North American Tree Rings, Climatic Extremes, and Social Disasters - Dendroclimatology - page 316

personal physician of King Phillip II. Dr. Hernandez, who was in Mexico during
the epidemic of 1576, described the symptoms of cocoliztli with clinical accuracy
and detail. The symptoms included acute fever; intense headache; vertigo; and great
effusions of blood from all body openings, especially the nose, ears, eyes, etc. Also
reported were black tongue, green urine and skin, a net-like rash, abscesses behind
the ears that invaded the neck and face, acute neurological disorder, insanity, and
frequently death in 3 or 4 days (Acuna-Soto et al. 2000 ) . Upon autopsy, the heart
was found to be black and drained yellow and black blood, the liver was enlarged,
and the lungs and spleen were semi-putrefied (Acuna-Soto et al. 2000 ) . These symp-
toms do not describe smallpox, typhus, or any other European disease known to Dr.
Hernandez, but more resemble a hemorrhagic fever such as Ebola or hemorrhagic
forms of hantavirus. The mortality during these cocoliztli epidemics reflected the
social order of sixteenth-century Mexico; deaths were highest among the native peo-
ple, then the Indian-African mestizos, the Indian-European mestizos, the Africans,
and finally even some Europeans died of this disease (Acuna-Soto et al. 2000 ) . The
severity of the epidemic may have been magnified among the native people by their
poor living conditions, poor diet, and their overwork incumbent on providing trib-
ute under the encomienda system. The geography of the 1545 and 1576 epidemics
is also interesting, indicating a preference for the highland areas of Mexico and an
absence from the warm low-lying coastal plains (Acuna-Soto et al. 2000 , 2004 ) .
Tree-ring data for Mexico during and after the sixteenth century support the
hypothesis that unusual climatic conditions may have aggravated the four worst
epidemics of cocoliztli, which began in the years 1545, 1576, 1736, and 1813. The
epidemics in 1545 and 1576 occurred during the sixteenth-century megadrought, but
all four of these most extreme cocoliztli epidemics actually occurred in wet years
following intense droughts (Figs. 10.13 and 10.14 ; Acuna-Soto, personal communi-
cation). This sequence of climatic extremes, particularly the drought years followed

Fig. 10.14 The four most
severe epidemics of cocoliztli
(hemorrhagic fever) in
Mexican history occurred in
1545, 1576, 1736, and 1813.
In each case, these epidemics
occurred in
tree-ring-estimated wet years
following severe drought.
This superposed epoch
analysis indicates that tree
growth (mean 1.0) in

Mexico was significantly
depressed 2 years prior to the
outbreak and elevated during
the year of outbreak during
these four epidemics ( ∗ = P <
0.05; ∗∗ = P < 0.01)

=