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{{EB1911
| volume = 28
| previous = Yeisk
| next = Yellowstone National Park
| wikipedia = Yellow fever
}}<!-- p. 910 --><!-- column 2 -->
'''YELLOW FEVER''', a specific infective tropical fever, the germ
of which is transmitted by the ''Stegomyia fasciata'' or domestic
mosquito, occurring endemically in certain limited areas. The
area of distribution includes the West Indies, Mexico, part of
Central America, the W. coast of Africa and Brazil.
The first authentic account of yellow fever comes from Bridgetown,
Barbados, in 1647, where it was recognized as a " nova
pestis " that was unaccountable in its origin, except that Ligon,
the historian of the colony, who was then on the spot, connected
it with the arrival of ships. It was the same new pestilence that
Dutertre, writing in 1667, described as having occurred in the
French colony of Guadeloupe in 1635 and 1640; it recurred at
Guadeloupe in 1648, and broke out in a peculiarly disastrous
form at St Kitts the same year, and again in 1652; in 1655 it
was at Port Royal, Jamaica; and from those years onwards
it became familiar at many harbours in the West Indies and
Spanish Main. It appeared at the Brazilian ports in 1849. In
1853 it appeared in Peru and in 1820 on the W. coast of Africa.
In Georgetown (British Guiana) 69% of the garrison died in
1840.
During the great period of yellow fever (1793–1805), and for
some years afterwards, the disease found its way time after time
to various ports of Spain. Cadiz suffered five epidemics in the
i8th century, Malaga one and Lisbon one; but from 1800 down
to 1821 the disease assumed much more alarming proportions,
Cadiz being still its chief seat, while Seville, Malaga, Cartagena,
Barcelona, Palma, Gibraltar and other shipping places suffered
severely, as well as some of the country districts nearest to the
ports. In the severe epidemic at Barcelona in the summer of
1821, 5000 persons died. At Lisbon in 1857 upwards of 6000
died in a few weeks. In New Orleans 7970 people died in 1853,
3093 in 1867, and 4056 in 1878. In Rio 4160 died in 1850,
1943 in 1852, and 1397 in 1886.
Certain distinct conditions have seemed to be necessary for
an outbreak. Foremost we may notice a high atmospheric
temperature, one of 75° F. or over. As the thermometer sinks,
the disease ceases to spread. Moisture favours the spread of
yellow fever, and epidemics in the tropics have usually occurred
about the rainy season. Seaport towns are most affected.
In many instances the elevated airy and hygienic quarters of
a town may escape, while the shore districts are decimated.
Usually the disease does not spread to villages or sparsely populated
districts. Certain houses become hotbeds of the disease,
case after case occurring in them; and it is usually in houses
that the disease is contracted. A house may be said to be
infected when it contains infected mosquitoes, whether there
be a yellow-fever patient there or not. Ships become infected
in the same way, the old wooden trading ships affording an ideal
hiding-place to the ''Stegomyia'' in a way that the modern and
airy steamship does not.
The incubation period of yellow fever is generally four or five
days, but it may be as short as twenty-four hours. There are
usually three marked stages: (1) the febrile period, (2) the period
of remission or lull, (3) in severe cases, the period of reaction. The
illness usually starts with languor, chilliness, headache, and muscular
pains, which might be the precursors of any febrile attack.
These are followed by a peculiar look of the eyes and face,
which is characteristic: the face is flushed, and the eyes suffused
at first and then congested or ferrety, the nostrils and lips red,
and the tongue scarlet—these being the most obvious signs of<!-- p. 911 -->
universal congestion of the skin, mucous membranes and organs.
Meanwhile the temperature has risen to fever heat, and may reach
a very high figure (maximum of 110° Fahr., it is said); the
pulse is quick, strong and full, but may not keep up in these
characters with the high temperature throughout. There are
all the usual accompaniments of high fever, including hot skin,
failure of appetite, thirst, nausea, restlessness and delirium
(which may or may not be violent); albumen will nearly always
be found in the urine. The fever is continued; but the febrile
excitement comes to an end after two or three days. In a certain
class of ambulatory or masked cases the febrile reaction may
never come out, and the shock of the infection after a brief
interval may lead unexpectedly and directly to prostration and
death. The cessation of the paroxysm makes the ''stadium'', or
lull, characteristic of yellow fever. The hitherto militant or
violent symptoms cease, and prostration or collapse ensues.
The internal heat falls below the normal; the action of the
heart (pulse) becomes slow and feeble, the skin cold and of a
lemon-yellow tint, the act of vomiting effortless, like that of an
infant, the first vomit being clear fluid, but afterwards black from
an admixture of blood. It is at this period that the prospect
of recovery or of a fatal issue declares itself. The prostration
following the paroxysm of fever may be no more than the weakness
of commencing recovery, with copious flow of urine, which
even then is very dark-coloured from the presence of blood.
The prostration will be all the more profound according to the
height reached by the temperature during the acute paroxysm.
Much blood in the vomit and in the stools, together with all other
hemorrhagic signs, is of evil omen. Death may also be ushered
in by suppression of urine, coma and convulsions, or by fainting
from failure of the heart. In severe types of the disease an
apoplectic, an algid and a choleric form have been described.
The case mortality averages from 12 to 80%. In Rio in 1898
it reached the appalling height of 94.5%. In cities where it is
endemic the case mortality is usually lower. In 269 cases
observed by Sternberg, the mean mortality was 27.7%. In
158 cases of yellow fever in Vera Cruz in 1905 there were 91
deaths. The death-rate, however, tends to vary in different
epidemics. In the epidemic occurring in Zacapa, Mexico, in 1905
in a population of 6000 there were 700 cases, and the mortality
among the infected was 40%.
''Treatment''.—The patient should be removed from the focus of
infection and nursed in a well-ventilated room, screened from
mosquitoes. The further treatment is symptomatic. A purgative,
followed by hot baths, is useful in the early stages to relieve
congestion, high temperature may be controlled by sponging;
vomiting, by ice; or, if hemorrhagic, by ergot, per chloride of iron
or other styptics; and pilocarpine may be given if the urine be
scanty. Sternberg has introduced a system of treatment by
alkalis to counteract the hyper acidity of the intestinal contents
and increase the flow of urine. Of 301 whites treated by this
method only 7.3% died, and of 72 blacks all recovered.
''Causation''.—The pathology of the disease is discussed in
the article {{EB1911 article link|Parasitic Diseases}}. In 1881 Dr Charles Finlay,
of Havana, propounded the theory that mosquitoes were the
carriers of the infection. Numerous theories had previously
been brought forward, notably that of the ''Bacillus icteroides'',
described by Sanarelli; but it is now certain that this organism
is not the cause. Other authorities held that the disease was
spread by contagion, by miasmata, or some other of the vague
agencies which have always been put forward in the absence of
exact knowledge. Finlay's mosquito theory remained in abeyance
until attention was again drawn to it by the demonstration
in recent years of the part played by these insects in the causation
of other tropical diseases. The mosquito selected by Finlay
was the ''Stegomyia fasciata'', a black insect with silvery markings
on the thorax, which is exceedingly common in the endemic
area. It frequents towns, and breeds in any stagnant water
about houses. Specimens were caught, fed upon yellow-fever
patients, kept for a fortnight, and then allowed to bite susceptible
persons established in a special camp with other susceptible
persons as a control. Those bitten developed the fever, the<!-- column 2 -->
others did not. An American commission was appointed in
1900, consisting of Walter Reed, James Carroll, A. Agramonte
and Lazear, and its conclusions were: that the ''Stegomyia''
''fasciata'' is the agent of infection, that the virus of yellow fever
is present in the blood during the first three days of the fever,
and is generally absent on the fourth; that the germ is so small
that it can pass through a Chamberland porcelain filter; that
the bite of all infected ''Stegomyia'' does not produce yellow fever
(about 35% of the experiments proving negative); that mosquitoes
fed on yellow-fever blood were not capable of giving rise
to infection until after a lapse of twelve or fourteen days, but the
insects retained their infective power for at least fifty-seven
days. It can therefore be concluded that the virus of yellow
fever is a parasite, requiring as in malaria an alternate passage
through a vertebrate and an insect host, the analogy to malaria
being very complete. E. Marchoux and P. L. Simond, of the
French Yellow Fever Commission to Rio de Janeiro, 1906, have
observed an interesting fact in connexion with the ''S. fasciata''.
In order to lay her eggs she must first have a feed of blood, three
days after which she lays them. Before she lays her eggs she
strikes both day and night, after that period at night only.
Persons bitten in the day-time, therefore, do not develop yellow
fever, while those bitten at night do. This may explain the
impunity with which Europeans may visit an infected district
in the day-time provided that they are careful not to sleep there
at night. It was stated by Marchoux and Simond that an
infected mosquito transmits the parasite to her eggs, the progeny
proving infective.
''Prophylaxis''.—Following on the publication of these experiments
there was instituted a vigorous campaign against mosquitoes
in Havana in 1901, based on the methods applied to the
suppression of malaria, and carried out under the direction of
Major W. C. Gorgas of the United States army, chief sanitary
officer of Havana. The work was begun on the 27th of February
1901. An order was issued that all receptacles containing water
were to be kept mosquito-proof; sanitary inspectors were told off
for each district to maintain a constant house-to-house inspection,
and to treat all puddles, &c., with oil; receptacles found to contain
larvae were destroyed and their owners fined; breeding-grounds
near the town were treated by draining and oil; hospitals
and houses containing yellow-fever patients were screened;
infected and adjacent buildings were fumigated with pyrethrum
powder. The results exceeded all expectation, and after January
1902 the disease entirely ceased to originate in Havana.
Cases occasionally now come into Havana from Mexican ports, but
are treated under screens with impunity in ordinary city hospitals
and never at any time infect the city. Thus in 1907 there was
one death from yellow fever, and the general death-rate of Havana
from all diseases was 17 per thousand. In the ''Bulletin of Public''
''Health and Charities of Cuba'' it is stated there only occurred
between 19059 a total of 345 cases of yellow fever in all Cuba,
where formerly they numbered many thousands, and in April
1910 the republic was declared to be entirely free from the
disease.
Among other modern outbreaks in which sanitary measures have
triumplied in the suppression of yellow fever were the outbreak in
New Orleans in 1905, in which a medical staff of 50 with subordinates
to the number of 1203 started immediately on the outbreak
to clean up the city; the outbreak in Belize, British Honduras, in
1905; the anti-yellow-fever campaign undertaken in the British
W. Indies in 1906-9. As soon as the Isthmian Canal commissioners
took over the administration of the Panama Canal Zone they
undertook a vigorous campaign against the mosquito, as the result
of which yellow fever was successfully banished. Colonel Gorgas
in his 1908 report wrote: " It is now three years since a case
of yellow fever has developed in the Isthmus, the last being in
November 1905."
Rio de Janeiro, which had lost 28,078 inhabitants in 13 years by
yellow fever, and Santo, have also waged war against the disease;
as a result of the anti-''Stegomyia'' policy the deaths from yellow
fever in Rio fell to 42 in 1906, 39 in 1907, 4 in 1908, and 0 in 1909.
See Sir P. Manson, ''Tropical Diseases'' (1907); article "Yellow Fever"
in Allbutt and Rolleston's ''System of Medicine'': Sir R. Boyce, ''Report''
''on Yellow Fever in Honduras'' (1906). and ''Health and Administration''
''in the West Indies'' (1910); ''Bulletins of the U.S. Yellow Fever Institute'';
''Annales de I'Institut Pasteur'' (January 1906).
{{DEFAULTSORT:Yellow Fever}}
[[Category:EB1911:Science:Medicine]]