The indirect hemagglutination test was used to measure malaria antibody levels in residents of an endemic area of Malaysia. Blood specimens were collected at 4-week intervals for a year. Seropositivity rates increased with age and number of episodes of malaria in young children. Although antibody levels were variable, titers tended to rise with parasitemia and fall in the absence of detected parasites. In general, the serologic indices tended to reflect the parasitologic findings.
A cohort of 62 persons living in a malaria-endemic area was examined by serology and by blood film 14 times over a 56-week period. Serologic responses (indirect hemagglutination test) of the group as a whole reflected the malaria transmission as determined by blood slide examination. The serologic responses of individuals showed titer changes that were not always consistent with blood slide results. The use of chloroquine may have modified the host's immune response.
While visiting Malaysia, a 22-year-old previously healthy Japanese man developed myalgia, headache, and fever, leading to a diagnosis of classical dengue fever. After improvement and returning to Japan after a five day hospitalization, he developed productive cough several days after defervescing from dengue. Computed tomography (CT) thorax scan showed multiple lung cavities. A sputum smear revealed leukocytes with phagocytized gram-positive cocci in clusters, and grew an isolate Staphylococcus aureus sensitive to semi-synthetic penicillin; he was treated successfully with ceftriaxone and cephalexin. This second reported case of pneumonia due to S. aureus occurring after dengue fever, was associated both with nosocomial exposure and might have been associated with dengue-associated immunosuppression. Clinicians should pay systematic attention to bacterial pneumonia following dengue fever to establish whether such a connection is causally associated.
Melioidosis is reported to cause a high fatality rate in children, even in the absence of risk factors for disease. The aim of this study was to identify characteristics of fatal pediatric melioidosis infection. We performed a retrospective analysis of children aged < 15 years with culture-confirmed melioidosis admitted to Bintulu Hospital in Sarawak, Malaysian Borneo, from January 2011 to December 2020. Forty-one children had culture-confirmed melioidosis. Nine (22%) had a fatal outcome; 8 (89%) had no predisposing risk factors. Bacteremia, septic shock, and acute respiratory distress syndrome were present in all fatalities. Demographic characteristics, presenting manifestation, and disseminated infection were not significantly associated with mortality, whereas the presence of splenomegaly, cytopenia, disseminated intravascular coagulation, and hepatobiliary dysfunction, all of which are features of hyperferritinemic sepsis-induced multiple-organ dysfunction syndrome, were associated with mortality. Hyperferritinemic sepsis-induced multiple-organ dysfunction syndrome may be a key component in the pathogenesis of fatal pediatric melioidosis.
Invasion of Plasmodium knowlesi merozoite into human erythrocytes involves molecular interaction between the parasite's Duffy binding protein (PkDBPαII) and the Duffy antigen receptor for chemokines on the erythrocytes. This study investigates the binding activity of human erythrocyte with PkDBPαII of P. knowlesi isolates from high and low parasitemic patients in an erythrocyte binding assay. The binding activity was determined by counting the number and measuring the size of rosettes formed in the assay. The protein PkDBPαII of P. knowlesi isolated from low parasitemia cases produced significantly higher number of rosettes with human erythrocytes than high parasitemia case isolates (65.5 ± 12.9 and 17.2 ± 5.5, respectively). Interestingly, PkDBPαII of isolates from high parasitemia cases formed significantly larger rosettes with human erythrocytes than PkDBPαII of isolates from low parasitemia cases (18,000 ± 13,000 µm2 and 1,315 ± 623 µm2, respectively).
Severe floods increase the risk of leptospirosis outbreaks in endemic areas. This study determines the spatial-temporal distribution of leptospirosis in relation to environmental factors after a major flooding event in Kelantan, Malaysia. We conducted an observational ecological study involving incident leptospirosis cases, from the 3 months before, during, and three months after flood, in reference to the severe 2014 Kelantan flooding event. Geographical information system was used to determine the spatial distribution while climatic factors that influenced the cases were also analyzed. A total of 1,229 leptospirosis cases were notified within the three study periods where incidence doubled in the postflood period. Twelve of 66 subdistricts recorded incidence rates of over 100 per 100,000 population in the postflood period, in comparison with only four subdistricts in the preflooding period. Average nearest neighborhood analysis indicated that the cases were more clustered in the postflood period as compared with the preflood period, with observed mean distance of 1,139 meters and 1,666 meters, respectively (both at P < 0.01). Global Moran's I was higher in the postflood period (0.19; P < 0.01) as compared with the preflood period (0.06; P < 0.01). Geographic weighted regression showed that living close to water bodies increased the risk of contracting the disease. Postflooding hotspots were concentrated in areas where garbage cleanup occurred and the incidence was significantly associated with temperature, humidity, rainfall, and river levels. Postflooding leptospirosis outbreak was associated with several factors. Understanding the spatial distribution and associated factors of leptospirosis can help improve future disease outbreak management after the floods.
The predictors of severe disease or death were determined for 85 melioidosis patients in Kuala Lumpur, Malaysia. Most of the patients were male, > 40 years old, and diabetic. Severe disease or death occurred in 28 (32.9%) cases. Lower lymphocyte counts and positive blood cultures were significant independent predictors of severe disease, but age, presentations with pneumonia, inappropriate empirical antibiotics, or flagellin types of the infecting isolates were not. Knowledge of local predictors of severe disease is useful for clinical management.
The presence of Rickettsia felis, Bartonella henselae and B. clarridgeiae in 209 fleas (Ctenocephalides felis) obtained from domestic cats and dogs in several locations in Malaysia was investigated in this study. Using a polymerase chain reaction specific for the citrate synthase (gltA) and 17-kD antigenic protein (17kD) genes of rickettsiae, we detected R. felis DNA in 6 (2.9%) fleas. For detection of bartonellae, amplification of the heme-binding protein (pap31) and riboflavin synthase (ribC) genes identified B. henselae and B. clarridgeiae DNA in 24 (11.5%) and 40 (19.1%) fleas, respectively. The DNA of B. henselae and B. clarridgeiae was detected in 10 (4.8%) fleas. Two B. henselae genogroups (Marseille and Houston-1) were detected in this study; genogroup Marseille (genotype Fizz) was found more often in the fleas. The findings in this study suggest fleas as potential vectors of rickettsioses and cat-scratch disease in this country.
Novel coronavirus disease (COVID-19), named a pandemic by the WHO, is the current global health crisis. National and international collaboration are indispensable for combating COVID-19 and other similar potential outbreaks. International efforts to tackle this complex problem have led to remarkable scientific advances. Yet, as a global society, we can and must take additional measures to fight this pandemic. Undoubtedly, our approach toward COVID-19 was not perfect, and testing has not been deployed fast enough to arrest the epidemic early on. It is critical that we revise our approaches to be more prepared for pandemics as a united body by promoting global cooperation and commitment.
Japanese encephalitis (JE) is endemic in Malaysia. Although JE vaccination is practiced in the neighboring state of Sarawak for a long time, little is known about JE in Sabah state in Borneo. As a result, informed policy formulation for JE in Sabah has not been accomplished. In the present study, we have analyzed JE cases that have been reported to the Sabah State Health Department from 2000 to 2018. A total of 92 JE cases were reported during 19 years, and three-fourths of the cases were attributed to children. The estimated mean incidence for JE cases is 0.161/100,000 population. Japanese encephalitis was predominant in Sabah during June, July, and August, peaking in July. In most cases, pigs were absent within a 400-m radius of the place of residence. We could not establish any relationship between the mapping of JE cases and the number of piggeries in each district. We could not establish a relationship between average rainfall and JE cases, either. We propose the cases reported are possibly showing the tip of an iceberg and continuous surveillance is needed, as JE is a public health challenge in Sabah.
The COVID-19 pandemic caught the world by surprise, causing millions of confirmed cases and hundreds of thousands of deaths. Hence, the Malaysian government announced a Movement Control Order at the start of the containment phase to flatten the epidemiological curve. Universiti Malaysia Sabah (UMS), a public university in Borneo, was accelerated into alert phase because of high risk of case importation from more than 400 China incoming undergraduates. Measures to mitigate the potential COVID-19 outbreaks in its population were taken by using conventional public health measures with special attention to task-shifting and widespread community mental health interventions. A Preparedness and Response Centre was established to overseer the mitigating measures happening inside the university. Measures taken included empowerment of frontline staff, strengthening of restrictions, strengthening university health center, vigorous contact tracing, widespread health education, maintaining cultural sensitivity, and establishment of early standard operating procedures and university continuity plans. Hence, UMS was able to ensure no importation of cases into its campus during both acute and containment phases at the nationwide level.
Piperaquine combined with dihydroartemisinin is one of the artemisinin derivative combination therapies, which can replace artesunate-mefloquine in treating uncomplicated falciparum malaria in Thailand. The aim of this study was to determine the in vitro sensitivity of Thai Plasmodium falciparum isolates against piperaquine and the influence of the pfmdr1 gene on in vitro response. One hundred and thirty-seven standard laboratory and adapted Thai isolates of P. falciparum were assessed for in vitro piperaquine sensitivity. Polymorphisms of the pfmdr1 gene were determined by polymerase chain reaction methods. The mean and standard deviation of the piperaquine IC50 in Thai isolates of P. falciparum were 16.7 ± 6.3 nM. The parasites exhibiting chloroquine IC50 of ≥ 100 nM were significantly less sensitive to piperaquine compared with the parasite with chloroquine IC50 of < 100 nM. No significant association between the pfmdr1 copy number and piperaquine IC50 values was found. In contrast, the parasites containing the pfmdr1 86Y allele exhibited significantly reduced piperaquine sensitivity. Before nationwide implementation of dihydroartemisinin-piperaquine as the first-line treatment in Thailand, in vitro and in vivo evaluations of this combination should be performed especially in areas where parasites containing the pfmdr1 86Y allele are predominant such as the Thai-Malaysian border.
Children with severe Trichuris trichiura infection pose significant social, clinical, and therapeutic problems in Malaysia. Thirty such children were investigated, and mebendazole was found to be safe and effective in the treatment of severe trichuriasis but it had to be given for a longer period than currently recommended. A poor correlation was found between egg load and worm burden in these children. Direct visualization of the rectal and colonic mucosa was the most reliable method of assessing severity in untreated cases, and response to treatment. The eggs of Trichuris that had been exposed to mebendazole were morphologically altered and not viable when incubated. This may be of considerable epidemiological importance.
Neorickettsia sennetsu has been described from Japan and Malaysia, causing a largely forgotten infectious mononucleosis-like disease. Because it is believed to be contracted from eating raw fish, frequently consumed in the Lao PDR, we looked for evidence of N. sennetsu among Lao patients and fish. A buffy coat from 1 of 91 patients with undifferentiated fever was positive by 16S rRNA amplification and sequencing and real-time polymerase chain reactions (PCR) targeting two N. sennetsu genes. Lao blood donors and patients with fever, hepatitis, or jaundice (N = 1,132) had a high prevalence (17%) of immunofluorescence assay IgG anti-N. sennetsu antibodies compared with 4% and 0% from febrile patients (N = 848) in Thailand and Malaysia, respectively. We found N. sennetsu DNA by PCR, for the first time, in a fish (Anabas testudineus). These data suggest that sennetsu may be an under-recognized cause of fever and are consistent with the hypothesis that it may be contracted from eating raw fish.
Characterization of 14,079 circulating dengue viruses in a cross-border surveillance program, UNITEDengue, revealed that the 2013 outbreaks in Singapore and Malaysia were associated with replacement of predominant serotype. While the predominant virus in Singapore switched from DENV2 to DENV1, DENV2 became predominant in neighboring Malaysia. Dominance of DENV2 was most evident on the southern states where higher fatality rates were observed.
Entamoeba histolytica is a protozoan parasite that causes amebiasis and poses a significant health risk for populations in endemic areas. The molecular mechanisms involved in the pathogenesis and regulation of the parasite are not well characterized. We aimed to identify and quantify the differentially abundant membrane proteins by comparing the membrane proteins of virulent and avirulent variants of E. histolytica HM-1:IMSS, and to investigate the potential associations among the differentially abundant membrane proteins. We performed quantitative proteomics analysis using isobaric tags for relative and absolute quantitation labeling, in combination with two mass spectrometry instruments, that is, nano-liquid chromatography (nanoLC)-matrix-assisted laser desorption/ionization-mass spectrometry/mass spectrometry and nanoLC-electrospray ionization tandem mass spectrometry. Overall, 37 membrane proteins were found to be differentially abundant, whereby 19 and 18 membrane proteins of the virulent variant of E. histolytica increased and decreased in abundance, respectively. Proteins that were differentially abundant include Rho family GTPase, calreticulin, a 70-kDa heat shock protein, and hypothetical proteins. Analysis by Protein ANalysis THrough Evolutionary Relationships database revealed that the differentially abundant membrane proteins were mainly involved in catalytic activities (29.7%) and metabolic processes (32.4%). Differentially abundant membrane proteins that were found to be involved mainly in the catalytic activities and the metabolic processes were highlighted together with their putative roles in relation to the virulence. Further investigations should be performed to elucidate the roles of these proteins in E. histolytica pathogenesis.
Although human infections of Plasmodium knowlesi have been found throughout Southeast Asia, most cases originated from Malaysian Borneo. In Thailand, P. knowlesi malaria was considered extremely rare. However, during October 2017-September 2018, there was a surge in the number of reported P. knowlesi cases. Here, a series of six cases of P. knowlesi malaria found during this period in Songkhla and Narathiwat provinces of southern Thailand are presented. All cases were confirmed by polymerase chain reaction. The unprecedented case number in the affected area is a warning sign of an increasing P. knowlesi burden in the south of Thailand.
We report a case of Ancylostoma ceylanicum infection detected by endoscopy. It was diagnosed and confirmed using polymerase chain reaction (PCR) and DNA sequencing. The patient is a 58-year-old Malaysian woman who lives in a rural area, where uncontrolled populations of stray and semidomesticated dogs live in close proximity with humans.
Species identification of human hookworm infections among eight communities in rural areas of Peninsular Malaysia was determined during 2009-2011. Fecal samples were examined by microscopy and subsequently, the internal transcribed spacer 2 and 28S ribosomal RNA region of Necator americanus and Ancylostoma spp. were sequenced. Overall, 9.1% (58 of 634) were identified positive by microscopy for hookworm infection, and 47 (81.0%) of 58 were successfully amplified and sequenced. Sequence comparison found that N. americanus (87.2%) was the most predominant hookworm identified, followed by Ancylostoma ceylanicum (23.4%). No A. duodenale infection was detected in this study. Detection of A. ceylanicum in humans highlighted the zoonotic transmission among humans living near dogs. Thus, implementation of effective control measures for hookworm infections in future should seriously consider this zoonotic implication.
This study aims to evaluate the current seroprevalence of toxoplasmosis among indigenous communities in Peninsular Malaysia and relate its association with epidemiological data. Overall seroprevalence of Toxoplasma gondii was 37.0% with 31.0% immunoglobulin (Ig) G, 1.8% IgM, and 4.2% seropositivity for both anti-Toxoplasma antibodies. Multivariate analysis showed that age above 12 years (odds ratio [OR] = 2.70, 95% confidence interval [CI] = 1.75-4.04, P < 0.001), using untreated river and mountain water supplies (OR = 1.50, 95% CI = 1.01-2.40, P = 0.050), and close proximity with cats (OR = 1.40, 95% CI = 1.10-1.76, P = 0.010) were factors associated with toxoplasmosis. Given the high seroprevalence of toxoplasmosis among these communities who live in poor socioeconomic conditions, a comprehensive health surveillance program and screening should be initiated among women of childbearing age and pregnant women during the antenatal period for early diagnosis and treatment. The role of domestic cats and environmental contamination with oocyst in soil and water has to be highlighted and addressed in future prevention strategies for these communities.