Spinose Ear Tick Otobius megnini Infestations in Race Horses

Spinose ear tick, Otobius megnini, has a worldwide distribution causing otoacariasis or parasitic otitis in animals and humans. It mainly infests horses and cattle. It is a nidicolous, one-host soft tick spread from the New World to the Old World and is now distributed across all the continents. Only the larvae and nymphs are parasitic, feeding inside the ear canal of the host for a long period. Adult males and females are free-living and nonfeeding, and mating occurs off the host. Being inside the ear canal of the host allows the tick to be distributed over a vast geographic region through the distribution of the host animals. The presence of infectious agents Coxiella burnetii, the agent of Q fever, spotted fever rickettsia, Ehrlichia canis, Borrelia burgdorferi, and Babesia in O. megnini has been reported, but its role as a vector has not been confirmed. Human infestations are mostly associated with horse riding and farming through close contacts with companion animals. Control measures involve use of acaricides, repellants, and biological control methods. However, controlling the tick population and its spread is extremely difficult due to its life cycle pattern, seasonal dynamics, and resistance to certain acaricides

Analysis of polymorphisms in the merozoite surface protein-3α gene and two microsatellite loci in Sri Lankan Plasmodium vivax: evidence of population substructure in Sri Lanka.

The geographical distribution of genetic variation in Plasmodium vivax samples (N = 386) from nine districts across Sri Lanka is described using three markers; the P. vivax merozoite surface protein-3α (Pvmsp-3α) gene, and the two microsatellites m1501 and m3502. At Pvmsp-3α, 11 alleles were found with an expected heterozygosity (H(e)) of 0.81, whereas at m1501 and m3502, 24 alleles (H(e) = 0.85) and 8 alleles (H(e) = 0.74) were detected, respectively. Overall, 95 unique three locus genotypes were detected among the 279 samples positive at all three loci (H(e) = 0.95). Calculating the pairwise fixation index (F(ST)) revealed statistically significant population structure. The presence of identical 2-loci microsatellite genotypes in a significant proportion of samples revealed local clusters of closely related isolates contributing to strong linkage disequilibrium between marker alleles. The results show evidence of high genetic diversity and possible population substructure of P. vivax populations in Sri Lanka

Effects of Tectonics and Large Scale Climatic Changes On the Evolutionary History of \u3ci\u3eHyalomma\u3c/i\u3e ticks

Hyalomma Koch, 1844 are ixodid ticks that infest mammals, birds and reptiles, to which 27 recognized species occur across the Afrotropical, Palearctic and Oriental regions. Despite their medical and veterinary importance, the evolutionary history of the group is enigmatic. To investigate various taxonomic hypotheses based on morphology, and also some of the mechanisms involved in the diversification of the genus, we sequenced and analysed data derived from two mtDNA fragments, three nuclear DNA genes and 47 morphological characters. Bayesian and Parsimony analyses based on the combined data (2242 characters for 84 taxa) provided maximum resolution and strongly supported the monophyly of Hyalomma and the subgenus Euhyalomma Filippova, 1984 (including H. punt Hoogstraal, Kaiser and Pedersen, 1969). A predicted close evolutionary association was found between morphologically similar H. dromedarii Koch, 1844, H. somalicum Tonelli Rondelli, 1935, H. impeltatum Schulze and Schlottke, 1929 and H. punt, and together they form a sister lineage to H. asiaticum Schulze and Schlottke, 1929, H. schulzei Olenev, 1931 and H. scupense Schulze, 1919. Congruent with morphological suggestions, H. anatolicum Koch, 1844, H. excavatum Koch, 1844 and H. lusitanicum Koch, 1844 form a clade and so also H. glabrum Delpy, 1949, H. marginatum Koch, 1844, H. turanicum Pomerantzev, 1946 and H. rufipes Koch, 1844. Wide scale continental sampling revealed cryptic divergences within African H. truncatum Koch, 1844 and H. rufipes and suggested that the taxonomy of these lineages is in need of a revision. The most basal lineages in Hyalomma represent taxa currently confined to Eurasia and molecular clock estimates suggest that members of the genus started to diverge approximately 36.25 million years ago (Mya). The early diversification event coincides well with the collision of the Indian and Eurasian Plates, an event that was also characterized by large scale faunal turnover in the region. Using S-Diva, we also propose that the closure of the Tethyan seaway allowed for the genus to first enter Africa approximately 17.73 Mya. In concert, our data supports the notion that tectonic events and large scale global changes in the environment contributed significantly to produce the rich species diversity currently found in the genus Hyalomma

Pre-elimination stage of malaria in Sri Lanka: assessing the level of hidden parasites in the population

<p>Abstract</p> <p>Background</p> <p>With the dramatic drop in the transmission of malaria in Sri Lanka in recent years, the country entered the malaria pre-elimination stage in 2008. Assessing the community prevalence of hidden malaria parasites following several years of extremely low transmission is central to the process of complete elimination. The existence of a parasite reservoir in a population free from clinical manifestations, would influence the strategy for surveillance and control towards complete elimination.</p> <p>Methods</p> <p>The prevalence of hidden parasite reservoirs in two historically malaria endemic districts, Anuradhapura and Kurunegala, previously considered as high malaria transmission areas in Sri Lanka, where peaks of transmission follow the rainy seasons was assessed. Blood samples of non-febrile individuals aged five to 55 years were collected from randomly selected areas in the two districts at community level and a questionnaire was used to collect demographic information and movement of the participants. A simple, highly sensitive nested PCR was carried out to detect both <it>Plasmodium falciparum </it>and <it>Plasmodium vivax</it>, simultaneously.</p> <p>Results</p> <p>In total, 3,023 individuals from 101 villages participated from both districts comprising mostly adults between the ages 19-55 years. Out of these, only about 1.4% of them (n = 19) could recall having had malaria during the past five years. Analysis of a subset of samples (n = 1322) from the two districts using PCR showed that none of the participants had hidden parasites.</p> <p>Discussion</p> <p>A reservoir of hidden parasites is unlikely to be a major concern or a barrier to the ongoing malaria elimination efforts in Sri Lanka. However, as very low numbers of indigenous cases are still recorded, an island-wide assessment and in particular, continued alertness and follow up action are still needed. The findings of this study indicate that any future assessments should be based on an adaptive sampling approach, involving prompt sampling of all subjects within a specified radius, whenever a malaria case is identified in a given focus.</p

Chapter 23: Eco-epidemiology of Tick-Borne Pathogens: Role of Tick Vectors and Host Animal Community Composition in Their Circulation and Source of Infections

Tick-borne infections (TBI) are on the rise globally, causing severe illness and death in humans and domestic animals. Among the arthropod vectors of diseases, ticks are second only to mosquitoes in transmitting human pathogens, but overall, ticks carry the most diverse array of infectious agents when both humans and domestic animals are considered. Human TBIs are emerging infections because of increasing contact with wildlife, primarily caused by human environmental modifications and expanding encroachment into wildlife habitats. Ticks and tick-borne pathogens (TBP) have coevolved in various wild reservoirs and often exist in a state of equilibrium. However, when domestic animals encounter wild animals due to the overlap of their habitats, novel ticks and TBPs can be introduced to humans. The epidemiology of TBIs reflects the geographic distribution and seasonal activities of the tick vectors and vertebrate hosts involved in maintaining these vectors and pathogens and the human behaviors that place individuals at risk for tick exposure. In this review, we compare detailed knowledge about well-studied TBI in the United States with the less known TBIs which need further investigations in Sri Lanka. The role of specific tick vectors and host community composition are important factors in the circulation and maintenance of TBPs. The epidemiology of many TBIs is more complex and complicated than of TBIs whose vectors carry a single pathogen and cause a defined disease in specific hosts. In complex TBIs, the interplay of many factors is involved; these include a diversity of tick vectors, overlap and variability in their distribution, each life stage requiring a blood meal, transovarial and trans-stadial transmission of pathogens, a diversity of coinfections with different agents, a wide range of host and reservoir diversity including birds, reptiles, mammals, and even amphibian hosts. The impact of changing ecological factors on the emergence and transmission of TBPs has become more apparent. Over the past two decades, the One Health approach to managing some disease systems has become more important in tackling these big questions

Gastrointestinal parasites of domesticated and Feral Horses (Equus Caballus) in Sri Lanka

Horses are not native to Sri Lanka. They are imported from neighbouring countries to be used for police work, sporting or riding and esthetic purposes. An isolated population of about 500 feral horses lives in the Delft Island in northern Sri Lanka. These feral horses served hundred years for western conquests and when they left Sri Lanka, horses were left behind in the Delft Island. There are no records of gastrointestinal (GI) parasites of horses in Sri Lanka and the present study was carried out to determine the GI parasites in the domesticated (free grazing and stabled) and feral horses. Fresh faecal samples were collected from horses and analysed qualitatively and quantitatively to determine the types of GI parasites and their prevalence and intensity. Qualitative analyses using direct saline and iodine mounts, simple test tube flotation, Sheather’s modified sucrose flotation and sedimentation technique were carried out followed by McMaster counting technique for the positive samples. Identification of parasites involved morphological, morphometric and molecular methods. A total of 73 horses were sampled. All the feral horses (n=14) were infected. Among the domesticated horses, free grazers had a significantly higher prevalence of GI infections (46.7%) than the stabled ones (18.2%; Chi square test χ2 = 4.787, df = 1, p = 0.029). There was no significant difference between helminth and protozoan infections among the three groups of horses (Chi square test, χ2 = 1.453, df = 2, p = 0.484). Six species of parasites: Anoplocephala sp., Parascaris equorum, Strongylus sp. Isospora sp. Entamoeba sp. and Giardia sp. were recorded. Strongylus infections were recorded in all the feral horses with a high intensity but not in any of the domesticated animals. Strongylus is a highly pathogenic and the most damaging parasite of horses worldwide. It is important to investigate whether Strongylus infection is responsible for the high mortality recorded in the feral horses in the Delft Island especially because the Department of Wildlife Conservation is to declare Delft Island a National Park to conserve the feral horses

Data from: Infection sequence alters disease severity—Effects of the sequential exposure of two larval trematodes to Polypedates cruciger tadpoles

Multiple pathogens co-exist in nature and the sequence in which the host encounters the parasites influences interactions between parasites and host pathology. Here the effects of infection by two larval trematodes, pleurolophocercous cercariae of Acanthostomum burminis and a furcocercous cercariae, on common hourglass tree frog (Polypedates cruciger) was examined. Ten days post-hatch tadpoles (Gosner stage 27/28) were used for infection exposures. First, infection of individuals was carried out by introducing each cercariae type to the tadpoles separately. Second, co-infection of the two cercariae was carried out by alternating the sequences of exposure. For all the experiments, appropriate controls were instituted. Tadpoles exposed to parasites had lower survival compared to controls. The highest survival was observed in the co-infection when furcocercous was introduced first (82.5%). The lowest survival was observed in the co-infection when the A. burminis cercariae was introduced first (65.0%). In co-infections, when A. burminis was introduced prior to furcocercous, survival of the tadpoles was reduced by 17.0% compared to the exposures of furcocercous prior to A. burminis. Prior infection with A. burminis induced negative effect on the host with an increased infection severity while prior infection with furcocercous had reduced infection severity than lone exposures. These results suggest that furcocercous infections can be beneficial for hosts challenged with A. burminis provided that A. burminis exposure occurs second. None of the treatments had an effect on the growth of the tadpoles but lengthening of developmental period was observed in some exposures. All exposed tadpoles developed malformations which were exclusively axial – kyphosis and scoliosis. However, there was no difference in the number of malformed individuals in the single infection (19.0-25.0%) compared to co-infection (20.0-22.5%) or between coinfections. The results suggest that the sequence of parasite exposure affects host parasite interactions and hence the disease outcomes

New records of small mammal hosts for five ectoparasite species from Sri Lanka

Ticks and fleas act as vectors for a number of zoonotic diseases, hence are medically important. Handful of studies carried out in Sri Lanka to date have reported 6 tick species and 11 flea species from murine rodents and shrews. Here, we report ticks and fleas infesting murine rodents and shrews collected from 18 selected sites in two districts in Sri Lanka, Kurunegala and Kandy. Two species of ticks (Rhipicephalus haemaphysaloides and Haemaphysalis spinigera), an unidentified Haemaphysalis larva and a flea Xenopsylla cheopis were found from Kurunegala. From Kandy, four species of ticks (R. haemaphysaloides, H. spinigera, Ixodis ceylonensis and Dermacentor auratus) and three species of fleas (X. cheopis, Stivalius phoberus and Stivalius aporus) were collected. Rhipicephalus haemaphysaloides was recorded from Rattus rattus, Bandicota indica, Mus fernandoni, Golunda ellioti and Suncus murinus; H. spinigera from R. rattus, B. indica and S. murinus; I. ceylonensis from M. cervicolor and R. rattus; D. auratus from R. rattus; both X. cheopis and S. phoberus were collected only from R. rattus; S. aporus from R. rattus and M. fernandoni. Though, all species of parasites reported here have been previously recorded from Sri Lanka, D. auratus and H. spinigera are reported for the first time from murine rodents and shrews. We also report here several new host records for the country: R. haemaphysaloides from B. indica, G. ellioti and S. murinus; H. spinigera from B. indica and S. murinus; D. auratus and S. aporus from R. rattus; larvae of I. ceylonensis from M. cervicolor

Coprological survey of gastrointestinal parasites of mammals in Dehiwala National Zoological Gardens, Sri Lanka

A cross sectional, coprological survey on gastrointestinal (GI) parasites of captive mammals in the Dehiwala National Zoological Gardens was carried out in 2014. Fresh faecal samples from all the mammal species belonging to nine orders: Primates, Carnivora, Perissodactyla, Artiodactyla, Proboscidea, Erinaceomorpha, Lagomorpha, Rodentia and Diprotodontia were analyzed. Intensity of parasite infections was determined using the McMaster technique. Of the 70 samples, 44 (62.9%) were positive for one or more GI parasites. A total of 13 types of GI parasite eggs, cysts and/or oocysts of Trichuris sp., Strongyloides sp., Toxocara sp., Spirometra sp., Moniezia sp., Nematodirus sp., Giardia sp., Blastocystis sp., Balantidium sp., Entamoeba spp., strongyle type eggs, hookworm, and coccidian oocyts were observed. The most common stage was strongyle type egg (17.1%) followed by cysts of Entamoeba spp. (14.3%). Of the infected individuals, 25% had mixed infections. A higher prevalence of helminths (81.8%) compared to protozoans (47.7%) was observed but this difference was not statistically significant (Chi square test; p&gt;0.05). There was no significant difference in the prevalence of infection among the captive bred, imported or wild caught individuals (Chi square test; p&gt;0.05). Mammals of seven orders were infected with GI parasites but lagomorphs and diprotodonts did not have any parasites. Among the herbivores, strongyle type, Moneizia, Entamoeba and coccidian infections were common while Nematodirus sp. in a porcupine and Spirometra sp. in a flying squirrel were rare. Common parasites of carnivores were, Toxocara and Entamoeba but Blastocystis sp. in coati was a rare infection. Trichuris and Giardia infections were common in Primates. High worm burden was evidenced in silver leaf monkey, Hamadryas baboon, African lion, black rhino, pony, porcupine and flying squirrel. Although regular deworming is carried out, results of this survey highlight the importance of faecal analysis before administering deworming and applying a more targeted approach to manage the pathogenic species. This study provides baseline data on the GI parasites of all the mammal orders at Dehiwala Zoological Gardens.</p