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Arthropod-borne Viruses of Senegal

A recent outbreak of suspected viral infection in Kedougou Region (http://www.promedmail.org/direct.php?id=3626668) highlights the complexity of establishing a specific etiological agent in West Africa.  At least twenty arthropod-borne viruses are associated with known or suspected human infection in Senegal.  The following alphabetical list is abstracted from Gideon www.GideonOnline.com and the Gideon e-book series [1]   (Primary references are available from Dr. Berger on request)

Bagaza – Bagaza virus has been recovered from mosquitoes in Senegal (Aedes fowleri, Culex neavei, Cx. Poicilipes and Mansonia, Mimomyia hispida, M. lacustris, M. splendens and Aedeomyia africana.

Bangui – Bangui virus was identified in mosquitoes in the Senegal River basin in 1988.

Bunyamwera – Bunyamwera virus has been identified in mosquitoes in the Barkedji region.

Chandipura – Chandipura virus has been identified in mosquitoes in the Barkedji region, and in phlebotomines in the Kedougou district.

Chikungunya – Outbreaks of Chikungunya were reported in Senegal in 1966, 1977, 1982, 1988, 1992, 1996 and 1997.  In 2006, a cluster of six cases in France was reported among travelers returning from Senegal. The virus has been found in a variety of local mosquito species, notably Aedes furcifer-taylori, Ae. luteocephalus, Ae. dalzieli and Stegomyia (Aedes) aegypti. Additional vectors may include Ae. vittatus, Anopheles rufipes and An. coustani.

Dengue – An outbreak of dengue was reported in Senegal during 1927 to 1928; and circulation of the virus was subsequently confirmed in 1974 and during 1999 to 2000. An epizootic among monkeys was reported in 1981; and the first human case was reported in 1983 (from Casamance). Several human and monkey infections were reported in 1990. In 2009, a dengue outbreak (196 cases, 1 fatal) was reported – the first reports of human dengue in Senegal for two decades. Italy reported a case of dengue hemorrhagic fever, imported from Senegal, and cases of dengue fever have been confirmed among French military personnel serving in this country.

Gabek Forest – Gabek Forest virus, a Phlebovirus, has been identified in sandflies (Phlebotomus species) in Senegal (1990 to 1995).

Koutango – Koutango virus (similar to Spondweni virus) has been identified in mosquitoes (Culex neavei) in the Barkedji region.

LeDantec – LeDantec virus is a rhabdovirus which is distinct from the vesicular stomatitis group 1. A single case of infection was reported in Senegal in 1965.

Ngari – Ngari virus has been identified in mosquitoes in the Barkedji region.  Two cases of Ngari virus infection were reported from Dakar,

O’nyong nyong – Although specific data are lacking for Senegal, circulation of O’nyong nyong virus is reported in this region of West Africa.

Rift Valley fever (RVF) – RVF virus was first isolated in West Africa in 1974, from Aedes (Aedimorphus) dalzieli in Senegal. Highest seroprevalence rates are found in the northwest and northcentral regions. Serological studies suggest that the disease was active in Diawara and Bakel (Eastern region) in 1998. Outbreaks were reported among goats, sheep and / or cattle in 2002, 2003, 2013 and 2014.  Carriage by mosquitoes and seroprevalence among sheep in the northern region increased during the 1990’s. Rift Valley virus was identified in mosquitoes in Barkedji in 1993, and re-emerged in 2002. A single isolated case of human Rift Valley fever was confirmed in a school teacher in Kedougou in 2012.

Rift Valley fever virus – seroprevalence surveys:

22.3% of Peul people of the North-central region

15.3% of the population in the Senegal River basin (1995 to 1996)

5% of children born after 1987, vs. 25.3% of the older population in Podor District (1999 publication)

5.2% of individuals in Diawara (1999)

2.9% of small ruminants tested in the Ferlo region (2003)

24.4% of sheep and goats in the Senegal River basin in 1988, 19.3% in 1989

17.2% of ungulates in the Senegal River Basin (1990)

3.8% of wild rodents, notably Rattus rattus, Mastomys huberti, A. niloticus and M. erythroleucus (2000 publication)

Semliki Forest – Semliki Forest virus has been recovered from mosquitoes (Aedes vittatus) and ticks (Rhipicephalus guilhoni) in Senegal.

Tataguine – Antibody toward Tataguine virus is found in 57% of the population.

Usutu – Zoonotic infection by Usutu virus has been identified in Senegal.

Wesselsbron – Seropositive humans were documented in Senegal during 1972 to 1975; and the virus itself has been identified in mosquitoes (Aedes vexans) in the Barkedji region.

West Nile – Seroprevalence rates for West Nile virus of 78.3% to 92% have been reported among horses. Infection of wild birds and dogs has also been identified. Vector mosquito species in this country are thought to include Culex neavei, Cx. tritaeniorhynchus, Cx. modestus, Cx. perfuscus group, Cx. poicilipes, Aedes vexans, Mimomyia hispida, Mi. lacustris, Mi. splendens, Aedeomyia africana and Mansonia uniformis

Yellow fever – Epidemics of yellow fever were reported in Senegal in 1768, 1769, 1778 to 1779 (50 deaths among Caucasians), 1814, 1816, 1828, 1830, 1837, 1840 to 1841, 1844, 1852, 1858, 1863, 1866, 1872, 1900 to 1901 (225 fatal cases) and 1923 to 1927. Aedes furcifer, A. metallicus and A. luteocephalus are involved in the wild vertebrate transmission cycle in this country. Yellow-fever activity among mosquitoes in Senegal has been used to monitor potential human disease in West Africa. Infected mosquitoes were identified during 1976 to 1979, 1983, 1987, 1989, 1990, 1992, 1993 and 2010.  Chronology of recent Yellow fever outbreaks in Senegal:

1965 – 243 cases were reported in Diourbel.

1965 to 1966 – 2,000 to 20,000 cases and 200 to 2,000 deaths were estimated.

1979 – Two French tourists contracted fatal yellow fever in Senegal.

1995 – Cases reported in Ribo-Escale and Guente-Pate Districts (vicinity of Koungheul).

1996 – Highest number of cases for any country (30.2% of the world’s total), including an epidemic centered at Kaffine town. {p 9855398}

2001 – Three cases were reported in Kedougou District (Health Ministry report not included in WHO data).

2002 – An outbreak (78 cases, 11 fatal) was reported – with 18 cases in Diourbel and Ziguinchor regions, and 60 cases in Touba, Mbacke and Bambey districts, Diourbel region; Gossas and Fatick districts, Fatick region; Tambacounda district in Tambacounda region; Louga, Koulda and Dakar regions.

2005 – Activity was reported in Tambacounda region (Goudiri, Kadira)

2010 – Two Senegalese fishermen acquired yellow fever in Gambia.

2011 – Three cases were reported in Kedougou and Saraya Health districts, near the borders with Mali and Guinea Conakry.

Zika – There is evidence for the occurrence of yearly epizootics of Zika virus infection in Senegal. In 2008, two American scientists contracted Zika in the country. Natural infection has been identified in two local primate species, Cercopithecus aethiops and Erythrocebus patas; and in 1.82% of mosquito pools (2011).

Zinga – Zinga virus, a variant of RVF virus, has been identified in humans and mosquitoes in Senegal.

 

Reference:

  1. Berger SA. Infectious Diseases of Senegal, 2015. 449 pages, 55 graphs, 1,864 references.  Gideon e-books, http://www.gideononline.com/ebooks/country/infectious-diseases-of-senegal/

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