16 May 2007

Rift Valley fever in Kenya, Somalia and Tanzania

Kenya

Between 30 November 2006 and 12 March 2007, 684 cases of Rift Valley fever (RVF) including 155 deaths were reported [1]. Two hundred and thirty four of these cases were laboratory confirmed. Forty-nine percent of the cases (333) were reported from North Eastern Province, 183 cases have been reported from Rift Valley Province, 141 from Coast Province, 14 from Central Province and 13 from Eastern Province.

Somalia

As of 20 February 2007, 114 cases of RVF, including 51 deaths, were reported. The majority of cases (64%) were reported from Lower Juba, although cases have also been reported from Gedo, Hiraan, Middle Juba, Middle Shabelle and Lower Shabelle. The difficult security situation in the area has hampered both surveillance and control activities. There is a lack of recent data on case numbers and only three of the cases reported up to 20 February 2007 were laboratory confirmed [1].

Tanzania

A total of 264 cases of RVF, including 109 deaths, were reported between 13 January and 3 May 2007. Of these cases, 154 were laboratory confirmed. One hundred and fifty six of the cases (59%) were reported from the region of Dodoma, and a further 50 cases were reported from Morogoro. Cases have also been reported from Arusha, Dar es Salaam, Iringa, Manyara, Mwanza, Pwani, Singida and Tanga. It is thought the number of cases reported underestimates the number of people infected as only severe cases have been detected through surveillance [1].

Rift Valley Fever

RVF is caused by a virus of the family Bunyaviridae. It is primarily a zoonosis affecting domestic animals including cattle, goats, and sheep, and may cause substantial morbidity and mortality in the animals. The virus can be transmitted to humans following a bite from an infected mosquito (most commonly Aedes spp and Culex spp mosquitoes), or contact with body fluids or organs from an infected animal.  

The majority of cases of RVF are brief influenza-like illnesses; about 1% of patients will, however, develop more severe manifestations of meningoencephalitis or haemorrhagic fever.

Advice for travellers

Vigilant insect bite avoidance measures should be taken to avoid exposure to the mosquito vector. Those who may have contact with infected animals should ensure that appropriate measures are taken to prevent exposure to their blood and body fluids. Milk or meat from infected animals should be boiled or cooked. There is no commercially available vaccine for humans.

References

1. World Health Organization. Rift Valley fever in Kenya, Somalia and the United Republic of Tanzania, 9 May 2007. [Accessed 15 May 2007]. Available at: http://www.who.int/csr/don/2007_05_09/en/index.html