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INFORMATION ON RIFT VALLEY FEVER

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INFORMATION ON RIFT VALLEY FEVER Powered By Docstoc
					             VETERINARY SERVICES
             15 Wodehouse Street King William’s Town . Private Bag X0040.Bisho.5605.
             REPUBLIC OF SOUTH AFRICA Website:www.agr.ecprov.gov.za
             Tel:+27(0)43 605 4200.Fax: +27(0)43 6426987. Zoleka.ntondini@agr.ecprov.gov.za


             INFORMATION ON RIFT VALLEY FEVER


BACKGROUND ON RIFT VALLEY FEVER

Rift Valley fever (RVF) is caused by a virus carried by mosquitoes. It affects cattle, sheep
and goats and causes abortions and deaths in especially young animals. It has been
reported to affect wild ruminants as well. Symptoms in infected animals are high lamb
mortalities, abortions, icterus, bloody diarrhoea, nose bleeding, fever and deaths.
Although RVF is a zoonosis (disease of animals transmissible to humans), there is no
need for the general public to panic, as transmission to humans, in most cases, is
through the handling of sick- or dead animals, or aborted foetuses. Transmission through
un-pasteurised milk is not known, but the public is advised to only buy pasteurised milk.


Outbreaks of RVF are associated with persistent heavy rainfall, with sustained flooding
and the appearance of large numbers of mosquitoes, the main vector.

For epidemics to occur, three factors must be present:
        i)          The pre-existence or introduction of the virus in the area;
        ii)         The presence of large populations of susceptible (unvaccinated)
                    ruminants; and
        iii)        Climatic or environmental conditions that encourage a massive build-up
                    in the vector mosquito population. The latter usually occurs when there
                    are warm conditions and unusually heavy and persistent rainfalls that
                    cause surface flooding and lead to the hatching of infected Aedes spp
                    mosquito eggs and large numbers of vector mosquitoes.


South Africa has seen a re-occurrence of this disease after a long period of absence
since 1999. RVF was first seen in South Africa in 1950 and very severe outbreaks
occurred during 1955 and 1974-76. After almost no outbreaks during the 1990’s and



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                   “Prosperous and sustainable livelihoods”

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early 2000’s, RVF reoccurred in South Africa in 2008 in the Mpumalanga-, Gauteng- and
North West Provinces as small localised outbreaks. During 2009, localised outbreaks
occurred in the Kwazulu-Natal-, Mpumalanga- and in the Northern Cape Provinces.
Farmers were alerted and advised to vaccinate susceptible animals. During 2010
outbreaks were experienced country wide in almost all provinces.


RIFT VALLEY FEVER IN HUMANS


Humans can be infected with RVF if they come into contact with the blood and other body
fluids of an infected animal, or an aborted foetus. Care should be taken when handling
possibly infected material and farmers are advised to use minimum protective clothing or
contact their State Veterinarian to assist with collecting the infected material. Symptoms
in humans are flu-like symptoms including headaches, nausea, muscle pain, joint pain,
and abdominal pain. A few individuals can develop more serious complications such as
blurred vision sometimes causing permanent blindness, encephalitis, hepatic disease
and haemorrhagic fever. If someone suspects that they might have become infected with
RVF, they must consult a medical doctor. RVF cannot be spread between humans, and
human infections from mosquito bites have never been recorded in South Africa.


RVF is a notifiable animal disease, but not a controlled animal disease. Suspicion of
disease must be reported to the nearest State Veterinarian. State Veterinary Services
collates all notification for reporting purposes and is available to give support and
information to farmers in affected areas. There are no State Veterinary restrictions on
farms or areas that are affected by RVF. It remains the responsibility of the animal
owners to vaccinate their animals and prevent losses. All livestock farmers in South
Africa are advised to vaccinate all their animals yearly, or at least once during weaning
against RVF.




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PREVENTATIVE MEASURES

Rift Valley Fever is a vector borne disease and the only practical preventative measure is
the continuous vaccination of susceptible animals.


The vector control is tedious and in most instances impractical.         Mosquitoes can be
controlled chemically by applying larvacides on the breeding sites. Animals should be
moved from low-lying areas to higher altitudes.       Where possible, animals should be
stabled in mosquito-proof facilities or sprayed with a registered insect repellent.


Immunization remains the only effective method for protecting livestock. A vaccine Clone
13 is produced by the Onderstepoort Biological Product (Ltd) (OBP), and is advisable to
use as it is safe and efficacious in pregnant and lactating animals. There are two other
vaccines available namely an inactivated (or dead) vaccine which requires two injections
and annual boosters and the modified-live vaccine which may cause abortions if used in
pregnant animals. It is advisable to vaccinate animals before the start of the rainy
season.




IMPORTANT CONSIDERATIONS


The general public is urged not to handle any sick animals or cut up any dead animals or
aborted foetuses and to contact their nearest veterinarian, should abortions in a herd be
observed. Anyone handling the carcasses should be wearing protective clothes, gloves
and goggles. All suspected material including carcasses must be disposed of by burying
or burning or both.     Livestock owners are advised to contact their nearest State
Veterinarian or a private veterinarian for advice should they wish to vaccinate their
livestock. Prevention by the use of insect repellents is also advocated, if practical and
affordable.




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                                  RVF OUTBREAK PROGRAMME

Date          Activity         Places                         Officers
07-02-11      Awareness     Sotho                   Ms Xoxo,Botwana,Tywini,Ms tenge
                ‘’          Morgan’s bay/Kei        Mvabaza,Tunyiswa,Nyikana,Kobokana
                            Mouth
                  ‘’        Ngxingxolo              Manamela,Mahlathini,Qobongo,Govuza
                  ‘’        Ncalukeni               Dyibishe,Howell,Caine,Ngaka
                    ‘’      Chefane                 Majavu,Ndwayana,Mntwapi,Ntalo, Hlathi
08/09-02-11   Vaccination   Sotho                   Sihola,Tywini
                 ‘’         Morgan’s bay, Kei       Mvabaza,Tunyiswa
                            mouth
                  ‘’        Ngxingxolo              Mahlathini,Ndwayana
                  ‘’        Ncalukeni               Govuza,Hlathi
                  ‘’        Chefane                 Mqolora,Mntwapi
10-02-11      Vaccination   Slatsha                 Sihola,Tywini.
                  ‘’        Belekumntana            Mvabaza,Tunyiswa
                  ‘’        Mandela,Mzwini          Mahlathini,Ndwayana
                  ‘’        Magrangxeni             Mqolora,Mntwapi
11-02-11      Awareness     Kwelerha                Botwana,Dyibishe,Howell




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