The authors investigated the prevalence of haemagglutination inhibition (HI) antibodies to four strains of influenza viruses among handlers of live pigs in Ibadan, Nigeria. Venous blood specimens were collected from thirty pig handlers (out of a total of forty-eight) at three locations in Ibadan in April and May 2008. The overall prevalence of antibodies to influenza viruses was 100%, while those of influenza A and B viruses were 68.3% and 58.3%, respectively. The prevalence of influenza A/Brisbane/59/2007 (H1N1), A/Brisbane/10/2007 (H3N2), B/Shanghai/361/2002-like and B/Malaysia/2506/2004-like was 46.7%, 90.0%, 76.7% and 40.0%, respectively. A total of 96.7% (n = 30) of pig handlers tested had polytypic influenza antibody reactions. This is the first report to document the prevalence of influenza antibodies among pig handlers in Nigeria and shows that humans who have regular and direct contact with live pigs in Ibadan are exposed to different strains of influenza viruses.
Hantaviruses are primarily rodent-borne and transmission is by inhalation of virus-contaminated aerosols of rodent excreta, especially urine and saliva. The genus Hantavirus, family Bunyaviridae, comprises at least 14 serotypes and the symptoms of clinical illness range from mild fever to severe hemorrhagic manifestations with renal complications. Many countries in Southeast Asia are unaware of the importance of hantavirus infections and give them low priority. Malaysia, like other countries in the region, has conducted very few studies on the epidemiology of hantaviruses - and even these were conducted in the 1980s. Using a more extensive range of hantavirus antigens, we conducted a seroprevalence study of rodents and humans and found further evidence of hantavirus infections. Moreover, the data from the antibody profiles strongly suggest the presence of different hantaviruses at the study sites.
As countries emerge from pandemic lockdown, many countries are relaxing international travel restrictions. Commercially available serologic tests for anti-SARS-CoV-2 antibodies are being performed. The concept of an 'immunity passport' has gained popularity, whereby evidence of SARS-CoV-2 antibody production would signal immunity to reinfection. For an immunity certificate to be validated for travel purposes, it should meet certain criteria. The introduction of such certificates faces multiple challenges. While there may be a future role for immunity passports in limited circumstances in the event that a protective vaccine becomes freely available, for now at least the risks of such an approach outweigh the perceived benefits.
Diseases caused by small ruminant lentiviruses, Mycobacterium avium ssp. paratuberculosis (MAP), Schmallenberg virus, and peste des petits ruminants virus (PPR) is globally recognised as serious threats to the ruminant industry due to their potential to spread rapidly across boundaries. Despite their global distribution and negative impacts on ruminant production, there is a gap in knowledge of the current trends in their epidemiology among sheep and goat populations in Peninsular Malaysia. This study was therefore designed to fill the gap of knowledge concerning the seroprevalence and contributing factors of CAEV, paratuberculosis, SBV, and PPRV among small ruminants from selected flocks in Selangor, Negeri Sembilan, and Pahang states in Peninsular Malaysia. A cross-sectional study design was used to collect animal data and blood samples for serological assays simultaneously. The ID Screen (ID.VET, France) indirect ELISA screening tests were used to detect serum antibodies directed against CAEV/MVV (VISNAS Ver 0922), paratuberculosis (PARAS Ver 0516), SBV (SBVC Ver 1114) and PPRV (PPRC Ver 0821). There was 45.4% (95% CI = 40.74-50.74), 6.8% (95% CI = 4.66-9.69), 27.8% (95% CI = 23.35-32.77), and 2.6% (95% CI = 1.11-0.51) true seroprevalence for CAEV, paratuberculosis, SBV, and PPR, respectively. Geographical location and species were the risk factors for CAEV and paratuberculosis, while the management system and age of small ruminants were the risk factors for SBV. The present study is the first to document a large-scale seroprevalence of MAP and PPR infection among sheep and goat flocks in Peninsular Malaysia. The presence of PPRV and MAP antibodies among small ruminant flocks is signalling current or previous exposure to the pathogens or cross reactions with similar antigens. This finding further suggests the potential for future outbreaks of these devastating diseases among sheep and goats in Malaysia. The high seroprevalence of CAEV and SBV among small ruminants indicates high levels of exposure to the viruses in the environment, which is a potential threat to production.
Nipah virus, family Paramyxoviridae, caused disease in pigs and humans in peninsular Malaysia in 1998-99. Because Nipah virus appears closely related to Hendra virus, wildlife surveillance focused primarily on pteropid bats (suborder Megachiroptera), a natural host of Hendra virus in Australia. We collected 324 bats from 14 species on peninsular Malaysia. Neutralizing antibodies to Nipah virus were demonstrated in five species, suggesting widespread infection in bat populations in peninsular Malaysia.
Commercially available diagnostic test kits for detection of dengue virus (DENV) non-structural protein 1 (NS1) and anti-DENV IgM were evaluated for their sensitivity and specificity and other performance characteristics by a diagnostic laboratory network developed by World Health Organization (WHO), the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) and the Pediatric Dengue Vaccine Initiative (PDVI). Each network laboratory contributed characterized serum specimens for the panels used in the evaluation. Microplate enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic test (RDT formats) were represented by the kits. Each ELISA was evaluated by 2 laboratories and RDTs were evaluated by at least 3 laboratories. The reference tests for IgM anti-DENV were laboratory developed assays produced by the Armed Forces Research Institute for Medical Science (AFRIMS) and the Centers for Disease Control and Prevention (CDC), and the NS1 reference test was reverse transcriptase polymerase chain reaction (RT-PCR). Results were analyzed to determine sensitivity, specificity, inter-laboratory and inter-reader agreement, lot-to-lot variation and ease-of-use. NS1 ELISA sensitivity was 60-75% and specificity 71-80%; NS1 RDT sensitivity was 38-71% and specificity 76-80%; the IgM anti-DENV RDTs sensitivity was 30-96%, with a specificity of 86-92%, and IgM anti-DENV ELISA sensitivity was 96-98% and specificity 78-91%. NS1 tests were generally more sensitive in specimens from the acute phase of dengue and in primary DENV infection, whereas IgM anti-DENV tests were less sensitive in secondary DENV infections. The reproducibility of the NS1 RDTs ranged from 92-99% and the IgM anti-DENV RDTs from 88-94%.
Nipah virus and Hendra virus are closely related and following natural or experimental exposure induce similar clinical disease. In humans, encephalitis is the most serious outcome of infection and, hitherto, research into the pathogenesis of henipavirus encephalitis has been limited by the lack of a suitable model. Recently we reported a wild-type mouse model of Hendra virus (HeV) encephalitis that should facilitate detailed investigations of its neuropathogenesis, including mechanisms of disease recrudescence. In this study we investigated the possibility of developing a similar model of Nipah virus encephalitis.
Rubella infection in pregnant women during the first trimester of pregnancy can lead to fetal anomalies, commonly known as congenital rubella syndrome (CRS). The objective of our study was to analyze the serological test results among infants suspected of having CRS aged < or = 12 months compared with their clinical status. Between January 2002 and December 2011, 3,279 serum samples from infants aged < or = 12 months from government hospitals in Malaysia were examined for rubella specific IgM and IgG antibodies using a Axsym, automated analyzer (Abbott Laboratories). Forty-eight samples were positive for rubella specific IgM antibodies and 494 samples were positive for rubella specific IgG antibodies. These were then age stratified and their clinical history reviewed for any CRS symptoms. Fifteen of 38 rubella IgM positive infants (39.5%) aged < 3 months, had a clinical appearance compatible with CRS. However, only 1 IgM positive infant aged 3 to 6 months and one infant aged 7 to 11 months had clinical appearance compatible with CRS. The most common abnormal findings in these cases were congenital heart defects and cataracts. Forty-eight point eight percent of IgM positive cases and 53.1% of IgG positive cases, had inadequate information in the chart to determine the presence of CRS. Clinical findings and timely laboratory diagnosis to determine the presence of CRS are important in infants born with congenital defects. Physicians should also be aware of the appropriate interpretation of these findings.
Hemophagocytic syndrome is a potentially fatal disorder. It is being increasingly reported but remained under-recognized in dengue. Most reported cases were in association with plasma leakage and shock but multi-organ impairment was also observed. We describe the time-lines of 6 cases of confirmed dengue with varying severities of hemophagocytosis. All had persistent fever, cytopenia and elevated transaminases with markedly elevated ferritin levels during and beyond the plasma leakage phase. Acute renal failure and central nervous system manifestation were observed in two patients. Morphological hemophagocytosis was demonstrated in three patients. All survivors showed clinical and biochemical resolution of hemophagocytosis indicating its transient nature. Persistence of fever and cytopenia together with multi-organ dysfunction, out of proportion to and beyond the plasma leakage phase should prompt clinicians to consider this phenomenon.
This study aimed to describe the transmission dynamics, the serological and virus excretion patterns of Nipah virus (NiV) in Pteropus vampyrus bats. Bats in captivity were sampled every 7-21 days over a 1-year period. The data revealed five NiV serological patterns categorized as high and low positives, waning, decreasing and increasing, and negative in these individuals. The findings strongly suggest that NiV circulates in wild bat populations and that antibody could be maintained for long periods. The study also found that pup and juvenile bats from seropositive dams tested seropositive, indicating that maternal antibodies against NiV are transmitted passively, and in this study population may last up to 14 months. NiV was isolated from the urine of one bat, and within a few weeks, two other seronegative bats seroconverted. Based on the temporal cluster of seroconversion, we strongly believe that the NiV isolated was recrudesced and then transmitted horizontally between bats during the study period.
An adult Malaysian woman returned to Japan from Kuala Lumpur and had onset of dengue fever-like symptoms including high fever, malaise and arthritis in early January 2009. Serum obtained on the following day was tested at the National Institute of Infectious Diseases in Tokyo, where it was determined to be positive for chikungunya virus (CHIKV) RNA. IgM antibody against CHIKV was negative on January 6 and sero-converted to be positive on January 14, confirming a recent CHIKV infection. Except for arthralgia, all her symptoms resolved uneventfully within 10 days.
Nipah encephalitis is a particular dangerous disease that affects animals and man. Fatal cases of the disease have been identified in the persons looking after pigs in the villages of Malaysia. The causative agent is presumably referred to as morbilliviruses of the Paramixoviridae family. Two hundred persons died among the ill patients with the signs of encephalitis. The principal hosts of the virus were fox-bats (Megaschiroptera) inhabiting in the surrounding forests. The present paper descries the epidemiological features of the disease, its clinical manifestations, abnormal anatomic changes, diagnosis, and implemented controlling measures.
Human cytomegalovirus (HCMV) is a species-specific DNA virus of the Herpetoviridae family. After a primary infection, HCMV persists in a latent form most probably in bone marrow progenitor cells or in peripheral blood monocytes. The virus can reactivate to result in shedding of the virus leading to virus dissemination and new infections. Immunocompromized patients are the ones most vulnerable to serious diseases occasionally acquired in blood transfusions. In a human population, HCMV seropositivity increases steadily with age to become approximately 100% in adults. This study was performed to detect seropositivity among regular blood donors in The Hospital of the Universiti Sains Malaysia, in the state of Kelantan. Using an enzyme immunoassay, it was found that 97.6% of blood donors were HCMV-positive. HCMV is highly prevalent and may be endemic in Kelantan. Hence, long-term strategies are required for the reduction of disease dissemination, and to prevent the exposure of immunocompromized patients to the virus.
The performance of a commercial rapid immunochromatographic dengue IgG/IgM assay device was evaluated against an in-place dengue IgM-capture ELISA in the National Public Health laboratory. Of the 239 serum samples from patients with clinical diagnosis of acute dengue illness, 140 and 99 samples were tested positive and negative respectively for anti-dengue IgM by the in-placed ELISA. Comparatively, 72 and 76 samples were tested positive and negative respectively, and 91 samples gave equivocal results by the rapid dengue test device. The rapid immunochromatographic assay device gave a relative sensitivity of 49.3% and a relative specificity of 62.6%. Though the rapid immunochromatographic assay device has the advantages of rapid testing which simultaneously detects both IgG and IgM and can also be performed with whole blood, serum or plasma, the user has to exercise extreme caution with the interpretation of the test result.
A 39-year-old patient developed a disseminated rash with scattered petechiae, fever, malaise and arthralgia after a trip to Malaysia. The patient displayed increasing dengue IgG titers and borderline dengue IgM titers. Dengue fever with a hemorrhagic course is a rare condition in adult patients. Patients who have previously had dengue fever and retained non-neutralizing heterotypic antibodies are more likely to develop this complication via the phenomenon of antibody-dependent enhancement.
The enzyme-linked Immunosorbent Assay (ELISA) is the gold standard clinical diagnostic tool for the detection and quantification of protein biomarkers. However, conventional ELISA tests have drawbacks in their requirement of time, expensive equipment and expertise for operation. Hence, for the purpose of rapid, high throughput screening and point-of-care diagnosis, researchers are miniaturizing sandwich ELISA procedures on Lab-on-a-Chip and Lab-on-Compact Disc (LOCD) platforms. This paper presents a novel integrated device to detect and interpret the ELISA test results on a LOCD platform. The system applies absorption spectrophotometry to measure the absorbance (optical density) of the sample using a monochromatic light source and optical sensor. The device performs automated analysis of the results and presents absorbance values and diagnostic test results via a graphical display or via Bluetooth to a smartphone platform which also acts as controller of the device. The efficacy of the device was evaluated by performing dengue antibody IgG ELISA on 64 hospitalized patients suspected of dengue. The results demonstrate high accuracy of the device, with 95% sensitivity and 100% specificity in detection when compared with gold standard commercial ELISA microplate readers. This sensor platform represents a significant step towards establishing ELISA as a rapid, inexpensive and automatic testing method for the purpose of point-of-care-testing (POCT) in resource-limited settings.
Evaluation of binding between analytes and its relevant ligands on surface plasmon resonance (SPR) biosensor is of considerable importance for accurate determination and screening of an interference in immunosensors. Dengue virus serotype 2 was used as a case study in this investigation. This research work compares and interprets the results obtained from analytical analysis with the experimental ones. Both the theoretical calculations and experimental results are verified with one sample from each category of dengue serotypes 2 (low, mid, and high positive), which have been examined in the database of established laboratorial diagnosis. In order to perform this investigation, the SPR angle variations are calculated, analyzed, and then validated via experimental SPR angle variations. Accordingly, the error ratios of 5.35, 6.54, and 3.72% were obtained for the low-, mid-, and high-positive-specific immune globulins of patient serums, respectively. In addition, the magnetic fields of the biosensor are numerically simulated to show the effect of different binding mediums.