Neospora caninum | |
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Neospora caninum | |
Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Alveolata |
Phylum: | Apicomplexa |
Class: | Conoidasida |
Order: | Eucoccidiorida |
Family: | Sarcocystidae |
Genus: | Neospora |
Species: | N. caninum |
Binomial name | |
Neospora caninum Dubey, Carpenter, speer, Topper & Uggla, 1988 | |
Neospora caninum is a coccidian parasite that was identified as a species in 1988. Prior to this, it was misclassified as Toxoplasma gondii due to structural similarities. [1] The genome sequence of Neospora caninum has been determined by the Wellcome Trust Sanger Institute and the University of Liverpool. [2] Neospora caninum is an important cause of spontaneous abortion in infected livestock.
Neospora caninum has a heteroxenous life cycle, with the sexually reproductive stage occurring in the intestine of a definitive host. Until recently, the only known definitive host was the domestic dog. [3] New research has determined that other canids such as coyotes (Canis latrans), gray wolves (Canis lupus), and Australian dingos (Canis lupus dingo) are also definitive hosts. [4] [5] [6]
Oocysts passed in the feces of the definitive host, such as canines or canids, are ingested by an intermediate host, such as cattle. After ingestion of an oocyst, motile and rapidly dividing tachyzoites are released. These tachyzoites disseminate throughout the host, and in response to the host immune response, differentiate into bradyzoites, which form cysts in muscle and tissue. Formation of these cysts results in chronic infection of the intermediate host. Ingestion of infected intermediate host tissue by the definitive host completes the life cycle. A second route of transmission is the congenital transmission from mother to offspring. [7] Transplacental transmission (passage from mother to offspring during pregnancy) has also been shown to occur in dogs, cats, sheep and cattle. If the intermediate host acquires the disease during pregnancy, it activates these cysts, and active infection often causes spontaneous abortion. [7] In addition, if the aborted fetus and membranes are then eaten by the definitive host, they cause further infection and the cycle is complete. Other carnivores, for example the red fox (Vulpes vulpes), may also be intermediate hosts, but they are not known to be definitive hosts. [8] Neospora caninum does not appear to be infectious to humans. In dogs, Neospora caninum can cause neurological signs, especially in congenitally infected puppies, where it can form cysts in the central nervous system. [9]
The discovery that coyotes are definitive hosts may increase the risk of transmission of N. caninum to domestic livestock as well as to wild ruminants such as white-tailed deer (Odocoileus virginianus). [10] Coyote range now includes most of North and Central America. [5] Studies suggest that the parasite may be widespread among wildlife and that infection cycles cross over between wild and domestic animals. [10]
Recent studies have broadened the list of known intermediate hosts to include birds. [11] N. caninum has recently been found to infect domestic chickens and house sparrows (Passer domesticus) which may become infected after ingesting parasite oocysts from the soil. [11] [12] Sparrows, which are common in urban and rural areas, may serve as a food source for wild and domestic carnivores. [12] N. caninum has also been detected in common buzzards (Buteo buteo) and magpies. [11] The presence of birds in cattle pastures has been correlated to higher infection rates in cattle. [13] Birds may be an important link in the transmission of N. caninum to other animals. [11]
Neosporosis is an infectious disease for many different canids and cattle. [7] Neuromuscular degeneration was first observed in canines in Norway, which led to hind limb paralysis. [7] Abortion in dairy cattle was also observed as a major cause of disease by neosporosis. [7] Although this disease is worldwide, it is of major concern in the United States, Netherlands, and New Zealand. [7]
N. caninum infections have been reported from most parts of the world with studies in the United States, New Zealand, the Netherlands, Estonia, Germany, and Portugal. [14] [15] 12-45% of aborted fetuses from dairy cattle are infected with the organism. Exposure is common in US dairy herds, ranging from 16% to 36% of dairy cows testing positive on serum. [16] The majority of calves that acquire a Neospora infection during gestation are born clinically normal except that they have precolostral antibody titers to Neospora caninum. [17]
In addition to being an important cause of cattle abortions, [7] neosporosis is a significant disease in dogs throughout the world. [18] If the disease is caught early, dogs may be successfully treated with clindamycin and other antiprotozoan drugs. [18] However, the disease is often fatal to young puppies. [18] Preventative vaccines have been tested on cattle. [19] [20] An inactivated vaccine was made commercially available but had mixed results. [21] A live vaccine using attenuated N. caninum tachyzoites has been more successful but is expensive to produce. [21] Other treatment options aim at prevention of the disease. Prevention requires an understanding of the transmission cycle, especially the connection between cattle and dogs (canids). Canids may pick up the parasite from eating infected material and spread the disease through contaminated feces. [21] One control method is to test for the disease and remove infected cattle from the herd. [21] Another method of control is preventing canids from entering the cattle holding area. [21]
From the neo- (Latin, "new") + spora (Greek, "seed") and canis (Latin, "dog"), Neospora caninum is a sporozoan parasite that was first described in 1984. [22]
Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, an apicomplexan. Infections with toxoplasmosis are associated with a variety of neuropsychiatric and behavioral conditions. Occasionally, people may have a few weeks or months of mild, flu-like illness such as muscle aches and tender lymph nodes. In a small number of people, eye problems may develop. In those with a weak immune system, severe symptoms such as seizures and poor coordination may occur. If a woman becomes infected during pregnancy, a condition known as congenital toxoplasmosis may affect the child.
Toxoplasma gondii is a parasitic protozoan that causes toxoplasmosis. Found worldwide, T. gondii is capable of infecting virtually all warm-blooded animals, but felids are the only known definitive hosts in which the parasite may undergo sexual reproduction.
Echinococcus granulosus, also called the hydatid worm or dog tapeworm, is a cyclophyllid cestode that dwells in the small intestine of canids as an adult, but which has important intermediate hosts such as livestock and humans, where it causes cystic echinococcosis, also known as hydatid disease. The adult tapeworm ranges in length from 3 mm to 6 mm and has three proglottids ("segments") when intact—an immature proglottid, mature proglottid and a gravid proglottid. The average number of eggs per gravid proglottid is 823. Like all cyclophyllideans, E. granulosus has four suckers on its scolex ("head"), and E. granulosus also has a rostellum with hooks. Several strains of E. granulosus have been identified, and all but two are noted to be infective in humans.
Hepatozoon is a genus of Apicomplexa alveolates which incorporates over 300 species of obligate intraerythrocytic parasites. Species have been described from all groups of tetrapod vertebrates, as well as a wide range of haematophagous arthropods, which serve as both the vectors and definitive hosts of the parasite. By far the most biodiverse and prevalent of all haemogregarines, the genus is distinguished by its unique reciprocal trophic lifecycle which lacks the salivary transmission between hosts commonly associated with other apicomplexans. While particularly prevalent in amphibians and reptiles, the genus is more well known in veterinary circles for causing a tick-borne disease called hepatozoonosis in some mammals.
Coccidiosis is a parasitic disease of the intestinal tract of animals caused by coccidian protozoa. The disease spreads from one animal to another by contact with infected feces or ingestion of infected tissue. Diarrhea, which may become bloody in severe cases, is the primary symptom. Most animals infected with coccidia are asymptomatic, but young or immunocompromised animals may suffer severe symptoms and death.
Besnoitia bennetti is a parasite that can cause besnoitiosis infections in donkeys. The range of this organism ranges from Africa to the United States. B. bennettii shares similar characteristics with Toxoplasma, Neospora, and Sarcocystis genera. Lab work onB. bennetti is conducted at biosafety level 1.
Besnoitia besnoiti is an apicomplexan protozoan parasite, closely related to Toxoplasma gondii and Neospora caninum,. It is part of a larger genus Besnoiti affecting multiple animal species, but Besnoita besnoiti, can affect livestock. and more specifically cattle as intermediate host, although some specific antibodies have been found in roe deer and red deer.
Sarcocystis is a genus of protozoan parasites, with many species infecting mammals, reptiles and birds. Its name is dervived from Greek sarx = flesh and kystis = bladder.
Neospora is a single celled parasite of livestock and companion animals. It was not discovered until 1984 in Norway, where it was found in dogs. Neosporosis, the disease that affects cattle and companion animals, has a worldwide distribution. Neosporosis causes abortions in cattle and paralysis in companion animals. It is highly transmissible and some herds can have up to a 90% prevalence. Up to 33% of pregnancies can result in aborted fetuses on one dairy farm. In many countries this organism is the main cause of abortion in cattle. Neosporosis is now considered as a major cause of abortion in cattle worldwide. Many reliable diagnostic tests are commercially available. Neospora caninum does not appear to be infectious to humans. In dogs, Neospora caninum can cause neurological signs, especially in congenitally infected puppies, where it can form cysts in the central nervous system.
Equine protozoal myeloencephalitis (EPM) is a disease that affects the central nervous system of horses. It is caused by a protozoal infection that is brought about by the apicomplexan parasites Sarcocystis neurona or Neospora hughesi. Most cases are caused by S. neurona. The lifecycle and transmission of N. hughesi is not well understood. The parasites create lesions in both the brain and spinal cord of the affected horses leading to neurological issues. Most horses infected with S. neurona do not exhibit neurological symptoms consistent with EPM.
The Sarcocystidae are a family of Apicomplexa associated with a variety of diseases in humans and other animals.
Toxocara canis is a worldwide-distributed helminth parasite that primarily infects dogs and other canids, but can also infect other animals including humans. The name is derived from the Greek word "toxon," meaning bow or quiver, and the Latin word "caro," meaning flesh. T. canis live in the small intestine of the definitive host. This parasite is very common in puppies and somewhat less common in adult dogs. In adult dogs, infection is usually asymptomatic but may be characterized by diarrhea. By contrast, untreated infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, pneumonia, enlarged abdomen, flatulence, poor growth rate, and other complications.
Ancylostoma caninum is a species of nematode known as a hookworm, which principally infects the small intestine of dogs. The result of A. caninum infection ranges from asymptomatic cases to death of the dog; better nourishment, increasing age, prior A. caninum exposure, or vaccination are all linked to improved survival. Other hosts include carnivores such as wolves, foxes, and cats, with a small number of cases having been reported in humans.
Hammondia is a genus of parasitic alveolates in the phylum Apicomplexa.
Behavior-altering parasites are parasites with two or more hosts, capable of causing changes in the behavior of one of their hosts to enhance their transmission, sometimes directly affecting the hosts' decision-making and behavior control mechanisms. They do this by making the intermediate host, where they may reproduce asexually, more likely to be eaten by a predator at a higher trophic level which becomes the definitive host where the parasite reproduces sexually; the mechanism is therefore sometimes called parasite increased trophic facilitation or parasite increased trophic transmission. Examples can be found in bacteria, protozoa, viruses, and animals. Parasites may also alter the host behaviour to increase protection of the parasites or their offspring; the term bodyguard manipulation is used for such mechanisms.
Taenia hydatigena is one of the adult forms of the canine and feline tapeworm. This infection has a worldwide geographic distribution. Humans with taeniasis can infect other humans or animal intermediate hosts by eggs and gravid proglottids passed in the feces.
Hammondia hammondi is a species of obligate heteroxenous parasitic alveolates of domestic cats. Intracellular cysts develop mainly in striated muscle. After the ingestion of cysts by cats, a multiplicative cycle precedes the development of gametocytes in the epithelium of the small intestine. Oocyst shedding persists for 10 to 28 days followed by immunity. Cysts in skeletal muscle measure between 100 and 340 μm in length and 40 and 95 μm in width. Some of the intermediate hosts develop low levels of antibody and some cross-immunity against Toxoplasma.
Wolves may suffer from various pathogens, both viral and bacterial, and parasite, both external and internal. Parasitic infection in wolves is of particular concern to people. Wolves can spread them to dogs, which in turn can carry the parasites to humans. In areas where wolves inhabit pastoral areas, the parasites can be spread to livestock.
Jennifer Faith Weston is a New Zealand veterinary scientist, and as of 2023 is a full professor at Massey University, specialising in dairy animals and their diseases.
Jitender P. Dubey is a veterinary parasitologist and microbiologist who pioneered the control and diagnosis of Toxoplasma gondii, Neospora caninum, and Sarcocystis neurona. Dubey discovered the life cycle of Toxoplasma gondii, and discovered and named both Neospora caninum and Sarcocystis neurona.
citing public domain text from the CDC