A cross-sectional serological survey of domestic animals in West Malaysia revealed that 25.5% of the animals examined had agglutinating antibodies to one or more antigens belonging to Leptospira interrogans. Significant prevalence of infection was observed in cattle (40.5%), buffaloes (31%) and pigs (16%). The Sejroe serogroup was shown to be the principal one involved in cattle and buffaloes, and to a lesser extent the Tarassovi and Pomona serogroups. Evidence of infection in domestic animals by strains bearing the other seven antigens appeared insignificant and was indicative of sporadic infection. A majority of the large (semi-intensive) cattle and buffalo farms demonstrated a high prevalence of leptospiral infection. In both species of domestic animals mentioned above, the prevalence of infection was significantly higher (P = 0.01) in the semi-intensive farms than in the smallholdings. Amongst cattle, the droughtmasters had the highest prevalence whilst the Kedah-Kelantan (an indigenous breed) had the lowest prevalence of leptospiral infection. In general, the temperate breeds of cattle had a significantly (P = 0.01) higher prevalence of infection than local breeds. Leptospiral infection in goats and sheep was shown to be sporadic, and the Pomona serogroup was the principal leptospiral serogroup involved in these small ruminants. The prevalence of infection in pigs was observed to decline during the study period, and it is suspected that pigs in West Malaysia are the maintenance host for serovar pomona whilst cattle are the maintenance host for serovar hardjo. Overall, it appears that domestic animals in Malaysia will play a bigger role in the epidemiology of leptospiral infection with the advent of sophisticated farming.
Ehrlichia sennetsu, the causative agent of human sennetsu rickettsiosis, was successfully propagated in primary canine blood monocyte cultures. The growth cycle of this organism appears to be similar to that of Ehrlichia canis. The antigen derived from our E. sennetsu cultures was used to develop an indirect fluorescent antibody test for detection and titration of serum antibodies to the organism. Using this test system, we found that five human serum samples obtained from patients clinically diagnosed as having sennetsu rickettsiosis were positive for anti-E. sennetsu antibodies. In addition, 29% of the serum samples obtained from 200 patients having a fever of unknown origin and residing in various regions of Malaysia were also serologically positive. All sera from apparently healthy individuals were negative in the test. Dogs inoculated with cell culture-adapted E. sennetsu developed a significant specific antibody titer to E. sennetsu, and the organism was subsequently isolated from their blood. These animals showed no clinical evidence of disease. The possibility of a higher prevalence of human sennetsu rickettsiosis in Southeast Asia and the potential usefulness of the canine model for studies of human sennetsu rickettsiosis are discussed.
Bartonella henselae is a recognized cause of neuroretinitis in cat scratch disease. Meanwhile, polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes (POEMS) syndrome with Castleman disease (evidence of lymph node hyperplasia), is a chronic debilitating condition that predisposes to various superimposed infections. B. henselae neuroretinitis implicated in POEMS syndrome has not been reported previously. A 34-year-old asymptomatic man was referred for an eye assessment. Examination showed visual acuity of 6/18 in the right eye and 6/24 in the left eye. On fundus examination, both eyes exhibited typical features of neuroretinitis (optic disc swelling and incomplete macular star). There was otherwise no vitritis or chorioretinitis. Serology for B. henselae revealed high immunoglobulin M (IgM) titer (1:96) indicative of acute disease, and positive immunoglobulin G (IgG) (1:156). He was treated with oral azithromycin for 6 weeks and a short course of oral prednisolone. Subsequently, the visual acuity in both eyes improved with resolution of macular star. However, both optic discs remained swollen.
A single antigen indirect immunofluorescence test was used to screen for chlamydial antibody among Malaysian infants, children, sexually active adults and prostitutes. Of 794 serum samples tested, 361 (45.5%) were positive. Seropositivity increased with age and sexual activity and ranged from 10 to 16% among children under 10 years old to 94.4% among prostitutes. Pregnant women and female adolescents showed a higher antibody prevalence than nonpregnant and older women. Six (13%) infants under 6 months of age were positive for chlamydial IgM.
OBJECTIVES:
The aims of the study were, first, to determine the prevalence of Helicobacter pylori (HP) among endoscopy personnel and a group of non-endoscopy volunteers and, second, to evaluate the usefulness of two noninvasive tests of diagnosis: serology and the urea breath test.
METHODS:
The two noninvasive methods of HP diagnosis, serology and 14C-urea breath test (UBT), were used in a cross-sectional survey of endoscopists, nurse-assistants, and non-endoscopy personnel.
RESULTS:
One hundred and thirty-five volunteers were recruited for the study. In 116, results of the two tests were in agreement (kappa = 0.645). Further analysis was based on the results of the UBT. Endoscopy personnel (endoscopists and nurse-assistants) as a group had a significantly higher incidence of HP than did controls (32.9% vs. 11.3%; p = 0.004). The two groups were comparable with regard to mean age, sex, ethnic distribution, and social class.
CONCLUSIONS:
HP infection is more prevalent among endoscopy personnel. Both diagnostic tests (serology and UBT) were convenient and relatively simple to perform, and results gave a high level of agreement.
An epidemiological study in a mature oil palm estate in Peninsular Malaysia has demonstrated a low prevalence of R. tsutsugamushi infection in small mammals. The direct fluorescent antibody technique for assaying infections in chiggers proved more sensitive than mouse inoculation. Most infections in both chiggers and rodents were caused by the Karp strain.
Dog sera, collected from different communities throughout Selangor, Peninsular Malaysia, were investigated for the presence of antibodies to R. tsutsugamushi and R. typhi. Scrub typhus antibodies were present in animals from the rural areas only, whereas murine typhus antibodies were observed in equal numbers of dogs from both rural and metropolitan areas. Greater percentage of dogs from suburban areas had demonstrable antibody titers to murine typhus than from the urban area.
In this study, recombinant proteins that encompassed the AD I-AD III regions of 56 kDa immunodominant gene of 2 Orientia tsutsugamushi (OT) serotypes; Gilliam and TA763 were expressed in Escherichia coli. Both recombinant proteins exhibited serologic cross-reactivity with the rabbit antisera against various OT serotypes, as evaluated by enzyme-linked immunosorbent assay (ELISA), but not against other rickettsial species, including Rickettsia typhi, R. prowazekii and TT118 SFG rickettsiae. The feasibility of using the recombinant proteins as a diagnostic reagent was further evaluated by ELISA using sera from blood donors and scrub typhus patients. The results suggested a higher affinity of the antihuman IgM than IgG with both recombinant proteins. The IgM ELISA findings were agreeable with the results of indirect immunoperoxidase (IIP) assay especially with sera of high antibody (1:1600). However, more than one antigen are probably needed for development of an effective assay for serodiagnosis of scrub typhus in endemic areas.
A serosurvey was conducted in 1995-97 among 1596 febrile patients from 8 health centres in Malaysia for antibodies against Orientia tsutsugamushi (OT), Rickettsia typhi (RT) and TT118 spotted fever group rickettsiae (SFGR) by using an indirect immunoperoxidase assay. A total of 51.4% patients had antibody against at least 1 of those rickettsiae. Antibody to SFGR was most prevalent (42.5%), followed by RT (28.1%) and OT (24.9%). The seroprevalences of antibodies to SFGR, RT or OT alone were 12.4, 3.6 and 4.3%, respectively. Antibodies against more than 1 species of rickettsiae were presence in 31.1% of the patients, suggesting the possibility of co-infection, previous exposures or serological cross-reactivities. Seroprevalence of the various rickettsiae varied according to locality, with SFGR antibodies being the most prevalent in most areas. There was no significant association of prevalence of rickettsial antibody with gender. The seroprevalence of OT, SFGR and RT increased with patient age but an increase of antibody titre with age was not significant. Those working in the agricultural sectors had significantly higher seroprevalence of OT, SFGR and RT than those not related with agricultural activities. Scrub typhus remains a public health problem with an estimated annual attack rate of 18.5%. Tick typhus and murine typhus as shown in this serosurvey appear much more widespread than scrub typhus in this country.
An indirect ELISA was used to detect antibodies against outer membrane protein preparations (OMPs) from Salmonella typhi. Sera from patients with a definitive diagnosis of typhoid fever (TF) gave a mean absorbance reading, at 414 nm, of 1.52 +/- 0.23 as compared to 0.30 +/- 0.11 for sera from healthy individuals. This gave a positive to negative ratio of absorbance readings of approximately 5.1. Suspected TF patients (no isolation of S. typhi), with positive and negative Widal titers had mean absorbance readings of 1.282 +/00.46 and 0.25 +/- 0.19, respectively. Sera from patients with leptospirosis, rickettsial typhus, dengue fever, and other infections gave mean absorbances of 0.20 +/- 0.08, 0.24 +/- 0.08, 0.27 +/- 0.08, and 0.31 +/- 0.16, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 94%, 80% and 100%, respectively. The antibody response detected in the definitive TF cases was predominantly IgG in nature and no cross-reactivity was seen with OMP preparations extracted from E. coli. Variable reactivity was noted with OMP preparations obtained from other Salmonella spp. Three major OMPs are presented in the antigen preparation and strong binding of positive sera was detected to all three bands.
A cross-sectional bacteriological survey of cattle in West Malaysia revealed 14.4% (32/222) had leptospiral infection. Isolates were obtained from all except one herd with prevalence of infection in herds ranging from 0-44.8%. A small number of buffalo urine samples were examined and all of them were found to be negative. A leptospiral isolate obtained from a bovine kidney proved to be a new serovar of Leptospira interrogans and the name unipertama was assigned to it. Six other leptospiral serovars were isolated, namely canicola, australis, javanica, ballum, pomona and hardjo. All six serovars were isolated for the first time in cattle in Malaysia. Cattle in Malaysia appear to be the maintenance host for serovar hardjo. The presence of the other serovars in cattle was probably due to contact with the maintenance hosts, pigs for serovar pomona and rodents for the other three serovars. It appears that the epidemiology of leptospiral infection in cattle in Malaysia is similar to that reported overseas.
The seroprevalence of Orientia tsutsugamushi (OT), Rickettsia typhi (RT) and TT118 spotted fever group rickettsiae (SFGR) among blood donors and febrile Malaysian patients in the urban areas was determined. Of the 240 blood donors, 5.4%, 9.2% and 1.7% had either present or previous exposure to OT, RT and SFG rickettsiae, respectively. Patients admitted to an urban hospital had high seroprevalences of OT (43.5%) and RT (22.9%), as compared to SFGR (11.6%). Antibody levels suggestive of recent infections of scrub typhus, murine typhus and tick typhus were detected in 16.8%, 12.7% and 8.2% of patients respectively. No significant difference was noted in the distribution of rickettsial antibodies among urban patients from 2 geographical locations. However, the serologic patterns of rickettsial infection in the urban areas were different form those of rural areas.
A seroepidemiological survey of 837 people and 383 febrile patients was performed in rural areas of Sabah. We determined that the rickettsial diseases scrub typhus and endemic typhus were uncommon causes of febrile illness, as was tick typhus, except in forest dwelling peoples. The rate of occurrence of SFGR specific antibody was 16.5% among 412 forest dwellers, indicating that tick typhus may be a frequent cause of illness in this population.
A single chain variable fragment (scFv) specific towards B. pseudomallei exotoxin had previously been generated from an existing hybridoma cell line (6E6AF83B) and cloned into the phage display vector pComb3H. In this study, the scFv was subcloned into the pComb3X vector to facilitate the detection and purification of expressed antibodies. Detection was facilitated by the presence of a hemagglutinin (HA) tag, and purification was facilitated by the presence of a histidine tag. The culture was grown at 30 degrees C until log phase was achieved and then induced with 1 mM IPTG in the absence of any additional carbon source. Induction was continued at 30 degrees C for five h. The scFv was discerned by dual processes-direct enzyme-linked immunosorbent assays (ELISA), and Western blotting. When compared to E. coli strains ER2537 and HB2151, scFv expression was observed to be highest in the E. coli strain Top10F'. The expressed scFv protein was purified via nickel-mediated affinity chromatography and results indicated that two proteins a 52 kDa protein, and a 30 kDa protein were co-purified. These antibodies, when blotted against immobilized exotoxin, exhibited significant specificity towards the exotoxin, compared to other B. pseudomallei antigens. Thus, these antibodies should serve as suitable reagents for future affinity purification of the exotoxin.
The objective of this study was to investigate the longevity of positive dot enzyme immunosorbent assay (dot EIA) results for IgM and IgG to a Salmonella typhi outer membrane protein in Malaysian children with enteric fever. The patients were children one month to 12 years of age with clinical evidence of typhoid fever, positive blood or stool cultures for S. typhi, and/or a positive Widal test result who were admitted over a two-year period to General Hospital (Kota Bharu, Malaysia). These patients received standard inpatient treatment for enteric fever including chloramphenicol therapy for 14 days. Dot EIA tests were performed as part of clinical and laboratory assessments on admission, at two weeks, and then at 3, 6, 9, 12, 15, 18, and 21 months postdischarge. Assessment of the longevity of positive dot EIA IgM and IgG titers was done by Kaplan-Meier analysis. In 94 evaluable patients, 28% were dot EIA IgM positive but IgG negative on admission, 50% were both IgM and IgG positive, and 22% were IgM negative and IgG positive. Mean persistence of IgM dot EIA positivity was 2.6 months (95% confidence interval = 2.0-3.1 months) and that of IgG was 5.4 months (4.5-6.3 months). There were no significant differences between the three subgroups. Thus, positive IgM and IgG results determined by dot EIA within four and seven months, respectively, following documented or suspected enteric fever in a child from an endemic area should be interpreted with caution. In other clinical situations, the dot EIA remains a rapid and reliable aid to diagnosis.