Epidemiology Of Parasitic Infections Research Articles

A Comparison in Terms of Prevalence, Morphological and Histopathological Changes between Eimeria spp. that Infect Local Rabbits (Oryctolagus cuniculus) in Some Regions of Saudi Arabia

Background: The epidemiology of parasitic infections is common in rabbit flocks and poses a significant threat to public health. And the most famous and influential of these causes are coccidia parasites, Coccidiosis in rabbits is an infection caused by intracellular protozoan parasites belonging to Eimeria, which is considered a major cause of significant morbidity and mortality. Methods: A total of 210 fresh feces samples of adult domestic rabbits (Oryctolagus cuniculus) were collected from Riyadh City, Al Kharj and ADilam in Saudi Arabia to examine the incidence of the Eimeria infection of microscopically. Feces concentrated by the floatation technique. After that, freshly collected non-sporulated oocysts were suspended in 2.5% (W/V) potassium dichromate, placed in Petri dishes in the air, and allowed to sporulate at room temperature (25±3oC). The morphometric and specific characteristics of sporulated oocysts were studied by an Olympus microscope (BX51ggTF, OLYMPUS, Tokyo, Japan) using the oil immersion lens. Specimens were taken from all parts intestine and liver, and the tissues were kept in 10% formalin immediately and make tissue sections and that to study the histopathological change under light microscopic. Result: An investigation was conducted in three cities in the Riyadh area (Riyadh, Al Kharj and Adilam) to determine the incidence of Eimeria species that parasitize local rabbits (Oryctolagus cuniculus). The overall frequency of these coccidial illnesses in rabbits in Riyadh City was 45.7%, in Adilam City it was 44.2% and in Al Kharj City it was 37.1%, respectively. There were five different species of Eimeria: E. magna, E. flavescens, E. exigua, E. striedae and E. coecicola, respectively. More than one species of Eimeria oocyst was obtained in the same examined sample. single-infection 13/90 (14.4%), dual-infection 39/90 (43.3%) and triple-infection 38/90 (42.2%). E. magna; E. flavescens; E. exigua; E. stiedae and E. coecicola, respectively. Significant differences (p less than 0.05) in prevalence were observed between the rabbits. Eimeria infection that affects the liver was confirmed by histopathological changes that were noted through the development of parasitic stages in the jejunum, ileum, cecum, end cecum and liver. It is possible to conclude that the current research offers pertinent information that aids in determining potential infection and future preventative measures against rabbit coccidiosis to lessen financial losses in the rabbit industry.

An Example of the Importance of Electronic Health Records from Mogadishu, Somalia: Hepatitis B Prevalence and Co-infections with Hepatitis C

The epidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV) has been discussed in detail from different aspects around the world. Current epidemiological data has critical importance in the planning and carrying out of public health policies for the prevention of transmission and spread of these infections, and the treatment of chronic infections, and to reduce the burden and mortality associated with complications such as cirrhosis and liver cancer by national health authorities and international health institutions, especially the World Health Organization. Elimination of a social health problem is possible by first raising awareness, then determining the dimensions of the problem, and planning and implementing interventions for a solution. Somalia was in the position of a region where access to diagnosis and treatment for many life-threatening diseases was difficult, aside from the monitoring of public health criteria due to the unstable situations that has continued for more than 40 years. Until recently, basic health parameters and epidemiological predictions in Somalia were monitored through estimates based on data from neighboring countries or on data obtained from small groups from Somalia immigrants settled different parts of the world. However, this situation is changing rapidly. A tertiary education and research hospital established in the capital, Mogadishu, with the coordination of the Türkiye and Somalia governments, and which has become the largest health center in the country today; contributes to understanding the extent of the serious health problems faced by the country by pioneering specialized training and scientific studies, in addition to providing health care. Electronic health records have been kept regularly since 2015 in this hospital, where hundreds of thousands of patients receive treatment or undergo health checks every year and it has been the source of numerous retrospective epidemiological studies some of which have exceeded 100 thousand cases, in different age groups and sub-populations. These studies include human immunodeficiency virus (HIV) prevalence and complications, HCV prevalence and genotype distribution, prevalence and epidemiology of parasitic infections, incidence of tuberculosis and related complications, cancer incidence and distribution, causes of blindness, thyroid diseases, antibiotic resistance profiles, and the epidemiology of various organ-specific diseases. Dozens of studies using the hospital records were included in the scientific literature between 2020 and 2023. In this study, a four-year period between November 2015 and November 2019, HBV serological test results of more than 100,000 different patients are presented. HBsAg and anti-HBs seropositivity for all age groups was found to be 8.1% (9,405/115,946) and 32.7% (25,988/79,410), respectively. When the anti-HCV test results of HBsAg positive patients were examined, the rate of HCV co-infections was found to be 0.9% (82/9,405). HBsAg and anti-HBs seropositivity were significantly higher in males than females (p<0.001). HBV, HCV, and co-infection incidence tended to decrease. Conversely, vaccination rates (especially in children under one year of age) tended to increase. While the comprehensive data presented in this study provide us with important and new information about the prevalence and co-infection rates of viral hepatitis in the country, many topics including HBV genotypes, hepatitis D frequency, access to treatment rates, complication rates, and HBV vaccination rates are still waiting to be researched in Somalia. In the region where it is not possible to carry out field studies, epidemiological data provided by electronic health records have become a country's window to the world.

Cold water reduces the severity of parasite-inflicted damage: support for wintertime recuperation in aquatic hosts.

The reduction in host fitness caused by parasite infections (virulence) depends on infection intensity and the degree of damage caused per parasite. Environmental conditions can shape both virulence components, but in contrast to infection intensity, environmental impacts on per-parasite damage are poorly understood. Here, we studied the effect of ambient temperature on per-parasite damage, which is jointly determined by the ability of parasites to induce harm (per-parasite pathogenicity) and the ability of hosts to limit damage (tolerance). We experimentally exposed two salmonid species, Atlantic salmon (Salmo salar) and sea trout (Salmo trutta), to replicated genotypes of the eye fluke Diplostomum pseudospathaceum. After development of health damage (eye cataracts) in warm water (16°C) during the first 12weeks post exposure, we maintained the fish at either 5°C (cold water) or 16°C for another 8weeks and quantified changes in cataracts as a function of parasite load. We found that per-parasite damage was reduced in cold compared to warm water, suggesting that cold temperatures improved host health. Per-parasite damage was also affected by parasite genotype and host species, but these effects did not change with temperature. Our findings suggest that cold-water seasons, which are often neglected in host-parasite studies due to low infection risk, could allow hosts to recuperate and thus, may have important implications for the ecology and epidemiology of parasite infections.

Gene duplications, divergence and recombination shape adaptive evolution of the fish ectoparasite Gyrodactylus bullatarudis.

Determining the molecular basis of parasite adaptation to its host is an important component in understanding host-parasite coevolution and the epidemiology of parasitic infections. Here, we investigate short- and long-term adaptive evolution in the eukaryotic parasite Gyrodactylus bullatarudis infecting Caribbean guppies (Poecilia reticulata), by comparing the reference genome of Tobagonian G.bullatarudis with other Platyhelminthes, and by analysing resequenced samples from local Trinidadian populations. At the macroevolutionary timescale, we observed duplication of G-protein and serine proteases genes, which are probably important in host-parasite arms races. Serine protease also showed strong evidence of ongoing, diversifying selection at the microevolutionary timescale. Furthermore, our analyses revealed that a hybridization event, involving two divergent genomes, followed by recombination has dramatically affected the genetic composition of Trinidadian populations. The recombinant genotypes invaded Trinidad and replaced local parasites in all populations. We localized more than 300 genes in regions fixed in local populations for variants of different origin, possibly due to diversifying selection pressure from local host populations. In addition, around 70 genes were localized in regions identified as heterozygous in some, but not all, individuals. This pattern is consistent with a very recent spread of recombinant parasites. Overall, our results are consistent with the idea that recombination between divergent genomes can result in particularly successful parasites.

A survey of Dictyocaulus arnfieldi (Nematoda) infections in equids in Urmia region, Iran

Dictyocaulus arnfieldi is a lungworm commonly found in equids; however, relatively little is known about it. The aim of the present study was to establish the prevalence of equine lungworms in naturally-infected working and sporting horses, donkeys and mules in rural areas of Urmia, northwest Iran. The fecal samples were collected from 299 working horses, 57 sporting horses, 66 donkeys and 37 mules during the period March 2014 to June 2016. The collected fecal samples were processed within 48 hours following rectal sampling. The larval count/g (LPG) of feces was determined using the Baermann technique. The larvae were identified morphologically, and the arithmetic mean of the LPG was calculated at each sampling point. The overall prevalence of lungworm in all equine species was found to be 19.20%., with specific values of 15.71%, 0%, 31.81% and 24.32% being found in working horses, sporting horses, donkeys and mules, respectively. The working horses, donkeys and mules were also found to be heavily infected with Dictyocaulus arnfieldi and in addition to donkeys and mules, working horses are considered natural hosts for lungworm, and this has effects on both the epidemiology of parasitic infections and performance of the equids.

Prevalence of <i>Giardia duodenalis</i> among dogs seized by the Center for Control of Zoonoses (CCZ) of the city of Lages, Santa Catarina, Brazil

The knowledge of the epidemiology of parasitic infections in stray and domestic animals, especially of its incidence and prevalence, is fundamental to adopting effective prophylactic measures. Stray dogs play an important role in environmental contamination favoring the transmission cycle of zoonotic agents. Among the parasitic infections that affect humans, Giardia duodenalis is the most common intestinal protozoa and was designated as a re-emerging infectious disease. This study aimed to determine the prevalence of G. duodenalis in dogs siezed by the Center for Control of Zoonoses (CCZ) of the city of Lages, Santa Catarina, Brazil using two diagnostic techniques. In 357 stool samples analysed, the prevalence of G. duodenalis cysts was 5.3% (19/357) and 4.8% (17/357) detected by floatation and sedimentation techniques, respecttively. No correspondence between gender and age was found among the methods used for analyzing the infected dogs in this study. Our data suggested that two diagnostic techniques should be used in a complementary way to ensure that false negatives are not neglected.

Parasitic infections of domestic cats, Felis catus, in western Hungary

During 2011, faeces from 235 owned domestic cats from a rural area in western Hungary were examined using standard coproscopical techniques. The overall prevalence of cats with endoparasites was 39.6% (95% CI 33.3–46.1). The most frequently identified faecal forms were those of ascarids (Toxocara, 17.4%; Toxascaris 7.2%), followed by those of Aelurostrongylus lungworms (14.5%), hookworms (11.1%), taeniid cestodes (4.7%), Cystoisospora coccidians (4.3%), and capillarids (3.8%). Single and multiple infections with up to five parasites concurrently were founded in 24.7% and 14.9% of the cats, respectively. Mixed endoparasite infections were recorded more frequently (p=0.0245) in cats greater than one year old compared to younger cats. Young cats (≤1 year) were parasitized more frequently (p<0.05) with ascarids and Cystoisospora spp. but demonstrated infections of hookworms, lungworms and taeniid cestodes less often than the older cats. Cats with taeniid infection were more likely (p<0.05) to harbour Toxocara, hookworm, Aelurostrongylus, and capillarid infections than cats without taeniid cestodes. Cats of owners who claimed the use of wormers were less frequently helminth-positive compared to cats whose owners did not use anthelmintics (21.2% vs. 44.4%; p=0.001).A subset of 115 faecal samples screened by a coproantigen ELISA revealed Giardia-specific antigen in 37.4% samples. Giardia cysts were found by immunofluorescent staining in 30 of the 43 samples tested positive for Giardia by ELISA.In addition, ectoparasites collected from 82 cats by body search and combing were identified. Fleas (1–30 per cat), biting lice (Felicola subrostratus), and ticks (1–5 per cat) were isolated from 58, 1 and 43 cats, respectively. Ctenocephalides felis was identified on all flea infested cats while single specimens of C. canis and Pulex irritans were recovered from three and two cats, respectively. All but one tick collected were adult Ixodes ricinus; the single other tick was a nymph of I. canisuga.By providing basic data on the epidemiology of parasitic infections, the results of this survey should emphasize the need of attending to parasites of cats from the veterinary point of view with respect to both appropriate diagnostics and control.

Preliminary testing of a rapid coupled methodology for quantitation/viability determination of helminth eggs in raw and treated wastewater

The use of raw and treated wastewater for irrigation of crops is a common practice in Mexico. In force since January 1997, the Water Quality Norms for helminth ova refer only to the number of eggs that can be present in the irrigation water, and ignore the assessment of viability because the conventional techniques are not suitable for routine application. However, since viability is of prime importance in the epidemiology of parasitic infections, work was done for the development of a rapid and reliable method to detect a metabolic activity or a physiological characteristic related to viability. As a result, a vital staining procedure was developed and validated, and it was coupled with two rapid quantitative procedures previously assessed, therefore, permitting the determination of the total number of helminth eggs and, simultaneously, the viable and non-viable fraction. The average recovering efficiency of the rapid quantitative methods is 54% for raw wastewater and 77% for treated wastewater; the staining technique for viability is equally reliable (within the 95% confidence limits) as the conventional in vitro procedure; the overall test takes from 4 to6 h to be completed when processing up to four samples at the same time, and the cost per sample (for unrecoverable materials) ranges from US$2.50 to $4.00.

Effects of metabolizable protein on performance and faecal egg count of the parasitized ewe

The periparturient relaxation (PPR) in acquired immunity in ewes has been ascribed to various factors, including poor nutrition (Barger, 1993). Clinically, the faecal egg count (FEC) may increase during PPR when the ewe is continuously infected with gastrointestinal parasites. As such, the periparturient ewe plays an important role in the epidemiology of parasitic infections. The nutritional basis of PPR probably includes metabolizable protein (MP), since host's responses, in terms of immunity and resilience, are highly proteinaceous by nature. We propose that the PPR directly results from less MP being available to maintain acquired immunity and resilience, since an increasing amount of MP is directed to bodily functions with higher priority (reproduction). It is hypothesized that the increased FEC in the parasitized periparturient ewe reduces if her MP-intake exceeds her assumed MP-requirement (AFRC, 1993).

The epidemiology of parasitic infections in horses in Japan

The epidemiology of parasitic infections in horses in Japan

Heterogeneities in transmission rates and the epidemiology of schistosome infection

Previous theoretical studies have suggested that heterogeneities in transmission rates can have significant effects on the epidemiology of parasite infections. However, the magnitude of these effects in practice remains uncertain because of the difficulty of quantifying such heterogeneities under natural conditions. In this paper we consider the effects of heterogeneous rates of contact with infective water bodies on the basic reproductive rate, R0, of human schistosomes. In particular, we examine the theoretical effects of differences in the distribution of contacts among individuals and among sites. We find that an individual's contribution to R0 depends not only on the net contact rate but also on how these contacts are distributed among sites--the contact pattern. Our analysis of field data suggests a substantial impact of heterogeneous contact rates on R0 in practice. Significant reductions in R0 may be possible if schistosomiasis control efforts are targeted at certain sites and, especially, certain individuals.

The pattern of infection with gastro-intestinal nematodes in young fattening lambs at pasture

The pattern of infection with gastrointestinal nematodes in young fattening lambs was determined during the period 1965-69 in 10 counties of the UK. On 25 farms with a history Nematodirus disease, 193 lambs were killed, mostly in pairs, at intervals of three weeks from the end of April to mid-July. In three of the seasons similar studies were extended to mid-September on 33 farms which had a history of parasitic gastroenteritis. Worms were counted 361 parasitic gastroenteritis. Worms were counted in 361 lambs killed at intervals of four weeks. The degree of infection and incidence of different genera covering the same period were identical in both series. The division into Nematodirus and parasitic gastroenteritis farms proved artificial and the results were combined to obtain an overall picture based on average worm burdens during weekly periods from the last week in April to the second week in September. An average total of 2500 worms was present in four-week-old lambs at the end of April and this rose steadily to a peak of 10, 000 during the first week in June. A gradual fall to 5500 in mid-July was followed by a rapid rise which had reached 22, 000 at the end of observations in mid-September. The first wave of infection up to mid-July consisted almost entirely of Nematodirus and Ostertagia in the approximate proportions 3;1, 2:1 and 1-5:1 midway through the months of May, June and July respectively. The second rise from mid-July onwards consisted principally of Ostertagia and Trichostrongylus. Nematodirus worm numbers remained at a lower level while a few Cooperia and Haemonchus had appeared. Unidentified third and fourth stage larvae in the abomasum and small intestine reflected the prevalence of Ostertagia and Nematodirus respectively. The significance of this infection pattern, which was common to all geopgraphical areas, in relation to the epidemiology of parasitic infections in lambs is discussed.

The significance of infra-specific variations of hosts and parasites in the epidemiology of helminths of medical importance.

The epidemiology of parasitic infections may be profoundly influenced by infra-specific variations in infectivity for either intermediate or definitive hosts. Such variations will decide the basic ecology of the host-parasite relationship, and variations in virulence and pathogenicity therefore determine different patterns of disease. While some of the evidence of infra-specific variations has been derived from experimental studies, much of it has been recorded by those concerned with investigations of the epidemiology and transmission of parasitic infections and the practical aspects of their control. The unequivocal demonstration of genetic heterogeneity of certain parasites of medical importance has therefore resulted in a better understanding of their epidemiology and, in some cases, is leading to greater precision in attempts to control them.

Craig and Faust's Clinical Parasitology

How does one write a review of a thousand-page textbook-reference book now in its 7th edition with a total of 17 reprintings written by two of the world's ablest parasitologists? This new edition has been brought up to date and additional illustrations have been added. One of its valuable contributions is the rather comprehensive bibliography at the end of each chapter. Although this volume is entitled “Clinical Parasitology,” in addition to covering the diagnosis, treatment and epidemiology of parasitic infections, it includes the essential details of morphology and taxonomy of parasites. All of us who work in the parasitic disease field will continue to lean heavily on this volume and it should be available for reference for public health students, medical students, and the house staff of our hospitals.