Ehrlichia and Anaplasma Infections: Serological Evidence and Tick Surveillance in Peninsular Malaysia

Abstract

Little information is available on human anaplasmosis and ehrlichiosis in Southeast Asia despite increasing reports of the detection of Anaplasma spp. and Ehrlichia spp. in the ticks. We report herein the serological findings against the tick-borne pathogens in a group of animal farm workers (n = 87) and indigenous people (n = 102) in Peninsular Malaysia. IgG antibodies against Ehrlichia chaffeensis were detected from 29.9% and 34.3% of farm workers and indigenous people, respectively, using commercial indirect immunofluorescence assays. Comparatively, only 6.9% of the indigenous people but none of the animal farm workers were seropositive to Anaplasma phagocytophilum. A polymerase chain reaction (PCR) assay targeting the 16S rRNA gene of Anaplasmataceae was used to identify Anaplastamataceae in ticks collected from various locations adjacent to the areas where the serological survey was conducted. In this study, a total of 61.5% of ticks infesting farm animals, 37.5% of ticks infesting peri-domestic animals in rural villages, 27.3% of ticks collected from wildlife animals, and 29.1% of questing ticks collected from forest vegetation were positive for Anaplasmataceae DNA. Sequence analyses of 16S rRNA gene region (238 bp) provide the identification for Anaplasma marginale, Anaplasma bovis, Anaplasma platys, A. phagocytophilum, and Anaplasma spp. closely related to Candidatus Cryptoplasma californiense in ticks. E. chaffeensis DNA was not detected from any ticks, instead, Ehrlichia sp. strain EBm52, Ehrlichia mineirensis and Candidatus Ehrlichia shimanensis are the only Ehrlichia sp. identified from cattle ticks in this study. Further investigation is required to ascertain the occurrence of zoonotic transmission of Ehrlichia and Anaplasma infections in Peninsular Malaysia.

A qualitative study to explore farmworkers’ knowledge, beliefs and preventive practices toward ticks and tick-borne diseases

“…A serosurvey of indigenous community and farmworkers in Peninsular Malaysia showed that these groups had a higher likelihood of rickettsial infections as compared to blood donors from urban areas [11]. Recent studies showed the detection of IgG antibodies against Ehrlichia chaffeensis (29.9%), R. felis (16.1%), and both rickettsia species R. felis and R. conorii (5.7%), and tick-borne encephalitis virus (4.2%) among farmworkers of this study [11][12][13]. Furthermore, ticks collected from farm animals, domestic animals in the rural areas and wildlife animals confirmed the presence of Rickettsia spp, Anaplasma spp.…”

“…They explained their experience as rashes, pain, itchiness, and in some cases fatigue and fever. Previous studies of these farms illustrated the potential exposure of farmworkers to ticks and TBDs [11][12][13]22].…”

“…The vector surveillance of these farms demonstrated the presence of various spotted fever group rickettsiae and R. felis in cattle ticks. Farmworkers of these farms also had detectable IgG antibodies to E. chaffeensis, rickettsial species R. conori and R. felis, and tick-borne encephalitis virus [11][12][13]. Hence, farmworkers as a high-risk group for the tick bite and TBDs should be informed of their susceptibility to tick bites.…”

Isolation and Characterization of a Novel Pathogenic Strain of Ehrlichia minasensis

“…In addition to R. microplus and other species of the genus Rhipicephalus , R. appendiculatus , R. eversti eversti, R. sanguineus s.l., and R. bursa [7,10,11], E. minasensis has also been identified in Amblyomma [11], Hyalomma [12,13], and Haemaphysalis [14], suggesting that several tick species could vector this bacterium. E. minasensis has a wide distribution; it has been reported in Canada [5,6], Brazil [7,9], Pakistan [13], Malaysia [15], China [14], Ethiopia [16], South Africa [11], and the Mediterranean island of Corsica [12]. These findings suggest that E. minasensis may be transmitted by more than one tick species which explain the wide geographical distribution of this bacterium [17].…”

Development and Clinical Validation of a Multiplex Real-Time Quantitative PCR Assay for Human Infection by Anaplasma phagocytophilum and Ehrlichia chaffeensis

“…Further, they require specific treatment (doxycycline) that is not used for empiric treatment of acute febrile illness.As advanced diagnostic methods are employed to identify etiologic agents of undifferentiated fever, rickettsial infections are increasingly recognized causes of febrile illness in the tropics with substantive morbidity and mortality [ 3 ]. Despite the increasing recognition of infections by Rickettsia and Orientia species in the Rickettsiaceae family, only limited study of human infection by Anaplasmataceae has been conducted in tropical regions [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. This sustained lack of progress occurs despite clear evidence of the presence of Anaplasma , Ehrlichia , and Neorickettsia species in vectors and as agents of disease in wild and domestic animals.…”