1.Current status of parasitic infections among Pangkor Island community in Peninsular Malaysia
Ahmad, A.F. ; Ngui, R. ; Muhammad Aidil ; R., Lim, Y.A.L. ; Rohela, M.
Tropical Biomedicine 2014;31(4):836-843
Limited data is available on the prevalence of parasitic infections among the
island communities in Malaysia with most studies performed between 1960s-1980s. This
study was conducted to determine the current prevalence status of parasitic infections
among communities living in Pangkor Island Peninsular Malaysia. A total of 131 stool and 298
serum samples were collected and subjected to microscopic examination for intestinal protozoa
and helminths and detection of Toxoplasma gondii antibodies using commercial ELISA kits
respectively. In addition, thin and thick peripheral blood films were microscopically screened
for the presence of Plasmodium spp. and microfilariae respectively. The overall prevalence
of intestinal parasitic infections among Pangkor Island community was 9.9% (13/131) with T.
trichiura (5.3%) being the most common intestinal parasite detected. Toxoplasmosis was
reported in almost 60% of the community with the seroprevalence being significantly high
among females (64.7%) compared to males (52.8%) (p=0.038). None of those examined samples
were infected with intestinal sarcocystosis, malaria and filariasis. This study revealed that
the prevalence of intestinal parasitic infections among Pangkor Island community has been
greatly reduced compared to that reported 35 years ago. Massive improvements in the
socioeconomic status, personal hygiene, water facilities and sanitation may have contributed
to the low prevalence of parasitic infections in this community. Nevertheless, further studies
still need to be performed to determine the possible risk factors for the high prevalence of
toxoplasmosis in this community.
2.Toxoplasma gondii infection among selected indigenous community in Sarawak, East Malaysia
Ngui, R. ; Hassan, N.A. ; Chang, L.Y. ; Teh, S.J.C. ; Chua, K.H. ; Kee, B.P. ; Hoe, S.Z. ; Lim, Y.A.L.
Tropical Biomedicine 2020;37(No.1):155-164
Toxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis in humans. To date, little is known about T. gondii infection among the indigenous community, particularly in East Malaysia. This study was conducted to determine the status of T. gondii infection and to investigate associated risk factors among the indigenous community of Sarawak, East Malaysia. The sociodemographic data was obtained using a pretested questionnaire. A serological test was done to detect the presence of specific IgM and IgG antibodies against T. gondii in serum samples. A nested polymerase chain reaction (PCR) was used to determine acute infection among seropositive individuals. The overall seroprevalence of T. gondii infection was 50% (95% CI = 43.3 – 56.7). From this subset, 40.1%, 5.7%, and 4.2% were positive for anti-T. Gondii IgG antibodies, IgM, and both IgG and IgM, respectively. Four seropositive samples were amplified through PCR. None of the pregnant women tested positive for T. gondii infection based on the serological and PCR assays. A significant association was found between age, low monthly household income, unemployment, usage of untreated water and close contact with T. gondii seropositive cats. These results provide basic information on T. gondii infection and may be useful for policymakers to initiate prevention and control programs, especially amongst pregnant women and women of childbearing age in the indigenous community.
3.Oral bacteria detection among children with cancer in a tertiary teaching hospital in Kuala Lumpur, Malaysia
Sidi Omar, S.F.N. ; Ngui, R. ; Ab Rahman, S.Z. ; Foo, J.C. ; Wang, Q.Y. ; Hassan, N.A. ; Lim, Y.A.L. ; Musa, S.
Tropical Biomedicine 2021;38(No.3):276-282
This study sought to determine the prevalence of pathogenic and non-pathogenic bacteria in the oral cavities of children with cancer. There were 68 paediatric patients with cancer who were included in this study. Oral swab samples from the dorsum of tongues and mouth floors of these patients were subjected to culture, staining, and molecular methods to detect the bacteria. The overall prevalence of gram-positive and gram-negative bacteria was 79.4% (54/68; 95% CI = 68.4 – 87.3) and 25% (17/68; 95% CI = 16.2 – 36.4), respectively. Streptococcus salivarius and Streptococcus parasanguinis were the predominant pathogenic grampositive bacteria, while Neisseria subflava and Neisseria perflava were the most common pathogenic gram-negative bacteria. The results revealed that the number of bacteria isolates recovered in patients receiving cancer treatment was higher (55.9%) than those who had not received treatment (16.2%). Therefore, more isolated pathogenic bacteria were observed post-therapy (54.4%). Pathogenic organisms can have significant implications on patient health. Awareness of the types of bacteria inhabiting the oral cavity is essential to predict and prevent dental problems, and their associated systemic complications. Findings on the diversity of oral microflora can also provide a better understanding of the aetiology of oral diseases in paediatric patients receiving cancer treatment.
4.A conventional multiplex PCR for the detection of four common soil-transmitted nematodes in human feces: development and validation
Hassan, N.A. ; Noor Badi, F.A. ; Mohd-Shaharuddin, N. ; Wan Yusoff, W.S. ; Lim, Y.A.L. ; Chua, K.H. ; Sidi Omar, S.F.N. ; Chang, L.Y. ; Majid, H.A. ; Ngui, R.
Tropical Biomedicine 2022;39(No.1):135-142
Soil-transmitted helminth (STH) infections, mainly caused by Ascaris lumbricoides, Trichuris
trichiura, and hookworms, are among the most common intestinal parasites that infect
humans. The infections are widely distributed throughout tropical and subtropical countries,
including Malaysia, particularly in underprivileged communities. Microscopic and culture
techniques have been used as a gold standard for diagnostic techniques. However, these
methods yield low sensitivity and specificity, laborious and time-consuming. Therefore,
simple, rapid, and accurate alternative methods are needed for the simultaneous detection
of STH infections. Although advanced technologies such as real-time multiplex PCR have
been established, the use of this technique as a routine diagnostic is limited due to the
high cost of the instrument. Therefore, a single-round multiplex conventional PCR assay for
rapid detection of four STH species in the fecal sample was developed in this study. To
perform the single-round multiplex PCR, each pair of species-specific primers was selected
from target genes, including Ancylostoma duodenale (Internal Transcribed Spacer 2; accession
No. AJ001594; 156 base pair), Necator americanus (ITS 2; accession No. AJ001599; 225 base pair),
Ascaris lumbricoides (Internal Transcribed Spacer 1; accession No. AJ000895; 334 base pair)
and Trichuris triciura (partial ITS 1, 5.8s rRNA and partial ITS 2; accession No. AM992981; 518
base pair). The results showed that the newly designed primers could detect the DNA of STH
at low concentrations (0.001 ng/μl) with no cross-amplification with other species. This
assay enables the differentiation of single infections as well as mixed infections. It could
be used as an alternative and is a convenient method for the detection of STHs, especially
for the differentiation of N. americanus and A. duodenale.
5.Detection of human Sarcocystosis using dried blood on filter papers: An Immunofluorescent Antibody Test
Sharudin, P.S. ; Rahimi, R. ; Latif, B. ; Kutty, M.K ; Muslim, A. ; Abdul Rahim, A.S. ; Abdul Aziz, M ; Mahfudz, A.S. ; Lim, Y.A.L ; Heo, C.C. ; Md Noor, S. ; Hiu, J ; Hussaini, J.
Tropical Biomedicine 2019;36(2):453-458
Sarcocystosis, a parasitic infection caused by a protozoa belonging to the genus
Sarcocystis, is found worldwide in both and animals. Sarcocystis spp., require two animal
hosts to complete their life cycle. The infection has gathered more global attention after
recent outbreaks, especially amongst wester travellers to Malaysia. Other than sporadic
cases and the current outbreaks, little information is available regarding human Sarcocystis
infection in Malaysia. The present study aims to determine the prevalence of sarcocystosis
among humans using an immunofluorescent antibody (IFA) test applied to dried blood on
filter papers. A total of 200 blood samples were collected on filter papers from autopsy cases
at two Malaysian hospitals: Sungai Buloh Hospital (peninsular Malaysia) and Queen Elizabeth
Hospital (Malaysian Borneo). Antigens were prepared from bradyzoites harvested from positive
goats’ muscle samples. Of the 200 samples, 32 (16%) had Sarcocystis antibodies that showed
positive fluorescence reactions on filter papers. There was no significant difference (t-test,
p value > 0.05) in prevalence rates between samples collected from autopsies at peninsular
Malaysia and Malaysian Borneo. The results demonstrated that the filter paper technique can
be used as one of the alternative serological tests in the diagnostic of human sarcocystosis.