Rickettsiae reservoirs among small mammals (Rats, Mice And Shrews) and their Arthropod Vectors in Sri Lanka

• Main Authors: Saranga Yathramullage, Jayantha Rajapakse, Suyama Boyagoda
• Format: Article
• Language: English
• Published: Faculty of Science, University of Peradeniya, Sri Lanka 2018-06-01
• Series: Ceylon Journal of Science
• Subjects: murine rodents; shrews; rickettsioses; kandy; kurunegala
• Online Access: https://cjs.sljol.info/articles/7514
• ISSN: 2513-2814; 2513-230X

Rickettsioses are a group of emerging diseases caused by closely related bacteria. In Sri Lanka, to date, studies have been focused mainly on human subjects. The present study aimed to identify small mammal reservoir hosts and vectors of <em>Rickettsia</em> spp. and <em>Orientia tsutsugamushi</em> in two districts of Sri Lanka. Quantitative-PCR was carried out to detect <em>Rickettsia</em> using citrate synthase gene and <em>Orientia</em> using 47-kD outer membrane protein antigen gene in blood of small rodents and their infested ectoparasites. In both districts ~7.5% blood samples were positive for <em>Rickettsia</em>. <em>Rattus rattus, Bandicota indica</em> and <em>Mus</em> <em>fernandoni</em> were carriers. Three individuals of <em>Suncus murinus, B. indica</em> and <em>Golunda ellioti</em> had only infected ectoparasites. Copies of gltA/100 μL ranged from 133-1.2 × 10⁴ in blood and 197-1.9 × 10⁷ in ectoparasites. Of small mammals with ectoparasites, 43% had <em>Rickettsia</em> positive ectoparasites. <em>Rhipicephalus haemaphysaloides, Ixodes ceylonensis, Haemaphysalis spinigera, Haemaphysalis</em> spp., <em>Stivalius aporus</em> and <em>Xenopsylla</em> <em>cheopis</em> were positive. All study sites except three had infected small mammals or ectoparasites. All samples were negative for <em>O. tsutsugamushi</em>. This is the first study to report <em>Rickettsia</em> spp. in small mammals and their ectoparasites in Sri Lanka. <em>Haemaphysalis spinigera</em>, <em>I. ceylonensis</em> and <em>S. aporus</em> are new records of vectors for <em>Rickettsia</em>. This is also the first report of endemic <em>M. fernandoni</em> as a carrier of <em>Rickettsia</em> and <em>G. ellioti</em> with <em>Rickettsia</em> infected ectoparasites. Though rickettsiosis is not life threatening in most cases, it can lead to severe or fatal disease in vertebrate animals and humans. Hence, the knowledge of the distribution of said pathogen in the reservoirs is essential to control the disease.