Anaplasmosis
Encyclopedia
Anaplasmosis is a disease caused by a rickettsia
l parasite of ruminant
s, Anaplasma
spp. The organism occurs in the white blood cells and is transmitted by natural means through a number of haematophagous species of ticks. It can also be transmitted iatrogenically
by the use of surgical, dehorning
, castration
, and tattoo
instruments and hypodermic needle
s that are not disinfected between uses.
Although the term is often associated with animal infection, it is also used to describe infection in humans.
in the gut of certain species of ticks but the flies appear to be only a mechanical vector, thus, not as important in maintaining the disease in any given area. The disease causes severe anemia
and wasting
in infected adult cattle
. Young cattle and most other ruminants will not show clinical signs if infected but may serve as carriers
. Since the organism "hides" from the body's immune system
in red blood cell
s, it is difficult if not impossible for an infection to be totally cleared. As the immune response wanes, the organism again builds up and the host relapse
s.
, anaplasmosis is notably present in the south and west where the tick hosts Dermacentor
spp. are found. Although vaccines have been developed, none is currently available in the United States. Early in the 20th century, this disease was considered one of major economic consequence in the western United States. In the 1980s and 1990s, control of ticks through new acaricides and practical treatment with prolonged-action antibiotics, notably tetracycline, has led to the point where the disease is no longer considered a major problem.
Cases of coinfection with tick-born microorganisms are being increasingly reported in the last decade , perhaps explaining the variable manifestations and clinical responses noted in some patients with tick-transmitted diseases. In such clinical settings, laboratory testing for coinfection is indicated to ensure that appropriate antimicrobial treatment is given.
In 2005, Anaplasma ovis was found in reindeer
populations in Mongolia
. This pathogen and its associated syndrome (characterized by lethargy, fever and pale mucous membranes) was previously only observed in wild sheep and goats in the region, and is the first observed event of A. ovis in reindeer.
. Haematuria may occur due to the lysis of red blood cells. General systemic signs such as diarrhoea, anorexia and weight loss may also be present. A blood smear stained with Giemsa should be observed for identification of infected red blood cells and will allow definitive diagnosis.
or a similar class of antibiotics. Oxytetracycline
and imidocarb
have also been shown to be effective. Supportive therapy such as blood products and fluids may be necessary.
Vaccine
s against anaplasmosis are available. Carrier animals should be eliminated from flocks. Tick control may also be useful although it can be difficult to implement.
announced that he had been infected with anaplasmosis
. He believes he was most likely bitten by an infected tick while camping with his 5-year-old son in their tree house
.
Rickettsia
Rickettsia is a genus of non-motile, Gram-negative, non-sporeforming, highly pleomorphic bacteria that can present as cocci , rods or thread-like . Being obligate intracellular parasites, the Rickettsia survival depends on entry, growth, and replication within the cytoplasm of eukaryotic host cells...
l parasite of ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
s, Anaplasma
Anaplasma
Anaplasma is a genus of rickettsiales bacteria.Anaplasmas reside in host red blood cells and lead to the disease anaplasmosis. The disease most commonly occurs in tropical areas of the world....
spp. The organism occurs in the white blood cells and is transmitted by natural means through a number of haematophagous species of ticks. It can also be transmitted iatrogenically
Iatrogenesis
Iatrogenesis, or an iatrogenic artifact is an inadvertent adverse effect or complication resulting from medical treatment or advice, including that of psychologists, therapists, pharmacists, nurses, physicians and dentists...
by the use of surgical, dehorning
Cattle dehorning
Dehorning or disbudding is the process of removing or stopping the growth of the horns of livestock. Cattle, sheep, and goats are often dehorned for economic and safety reasons. Horns can pose a risk to humans, to other animals, and to the bearers of the horns themselves...
, castration
Castration
Castration is any action, surgical, chemical, or otherwise, by which a male loses the functions of the testicles or a female loses the functions of the ovaries.-Humans:...
, and tattoo
Tattoo
A tattoo is made by inserting indelible ink into the dermis layer of the skin to change the pigment. Tattoos on humans are a type of body modification, and tattoos on other animals are most commonly used for identification purposes...
instruments and hypodermic needle
Hypodermic needle
A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...
s that are not disinfected between uses.
Although the term is often associated with animal infection, it is also used to describe infection in humans.
Life cycle
The organism can go through a complete lifecycleBiological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
in the gut of certain species of ticks but the flies appear to be only a mechanical vector, thus, not as important in maintaining the disease in any given area. The disease causes severe anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
and wasting
Wasting
In medicine, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as...
in infected adult cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
. Young cattle and most other ruminants will not show clinical signs if infected but may serve as carriers
Asymptomatic carrier
An asymptomatic carrier is a person or other organism that has contracted an infectious disease, but who displays no symptoms. Although unaffected by the disease themselves, carriers can transmit it to others...
. Since the organism "hides" from the body's immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
in red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s, it is difficult if not impossible for an infection to be totally cleared. As the immune response wanes, the organism again builds up and the host relapse
Relapse
Relapse, in relation to drug misuse, is resuming the use of a drug or a dependent substance after one or more periods of abstinence. The term is a landmark feature of both substance dependence and substance abuse, which are learned behaviors, and is maintained by neuronal adaptations that mediate...
s.
Distribution
In the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, anaplasmosis is notably present in the south and west where the tick hosts Dermacentor
Dermacentor
Dermacentor is a genus of hard-bodied ticks.-Species:* Dermacentor abaensis Teng, 1963* Dermacentor albipictus Packard, 1869* Dermacentor andersoni Stiles 1908* Dermacentor asper Arthur, 1960...
spp. are found. Although vaccines have been developed, none is currently available in the United States. Early in the 20th century, this disease was considered one of major economic consequence in the western United States. In the 1980s and 1990s, control of ticks through new acaricides and practical treatment with prolonged-action antibiotics, notably tetracycline, has led to the point where the disease is no longer considered a major problem.
Cases of coinfection with tick-born microorganisms are being increasingly reported in the last decade , perhaps explaining the variable manifestations and clinical responses noted in some patients with tick-transmitted diseases. In such clinical settings, laboratory testing for coinfection is indicated to ensure that appropriate antimicrobial treatment is given.
In 2005, Anaplasma ovis was found in reindeer
Reindeer
The reindeer , also known as the caribou in North America, is a deer from the Arctic and Subarctic, including both resident and migratory populations. While overall widespread and numerous, some of its subspecies are rare and one has already gone extinct.Reindeer vary considerably in color and size...
populations in Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
. This pathogen and its associated syndrome (characterized by lethargy, fever and pale mucous membranes) was previously only observed in wild sheep and goats in the region, and is the first observed event of A. ovis in reindeer.
Clinical signs and diagnosis
Anaemia may be severe and result in cardiovascular changes such as an increase in heart rateTachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
. Haematuria may occur due to the lysis of red blood cells. General systemic signs such as diarrhoea, anorexia and weight loss may also be present. A blood smear stained with Giemsa should be observed for identification of infected red blood cells and will allow definitive diagnosis.
Treatment and control
Treatment usually involves a prescription of doxycyclineDoxycycline
Doxycycline INN is a member of the tetracycline antibiotics group, and is commonly used to treat a variety of infections. Doxycycline is a semisynthetic tetracycline invented and clinically developed in the early 1960s by Pfizer Inc. and marketed under the brand name Vibramycin. Vibramycin...
or a similar class of antibiotics. Oxytetracycline
Oxytetracycline
Oxytetracycline was the second of the broad-spectrum tetracycline group of antibiotics to be discovered.Oxytetracycline works by interfering with the ability of bacteria to produce proteins that are essential to them. Without these proteins the bacteria cannot grow, multiply and increase in numbers...
and imidocarb
Imidocarb
Imidocarb is a urea derivative used in veterinary medicine as an antiprotozoal agent for the treatment of infection with Babesia and other parasites....
have also been shown to be effective. Supportive therapy such as blood products and fluids may be necessary.
Vaccine
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
s against anaplasmosis are available. Carrier animals should be eliminated from flocks. Tick control may also be useful although it can be difficult to implement.
Notable cases
On July 30, 2009, David LettermanDavid Letterman
David Michael Letterman is an American television host and comedian. He hosts the late night television talk show, Late Show with David Letterman, broadcast on CBS. Letterman has been a fixture on late night television since the 1982 debut of Late Night with David Letterman on NBC...
announced that he had been infected with anaplasmosis
Human granulocytic anaplasmosis
Human granulocytic anaplasmosis is an infectious disease caused by Anaplasma phagocytophilum, an obligate intracellular bacterium that is typically transmitted to humans by at least three kinds of ticks, including Ixodes scapularis, Ixodes pacificus, and Dermacentor variabilis...
. He believes he was most likely bitten by an infected tick while camping with his 5-year-old son in their tree house
Tree house
Tree houses, treehouses, or tree forts, are platforms or buildings constructed around, next to or among the trunk or branches of one or more mature trees while above ground level...
.
External links
- CFIA Animal Disease Information
- Anaplasmosis fact sheet
- Biosecurity training video
- Farm-level biosecurity practices