50 research outputs found
Emerg Infect Dis
No full textAlthough hookworm is highly prevalent in the Solomon Islands, the species involved are unknown. We initiated this study in response to finding Ancylostoma ceylanicum hookworm in a peacekeeper in Australia who had returned from the Solomon Islands. Kato-Katz fecal surveys performed in 2013 and 2014 in 2 village groups in East Malaita, Solomon Islands, identified hookworm-positive samples. These specimens were tested by cytochrome oxidase 1 (cox-1) gene multiplex PCR and sequenced. Of 66 positive specimens, 54 (81.8%) contained only Necator americanus, 11 (16.7%) contained only A. ceylanicum, and 1 (1.5%) contained both species. A. duodenale was not found. Haplotype analysis of cox-1 sequences placed all human isolates (99% bootstrap support) of A. ceylanicum within the zoonotic clade rather than the human-specific clade. This study confirms that A. ceylanicum is endemic in the East Malaita region of this Pacific Island nation. The strain of the A. ceylanicum in this region can be shared among humans, dogs, and cats
Molecular evidence of novel spotted fever group rickettsia species in amblyomma albolimbatum ticks from the shingleback skink (Tiliqua rugosa) in southern western australia
No full textTick-borne infectious diseases caused by obligate intracellular bacteria of the genus Rickettsia are a growing global problem to human and animal health. Surveillance of these pathogens at the wildlife interface is critical to informing public health strategies to limit their impact. In Australia, reptile-associated ticks such as Bothriocroton hydrosauri are the reservoirs for Rickettsia honei, the causative agent of Flinders Island spotted fever. In an effort to gain further insight into the potential for reptile-associated ticks to act as reservoirs for rickettsial infection, Rickettsia-specific PCR screening was performed on 64 Ambylomma albolimbatum ticks taken from shingleback skinks (Tiliqua rugosa) located in southern Western Australia. PCR screening revealed 92% positivity for rickettsial DNA. PCR amplification and sequencing of phylogenetically informative rickettsial genes (ompA, ompB, gltA, sca4, and 17kda) suggested that the single rickettsial genotype detected represented a novel rickettsial species, genetically distinct from but closely related to Rickettsia gravesii and within the rickettsia spotted fever group (SFG). On the basis of this study and previous investigations, it would appear that Rickettsia spp. are endemic to reptile-associated tick species in Australia, with geographically distinct populations of the same tick species harboring genetically distinct SFG Rickettsia species. Further molecular epidemiology studies are required to understand the relationship between these diverse Rickettsiae and their tick hosts and the risk that they may pose to human and animal health
Ancylostoma ceylanicum Hookworm in the Solomon Islands
No full textAlthough hookworm is highly prevalent in the Solomon Islands, the species involved are unknown. We initiated this study in response to finding Ancylostoma ceylanicum hookworm in a peacekeeper in Australia who had returned from the Solomon Islands. Kato-Katz fecal surveys performed in 2013 and 2014 in 2 village groups in East Malaita, Solomon Islands, identified hookworm-positive samples. These specimens were tested by cytochrome oxidase 1 (cox-1) gene multiplex PCR and sequenced. Of 66 positive specimens, 54 (81.8%) contained only Necator americanus, 11 (16.7%) contained only A. ceylanicum, and 1 (1.5%) contained both species. A. duodenale was not found. Haplotype analysis of cox-1 sequences placed all human isolates (99% bootstrap support) of A. ceylanicum within the zoonotic clade rather than the human-specific clade. This study confirms that A. ceylanicum is endemic in the East Malaita region of this Pacific Island nation. The strain of the A. ceylanicum in this region can be shared among humans, dogs, and cats
Canine vector-borne pathogens in semi-domesticated dogs residing in northern Cambodia
No full textBACKGROUND: In Southeast Asia, the canine vector-borne pathogens Babesia spp., Ehrlichia canis, Anaplasma platys, Hepatozoon canis, haemotropic mycoplasmas and Dirofilaria immitis cause significant morbidity and mortality in dogs. Moreover, dogs have also been implicated as natural reservoirs for Rickettsia felis, the agent of flea-borne spotted fever, increasingly implicated as a cause of undifferentiated fever in humans in Southeast Asia. The objective of this study was to determine the prevalence and diversity of canine vector-borne pathogens in 101 semi-domesticated dogs from rural Cambodia using molecular diagnostic techniques. RESULTS: The most common canine vector-borne pathogens found infecting dogs in this study were Babesia vogeli (32.7 %) followed by Ehrlichia canis (21.8 %), Dirofilaria immitis (15.8 %), Hepatozoon canis (10.9 %), Mycoplasma haemocanis (9.9 %) and "Candidatus Mycoplasma haematoparvum" (2.9 %). A high level of co-infection with CVBD agents (23.8 %) was present, most commonly B. vogeli and E. canis. Naturally occurring R. felis infection was also detected in 10.9 % of dogs in support of their role as a natural mammalian reservoir for flea-borne spotted fever in humans. CONCLUSIONS: This study reports for the first time, the prevalence and diversity of CVBD pathogens in dogs in Cambodia. In total, five species of CVBD pathogens were found infecting semi-domesticated dogs and many were co-infected with two or more pathogens. This study supports the role of dogs as natural mammalian reservoirs for R. felis, the agent of flea-borne spotted fever in humans
Evidence of exposure to Rickettsia felis in Australian patients
No full textAbstractRickettsia felis is an emerging zoonosis, causing flea-borne spotted fever (FBSF). Serological diagnosis is typically confounded by cross-reactivity with typhus group rickettsiae and prior to the development of specific serological methods, cases of FBSF in Australia were misdiagnosed.Patient sera tested between August 2010 and December 2013 and known to be seropositive to R. typhi by immunofluorescence antibody testing (IFAT) were subsequently retested against R. felis using an R. felis-specific IFAT. Sera of 49 patients were of a sufficient quality to be included in re-analysis. A classification of FBSF and murine typhus (MT) was attributed to fourteen and seven patients respectively, based on a minimum four-fold higher antibody titre to R. felis than to R. typhi and vice versa. Twenty-eight patients were classified as indeterminate for either R. felis or R. typhi (antibody titres within two-fold of one another).Historically, it is likely that Australian patients clinically ill with FBSF were misdiagnosed. It is important that medical practitioners consider FBSF as part of their differential diagnoses, and obtain relevant history with regard to patient's exposure to domestic pets and their fleas. Australian microbiology diagnostic laboratories should include serological testing for R. felis as part of the diagnostic panel for febrile diseases. Veterinarians are encouraged to increase their awareness of this emerging zoonosis and advocate flea control in pets
Serological evidence of exposure to Rickettsia felis and Rickettsia typhi in Australian veterinarians
No full textBACKGROUND: Rickettsia felis and Rickettsia typhi are emerging arthropod-borne zoonoses causing fever and flu-like symptoms. Seroprevalence and risk factors associated with exposure to these organisms was explored in Australian veterinarians. METHODS: One hundred and thirty-one veterinarians from across Australia were recruited to participate in a cross-sectional survey. Veterinarians provided a single blood sample and answered a questionnaire on potential risk factors influencing their exposure to R. felis and R. typhi. Indirect microimmunofluorescence antibody testing (IFAT) was used to identify evidence of serological exposure of the participants to R. felis and R. typhi. Results were analyzed and a logistical regression model performed to predict risk factors associated with seropositivity. RESULTS: In total, 16.0% of participants were seropositive to R. felis, 4.6% to R. typhi and 35.1% seropositive to both, where cross-reactivity of the IFAT between R. felis and R. typhi precluded a definitive diagnosis. Veterinarians residing within the south-eastern states of Victoria and Tasmania were at a higher risk of exposure to R. felis or generalised R. felis or R. typhi exposure. Older veterinarians and those that recommended flea treatment to their clients were found to be significantly protected from exposure. CONCLUSIONS: The high exposure to R. felis amongst veterinary professionals suggests that flea-borne spotted fever is an important cause of undifferentiated fever conditions that may not be adequately recognized in Australia
Kinetic Analysis of Rice Husk Pyrolysis Using Kissinger-Akahira-Sunose (KAS) Method
No full textAbstractThe pyrolysis of rice husk is studied using thermogravimetric analysis (TGA) equipment. The present study investigates the thermal degradation behavior and determination of the kinetic parameter such as activation energy, E using Kissinger-Akahira-Sunose (KAS) method. The kinetic data is produced based on first order rate of reaction. In the present study, the experiments are conducted at different heating rates of 10, 20, 30, and 50 K/min at non-isothermal condition with carrier nitrogen gas flowrate of 100 mL/min. The temperature range studied is 323-1173 K. Results showed that the maximum degradation rate of rice husk increases from 4.42 to 21.87 wt%/min as heating rate increases from 10 to 50 K/min. In addition, the predicted E values ranged from 48.64 to 54.21 kJ/mol meanwhile the average E values achieved is 51.19 kJ/mol in the range of heating rates studied using KAS method
Domestic dogs are mammalian reservoirs for the emerging zoonosis flea-borne spotted fever, caused by Rickettsia felis
No full textRickettsia felis is an obligate intracellular bacterium that is being increasingly recognized as an etiological agent of human rickettsial disease globally. The agent is transmitted through the bite of an infected vector, the cat flea, Ctenocephalides felis, however there is to date, no consensus on the pathogen's vertebrate reservoir, required for the maintenance of this agent in nature. This study for the first time, demonstrates the role of the domestic dog (Canis familiaris) as a vertebrate reservoir of R. felis. The ability of dogs to sustain prolonged periods of rickettsemia, ability to remain asymptomatically infected with normal haematological parameters and ability to act as biological vehicles for the horizontal transmission of R. felis between infected and uninfected fleas provides indication of their status as a mammalian reservoir of this emerging zoonosis
Screening for rickettsia, coxiella and borrelia species in ticks from Queensland, Australia
No full textTick bites in Australia are linked to the transmission of a variety of infectious diseases in humans, livestock and wildlife. Despite this recognition, little is currently known about the variety of potential pathogens that are carried and transmitted by Australian ticks. In this study, we attempted to expand knowledge of Australian tick-borne bacterial pathogens by analyzing various tick species from the state of Queensland for potential human pathogens belonging to the Rickettsia, Coxiella and Borrelia genera. A total of 203 ticks, comprising of four genera and nine different tick species, were screened by specific qPCR assays. An overall Rickettsia qPCR positivity of 6.4% (13/203) was detected with rickettsial DNA found in four tick species (Ixodes holocyclus, I. tasmani, Amblyommatriguttatum, and Haemaphysalis longicornis). Amplification and analysis of several rickettsial genes from rickettsial qPCR positive samples identified sequences closely related to but genetically distinct from several previously described cultured and uncultured rickettsial species in the Rickettsia spotted fever subgroup. No ticks were positive for either Coxiella or Borrelia DNA. This work suggests that a further diversity of rickettsiae remain to be described in Australian ticks with the full importance of these bacteria to human and animal health yet to be elucidated
