The o'nyong'nyong virus (ONNV) was first isolated by researchers at the

Uganda Virus Research Institute The Uganda Virus Research Institute (UVRI) is a medical research institute owned by the Uganda government that carries out research on communicable diseases in man and animals, with emphasis on viral transmitted infections. UVRI is a component of ...

Entebbe Entebbe is a city in Central Uganda. Located on a Lake Victoria peninsula, approximately southwest of the Ugandan capital city, Kampala. Entebbe was once the seat of government for the Protectorate of Uganda prior to independence, in 1962. The c ...

Uganda }), is a landlocked country in East Africa East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territor ...

, during a large outbreak of a disease in 1959 that resembled

dengue fever Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characterist ...

. ONNV is a

togavirus ''Alphavirus'' is a genus of RNA viruses, the sole genus in the ''Togaviridae'' family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 32 alphaviruses, ...

(family Togaviridae), genus ''

Alphavirus ''Alphavirus'' is a genus of RNA viruses, the sole genus in the ''Togaviridae'' family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 32 alphaviruses ...

'', is closely related to the

chikungunya Chikungunya is an infection caused by the ''Chikungunya virus'' (CHIKV). Symptoms include fever and joint pains. These typically occur two to twelve days after exposure. Other symptoms may include headache, muscle pain, joint swelling, and a ra ...

and Igbo Ora viruses, and is a member of the Semliki Forest antigenic complex. The name was given to the disease by the Acholi tribe during the 1959 outbreak. The name comes from the

Nilotic language The Nilotic languages are a group of related languages spoken across a wide area between South Sudan and Tanzania by the Nilotic peoples. Etymology The word Nilotic means of or relating to the Nile River or to the Nile region of Africa. Dem ...

of Uganda and

Sudan Sudan ( or ; ar, السودان, as-Sūdān, officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It shares borders with the Central African Republic t ...

and means “weakening of the joints". The virus can infect humans and may cause disease.

Signs and symptoms

Common symptoms of infection with the virus are

polyarthritis Polyarthritis is any type of arthritis that involves 5 or more joints simultaneously. It is usually associated with autoimmune conditions and may be experienced at any age and is not sex specific. Causes Polyarthritis is most often caused by an au ...

rash A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cr ...

and

fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...

. Other symptoms include eye pain, chest pain,

lymphadenitis Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammatory type (the most common type) is lymphadenitis, producing swollen or enlarged lymph nodes. In cli ...

and lethargy. The disease is self-limiting. No fatalities due to infection are known.

Cause

Strains

ONNV has at least three major subtypes, or strains, the genomic sequences of which are currently available on genome databases.

Transmission

ONNV is transmitted by bites from an infected

mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...

. It is the only virus whose primary vectors are anopheline mosquitoes (''Anopheles funestus'' and ''

Anopheles gambiae The ''Anopheles gambiae'' complex consists of at least seven morphologically indistinguishable species of mosquitoes in the genus ''Anopheles''. The complex was recognised in the 1960s and includes the most important vectors of malaria in sub- ...

'').

Epidemiology

There have been two epidemics of o’nyong’nyong fever. The first occurred from 1959 to 1962, spreading from Uganda to

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...

, Zaire (

Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

Malawi Malawi (; or aláwi Tumbuka: ''Malaŵi''), officially the Republic of Malawi, is a landlocked country in Southeastern Africa that was formerly known as Nyasaland. It is bordered by Zambia to the west, Tanzania to the north and northeast ...

and

Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...

, and affecting over two million people, one of the largest

arbovirus Arbovirus is an informal name for any virus that is transmitted by arthropod vectors. The term ''arbovirus'' is a portmanteau word (''ar''thropod-''bo''rne ''virus''). ''Tibovirus'' (''ti''ck-''bo''rne ''virus'') is sometimes used to more spe ...

epidemics ever recorded. The first virus isolates were obtained during this outbreak from mosquitoes and human blood samples collected from

Gulu Gulu is a city in the Northern Region of Uganda. It is the commercial and administrative centre of Gulu District. The coordinates of the city of Gulu are 2°46'54.0"N 32°17'57.0"E. The distance from Gulu to Kampala, Uganda's capital and large ...

in northern Uganda in 1959. The second epidemic in 1996–1997 was confined to Uganda. The 35-year hiatus between the two outbreaks and evidence of an outbreak in 1904–1906 in Uganda indicate a 30–50 year cycle for epidemics. In 2013, ONNV was confirmed as the cause of disease in a 60-year-old German woman who became infected while traveling in East Africa. In 2015–2016 there was a minor outbreak in Uganda with 51 suspected cases. There has been a minor outbreak in Mombasa (Kenya) and the County Government of Mombasa issued a warning. A 2015 study indicated that ONNV is endemic in coastal East Africa, along with

virus.

References

External links

{{Taxonbar, from=Q1407583 Alphaviruses Arthropod-borne viral fevers and viral haemorrhagic fevers