Changes in tick-vector densities and a resultant incidence of tick-borne diseases are
caused mainly by human activities affecting the environmental ecosystem, especially in tropical
countries. As one of the most important invertebrate arthropod vectors of disease transmission, ticks
are susceptible to changes in their environment due to their sole dependence of all their life stages on
prevailing environment. Upon completion of their lifecycle, ticks depend on the availability of hosts
and other several factors related to their surroundings to survive. This review discusses the major
factors that influence the prevalence and distribution of tick-borne diseases among domestic animals
in Malaysia. It is highly imperative to understand the factors that lead to increase in tick-vector
populations, infection intensity and hence the spatial distribution of ticks and tick-borne diseases in
order to prevent their emergence and resurgence as well as to serve as a basis for effectivecontrol.
Leptospirosis is a serious bacterial disease that affects both humans and animals. A wide range of symptoms have been described in humans; the disease in dogs is commonly associated with kidney and/or liver disease. In Malaysia, information about the common serovars infecting dogs is limited. Therefore, we investigated the occurrences of leptospirosis in 124 pet dogs diagnosed with kidney and/or liver disease. Blood, urine, abdominal effusion, and/or kidney and liver were collected from the dogs. Based on microscopic agglutination testing, 53 of 124 (42.7%) dogs were seropositive for leptospiral exposure. Sera were frequently positive to serovars Bataviae (n = 12), Javanica (n = 10), and Icterohaemorrhagiae (n = 10). Direct detection using PCR showed that 42 of 124 (33.9%) of the whole blood and 36 of 113 (31.9%) urine samples were positive for pathogenic Leptospira spp. By PCR, 2 of 23 (9.1%) kidney and 2 of 23 (9.1%) liver were positive for pathogenic Leptospira spp. Abdominal effusion from 4 dogs were PCR-positive for pathogenic Leptospira spp. The species detected were L. interrogans, L. borgpetersenii, L. kirschneri, and L. kmetyi by partial 16S rRNA sequencing. We further identified and characterized 11 Leptospira spp. isolates from 8 dogs as serovars Bataviae, Javanica, and Australis. The mortality rate of the Leptospira-infected dogs was high (18 of 53; 34%).