Oropouche fever is a tropical viral infection, a zoonosis

Zoonosis

A zoonosis or zoonoseis any infectious disease that can be transmitted from non-human animals to humans or from humans to non-human animals . In a study of 1415 pathogens known to affect humans, 61% were zoonotic...

 similar to dengue fever

Dengue fever

Dengue fever , also known as breakbone fever, is an infectious tropical disease caused by the dengue virus. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles...

, transmitted by biting midge

Midge (insect)

Midges comprise many kinds of very small two-winged flies found world-wide. The term does not encapsulate a well-defined taxonomic group, but includes animals in several families of Nematoceran Diptera. While some midges are vectors for disease, many others play useful roles as prey items for...

 (species Culicoides paraensis

Culicoides paraensis

Culicoides paraensis is a species of midge found from the northern United States to Argentina, which acts as the vector of the Oropouche fever virus....

) and mosquito

Mosquito

Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

es from the blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 of sloth

Sloth

Sloths are the six species of medium-sized mammals belonging to the families Megalonychidae and Bradypodidae , part of the order Pilosa and therefore related to armadillos and anteaters, which sport a similar set of specialized claws.They are arboreal residents of the jungles of Central and South...

s to human

Human

Humans are the only living species in the Homo genus...

s. It occurs mainly in the Amazonic

Amazon Basin

The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...

 region, the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

 and Panama

Panama

Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

. The disease is named after the region where it was first described and isolated at the Trinidad Regional Virus Laboratory

Trinidad Regional Virus Laboratory

The Trinidad Regional Virus Laboratory was established in Port of Spain, in 1953 by the Rockefeller Foundation in co-operation with the Government of Trinidad and Tobago. It was originally housed in an old wooden army barracks near the docks in Port of Spain...

, in 1955, the Oropouche River in Trinidad and Tobago

Trinidad and Tobago

Trinidad and Tobago officially the Republic of Trinidad and Tobago is an archipelagic state in the southern Caribbean, lying just off the coast of northeastern Venezuela and south of Grenada in the Lesser Antilles...

 and is caused by a specific arbovirus

Arbovirus

Arbovirus is a term used to refer to a group of viruses that are transmitted by arthropod vectors. The word arbovirus is an acronym . Some arboviruses are able to cause emergent disease.-Transmission:...

, the Oropouche virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 (OROV), of the Bunyaviridae

Bunyaviridae

Bunyaviridae is a family of negative-stranded RNA viruses. Though generally found in arthropods or rodents, certain viruses in this family occasionally infect humans. Some of them also infect plants....

 family.

History

OROV was first described in Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 in 1960, isolated from the blood of a sloth (Bradypus tridactylus) captured in the rain forest during the construction of the Belém-Brasília Highway. The Ochlerotatus serratus

Ochlerotatus serratus

Ochlerotatus serratus is a species of mosquito....

mosquito

Mosquito

Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

 was implicated as a possible vector, because OROV was found in their blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 too.

According to Nunes et al. (2005), "the OROV genome

Genome

In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....

 consists of 3 partite, single-stranded, negative-sense RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

s, named large (L), medium (M), and small (S) RNA. These RNAs are predicted to encode a large protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 (L: polymerase

Polymerase

A polymerase is an enzyme whose central function is associated with polymers of nucleic acids such as RNA and DNA.The primary function of a polymerase is the polymerization of new DNA or RNA against an existing DNA or RNA template in the processes of replication and transcription...

 activity), viral surface glycoprotein

Glycoprotein

Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...

s (Gc and Gn), and nonstructural NSM protein, as well as both nucleocapsid (N) and NSS proteins. Complete nucleotide

Nucleotide

Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...

 sequences have been determined for all 3 RNA segments, and previous studies of the molecular biology

Molecular biology

Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

 of the N gene (SRNA) of 28 different OROV strains

Strain (biology)

In biology, a strain is a low-level taxonomic rank used in three related ways.-Microbiology and virology:A strain is a genetic variant or subtype of a micro-organism . For example, a "flu strain" is a certain biological form of the influenza or "flu" virus...

 indicated the existence of 3 genotype

Genotype

The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...

s, designated I, II, and III."

Epidemiology

Large epidemics are common and very swift, one the earliest larger one having occurred at the city of Belém

Belém

Belém is a Brazilian city, the capital and largest city of state of Pará, in the country's north region. It is the entrance gate to the Amazon with a busy port, airport and bus/coach station...

, in the Brazilian Amazon state of Pará

Pará

Pará is a state in the north of Brazil. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest it also borders Guyana and Suriname, and to the northeast it borders the Atlantic Ocean. The capital is Belém.Pará is the most populous state...

, with 11,000 recorded cases. In the Brazilian Amazon, oropouche is the second most frequent viral disease, after dengue fever. Several epidemics have generated more than 263,000 cases, of which 130,000 alone occurred in the period from 1978 to 1980. Presently, in Brazil alone it is estimated that more than half million cases have occurred.

Presentation

Oropouche fever has an abrupt onset fever, initially with generic symptoms similar to those seen in dengue fever. such as chill

Chill

Chill may refer to:* Chills that occur during high fevers as a result of immune response to disease* Shivering, a bodily function in response to early hypothermia in warm-blooded animals...

s, headache

Headache

A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...

, anorexia

Anorexia (symptom)

Anorexia is the decreased sensation of appetite...

, muscle pain and joint pain and vomiting

Vomiting

Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...

. Patients may develop symptoms of meningitis

Meningitis

Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...

. Diagnosis is achieved by dosing the serum levels of the specific antibody

Antibody

An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

 to the virus.

Treatment and prognosis

The illness has no specific therapy, but usually symptomatic treatment

Symptomatic treatment

Symptomatic treatment is any medical therapy of a disease that only affects its symptoms, not its cause, i.e., its etiology. It is usually aimed at reducing the signs and symptoms for the comfort and well-being of the patient, but it also may be useful in reducing organic consequences and sequelae...

 is introduced, by using certain oral analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 and anti-inflammatory agents. which should be prescribed by a physician, because some of them (such as aspirin

Aspirin

Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...

) are dangerous because they reduce blood clotting activity and may aggravate the hemorrhagic effects;

The infection is usually self-limiting and complications are rare. Patients usually recover fully with no long term ill effects.

External links

• Oropouche fever. MedicDirect.
• Brazilian Viruses of the Bunyaviridae Family. Medicina Ribeirão (in Portuguese)