Surra
Encyclopedia
Surra is a disease of vertebrate animals. The disease is caused by protozoa
n trypanosomes, specifically Trypanosoma evansi
, of several species which infect the blood of the vertebrate host, causing fever, weakness, and lethargy which lead to weight loss and anemia. In some animals the disease is fatal unless treated.
(Steel
1885) Balbiani 1888, and is transmitted by horse-flies
, and also by the vampire bat, Desmodus rotundus, in South-America. This form occurs in South America, Northern Africa, and the Middle East. This was the first form of pathogenic trypanosome discovered and was first described by Griffith Evans in 1880 while working in India
.
A chronic form of the disease, which is milder but persistent, occurs in pigs, sheep, and goats. This form is caused by Trypanosoma suis
and is transmitted by tsetse
. This form occurs in Africa.
On September 8, 2007, Veterinary officials in South Cotabato
, Philippines
said that laboratory
tests on samples from cows, carabaos, and horses in the province
's 10 town
s and lone city
showed the level of infection
at 89.5%, a sudden increase of positive cases Fasciolosis or liver
fluke
disease among large livestock
due to the erratic
weather
condition in the area. They must be treated forthwith to prevent complications with Surra and Hemorrhagic Septicemia diseases. Surra already affected all barangays of the Surallah town
.
although monomorphic in most cases, can be pleomorphic in some strains. They are characterized by a long free flagellum with a narrow drawn out posterior. Kinetoplast and dyskinetoplastic forms appear. Kinetoplast is either terminal or subterminal.
flies
, Trypanosoma evansi
development does not take place in the actual vector. In order for the transmission to be successful, trypanosomes need to survive in the gut of the flies and be regurgitated during subsequent feeding. Since tabanidae are most abundant during rainy and post rainy seasons, that is when most outbreaks of Surra occur.
In order for the transfer of the disease from the flies to the animals, interruption of feeding habits needs to occur. This direct transmission technique involves them cutting the skin with their mouths, then lapping up the blood along with connective tissue fluid. This means a good indicator of disease would be looking at trypanosome density in capillary blood and connective tissue. After transferring the infectious organisms to the host species, the flies leave to rest and during that time transmission was successful only in some cases. Because the trypanosomes remain in the food canal of the flies for 4-8 hours depending on the species, the flies can feed off of one animal's blood more than one time, thus increasing the chance of successful transmission.
Although the most common method of transferring trypanosomes to other species is through tabanus
flies, there are other insects that can also transmit this disease to livestock. These blood sucking insects are Stomoxys
, Lyperosia, Hematopota, and Ornithordorus.
Other methods of transmission still being studied are looking at passing T.evansi thorough iatrogenic transmission. Evidence has been seen of transmission through sexual intercourse, through eating infected meat, and also through vampire bats in geographical areas where they are found.
depends on what species the host is, the virulence of the trypanosoma evansi
strain, and the dose received by the host. Many species such as dogs, horses and rats, have been shown to have immunological reactions to the infection, such as anemia due to decrease in erythrocytes and hemoglobin
. Although not fully understood at this point in time, some theories believe that the erythrocytes could acquire trypaonosomal antigen, resulting in a negative immunological reaction.
Animals that have been infected show loss of appetite, weight loss, anaemia, odema, fever, salivations, lacrimation, and abortion
. The proteases that are released during infection of T.evansi might degrade the host tissue proteins and are a huge force in the pathogenesis. That is why scientists are looking at immune targeting of these proteases to protect the infected host.
infections are undetectable by direct microscopy. Since CPT is not very sensitive, it cannot be used as a sole method of diagnosis.
The Haematocrit Centrifugation Technique (HCT) is a much better alternative. Using HCT trypanosomes can be detected in the blood even in field conditions. Buffy Coat
can be used to increase detection. Detection with this method is approx 85 trypanosomes per mililitre.
Rather than using live animals as test subjects, Canada used serological tests such as complement fixation tests to detect trypanosomes, and have been very successful. Other tests used look at detecting antibodies generated by the host species against T.evansi antigens. This is done using the enzyme-linked immunosorbent assays (ELISA) method. Now polymerase chain reaction
(PCR) and DNA probes are being used to detect Surra in animals.
, and chemo prophylaxis in animals.
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
n trypanosomes, specifically Trypanosoma evansi
Trypanosoma evansi
Trypanosoma evansi is a protozoan trypanosome in the genus trypanosoma that causes one form of the surra disease in animals. It has been proposed that T. evansi is - like T. equiperdum- originally a subspecies of T. brucei brucei. Due to this loss of part of the mitochondrional DNA T...
, of several species which infect the blood of the vertebrate host, causing fever, weakness, and lethargy which lead to weight loss and anemia. In some animals the disease is fatal unless treated.
Overview
An acute form of the disease, which is generally fatal unless treated, occurs in horses, donkeys, mules, cattle, buffalo, deer, camels, llamas, dogs, and cats. This form is caused by Trypanosoma evansiTrypanosoma evansi
Trypanosoma evansi is a protozoan trypanosome in the genus trypanosoma that causes one form of the surra disease in animals. It has been proposed that T. evansi is - like T. equiperdum- originally a subspecies of T. brucei brucei. Due to this loss of part of the mitochondrional DNA T...
(Steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
1885) Balbiani 1888, and is transmitted by horse-flies
Horse-fly
Insects in the order Diptera, family Tabanidae, are commonly called horse flies. Often considered pests for the bites that many inflict, they are among the world's largest true flies. They are known to be extremely noisy during flight. They are also important pollinators of flowers, especially in...
, and also by the vampire bat, Desmodus rotundus, in South-America. This form occurs in South America, Northern Africa, and the Middle East. This was the first form of pathogenic trypanosome discovered and was first described by Griffith Evans in 1880 while working in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
.
A chronic form of the disease, which is milder but persistent, occurs in pigs, sheep, and goats. This form is caused by Trypanosoma suis
Trypanosoma suis
Trypanosoma suis is a protozoan trypanosome in the genus Trypanosoma that causes one form of the surra disease in animals. It infects pigs. It does not infect humans.-Discovery:...
and is transmitted by tsetse
Tsetse fly
Tsetse , sometimes spelled tzetze and also known as tik-tik flies, are large biting flies that inhabit much of mid-continental Africa between the Sahara and the Kalahari deserts. They live by feeding on the blood of vertebrate animals and are the primary biological vectors of trypanosomes, which...
. This form occurs in Africa.
On September 8, 2007, Veterinary officials in South Cotabato
South Cotabato
South Cotabato is a province of the Philippines located in the SOCCSKSARGEN region in Mindanao. Its capital is Koronadal City, and it borders Sultan Kudarat to the north and west, Sarangani to the south and east, and Davao del Sur to the east...
, Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
said that laboratory
Laboratory
A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
tests on samples from cows, carabaos, and horses in the province
Province
A province is a territorial unit, almost always an administrative division, within a country or state.-Etymology:The English word "province" is attested since about 1330 and derives from the 13th-century Old French "province," which itself comes from the Latin word "provincia," which referred to...
's 10 town
Town
A town is a human settlement larger than a village but smaller than a city. The size a settlement must be in order to be called a "town" varies considerably in different parts of the world, so that, for example, many American "small towns" seem to British people to be no more than villages, while...
s and lone city
City
A city is a relatively large and permanent settlement. Although there is no agreement on how a city is distinguished from a town within general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.For example, in the U.S...
showed the level of infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
at 89.5%, a sudden increase of positive cases Fasciolosis or liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
fluke
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
disease among large livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
due to the erratic
Erratic
Erratic can refer to:* Erratic, a project of music artist Jan Robbe* Glacial erratic, is a piece of rock that differs from the size and type of rock native to the area in which it rests* Erratic ant, a species...
weather
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
condition in the area. They must be treated forthwith to prevent complications with Surra and Hemorrhagic Septicemia diseases. Surra already affected all barangays of the Surallah town
Town
A town is a human settlement larger than a village but smaller than a city. The size a settlement must be in order to be called a "town" varies considerably in different parts of the world, so that, for example, many American "small towns" seem to British people to be no more than villages, while...
.
Morphology
Trypanosoma evansiTrypanosoma evansi
Trypanosoma evansi is a protozoan trypanosome in the genus trypanosoma that causes one form of the surra disease in animals. It has been proposed that T. evansi is - like T. equiperdum- originally a subspecies of T. brucei brucei. Due to this loss of part of the mitochondrional DNA T...
although monomorphic in most cases, can be pleomorphic in some strains. They are characterized by a long free flagellum with a narrow drawn out posterior. Kinetoplast and dyskinetoplastic forms appear. Kinetoplast is either terminal or subterminal.
Transmission
Transferred by species of TabanusTabanus
Tabanus is a genus of biting horseflies of the family Tabanidae. Females have scissor-like mouthparts that aim to cut the skin. The horsefly can then lap up the blood. Horseflies of this genus are known to be potential vectors of anthrax, worms and trypanosomes. Some species, such as Tabanus...
flies
Fließ
Fließ is a municipality in the Landeck district and is located5 km south of Landeck on the upper course of the Inn River. It has 9 hamlets and was already populated at the roman age; the village itself was founded around the 6th century. After a conflagration in 1933 Fließ was restored more...
, Trypanosoma evansi
Trypanosoma evansi
Trypanosoma evansi is a protozoan trypanosome in the genus trypanosoma that causes one form of the surra disease in animals. It has been proposed that T. evansi is - like T. equiperdum- originally a subspecies of T. brucei brucei. Due to this loss of part of the mitochondrional DNA T...
development does not take place in the actual vector. In order for the transmission to be successful, trypanosomes need to survive in the gut of the flies and be regurgitated during subsequent feeding. Since tabanidae are most abundant during rainy and post rainy seasons, that is when most outbreaks of Surra occur.
In order for the transfer of the disease from the flies to the animals, interruption of feeding habits needs to occur. This direct transmission technique involves them cutting the skin with their mouths, then lapping up the blood along with connective tissue fluid. This means a good indicator of disease would be looking at trypanosome density in capillary blood and connective tissue. After transferring the infectious organisms to the host species, the flies leave to rest and during that time transmission was successful only in some cases. Because the trypanosomes remain in the food canal of the flies for 4-8 hours depending on the species, the flies can feed off of one animal's blood more than one time, thus increasing the chance of successful transmission.
Although the most common method of transferring trypanosomes to other species is through tabanus
Tabanus
Tabanus is a genus of biting horseflies of the family Tabanidae. Females have scissor-like mouthparts that aim to cut the skin. The horsefly can then lap up the blood. Horseflies of this genus are known to be potential vectors of anthrax, worms and trypanosomes. Some species, such as Tabanus...
flies, there are other insects that can also transmit this disease to livestock. These blood sucking insects are Stomoxys
Stomoxys
Stomoxys is a genus of flies in the family Muscidae. The genus is unusual among the Muscidae in that it includes species that are bloodsucking ectoparasites of mammals...
, Lyperosia, Hematopota, and Ornithordorus.
Other methods of transmission still being studied are looking at passing T.evansi thorough iatrogenic transmission. Evidence has been seen of transmission through sexual intercourse, through eating infected meat, and also through vampire bats in geographical areas where they are found.
Pathenogenesis
The degree of pathogenicityPathogenicity
Pathogenicity is the ability of a pathogen to produce an infectious disease in an organism.It is often used interchangeably with the term "virulence", although virulence is used more specifically to describe the relative degree of damage done by a pathogen, or the degree of pathogenicity caused by...
depends on what species the host is, the virulence of the trypanosoma evansi
Trypanosoma evansi
Trypanosoma evansi is a protozoan trypanosome in the genus trypanosoma that causes one form of the surra disease in animals. It has been proposed that T. evansi is - like T. equiperdum- originally a subspecies of T. brucei brucei. Due to this loss of part of the mitochondrional DNA T...
strain, and the dose received by the host. Many species such as dogs, horses and rats, have been shown to have immunological reactions to the infection, such as anemia due to decrease in erythrocytes and hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
. Although not fully understood at this point in time, some theories believe that the erythrocytes could acquire trypaonosomal antigen, resulting in a negative immunological reaction.
Animals that have been infected show loss of appetite, weight loss, anaemia, odema, fever, salivations, lacrimation, and abortion
Abortion
Abortion is defined as the termination of pregnancy by the removal or expulsion from the uterus of a fetus or embryo prior to viability. An abortion can occur spontaneously, in which case it is usually called a miscarriage, or it can be purposely induced...
. The proteases that are released during infection of T.evansi might degrade the host tissue proteins and are a huge force in the pathogenesis. That is why scientists are looking at immune targeting of these proteases to protect the infected host.
Diagnosis
Some conventional parasitological techniques (CPT) such as wet blood film, and stained blood smears are used because so far, the best identifier is looking at the blood of the potentially infected host. Other tissues can be looked at, but the gold standard is identifying trypanosomes in the blood. Before the infection becomes severe, it is difficult to catch as many times these crypticCryptic
Cryptic can refer to:* Crypsis, of animals that are difficult to observe* Cryptic crossword, a crossword with cryptic clues* Cryptic era, earliest period of the Earth* Cryptic, an album by Edge of Sanity* Cryptic Writings, an album by Megadeth...
infections are undetectable by direct microscopy. Since CPT is not very sensitive, it cannot be used as a sole method of diagnosis.
The Haematocrit Centrifugation Technique (HCT) is a much better alternative. Using HCT trypanosomes can be detected in the blood even in field conditions. Buffy Coat
Buffy coat
The buffy coat is the fraction of an anticoagulated blood sample after density gradient centrifugation that contains most of the white blood cells and platelets.-Description:...
can be used to increase detection. Detection with this method is approx 85 trypanosomes per mililitre.
Rather than using live animals as test subjects, Canada used serological tests such as complement fixation tests to detect trypanosomes, and have been very successful. Other tests used look at detecting antibodies generated by the host species against T.evansi antigens. This is done using the enzyme-linked immunosorbent assays (ELISA) method. Now polymerase chain reaction
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
(PCR) and DNA probes are being used to detect Surra in animals.
Treatment
The main methods of controlling surra has been chemotherapyChemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
, and chemo prophylaxis in animals.