Epidemiology Of Parasitic Diseases Research Articles

Potential of cell-free DNA as a screening marker for parasite infections in dog

Parasitic infections are common in stray dogs and accurate knowledge of parasite communities in dogs would provide insight into the epidemiology of parasitic diseases. In this study, we used Illumina sequencing technology to evaluate cell-free DNA (cfDNA) as a marker for screening of parasitic infections in dogs. Plasma samples from 14 stray dogs captured in Bangladesh were used in the experiments. An average of 2.3 million reads was obtained for each sample. BLASTn analysis identified 150 reads with high similarity with parasites from 19 different genera. In particular, we detected sequences of Babesia spp. in five dogs; consistent with this, a previous study using conventional PCR showed that four of these dogs were positive for B. gibsoni. Several reads with similarity to Leishmania and filarial nematodes were also identified. These findings indicate that cfDNA in blood can be a potential screening marker for identifying parasite diversity in dogs.

A Cross-Sectional Study of Intestinal Parasitic Infections in Children in Ghettoed, Diverse and Affluent Communities in Dschang, West Region, Cameroon

Background: There is a paucity of knowledge on the epidemiology of parasitic diseases which remain rampant in the Dschang municipality. Three communities around Dschang town—Ngui (slummy), Paidground (heterogeneous) and the Administrative Quarter-AQ (wealthy) were investigated to highlight the aetiology of intestinal parasitic infections (IPIs) in children in order to enhance health policy intervention priorities. Methods: Between July and November 2009, 31 stools amples were collected from children aged six months to 18 years (mean 9 years) in 295 house-holds across the three communities. A structured questionnaire was used to obtain information on socio-demographic characteristics, source of water supply, de-worming practice and treatment history. Stool samples were screened for ova/larvae of intestinal parasites using direct wet mount, brine floatation and formol-ether sedimentation methods. Results from stool tests and information obtained from questionnaires were analyzed using SPSS. Results: In total, 223 (26.8%) children had single (19.9%) and multiple (7%) infections from seven parasites: the overall prevalence was 34.7%; helminthes 19.3% and protozoa 15.4% (χ2 = 4.3, P Entamoeba histolytica 8.8%, Ascaris lumbricoides 7.5%, Trichuris trichiura 6.8%, Entamoeba coli (5.8%), hookworm 4.6%, Giardia lamblia 0.8% and Vampirolepis (Syn: Hymenolepis) nana 0.4%. Infections were more severe and rates significantly higher in Ngui (45.9%, χ2 = 86.83, P 2 = 111.97, P < 0.0001). Conclusion: Regular sustained synchronized deworming alongside antiprotozoaics, periodic diSagnostics for all children and slummed residents which lend to intestinal protozoa; sanitary inspection of homes and water supplies; adequate drainage and community wastes disposal; and prevention education on hygiene, sanitation, safe water and health were desirable.

Detection of parasites and parasitic infections of free-ranging wildlife on a game ranch in zambia: a challenge for disease control.

Ex-situ conservancies are expanding alternatives to livestock production in Zambia albeit the lack of information on circulating infectious parasites from wildlife. Therefore, 12 wildlife species were examined on a game ranch were all species were found to be infected by Rhipecephalus spp. Haemoparasite infections were estimated at 7.37% (n = 95) with Babesia spp. detected in bushbuck (Tragelaphus scriptus); Anaplasma marginale in impala (Aepyceros melampus) and puku (Kobus vardonii) for the first time in Zambia. The majority of worm species isolated from bovids were not detected in equids and, vice versa. Our findings intimate ecological and behavioural patterns of some animals as deterministic to exposure. Kafue lechwe (Kobus leche kafuensis) had the widest range of worm species with more infected organs than other animals suggesting their semi aquatic nature contributory to prolonged worm exposure compared to other animals. On the other hand, Kafue lechwe had the least tick infections attributable more to shorter attachment periods as they spend prolonged periods submerged in water. Our findings indicate the vital role that wildlife plays in the epidemiology of parasitic diseases. To reduce the infection burden, control measures should be focused on reducing transmission to highly susceptible animal species as described herein.

Tapping Indigenous Knowledge to Time Strategic De-worming Treatment of Livestock on Communal Grazing Lands in the East of Namibia

Strategic de-worming is a cost-effective management intervention to which farm animals are subjected at specific times in the year to prevent pasture contamination, reduce infestation rates and eliminate the negative effects of parasitosis to maximize production and economic gain. No studies, on which strategic de-worming interventions could be based, have been undertaken to establish the epidemiology of parasitic diseases on communal livestock farms in Namibia. In this study, the participatory workshop approach (PWA), whereby communal farmers were involved in generating epidemiological information based on local experiences, was used. The PWA was found to be a useful tool in shedding light on the evolution of annual events related to local environment, farm management, and the health conditions of animals, which determine infestation rates and the onset of manifestations caused by parasites in farm animals. It was found that there exist seasonal variations in local environmental conditions, some of which are favourable others unfavourable for free-living forms of parasites. It was also found that the negative effect of parasites on livestock was most severe during the hot-dry season (September – December), a season when available livestock feed is generally scarce. Based on the findings, the first halt of winter was suggested as an optimum time for the strategic de-worming of farm animals in the eastern communal area of Namibia.

Modelling parasite density in ruminants

Models of parasite density in ruminants usually involve three nonlinear, coupled, ordinary differential equations for larval density, adult parasite density and host resistance. We deal with the inverse problem of objectively determining the nonlinear coefficients within the equations using available data. Experiments are suggested to allow efficient calculation of these coefficients. An alternative model is also proposed which reproduces key features of experimental results and shows the importance of including time delay equations in parasite modelling. References Anderson, R. M. and May, R. M. Herd immunity to helminth infection and implications for parasite control. Nature 315, 493--496, 1985. doi:10.1038/315493a0 Gordon, H. M. The epidemiology of parasitic diseases, with special reference to studies with nematode parasites of sheep. Australian Veterinary Journal 24, 17--45, 1948. doi:10.1111/j.1751-0813.1948.tb01569.x Hansen, J. and Perry, B. The epidemiology, diagnosis and control of helminth parasites of ruminants. International Laboratory for Research on Animal Diseases, 1994. Kao, R. R., Leathwick, D. M., Roberts, M. G. and Sutherland, I. A. Nematode parasites of sheep: a survey of epidemiological parameters and their application in a simple model. Parasitology 121, 85--103, 2000. http://journals.cambridge.org/action/displayIssue?jid=PAR&volumeId=121&issueId=01&iid=53786 Louie, K., Vlassoff, A. and Mackay, A. Nematode parasites of sheep: extension of a simple model to include host variability. Parasitology 130, 437--446, 2005. doi:10.1017/S003118200400678X Roberts, M. G. and Grenfell, B. T. The population dynamics of nematode infections of ruminants: periodic perturbations as a model for management. IMA Journal of Mathematics Applied in Medicine and Biology 8, 83--93, 1991. doi:10.1093/imammb/8.2.83 Roberts. M. G. and Heesterbeek, J. A. P. A simple parasite model with complicated dynamics. J. Math. Biol., 37: 272--290, 1998. doi:10.1007/s002850050129 Sargison, N. D, Wilson, D. J, Bartley, D. J, Penny, C. D and Jackson, F. Haemonchosis and teladosagiosis in a Scottish sheep flock putatively associated with the overwintering of hypobiotic fourth stage larvae, Veterinary Parasitology 147, 326--331, 2007. doi:10.1016/j.vetpar.2007.04.011 Vlassoff, A., Leathwick, D. M. and Heath, A. C. G. The epidemiology of nematode infections of sheep. New Zealand Veterinary Journal 49, 213--221, 2001. http://www.sciquest.org.nz/default.asp?pageid=69&pub=2&vol=49&iss=6 Waller, P. J., Dobson, R. J., Donald, A. D. and Thomas, R. J. Populations of strongylid nematode infective stages in sheep pastures: comparison between direct pasture sampling and tracer lambs as estimators of larval abundance. International Journal of Parasitology 11, 359--367, 1981. doi:10.1016/0020-7519(81)90006-0

New paleoparasitological techniques

Ruffer was the first researcher to show, using hydration of samples and histological techniques, the presence of Schistosoma haematobium eggs in the kidneys of Egyptian mummies dating between 1250 BC and 1000 BC. Since then, with the collaboration of archaeologists, palynologists, parasitologists, biologists, entomologists, ecologists, malacologists…new ideas have arisen and different techniques have been adapted for the study of parasites in an archaeological context. Research into the hydration of samples has been carried out, and flotation and sedimentation techniques started to be used, testing different solutions. Eggs, larvae and adults of both ecto- and endoparasites, as well as non-parasitic arthropods have been found, but none of the methods used have enabled to quantify the parasitic forms found, which is important to know the epidemiology of parasitic diseases and to carry out comparative studies. At present, the development of molecular biology techniques applied to palaeoparasitology is permitting the detection of traces of parasites in the past. Different samples taken from the 13 tombs existing in the royal burial chamber at St Isidoro's Collegiate-Basilica in León, Spain were sent to our laboratory. But the main object of this study is to contribute to the application of other methods used successfully in the field of palaeoparasitology: the hydration, the McMaster method, the use of the compressorium and triquineloscope, as well as the different methods used to analyse hair samples.

Tick-borne parasitic diseases in cattle: current knowledge and prospective risk analysis related to the ongoing evolution in French cattle farming systems.

Parasitic diseases, like babesiosis and theileriosis are transmitted by ticks: their occurrence is therefore linked to the size of the tick stock and the seasonality of the vectors. Babesia divergens bovine babesiosis transmitted by Ixodes ricinus is widespread and often reported in France. Serological prevalence is high, ranging from 20 to 80% according to the farms. Clinical incidence is low: around 0.4% for the whole cattle population. The endemic situation is unstable and clinical cases occur more frequently with farming system modifications. L. ricinus is a tick essentially found in woodlands and so, for the most part, is found in closed rural areas. The situation of the other bovine babesiosis (Babesia major) and theileriosis (Theileria orientalis) is not well documented in France. However, the epidemiology of parasitic diseases is changing, especially because of changes in the environmental characteristics, i.e. both farm and herd management conditions and also climatic conditions. These modifications can provoke an increase in the tick stocks, an increase in the contact rate between cattle and ticks, and an increase in the contact rate between cattle and the wild fauna, especially deer. This results in likely modifications of the endemic situation, with a higher risk of clinical babesiosis in the medium term.

Movimentos migratórios e sua importância na epidemiologia de doenças parasitárias no Brasil

Depois de analisar, de um modo geral, o problema da grande mobilidade do homem brasileiro, ilustrando com alguns dados o vulto das principais correntes migratórias internas que se verificam em nosso País, o autor discute a influência que êstes deslocamentos humanos têm na epidemiologia de nossas endemias parasitárias. Para isto considera os movimentos migratórios ligados aos seguintes tipos de atividades humanas: 1) deslocamento da fronteira agrícola, quer por expansão de áreas já colonizadas, quer pela instalação de núcleos coloniais com pontos remotos da zona pioneira, criando novas ilhas demográficas nos grandes espaços vazios da população brasileira; 2) cultura itinerante caracterizada pela constante procura de áreas virgens para o plantio, com abandono das áreas velhas já esgotadas; 3) indústria extrativa vegetal e mineral; 4) construção de ferrovias e rodovias de penetração, com estabelecimento e desenvolvimento de núcleos populacionais ao longo delas; 5) construção de Brasília e desenvolvimento do Brasil Centro-Ocidental; 6) mecanização da agricultura e industrialização dos centros urbanos condicionando o êxodo rural.