectives of this review were to understand the epidemiology and outbreak of NiV infection and to discuss the preventive and control measures across different regions. We searched PubMed and Scopus for relevant articles from January 1999 to July 2018 and identified 927 articles which were screened for titles, abstracts and full texts by two review authors independently. The screening process resulted in 44 articles which were used to extract relevant information. Information on epidemiology of NiV, outbreaks in Malaysia, Singapore, Bangladesh, India and Philippines, including diagnosis, prevention, treatment, vaccines, control, surveillance and economic burden due to NiV were discussed. Interdisciplinary and multi sectoral approach is vital in preventing the emergence of NiV. It is necessary to undertake rigorous research for developing vaccines and medicines to prevent and treat NiV.
Bats of the genus Pteropus have been identified as the reservoir hosts for the henipaviruses Hendra virus (HeV) and Nipah virus (NiV). The aim of these studies was to assess likely mechanisms for henipaviruses transmission from bats. In a series of experiments, Pteropus bats from Malaysia and Australia were inoculated with NiV and HeV, respectively, by natural routes of infection. Despite an intensive sampling strategy, no NiV was recovered from the Malaysian bats and HeV was reisolated from only one Australian bat; no disease was seen. These experiments suggest that opportunities for henipavirus transmission may be limited; therefore, the probability of a spillover event is low. For spillover to occur, a range of conditions and events must coincide. An alternate assessment framework is required if we are to fully understand how this reservoir host maintains and transmits not only these but all viruses with which it has been associated.
Until the Nipah outbreak in Malaysia in 1999, knowledge of human infections with the henipaviruses was limited to the small number of cases associated with the emergence of Hendra virus in Australia in 1994. The Nipah outbreak in Malaysia alerted the global public health community to the severe pathogenic potential and widespread distribution of these unique paramyxoviruses. This chapter briefly describes the initial discovery of Nipah virus and the challenges encountered during the initial identification and characterisation of the aetiological agent responsible for the outbreak of febrile encephalitis. The initial attempts to isolate Nipah virus from the bat reservoir host are also described.
Avian influenza viruses are highly infectious micro-organisms that primarily affect birds. Nevertheless, they have also been isolated from a number of mammals, including humans. Avian influenza virus can cause large economic losses to the poultry industry because of its high mortality. Although there are pathogenic variants with a low virulence and which generally cause only mild, if any, clinical symptoms, the subtypes H5 and H7 can mutate from a low to a highly virulent (pathogenic) virus and should be taken into consideration in eradication strategies. The primary source of infection for commercial poultry is direct and indirect contact with wild birds, with waterfowl forming a natural reservoir of the virus. Live-poultry markets, exotic birds, and ostriches also play a significant role in the epidemiology of avian influenza. The secondary transmission (i.e., between poultry farms) of avian influenza virus is attributed primarily to fomites and people. Airborne transmission is also important, and the virus can be spread by aerosol in humans. Diagnostic tests detect viral proteins and genes. Virus-specific antibodies can be traced by serological tests, with virus isolation and identification being complementary procedures. The number of outbreaks of avian influenza seems to be increasing - over the last 5 years outbreaks have been reported in Italy, Hong Kong, Chile, the Netherlands, South Korea, Vietnam, Japan, Thailand, Cambodia, Indonesia, Laos, China, Pakistan, United States of America, Canada, South Africa, and Malaysia. Moreover, a growing number of human cases of avian influenza, in some cases fatal, have paralleled the outbreaks in commercial poultry. There is great concern about the possibility that a new virus subtype with pandemic potential could emerge from these outbreaks. From the perspective of human health, it is essential to eradicate the virus from poultry; however, the large number of small-holdings with poultry, the lack of control experience and resources, and the international scale of transmission and infection make rapid control and long-term prevention of recurrence extremely difficult. In the Western world, the renewed interest in free-range housing carries a threat for future outbreaks. The growing ethical objections to the largescale culling of birds require a different approach to the eradication of avian influenza.
Anaplasma spp. are Gram-negative obligate intracellular, tick-borne bacteria which are of medical and veterinary importance. Little information is available on Anaplasma infection affecting domestic and wildlife animals in Malaysia. This study investigated the presence of Anaplasma spp. in the blood samples of domestic and wildlife animals in Peninsular Malaysia, using polymerase chain reaction (EHR-PCR) assays targeting the 16S rRNA gene of Anaplasmataceae. High detection rates (60.7% and 59.0%, respectively) of Anaplasma DNA were noted in 224 cattle (Bos taurus) and 78 deer (77 Rusa timorensis and one Rusa unicolor) investigated in this study. Of the 60 amplified fragments obtained for sequence analysis, Anaplasma marginale was exclusively detected in cattle while Anaplasma platys/Anaplasma phagocytophilum was predominantly detected in the deer. Based on sequence analyses of the longer fragment of the 16S rRNA gene (approximately 1000 bp), the occurrence of A. marginale, Anaplasma capra and Candidatus Anaplasma camelii in cattle, Candidatus A. camelii in deer and Anaplasma bovis in a goat was identified in this study. To assess whether animals were infected with more than one species of Anaplasma, nested amplification of A. phagocytophilum, A. bovis and Ehrlichia chaffeensis DNA was performed for 33 animal samples initially screened positive for Anaplasmataceae. No amplification of E. chaffeensis DNA was obtained from animals investigated. BLAST analyses of the 16S rDNA sequences from three deer (R. timorensis), a buffalo (Bubalus bubalis) and a cow (B. taurus) reveal similarity with that of Candidatus Anaplasma boleense strain (GenBank accession no.: KX987335). Sequence analyses of the partial gene fragments of major surface protein (msp4) gene from two deer (R. timorensis) and a monitor lizard (Varanus salvator) show the detection of a strain highly similar (99%) to that of A. phagocytophilum strain ZJ-China (EU008082). The findings in this study show the occurrence of various Anaplasma species including those newly reported species in Malaysian domestic and wildlife animals. The role of these animals as reservoirs/maintenance hosts for Anaplasma infection are yet to be determined.
Nipah virus is a recently emergent paramyxovirus that is capable of causing severe disease in both humans and animals. The first outbreak of Nipah virus occurred in Malaysia and Singapore in 1999 and, more recently, outbreaks were detected in Bangladesh. In humans, Nipah virus causes febrile encephalitis with respiratory syndrome that has a high mortality rate. The reservoir for Nipah virus is believed to be fruit bats, and humans are infected by contact with infected bats or by contact with an intermediate animal host such as pigs. Person to person spread of the virus has also been described. Nipah virus retains many of the genetic and biologic properties found in other paramyxoviruses, though it also has several unique characteristics. However, the virologic characteristics that allow the virus to cause severe disease over a broad host range, and the epidemiologic, environmental and virologic features that favor transmission to humans are unknown. This review summarizes what is known about the virology, epidemiology, pathology, diagnosis and control of this novel pathogen.