Following a series of H5N1 cases in chickens and birds in a few states in Malaysia, there was much interest in the influenza A viruses subtypes that circulate among the local pig populations. Pigs may act as a mixing vessel for avian and mammal influenza viruses, resulting in new reassorted viruses. This study investigated the presence of antibodies against influenza H1N1 and H3N2 viruses in pigs from Peninsular Malaysia using Herdcheck Swine Influenza H1N1 and H3N2 Antibody Test Kits. At the same time, the presence of influenza virus was examined from the nasal swabs of seropositive pigs by virus isolation and real time RT-PCR. The list of pig farms was obtained from the headquarters of the Department of Veterinary Services, Malaysia, and pig herds were selected randomly from six of 11 states in Peninsular Malaysia. A total of 727 serum and nasal swab samples were collected from 4- to 6-month-old pigs between May and August 2005. By ELISA, the seroprevalences of swine influenza H1N1 and H3N2 among pigs were 12.2% and 12.1% respectively. Seropositivity for either of the virus subtypes was detected in less than half of the 41 sampled farms (41.4%). Combination of both subtypes was detected in 4% of all pigs and in 22% of sampled farms. However, no virus or viral nucleic acid was detected from nasal samples. This study identified that the seropositivity of pigs to H1N1 and H3N2 based on ELISA was significantly associated with factors such as size of farm, importation or purchase of pigs, proximity of farm to other pig farms and the presence of mammalian pets within the farm.
Nipah disease is a highly fatal zoonosis which is caused by the Nipah virus. The Nipah virus is a BSL-4 virus with fruit bats being its natural host. It is mainly prevalent in Southeast Asia. The virus was first discovered in 1997 in Negeri Sembilan, Malaysia. Currently, it is mainly harmful to pigs and humans with a high mortality rate. This study describes the route of transmission of the Nipah virus in different countries and analyzes the possibility of the primary disease being in China and the method of its transmission to China. The risk factors are analyzed for different susceptible populations to Nipah disease. The aim is to improve people's risk awareness and prevention and control of the disease and reduce its risk of occurring and spreading in China.
The emergence of Hendra and Nipah viruses in the 1990s has been followed by the further emergence of these viruses in the tropical Old World. The history and current knowledge of the disease, the viruses and their epidemiology is reviewed in this article. A historical aside summarizes the role that Dr. Brian W.J. Mahy played at critical junctures in the early stories of these viruses.
Anaplasma spp. infects a wide variety of wildlife and domestic animals. This study describes the identification of a novel species of Anaplasma (Candidatus Anaplasma pangolinii) from pangolins (Manis javanica) and Anaplasma bovis from wild boars (Sus scrofa) in Malaysia. Based on 16S rRNA gene sequences, Candidatus Anaplasma pangolinii is identified in a distinct branch within the family Anaplasmataceae, exhibiting the closest sequence similarity with the type strains of Anaplasma bovis (97.7%) and Anaplasma phagocytophilum (97.6%). The sequence also aligned closely (99.9%) with that of an Anaplasma spp. (strain AnAj360) detected from Amblyomma javanense ticks. The nearly full length sequence of the 16S rRNA gene derived from two wild boars in this study demonstrated the highest sequence similarity (99.7%) to the A. bovis type strain. Partial 16S rRNA gene fragments of A. bovis were also detected from a small population of Haemaphysalis bispinosa cattle ticks in this study. Our finding suggests a possible spread of two Anaplasma species in the Malaysian wildlife and ticks. The zoonotic potential of the Anaplasma species identified in this study is yet to be determined.
Nipah virus (NiV; Paramyxoviridae) caused fatal encephalitis in humans during an outbreak in Malaysia in 1998/1999 after transmission from infected pigs. Our previous study demonstrated that the respiratory, lymphatic and central nervous systems are targets for virus replication in experimentally infected pigs. To continue the studies on pathogenesis of NiV in swine, six piglets were inoculated oronasally with 2.5 x 10(5) PFU per animal. Four pigs developed mild clinical signs, one exudative epidermitis, and one neurologic signs due to suppurative meningoencephalitis, and was euthanized at 11 days post-inoculation (dpi). Neutralizing antibodies reached in surviving animals titers around 1280 at 16 dpi. Nasal and oro-pharyngeal shedding of the NiV was detected between 2 and 17 dpi. Virus appeared to be cleared from the tissues of the infected animals by 23 dpi, with low amount of RNA detected in submandibular and bronchial lymph nodes of three pigs, and olfactory bulb of one animal. Despite the presence of neutralizing antibodies, virus was isolated from serum at 24 dpi, and the viral RNA was still detected in serum at 29 dpi. Our results indicate slower clearance of NiV from some of the infected pigs. Bacteria were detected in the cerebrospinal fluid of five NiV inoculated animals, with isolation of Streptococcus suis and Enterococcus faecalis. Staphylococcus hyicus was isolated from the skin lesions of the animal with exudative epidermitis. Along with the observed lymphoid depletion in the lymph nodes of all NiV-infected animals, and the demonstrated ability of NiV to infect porcine peripheral blood mononuclear cells in vitro, this finding warrants further investigation into a possible NiV-induced immunosuppression of the swine host.
Hendra virus (HeV) and Nipah virus (NiV), belonging to the genus Henipavirus, are among the most pathogenic of viruses in humans. Old World fruit bats (family Pteropodidae) are the natural reservoir hosts. Molecular and serological studies found evidence of henipavirus infection in fruit bats from several African countries. However, little is known about the potential for spillover into domestic animals in East Africa, particularly pigs, which served as amplifying hosts during the first outbreak of NiV in Malaysia and Singapore. We collected sera from 661 pigs presented for slaughter in Uganda between December 2015 and October 2016. Using HeV G and NiV G indirect ELISAs, 14 pigs (2%) were seroreactive in at least one ELISA. Seroprevalence increased to 5.4% in October 2016, when pigs were 9.5 times more likely to be seroreactive than pigs sampled in December 2015 (p = 0.04). Eight of the 14 ELISA-positive samples reacted with HeV N antigen in Western blot. None of the sera neutralized HeV or NiV in plaque reduction neutralization tests. Although we did not detect neutralizing antibodies, our results suggest that pigs in Uganda are exposed to henipaviruses or henipa-like viruses. Pigs in this study were sourced from many farms throughout Uganda, suggesting multiple (albeit rare) introductions of henipaviruses into the pig population. We postulate that given the widespread distribution of Old World fruit bats in Africa, spillover of henipaviruses from fruit bats to pigs in Uganda could result in exposure of pigs at multiple locations. A higher risk of a spillover event at the end of the dry season might be explained by higher densities of bats and contact with pigs at this time of the year, exacerbated by nutritional stress in bat populations and their reproductive cycle. Future studies should prioritize determining the risk of spillover of henipaviruses from pigs to people, so that potential risks can be mitigated.
The present study was aimed to assess the diversity of influenza A viruses (IAV) circulating in pig farms in the Iberian Peninsula. The study included two different situations: farms suffering respiratory disease outbreaks compatible with IAV (n = 211) and randomly selected farms without overt respiratory disease (n = 19). Initially, the presence of IAV and lineage determination was assessed by qRT-PCR using nasal swabs. IAV was confirmed in 145 outbreaks (68.7%), mostly in nurseries (53/145; 36.5%). Subtyping by RT-qPCR was possible in 94 of those cases being H1avN2hu (33.6%), H1avN1av (24.3%) and H1huN2hu (18.7%), the most common lineages. H3huN2hu and H1pdmN1pdm represented 7.5% and 6.5% of the cases, respectively. As for the randomly selected farms, 15/19 (78.9%) were positive for IAV. Again, the virus was mostly found in nurseries and H1avN2hu was the predominant lineage. Virus isolation in MDCK cells was attempted from positive cases. Sixty of the isolates were fully sequenced with Illumina MiSeq®. Within those 60 isolates, the most frequent genotypes had internal genes of avian origin, and these were D (19/60; 31.7%) and A (11/60; 18.3%), H1avN2hu and H1avN1av, respectively. In addition, seven previously unreported genotypes were identified. In two samples, more than one H or N were found and it was not possible to precisely establish their genotypes. A great diversity was observed in the phylogenetic analysis. Notably, four H3 sequences clustered with human isolates from 2004-05 (Malaysia and Denmark) that were considered uncommon in pigs. Overall, this study indicates that IAV is a very common agent in respiratory disease outbreaks in Spanish pig farms. The genetic diversity of this virus is continuously expanding with clear changes in the predominant subtypes and lineages in relatively short periods of time. The current genotyping scheme has to be enlarged to include the new genotypes that could be found in the future.
Ticks are hematophagous vectors of arthropod-borne disease agents globally. In Malaysia, despite seroprevalence studies indicating the presence of tick-borne diseases among the indigenous people, the etiological agents of these diseases are still unclear. These indigenous people, also known as the Orang Asli, still live in forested areas with frequent contact with wildlife. Wild boar are ubiquitously found in the forested areas where the Orang Asli communities are located and are commonly hunted as a food supplement. In this study, we aim to determine the tick species parasitizing wild boar from an Orang Asli community, and explore the tick-associated bacterial communities using 16 s rRNA amplicon sequencing on the Ion Torrent PGM™ platform. A total of 72 ticks were collected from three wild boar and were morphologically identified as Haemaphysalis hystricis (n = 32), Dermacentor compactus (n = 15), Amblyomma testudinarium (n = 13), Dermacentor steini (n = 10) and Dermacentor atrosignatus (n = 2). Across all tick samples, 910 bacterial taxa were identified. Although the bacterial communities were not significantly distinct between tick species in beta-diversity analyses, Coxiella, Rickettsia and Francisella were detected at high relative abundance in H. hystricis, D. compactus and D. steini respectively. Many other bacterial genera, including those that have been described in many different tick species, were also identified, including Pseudomonas, Acinetobacter, Staphylococcus and Corynebacterium. Beta-diversity analyses also showed that the bacterial communities were separated based on the animal host from which the ticks were collected from, suggesting that the bacterial communities here may be influenced by the animal skin microflora, host blood or the environment. PCR screening confirmed the presence of Rickettsia sp. related to spotted fever group Rickettsia in some of the ticks. This study provides baseline knowledge of the microbiome of H. hystricis, D. atrosignatus, D. compactus, D. steini and A. testudinarium parasitizing wild boar in this region. The information gained in this study provides the basis to target our efforts in H. hystricis, D. compactus and D. steini for the future investigation of vector competence and the zoonotic potential for the Coxiella, Rickettsia and Francisella detected here, as well as their implications for the risks of tick-borne diseases among the Orang Asli communities.
Viruses belonging to the family Paramyxoviridae generally have not been recognized as a significant cause of disease in pigs until recently. Between 1997 and 1999, there were large outbreaks of disease in pigs in Australia and Malaysia due to infection with viruses that have been shown to be new members of the Paramyxoviridae family. This article reviews current knowledge of Menangle and Nipah virus infections in pigs, the only major species of domestic animals to experience serious disease after infection with these viruses.
A dot enzyme immunoassay for determination of antibodies to Japanese encephalitis virus was designed for use as a field technique for the surveillance of Japanese encephalitis virus activity among domestic pigs. The test was compared with the neutralization test and the hemagglutination inhibition test and found to be more sensitive than the hemagglutination inhibition test and comparable to the neutralization test in sensitivity but more simple to perform than either the neutralization or the hemagglutination inhibition tests. An IgM capture ELISA for the determination of JEV specific porcine IgM was also utilized to determine current infection rates in pigs. The tests which do not involve the determination of specific IgM are better used for testing sentinel animals for providing clues as to the rate of transmission of JEV among pigs. IgM tests determining acute infection are less likely to be useful unless animals are tested very frequently or if a great number of animals are tested at any one time.
An outbreak of acute febrile encephalitis affecting pig-farm workers and owners was recognized in peninsular Malaysia as early as September 1998. The outbreak was initially thought to be due to Japanese encephalitis (JE) virus and thus very intensive prevention, control and communication strategies directed at JE virus were undertaken by the Ministry of Health and Ministry of Agriculture of Malaysia. There was an immediate change in the prevention, control and communication strategies with focus and strategies on infected pigs as the source of infections for humans and other animals following the discovery of Nipah virus. Information and understanding the risks of Nipah virus infections and modes of transmission strengthened the directions of prevention, control and communication strategies. A number of epidemiological surveillances and field investigations which were broadly divided into 3 groups covering human health sector, animal health sector and reservoir hosts were carried out as forms of risk assessment to determine and assess the factors and degree of risk of infections by the virus. Data showed that there was significant association between Nipah virus infection and performing activities involving close contact with pigs, such as processing of piglets, administering injection or medication to pigs, assisting in the birth of piglets, assisting in pig breeding, and handling of dead pigs in the affected farms. A complex process of anthropogenic driven deforestation, climatic changes brought on by El Niño-related drought, forest fire and severe haze, and ecological factors of mixed agro-pig farming practices and design of pig-sties led to the spillovers of the virus from its wildlife reservoir into pig population.
The outbreak of Nipah virus, affecting pigs and pig-farm workers, was first noted in September 1998 in the north-western part of peninsular Malaysia. By March 1999, the outbreak had spread to other pig-farming areas of the country, inclusive of the neighbouring country, Singapore. A total of 283 human cases of viral encephalitis with 109 deaths were recorded in Malaysia from 29 September 1998 to December 1999. During the outbreak period, a number of surveillances under three broad groups; Surveillance in Human Health Sector, Surveillance in Animal Health Sector, and Surveillance for the Reservoir Hosts, were carried out to determine the prevalence, risk of virus infections and transmission in human and swine populations as well as the source and reservoir hosts of Nipah virus. Surveillance data showed that the virus spread rapidly among pigs within infected farms and transmission was attributed to direct contact with infective excretions and secretions. The spread of the virus among pig farms within and between states of peninsular Malaysia was due to movement of pigs. The transmission of the virus to humans was through close contact with infected pigs. Human to human transmission was considered a rare event though the Nipah virus could be isolated from saliva, urine, nasal and pharyngeal secretions of patients. Field investigations identified fruitbats of the Pteropid species as the natural reservoir hosts of the viruses. The outbreak was effectively brought under control following the discovery of the virus and institution of correct control measures through a combined effort of multi-ministerial and multidisciplinary teams working in close co-operation and collaboration with other international agencies.
In late 1998, a novel paramyxovirus named Nipah virus, emerged in Malaysia, causing fatal disease in domestic pigs and humans with substantial economic loss to the local pig industry. Pteropid fruitbats have since been identified as a natural reservoir host. Over the last two decades, the forest habitat of these bats in Southeast Asia has been substantially reduced by deforestation for pulpwood and industrial plantation. In 1997/1998, slash-and-burn deforestation resulted in the formation of a severe haze that blanketed much of Southeast Asia in the months directly preceding the Nipah virus disease outbreak. This was exacerbated by a drought driven by the severe 1997-1998 El Niño Southern Oscillation (ENSO) event. We present data suggesting that this series of events led to a reduction in the availability of flowering and fruiting forest trees for foraging by fruitbats and culminated in unprecedented encroachment of fruitbats into cultivated fruit orchards in 1997/1998. These anthropogenic events, coupled with the location of piggeries in orchards and the design of pigsties allowed transmission of a novel paramyxovirus from its reservoir host to the domestic pig and ultimately to the human population.
Eight clones of monoclonal antibodies (Mabs) to Nipah virus (NV) were produced against formalin-inactivated NV antigens. They reacted positive by indirect immunofluorescent antibody test, and one of them also demonstrated virus neutralizing activity. They were classified into six different types based on their biological properties. These Mabs will be useful for immunodiagnosis of NV infections in animals and further research studies involving the genomes and proteins of NV.
The report summarizes a one year period of investigation of death losses in West Malaysian livestock. Lesions and etiological agents are mentioned for cattle, sheep, goats, swine, poultry and companion animals as well as some miscellaneous species. Special observations related to a common paramphistome induced hepatic biliary infestation in cattle, a serious malignant head catarrh outbreak in which possible cattle to cow aerosol transmission occurred. Trismus observed in some cattle with malignant head catarrh was associated with arteriolitis and ganglioneuritis of the V cranial nerve. Parasitic, bacterial, viral toxic and neoplastic diseases are recorded in the various species. The occurrence of fatal chronic fluorosis in laboratory guinea pigs and cerebral nematodiasis in a Thoroughbred racehorse are documented.