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habitats (semi-domesticated) [20]. The larva can grow in a
wide number of places, for example plant pots, used tyres,
water jugs, cans and many other everyday objects which
may contain even a tiny amount of water.The adult mosqui-
to shows a great preference towards humans as a source of
blood.
In America, two cycles of transmission occur: the jungle
cycle, also known as the sylvatic cycle and the urban cycle,
while in Africa we can find three:
1. The Jungle / sylvatic cycle is found in wet tropical forests
where the infected mosquitoes bite the monkeys who in turn
transmit the virus to other mosquitoes who then pass it on
to humans who are normally young woodcutters who work
in the forest.
2. The Intermediate cycle or savannah cycle: the semi-do-
mesticated mosquitoes which inhabit the forests near houses
bite humans and monkeys alike. This is the most common
form of transmission and can cause short epidemics which
can become more serious if they reach densely populated
areas.
3. The Urban cycle: the infected people spread the virus in
highly populated areas where there are a large number of Ae-
des mosquitoes as well as non-immune people, which results
in serious epidemics.The infected mosquitoes pass the virus
on from one person to another [21].
Clinical diagnosis
The incubation period lasts between three and seven days
and the illness itself lasts, where a cure is found, just one
week. After incubation, the illness may take two different
courses:
A. Light: sufferers feel arthralgia, myalgia, headache, vomi-
ting, etc., which lasts about one or three days, and clears up
without any complications.
B. Severe or classical: which includes epistaxis, bleeding of
the gums, kidney and liver failure, haematemesis with blood
vomit and ictericia, all of which lead to death in about ten to
fourteen days [22].
The diagnosis is clinical and by using very specific laboratory
tests, other diseases can be ruled out, such as the Zica, the
Bolivian fever, the Argentinean fever, Chikunguaya, Ebola as
well as malaria, dengue fever and hepatitis [11].
Treatment
There is no treatment to cure yellow fever. It is symptomatic
and treatment aims to alleviate the symptoms and to main-
tain the well-being of the patient and of course, to combat
the mosquito. Vaccination is the most important method of
prevention against yellow fever.The vaccine is safe, afforda-
ble, very efficient, and one single dose is sufficient to give
immunity and life-long protection without the need of a
booster dose. The vaccine offers an effective immunity in
99% of vaccinated people in the space of 30 days [14].
Yellow fever in the south-west
of Extremadura in the XIX century
The very first European epidemic of yellow fever occurred
in Lisbon in 1728 [23: 280]. Later other epidemics broke
out in meridional areas [24: 91]: Cadiz (1730, 1800, 1804,
1810, 1819), Málaga (1741, 1803, 1804, 1810-1812, 1821),
Barcelona (1821) and Pasajes (1823) [25: 65].
When the breakout of the yellow fever epidemic occurred
in Cadiz in 1800, a great fear of infection spread among the
population as the Peset brothers pointed out “Panic spread
all over Spain” [26: 107].
The measures adopted against yellow fever are similar to
those used against the great plague which devastated Europe
up to 1720 in Marseilles: material measures of protection
were reinforced and trading links were broken, vigilance and
closure of the city grounds took place as well as isolation of
the infected people, ports also had to be controlled, burning
of the infected peoples belongings, even prayers were said
and processions took place as well as invocations to certain
saints as the plague was considered by many to be a divine
punishment [27]. The same measures were taken when the
cholera epidemic broke out in Spain in 1833 [28].
Certain printed documents state that in 1819, the Board
of Health ordered the mayors of the towns along with the
local health authorities of each town such as that of Zafra,
not to allow people or goods coming from Seville or its sur-
rounding areas to enter the town, as yellow fever had hit
those areas and some of the streets there had been cut off.
Isolation or incommunication is one of the main measures
used to deal with the disease [29]. From the beginning of
the century, epidemics were constantly arriving from Ame-
rica due to commercial trade and bad health organization, as
well as the lack of control over the smuggling of goods [30].
Warnings were sent from Mérida to all the towns involved
to adopt the necessary defence measures in order to avoid
infection in Extremadura [31, 32].These measures included
the following:
1. Fumigation of all correspondence and mail.
2. Meticulous and continuous cleaning of the streets.
3. Setting up of a barracks in a suitable location whose pur-
pose was to fumigate the general public passing through as
well as any goods and merchandise coming from outside.
4. The establishment of a warehouse to gather merchandise
coming from infected places.
5. The establishment of another warehouse to serve as a hos-
pital for suspected diseases.
6. Banning of airing leather, skins or fur within the radius of
the town.