1.Detection of Bartonella sp. in ticks and their small mammal hosts in mangrove forests of Peninsular Malaysia
Asyikha, R. ; Sulaiman, N. ; Mohd-Taib, F.S.
Tropical Biomedicine 2020;37(No.4):919-931
Bacteria of the genus Bartonella have been known as emerging zoonotic pathogens
for several human diseases including cat scratch disease, Carrion’s disease and trench fever.
Numerous species of small mammals have been reported to play a role as a suitable reservoir
to many pathogenic Bartonella. These infections are thought to be transmitted through
blood-feeding arthropod vectors such as ticks, fleas and lice. The purpose of this study is to
detect the presence of Bartonella species from tick samples collected from small mammals
in mangrove forests of Peninsular Malaysia. Herein, 38 individual ticks and their small mammals
host were evaluated for the presence of Bartonella DNA by conventional PCR targeting the
16S rRNA intergenic spacer region (ITS) and partial sequencing of 460 bp from this locususing
Bartonella genus-specific primers. Two tick individuals from Dermacentor auratus and
Haemaphysalis hystricis collected from Rattus tiomanicus (host), were PCR-positive for
Bartonella DNA amplification. No Bartonella amplification was possible in other tick species
(Amblyomma sp.). Phylogenetic analysis of ITS fragments demonstrated that the sequences
from ticks were closely related to Bartonella phoceensis, a species that has been reported
from black rats (Rattus rattus) in Australia. This is the first report of a Bartonella bacteria
detected in ticks from small mammals in Malaysia. Further research should be warranted to
investigate the transmission of Bartonella and the potential impact of this zoonotic pathogen
in animals and humans as this mangrove ecosystem is significant for local economy and
tourism
2.Leptospirosis: An insight into community structure of small mammal’s host in urban environment
Mohd-Taib, F.S. ; Ishak, S.N. ; Yusof, M.A. ; Azhari, N.N. ; Md-Lasim, A. ; Md. Nor, S. ; Mohd-Sah, S.A. ; Neela, V.K.
Tropical Biomedicine 2020;37(No.1):142-154
Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira and most often acquired through contact with environments contaminated with leptospires shed in the urine of infected mammals. In urban environment, rodents are well-known as the main carriers of this bacteria, however there were no intensive study on the population structure of these animals, and how it associated with this disease. Hence, we use a case study from an outbreak in a residential area in Selangor, Malaysia, to investigate how community structure of small mammals, associated with the prevalence of Leptospira. One hundred cage traps were placed randomly in and around these houses in five phases with two months interval for a year. Community structures (species, sex, and age) were assigned for each individual, prior to screening for pathogenic Leptospira, using a partial lipL32 gene from the kidney samples. 185 small mammals from four species were captured, Rattus norvegicus (74.5%, N=138), R. rattus (20%, N=37), Tupaia glis (5%, N=9), and Suncus murinus (0.5%, N=1). From this number, 29 individuals were found PCR positive for pathogenic Leptospira (R. norvegicus, N=20; R. rattus, N=6; T. glis, N=2; S. murinus, N=1). The study shows that Leptospira occurrence in the small mammals were significantly correlated to age category and sampling phases, with Spearman Correlation (rs) p=0.02 and p=0.04 respectively. Adult individuals were significantly more prevalent with Leptospira infection, whereby March and June were found to associate with higher Leptospira prevalent among the small mammals, potentially coincide with low rainfall and relative humidity level. This information is important in designing a specific control method for rodents in Leptospira outbreak areas. In addition, intensive sampling and regular cleaning effort were found to significantly reduce the small mammal Leptospira reservoir, thus should be implemented in intervention strategies in the urban environment.
3.Characterization of internal transcribed spacer-1 and apical membrane antigen-1 sequences provides insights into the genetic diversity of Eimeria tenella strains
Loo, S.-S. ; Mohd-Taib, F.S. ; Khoo, C.-K. ; Wan, K.-L.
Tropical Biomedicine 2022;39(No.3):476-482
Coccidiosis is a major recurring problem in the poultry industry and is caused by infection of one or more
of the seven Eimeria species known to infect chickens, with Eimeria tenella among the best studied
and economically important. Studies on the genetic diversity of E. tenella strains is essential for the
development of universally acceptable diagnostic markers and vaccines against the disease. Eimeria
tenella internal transcribed spacer-1 (ITS-1) and apical membrane antigen-1 (AMA-1) sequences from
different parts of the world are available in the public domain and therefore provide suitable comparative
markers for genetic diversity study. In this study, the ITS-1 and AMA-1 sequence diversity of two local
E. tenella strains, namely EtNSN6 and EtSGR6 were characterized. Both ITS-1 and AMA-1 sequences
for EtNSN6 and EtSGR6 were retrieved by mapping to their respective genome sequences generated
using next generation sequencing. Multiple sequence alignment of the ITS-1 and AMA-1 sequences
with selected homologous sequences revealed the presence of a total of five and 13 single nucleotide
polymorphisms (SNPs) respectively. All SNPs appeared to occur at random and did not show any unique
pattern based on geographical regions while no insertions and deletions (indels) was found to occur in
the aligned sequences. However, unique bases that defined certain strains were detected. Phylogenetics
analyses performed with Maximum Parsimony (MP) and Maximum Likelihood (ML) methods revealed
similar topology for the internal groups with all the E. tenella ITS-1 and AMA-1 sequences grouped in
the same clade supported by high bootstrap confidence. This confirmed that both EtNSN6 and EtSGR6
samples are E. tenella strains. Sequence comparison and phylogenetics analyses further suggest the
possibility of low genetic diversity among E. tenella strains.
4.Culturable pathogenic bacteria in ticks parasitizing farm animals and rodents in Malaysia
Loong, S.K. ; Lim, F.S. ; Khoo, J.J. ; Lee, H.Y. ; Suntharalingam, C. ; Ishak, S.N. ; Mohd-Taib, F.S. ; AbuBakar, S.
Tropical Biomedicine 2020;37(No.3):803-811
Ticks are vectors of bacteria, protozoa and viruses capable of causing serious and life threatening diseases in humans and animals. Disease transmission occurs through the transfer of pathogen from tick bites to susceptible humans or animals. Most commonly known tick-borne pathogens are obligate intracellular microorganisms but little is known on the prevalence of culturable pathogenic bacteria from ticks capable of growth on artificial nutrient media. One hundred and forty seven ticks originating from dairy cattle, goats and rodents were collected from nine selected sites in Peninsular Malaysia. The culture of surfacesterilized tick homogenates revealed the isolation of various pathogenic bacteria including, Staphylococcus sp., Corynebacterium sp., Rothia sp., Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli and Bacillus sp. and its derived genera. These pathogens are among those that affect humans and animals. Findings from this study suggest that in addition to the regular intracellular pathogens, ticks could also harbor extracellular pathogenic bacteria. Further studies, hence, would be needed to determine if these extracellular pathogens could contribute to human or animal infection.