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Cattle lice are obligatory blood-sucking parasites, which is the cause of animal health problems worldwide. Recently, several studies have revealed that pathogenic bacteria could be found in cattle lice, and it can act as a potential vector for transmitting louse-borne diseases. However, the cattle lice and their pathogenic bacteria in Thailand have never been evaluated. In the present study, we aim to determine the presence of bacterial pathogens in cattle lice collected from three localities of Thailand. Total genomic DNA was extracted from 109 cattle louse samples and the Polymerase Chain Reaction (PCR) of 18S rRNA was developed to identify the cattle louse. Moreover, PCR was used for screening Bartonella spp., Acinetobacter spp., and Rickettsia spp. in cattle louse samples. The positive PCR products were cloned and sequenced. The phylogenetic tree based on the partial 18S rRNA sequences demonstrated that cattle lice species in this study are classified into two groups according to reference sequences; Haematopinus quadripertusus and Haematopinus spp. closely related to H. tuberculatus. The pathogen detection revealed that Bartonella spp. DNA of gltA and rpoB were detected in 25 of 109 samples (22.93%) both egg and adult stages, whereas Acinetobacter spp. and Rickettsia spp. were not detected in all cattle lice DNA samples. The gltA and rpoB sequences showed that the Bartonella spp. DNA was found in both H. quadripertusus and Haematopinus spp. closely related to H. tuberculatus. This study is the first report of the Bartonella spp. detected in cattle lice from Thailand. The finding obtained from this study could be used to determine whether the cattle lice can serve as a potential vector to transmit these pathogenic bacteria among cattle and may affect animal to human health.

IntroductionParasitic nematodes of the genus Trichinella are the etiological agents of the disease called trichinellosis which has a wide host range including birds, reptiles, several mammals as well as human. Trichinella behaves as an intracellular parasite of the striated muscle cell. There are two clades in this genus encompassing encapsulated and non-encapsulated species differentiated by the presence or absence collagen capsule around the nurse cell. T. spiralis, the most common encapsulated species, infects the muscle cell and induces remarkable changes that transform the infected muscle cell into a nurse cell that supports the growth and development of the parasite. This process is termed nurse cell formation which involves the loss of muscle proteins, enlargement and division of nurse cell nuclei, mitochondrial damage and formation of collagen [1]. Another obvious feature of the nurse cell in T. spiralis infection is the presence of a vascular network called circulatory rete surrounding it [2]. This feature probably corresponds to many observations indicating that larval and nurse cell energy metabolisms are anaerobic [3]. The anaerobic condition could be seen mimicking tissue hypoxia that stimulates angiogenesis through angiogenic factors such as vascular endothelial growth factor (VEGF) in response to hypoxic events [4]. In T. spiralis infection, it was shown that VEGF was expressed in the nurse cell from day 7 up to 8 months and angiogene-sis around the nurse cell began at approximately day 12 and ceased by day 26 [1,5]. Additionally, the in vitro production of VEGF was directly stimulated by T. spiralis antigens but not by those of T. pseudospiralis [6]. A recent study showed that VEGF protein expression increased in T. spiralis-infected muscles at an early phase of infection beginning 7 days after infection and diminished after 3 weeks [7]. The non-encapsulated T. pseudospiralis is also able to form the nurse cell but the collagen capsule, unlike in T. spiralis, is poorly developed [8,9]. Nevertheless, there has not been any study to demonstrate the presence of angiogenesis around the nurse cell of T. pseudospiralis. VEGF has been hypothesized to be involved in the development of the nurse cell-parasite complex in Trichinella infection. However, there has been so far no quantitative study of VEGF transcripts during the development of the nurse cell of both T. spiralis and T. pseudospiralis. In the present study, we attempt to determine VEGF expression in both mRNA and protein levels and localize VEGF mRNA transcript during nurse cell formation in T. spiralis and T. pseudospiralis infections.

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