Rift Valley Fever: Kenya, Somalia and Tanzania

I recently returned from Tanzania having spent two weeks in Arusha. The headline in the Arusha Times the day after we arrived read “Fear grips town as Rift Valley Fever spreads.” The article described fear surrounding the outbreak of Rift Valley fever that had spread through Kenya and was then suspected in Arusha and surrounding areas. Had I not understood how Rift Valley Fever is spread, I may have been alarmed, as many of the residents in Arusha were. Because of the outbreak, the prices of chicken and fish became prohibitive for many people, and butchers could not give away their beef. Goat meat was even less desired, because the first two reported deaths resulting from Rift Valley fever in Tanzania were supposedly related to goat meat.

Rift Valley fever is caused by the Rift Valley virus, named for the Rift Valley of Kenya where it was first isolated in 1930. The Rift Valley fever virus (RVF virus) is a member of the Bunyaviridae family of viruses (RVF virus, Hantaan virus, Dugbe virus and Bunyamwera virus).

Rift Valley fever primarily affects livestock and can cause disease in a large number of domestic animals including cattle, sheet, goats, and camels. RVF is spread by infected mosquitos and other biting insects (animal-to-animal, animal-to-human and human-to-human). Rift Valley fever is also occasionally transmitted to humans through contact with blood, body fluids or tissues of infected animals (veterinarians, slaughter-house workers, etc.).

The risk of RVF infection associated with eating beef, goat or any other animal that may be infected with the virus is minimal, especially if the meat is properly cooked. It would seem that the fear that has affected the eating habits of residents and livelihood of numerous people associated with the meat industry is largely unwarranted.

Rift Valley fever periodically occurs in sub-Saharan Africa, but has also occurred in Egypt, the Arabian Peninsula, and Madagascar (see Map).

The outbreak of Rift Valley fever that began last fall in Kenya is believed to be on the decline. RVF has occurred in the North Eastern, Coast, Eastern, Central and Rift Valley Provinces of Kenya. As of January 30, 2007, 411 suspected cases were reported, including 121 deaths.

An outbreak of Rift Valley fever has also been reported in Somalia. As of January 30, 2007, 100 suspected cases were reported in Somalia, including 48 deaths.

Symptoms associated with RVF are mild for most people infected: fever, generalized weakness, back pain, and dizziness lasting 2-7 days. However, some patients progress to a severe hemorrhagic fever, encephalitis or ocular disease.

The risk of acquiring Rift Valley fever when traveling to an outbreak area is relative to the risk of exposure to mosquitos carrying the virus from infected animals. As there is no licensed preventive vaccine currently available, prevention involves avoiding contact with mosquitos and other blood-sucking insects! See aritcles under "related content" below for precautions against mosquito-borne diseases.

The copyright of the article Rift Valley Fever in Microbiology is owned by Judy Arbique. Permission to republish Rift Valley Fever in print or online must be granted by the author in writing.

Apr 2, 2007 12:58 PM

dodoma :

This is a good example of how microbiology spreads into other areas! We have suffered drought for some years, causing all sorts of problems but with an El nino year there is no shortage of rain. Instead of drought we get RVF from dormant Aedes mosquito eggs.
In terms of relative impact, malaria causes many more deaths than we have seen from RVF (even though many more types of mosquito transmit RVF) but the affect on peoples livelihoods has been marked. People can't sell meat or milk, have lost unborn calves and kids and so won't have meat or milk to sell in the future and are fearful of being around their animals in case they catch RVF.
Most people won't suffer unduly if they do get RVF but as usual it is the most vulnerable who suffer most - the old, malnourished and sick

Apr 2, 2007 3:01 PM

Judy Arbique :

Thank-you very much for your comments. It's great to have information from someone who has experienced the topic, although I wish the situation was different.

Perhaps the reason that malaria is much more prevalent than RVF is that overall relatively few animals are infected, with the exception of pockets of areas where there are higher infection rates.

Would you mind sharing with us where you are from?

judy

Apr 2, 2007 11:21 PM

dodoma :

Dodoma, Central Tanzania
as of two weeks ago the ministry of health reported that Dodoma region had more cases/suspected cases of RVF than the rest of the country put together. I have not got more up to date figures than this

Apr 3, 2007 9:29 AM

dodoma :

I forgot to mention yesterday. From what I have heard (not seen published) we have quite a lot of animals that have been infected (that was as specific as it got).
With malaria, a high proportion of previously unexposed children get sick and even adults who have had malaria can get it again.
With RVF only about 1% get sick enough to die and only a few 2-10% may get hospitalised. The rest will never know they have had RVF so there are a lot of infected people out there (mostly old >40 male as they are most at risk of exposure in this area, it will vary, I assume, for other areas on cultural grounds).

Apr 3, 2007 3:21 PM

Judy Arbique :

Here I thought your "name" was Dodomo, but Dodomo is actually the area where you live. For those who don't know where Dodomo is, it is a region of Tanzania, of which is the city of Domomo. Dodomo is the official capital of Tanzania as well, isn't it?

Is it likely that RVF will continue to spread from now through your hot summer as well?

Apr 11, 2007 10:31 AM

dodoma :

Yes, Dodoma is the capital of Tanzania though it is hard to believe at times! Dodoma is slap bang in the centre of the county which is very democratic as it is a far from every where as possible.

I would expect that RVF will start to tail off soon as the rains are coming to an end and so the mosquito population will start to fall soon. I have no documentary evidence for this, but it seems logical since the outbreak started as a result of the unusually heavy rain which bumped up the mosi population and woke up dormant infected mosquito eggs.
It probably also means that as water dries up many infected eggs will be laying dormant for the next 10 years when we see a repeat of El Nino.