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Rickettsia tsutsugamushi infections in chiggers and small mammals on a mature oil palm estate

Shirai A, Robinson DM, Lim BL, Dohany AL, Huxsoll DL

Southeast Asian J Trop Med Public Health, 1978 Sep;9(3):356-60.
PMID: 107596

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.

Matched MeSH terms: Orientia tsutsugamushi/immunology
Presence of antibodies to scrub typhus and murine typhus in dogs from Selangor, Peninsular, Malaysia

Huxsoll DL, Shirai A, Robinson DM, Yap LF, Lim BL

Southeast Asian J Trop Med Public Health, 1977 Jun;8(2):232-5.
PMID: 411180

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.

Matched MeSH terms: Orientia tsutsugamushi/immunology
Fulltext Antibody prevalence and factors associated with exposure to Orientia tsutsugamushi in different aboriginal subgroups in West Malaysia

Tay ST, Mohamed Zan HA, Lim YA, Ngui R

PLoS Negl Trop Dis, 2013;7(8):e2341.
PMID: 23936576 DOI: 10.1371/journal.pntd.0002341

BACKGROUND: Limited data is available on the current status of scrub typhus infection in the aboriginal population in Malaysia. This study was aimed to provide recent data on the degree of exposure of 280 individuals from seven aboriginal subgroups to Orientia tsutsugamushi (causative agent of scrub typhus) in West Malaysia. The environment, socioeconomic and behavioural risk factors associated with the disease were also investigated.
METHODS/FINDINGS: The antibody prevalence to O. tsutsugamushi ranged from 0 to 36.4% in seven subgroups, with high prevalence rates noted in subgroups involved in agricultural activity and the lowest prevalence rates noted in subgroups whose main occupations were associated to fishing. Univariate analysis indicated populations with age above 18 years (OR = 1.15, 95% CI = 1.02-1.30, P = 0.015), working (OR = 1.99, 95% CI = 1.01-3.92, P = 0.044), working at agriculture area (OR = 1.18, 95% CI = 0.98-1.42, P = 0.031), receiving household income less than US$ 166.7 (RM500) per month (OR = 2.43, 95% CI = 1.16-5.11, P = 0.016) and having close contact with animal pets (OR = 4.06, 95% CI = 1.20-13.76, P = 0.016) are significantly associated with exposure to O. tsutsugamushi. Multivariate analysis confirms that participants who are above 18 years old, receiving household income less than US$ 166.7 (RM500) per month and having close contact with animal pets are 3.6 times (95% CI = 1.81-7.03, P<0.001), 1.3 times (95% CI = 1.14-1.64, P = 0.002) and 1.2 times (95% CI = 1.05-1.06, P = 0.006) more likely to have exposure to O. tsutsugamushi, respectively.
CONCLUSION: The present study indicates that scrub typhus is still an important disease in the aboriginal population in Malaysia. Awareness about the disease and education on the preventive measures are important in reducing the risk of acquiring scrub typhus in the population studied.

Matched MeSH terms: Orientia tsutsugamushi/immunology*
Expression of recombinant proteins of Orientia tsutsugamushi and their applications in the serodiagnosis of scrub typhus

Tay ST, Rohani MY, Ho TM, Devi S

Diagn Microbiol Infect Dis, 2002 Oct;44(2):137-42.
PMID: 12458119

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.

Matched MeSH terms: Orientia tsutsugamushi/immunology*
Antibodies to Orientia tsutsugamushi, Rickettsia typhi and spotted fever group rickettsiae among febrile patients in rural areas of Malaysia

Tay ST, Ho TM, Rohani MY, Devi S

Trans R Soc Trop Med Hyg, 2000 9 7;94(3):280-4.
PMID: 10974999

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.

Matched MeSH terms: Orientia tsutsugamushi/immunology*
Seroepidemiologic survey of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group rickettsiae in rubber estate workers in Malaysia

Tee TS, Kamalanathan M, Suan KA, Chun SS, Ming HT, Yasin RM, et al.

Am J Trop Med Hyg, 1999 Jul;61(1):73-7.
PMID: 10432060

The seroprevalence of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group (SFG) rickettsiae in 300 rubber estate workers in Slim River, Malaysia was determined in December 1996 and March 1997. In December, which was the wet season, 23.3%, 3.0%, and 57.3% of the population had antibodies detected against the three rickettsiae, respectively. The highest seropositive rate of 40% was detected for single infection with SFG rickettsiae, followed by a rate of 15.3% for both O. tsutsugamushi and SFG rickettsiae among the rubber estate workers. Subjects less than 21 years old had a lower seroprevalence of SFG rickettsiae compared with the other age groups. Indians had a higher seroprevalence of O. tsutsugamushi compared with other ethnic groups. Rubber tappers had a higher seroprevalence of SFG rickettsiae compared with other occupational groups. During the dry season in March 1997, there was a significant increase in the seroprevalence of R. typhi. The seroconversion rates for IgM against O. tsutsugamushi, R. typhi, and SFG rickettsiae were 5.7%, 12.3%, and 15.1%, respectively, during the four-month period. Significant variations of antibody titers towards the three rickettsiae was noted among subjects who were bled twice. This suggests a significant and continual exposure of rubber estate workers to the three rickettsiae.

Matched MeSH terms: Orientia tsutsugamushi/immunology
Antibody prevalence of Orientia tsutsugamushi, Rickettsia typhi and TT118 spotted fever group rickettsiae among Malaysian blood donors and febrile patients in the urban areas

Tay ST, Kamalanathan M, Rohani MY

Southeast Asian J Trop Med Public Health, 2003 Mar;34(1):165-70.
PMID: 12971530

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.

Matched MeSH terms: Orientia tsutsugamushi/immunology*
A serological survey of scrub, tick, and endemic typhus in Sabah, East Malaysia

Taylor AC, Hii J, Kelly DJ, Davis DR, Lewis GE

Southeast Asian J Trop Med Public Health, 1986 Dec;17(4):613-9.
PMID: 3107139

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.

Matched MeSH terms: Orientia tsutsugamushi/immunology