Louse Infestation of the Chiribaya Culture, Southern Peru: Variation in Prevalence by Age and Sex

Abstract

In order to improve the interpretive potential of archaeoparasitology, it is important to demonstrate that the epidemiology of ancient parasites is comparable to that of modern parasites. Once this is demonstrated, then we can be secure that the evidence of ancient parasitism truly reflects the pathoecology of parasitic disease. Presented here is an analysis of the paleoepidemiology of Pediculus humanus infestation from 146 mummies from the Chiribaya culture 1000-1250 AD of Southern Peru. The study demonstrates the modern parasitological axiom that 10% of the population harbors 70% of the parasites holds true for ancient louse infestation. This is the first demonstration of the paleoepidemiology of prehistoric lice infestation.

Full text

173Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 98(Suppl. I): 173-179, 2003
Louse Infestation of the Chiribaya Culture, Southern Peru:
Variation in Prevalence by Age and Sex
Karl J Reinhard/
+
, Jane Buikstra*
School of Natural Resource Sciences, University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 685-0340 USA
*Department of Anthropology, University of New Mexico, Albuquerque, New Mexico, USA
In order to improve the interpretive potential of archaeoparasitology, it is important to demonstrate that the
epidemiology of ancient parasites is comparable to that of modern parasites. Once this is demonstrated, then we can
be secure that the evidence of ancient parasitism truly reflects the pathoecology of parasitic disease. Presented here
is an analysis of the paleoepidemiology of Pediculus humanus infestation from 146 mummies from the Chiribaya
culture 1000-1250 AD of Southern Peru. The study demonstrates the modern parasitological axiom that 10% of the
population harbors 70% of the parasites holds true for ancient louse infestation. This is the first demonstration of
the paleoepidemiology of prehistoric lice infestation.
Key words: Pediculus humanus - pathoecology - paleoepidemiology - archaeoparasitology - Peru
In archaeoparasitology, as with any field of parasitol-
ogy, interpretive strength is based on reliable analysis of
large numbers of observations. For those of us depen-
dent on archaeological excavations, the biggest challenge
is obtaining large numbers of observations. Often times
factors of preservation, field sampling conditions, and
other aspects of archaeology reduce the number of ob-
servations to a handful of data points. This in turn limits
the strength of interpretations about prehistoric infec-
tions, infestations and health.
Dr Jane Buikstra’s Programa Contisuyo excavations
in the Moquegua Valley of Southern Peru offered the op-
portunity to collect archaeoparasitology data from a large
series of mummies. During dissection of the mummies, we
noted the presence of louse nits and eggs in the hair and
realized that a survey of the mummies for nits and eggs
would provide an unparalleled source of intersite com-
parative data. We examined 146 mummified or partially
mummified individuals from the sites of San Geronimo,
Chiribaya Alta, Algodonal, and El Yaral.
MATERIALS AND METHODS
During the month of August, 1990, we collected data
on louse parasitism for every individual that had been
dissected to date and could be located in the Ilo Programa
Contisuyo Laboratory from the sites of Chiriabya Alta,
Algodonal, El Yaral and San Geronimo. One problem that
we encountered was that many of the mummies had al-
ready been dissected and cleaned. Therefore, it was not
possible to quantify all of the infestations. Of 164 indi-
viduals from all sites, we located 146 and examined them
for lice nits/eggs. Not every specimen was acceptable for
study. Some individuals had hair or scalp tissue that was
+
Corresponding author. Fax: +402-472.6858. E-mail:
kreinhard1@unl.edu
Received 26 August 2002
Accepted 25 November 2002
too poorly preserved for analysis. These individuals were
so noted in the field to prevent their inclusion in later
comparative analysis (Table I). Because examination of
hair did not require dissection, it was possible to analyze
several mummies from El Yaral as they were unwrapped.
The technique improvised for this study was based
on the examination of the hair bases at the scalp (referred
to subsequently as scalp measurements) and hair shafts
located several inches away from the scalp (referred to
subsequently as hair measurements). The scalps were
examined to identify areas of maximum nit density and
minimum nit density. Maximum density usually was on
the parietal area, and in the area above and behind the
ears. A 2 x 2 cm square was cut into a cardboard strip.
The cardboard strip was then placed on the identified
areas and all nits/eggs within the 2 x 2 cm area were
counted. Three observations were taken for each area of
scalp minimum density and scalp maximum density (Table
II). The hair was also examined for areas of minimum and
maximum nit/egg density. An optimal distance of 5 inches
from the scalp was preferred, but in some cases, observa-
tions were made 4-6 cm from the scalp when the hair was
not well preserved at 10 cm. The cardboard strip was then
placed on the identified areas and all nits/eggs within the
2 x 2 cm area were counted.
RESULTS
Of 146 individuals examined, not all were sufficiently
preserved for analysis (Table I). In some cases, the scalp
was poorly preserved but the hair was well preserved.
More rarely, the hair was poorly preserved or absent, but
the scalp was well preserved. A few individuals exhibited
poor preservation of scalp and hair. The San Geronimo
individuals especially exhibited poor preservation of the
hair and scalp tissue. Consequently, this site had to be
dropped from comparative study because of poor over-
all preservation.
Generally, individuals who had lice nits/eggs on the
scalp had louse nits/eggs on the hair. From all 4 sites, 75
mummies had both scalp and hair present. Twenty (27%)
individuals had nits/eggs on the hair immediately adja-

174 Chiribaya Louse Infestation  KJ Reinhard, J Buikstra
TABLE I
Provenience and condition of individuals examined for louse infestation. Asterisks indicate individuals whose scalp or hair was
too poorly preserved for study. Chiribaya Culture mummies, Peru
324-3751 -* No hair, no scalp
320-3792 No* Small hair fragments, no scalp
728-2743 -* No hair, no scalp
610-2291 -* No hair, no scalp
318-3477 Yes Scalp and hair present
609-2079 No Scalp and hair present
746-2970 No Scalp and hair present
437-3947 Yes Hair present, no scalp
439-3955 Yes Scalp present, no hair
328-3757 -* Not located for study
241-3545 -* Not located for study
328-3759 No Hair present, no scalp
302-1012 No Scalp and hair present
16-286 -* No hair, no scalp
327-3756 -* No hair, no scalp
401-1206 -* No hair, no scalp
901-2059 Yes Scalp and hair present
304-1068 Yes Scalp and hair present
428-2642 Yes Scalp and hair present
313-1155 No Scalp and hair present
313-1252 No Scalp and hair present
326-3754 Yes Scalp and hair present
313-1252 No Scalp and hair present
714-1766 Yes Scalp and hair present
307-1128 No Hair present, no scalp
326-3754 Yes Scalp and hair present
305-1079,10 Yes Hair present, no scalp
305-1079,06 No Hair present, no scalp
321-1174-A No Hair present, no scalp
321-1174-B No Scalp and hair present
429-3911 No Scalp and hair present
502-1671 No Hair present, no scalp
402-1219 No Hair present, no scalp
415-3364 No Scalp and hair present
615-1369 No Scalp and hair present
436-3941 No Hair present, no scalp
718-2016 No Hair present, no scalp
758-3274 No Hair present, no scalp
702-1443 No Hair present, no scalp
740-2705 No Scalp and hair present
704-1487 No Hair present, no scalp
229-2314 Yes Scalp and hair present
10-147 Yes Scalp and hair present
1-60 No Hair present, no scalp
512-1866 -* Not located for study
608-2026 -* No hair, no scalp
101-2051 -* No hair, no scalp
317-1173 Yes Scalp and hair, hair cut
38-251 -* No hair, no scalp
21-222 No Scalp and hair
907-2169 -* Not located for study
322-3495 -* Not located for study
331-3854 -* Not located for study
329-3765 -* Not located for study
211-2225 -* Not located for study
303-1028 -* not located for study
7-151 -* not located for study
240-2815 -* Not located for study
755-3251 -* Not located for study
Nits/eggs
Provenience Present? Condition
Algodonal
T-330-1 Yes Scalp and hair present
T-342 Yes Scalp and hair present
T-338 Yes Scalp and hair present
T-388-2-1 No Scalp and hair present
T-521-16-2 Yes Scalp and hair present
T-369-1-1 No Scalp and hair present
T-526-1-1 Yes Scalp and hair present
San Geronimo
92-4032 No* Scalp and hair fragments
30-2020 No* Single braid, no scalp
30-2363 No* Some hair present, no scalp
30-2365 No* Some hair present, no scalp
8- 459 Yes* Some hair present, no scalp
24- 862 No* Some hair present, no scalp
84-3575 No* Some hair present, no scalp
84-2067 No* Small hair fragments, no scalp
84-1585 No* Small hair fragments, no scalp
84- 128 No* Small hair fragments, no scalp
84-1391 No* One small braid, no scalp
El Yaral
142-10218 No Scalp and hair present
238-10563 No Scalp and hair present
131-10166 No Scalp and hair present
107-10033 No Scalp and hair present
206-10296 No Scalp and hair present
134-10178 No Scalp and hair present
109-10047 No* Small hair fragments only
231-10461 No Scalp and hair present
203F-10592 No Scalp and hair present
101F-10024 Yes Scalp and hair present
116-10088 Yes Scalp and hair present
247-10594 No Scalp and hair present
137-10200 No Hair present, no scalp
236-10560 No Scalp and hair present
101F-10024 Yes Scalp and hair present
234-10485 No Scalp and hair present
233-10480 No Scalp and hair present
246-10593 Yes Scalp and hair present
243-10566 No Scalp and hair present
229-10427 No Scalp and hair present
225-10441 No Scalp and hair present
216-10360 No Scalp and hair present
219-10369 No Scalp and hair present
Chiribaya Alta
217-2247 No* Scalp fragments only
325-3763 Yes Hair present, no scalp
516-1926 Yes Scalp and hair present
322-3495 -* Not located for study
802-1371 -* Scalp and hair matted,
uncountable
322-3495 No No hair, scalp fragmentpresent
711-1604 No Scalp and hair present
211-11 Yes Scalp and hair present
11-222 Yes Scalp and hair present
755-3251 No Scalp and hair present
416-3398 No Scalp and hair present
907-2169 No Scalp and hair present
Nits/eggs
Provenience Present? Condition
99

175Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 98(Suppl. I), 2003
cent to the scalp and on the hair away from the scalp, 4
(5%) had nits/eggs on the hair only, and 9 (12%) had nits/
eggs on the scalp hairs only. In general, there was a ten-
dency for maximum density of nits/eggs to decrease from
the scalp to the hair away from the scalp. Twenty (27%)
individuals had fewer nits/eggs on the hair in comparison
to the scalp, and 11 (17%) showed more nits/eggs on the
hair than on the scalp.
Only seven individuals from Algodonal were avail-
able for field analysis. Of these, 5 (71%) were infested
with lice. From El Yaral, 22 individuals were available and
were sufficiently preserved for analysis. Of these, 4 (18%)
were infested. From Chiribaya Alta, 69 individuals could
be studied of which 25 (36%) were infested. Statistical
significance in prevalence beyond the 0.05 level is present
in El Yaral-Algodonal and Alta-Algodonal comparison (χ
2
= 9.742, 0.005 > P > 0.001 and χ
2
= 4.933, 0.05 > P > 0.025
respectively). Significance at the near 0.05 level is evi-
dent in the El Yaral-Chiribaya Alta comparison (χ
2
= 3.403,
0.10 > P > 0.05). Therefore, louse prevalence is signifi-
cantly variable between sites (Table III). Sex is a variable
that can affect parasite prevalence (Table III). The sites
were pooled for this comparison. Of 21 women, 8 (38%)
were infested. Of 18 men, 10 (56%) were infested. This
difference is not statistically different at the 0.05 probabil-
ity level (χ
2
= 1.995, 0.25 > P > 0.10). There was variation
between adults and children. Of 49 subadults from
Chiribaya Alta and El Yaral, 12 (24%) show infestation. Of
43 adults, 19 (44%) show infestation. The difference is
statistically significant beyond the 0.05 confidence inter-
val (χ
2
= 4.907, 0.05 > P > 0.025).
The scalp maximum nit/egg densities (column 1 in
Table II) are insightful with regard to parasitism at or
around the time of death for the individuals under study.
We believe that this provides a better idea of how many
active louse infestations occurred in the population as
opposed to measurements from the hair shafts which in-
festations represent several months before death. An
examination of the distribution of infection (Fig. 1) shows
that the louse nits/eggs are not evenly distributed in the
human host population. Most individuals were not in-
fected or had small numbers of eggs/cm
2
of scalp. Only a
few individuals were heavily infected. For all of the sites,
194 nits/eggs were observed. Of these, 118 (61%) were
observed on 5 (6%) of the mummies. For the site with the
largest sample size, Chiribaya Alta, 95 nits/eggs were ob-
served. Of these, 70 (74%) were found on 5 (4%) of the
mummies.
The mean maximum louse density also varied per site.
The highest mean maximum density of 8.9 nits/eggs/cm
2
was found for Algodonal. The mean maximum density for
Chiribaya Alta and El Yaral were 1.7 and 1.73 nits/eggs/
cm
2
respectively. The value for all sites was 2.28 nits/
eggs/cm
2
. The mean maximum nit/egg density varied be-
tween children, men and women. Children had a mean
maximum value of 0.8 nits/eggs/cm
2
as opposed to 2.6 for
women and 3.5 for men.
The highest concentrations occurred among adults.
Among the adults, infestation was limited to 31 (34%) of
92 people in the sample. Of those people infested, most
have a mean maximum scalp value of 1 nit/cm
2
or less. We
consider a mean maximum density of 5 nits/eggs/cm
2
or
more to represent heavy infestations. Only 8 individuals
had heavy infestations which ranged from mean maximum
scalp value of 5 nits/eggs/cm
2
to 22 nits/eggs/cm
2
. Of
the total number of nits/eggs counted in the study, 69%
were found on these eight individuals who make up only
9% of the 92 individuals studied.
DISCUSSION
In modern parasitology, it is axiomatic that 10% of the
hosts will harbor 70% of the parasites. These numbers
are approximated in the data for El Yaral and Chiribaya
Alta. For El Yaral, 84% of the parasites found in the 2
(10%) of the most heavily infested mummies. For Chiribaya
Alta, 74% of the parasites were observed on 5 (9%) of the
most heavily infested mummies (Figs 1, 2). Statistically,
these are the most important points that come from this
analysis. This demonstrates that it is possible to retrieve
paleoepidemiological data from archaeoparasitology stud-
ies that approximate the modern world. This is an essen-
tial basis for going on to more fine-tuned paleoepidemio-
logical interpretations.
Several basic points can be distilled from Table III.
First of all, there is significant variation between the sites
in the percentage of mummies infested (Fig. 3). This indi-
cates that the pathoecology of the sites was variable.
1-35 -* Not located for study
763-3468 -* Not located for study
416-3398 -* Not located for study
308-1130 No Hair present, no scalp
804-1383 No Scalp and hair present
14-175 Yes Scalp and hair present
21-246 Yes Scalp and hair present
850-1391 Yes Scalp and hair present
1-120 No Scalp and hair present
30-316 No Scalp and hair present
3-93 Yes Scalp and hair present
17-319 Yes Scalp and hair present
809-1405 Yes Scalp and hair present
705-1502 Yes Scalp and hair present
707-1563 -* No scalp, no hair
407-1304 Yes Scalp and hair present
411-1354 No Scalp and hair present
706-1546 No Scalp and hair present
301-1000 No Scalp and hair present
309-1132 No Scalp and hair present
504-1700 Yes Scalp and hair present
1-1213 No Scalp and hair present
717-1771 -* No scalp, no hair
702-1443 No Scalp and hair present
806-1396 Yes Scalp and hair present
714-1766 No Hair present, no scalp
712-1644 No Hair present, no scalp
704-1487 No Hair present, no scalp
803-1380 -* Not located for study
510-1850 -* Not located for study
412-1364/1365 No Hair present, no scalp
Nits/eggs
Provenience Present? Condition

176 Chiribaya Louse Infestation  KJ Reinhard, J Buikstra
TABLE II
Louse nit counts from specified individuals. Three observations were taken for four categories, scalp maximum density, scalp
minimum density, hair maximum density, and hair minimum density. Observations are presented in terms of number of nits/eggs
present per 2 x 2 cm areas. Chiribaya Culture mummies, Peru
Provenience Scalp Max Scalp Min Hair Max Hair Min Sex
Algodonal
T-330-1 10/12/4 0/0/0 0/0/0 0/0/0 ?
T-342 1/1/1 0/0/0 1/1/1 0/0/0 ?
T-338 50/25/58 4/10/9 8/10/12 3/3/1 ?
T-388-2-1 0/0/0 0/0/0 0/0/0 0/0/0 ?
T-521-16-2 3/2/1 0/0/0 3/4/5 0/0/0 ?
T-369-1-1 0/0/0 0/0/0 0/0/0 0/0/0 ?
T-526-1-1 6/11/1 0/0/0 1/2/3 0/0/0 ?
El Yaral
142-10218 0/0/0 0/0/0 0/0/0 0/0/0 S
238-10563 0/0/0 0/0/0 0/0/0 0/0/0 S
131-10166 0/0/0 0/0/0 0/0/0 0/0/0 E
107-10033 0/0/0 0/0/0 0/0/0 0/0/0 G
206-10296 0/0/0 0/0/0 0/0/0 0/0/0 S
134-10178 0/0/0 0/0/0 0/0/0 0/0/0 S
231-10461 0/0/0 0/0/0 0/0/0 0/0/0 S
203F-10592 0/0/0 0/0/0 0/0/0 0/0/0 S
101F-10024 14/12/0 0/0/0 1/0/0 0/0/0 S
101F-10024 1/6/7 0/0/0 0/0/0 0/0/0 S
116-10088 24/29/14 0/0/0 9/1/1 0/0/0 G
247-10594 0/0/0 0/0/0 0/0/0 0/0/0 S
137-10200 0/0/0 0/0/0 0/0/0 0/0/0 S
236-10560 0/0/0 0/0/0 0/0/0 0/0/0 S
234-10485 0/0/0 0/0/0 0/0/0 0/0/0 E
233-10480 0/0/0 0/0/0 0/0/0 0/0/0 ?
246-10593 2/0 0/0/0 0/0/0 0/0/0 G
243-10566 0/0/0 0/0/0 0/0/0 0/0/0 S
229-10427 0/0/0 0/0/0 0/0/0 0/0/0 G
225-10441 0/0/0 0/0/0 0/0/0 0/0/0 G
216-10360 0/0/0 0/0/0 0/0/0 0/0/0 S
219-10369 0/0/0 0/0/0 0/0/0 0/0/0 S
Chiribaya Alta
325-3763 —— —— 3/1/1 0/0/0 E
516-1926 2/3 0/0/0 2/2/4 0/0/1 S
711-1604 0/0/0 0/0/0 0/0/0 0/0/0 S
211-2225 10/17/13 1/0/0 4/5/1 0/0/0 E
21-222 1/1/1 0/0/1 0/0/1 0/0/1 S
755-3251 0/0/0 0/0/0 0/0/0 0/0/0 S
416-3398 0/0/0 0/0/0 0/0/0 0/0/0 ?
907-2169 0/0/0 0/0/0 0/0/0 0/0/0 E
318-3477 0/0/0 0/0/0 1/2/3 0/0/0 G
609-2079 0/0/0 0/0/0 0/0/0 0/0/0 G
746-2975 0/0/0 0/0/0 0/0/0 0/0/0 E
437-3947 —— —— 3/2/1 0/0/0 G
439-3955 6/0/0 0/0/0 0/0/0 0/0/0 S
328-3759 —— —— 0/0/0 0/0/0 S
302-1012 0/0/0 0/0/0 0/0/0 0/0/0 E
901-2059 9/3/3 0/0/0 22/6/4 0/0/0 E
304-1068 1/0/0 0/0/0 1/0/0 0/0/0 G
428-2642 1/0/0 0/0/0 0/0/0 0/0/0 S
313-1155 0/0/0 0/0/0 0/0/0 0/0/0 S
313-1252 0/0/0 0/0/0 0/0/0 0/0/0 S
326-3754 2/7/3 1/1/1 0/0/0 0/0/0 S
313-1252 0/0/0 0/0/0 0/0/0 0/0/0 S
714-1766 0/0/0 0/0/0 0/0/0 0/0/0 S
307-1128 —— —— 0/0/0 0/0/0 S
326-3754 10/6/7 3/5/3 0/0/0 0/0/0 S
305-1079,10 —— —— 1/1/1 0/0/0 E
305-1079,06 —— —— 0/0/0 0/0/0 S
9

177Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 98(Suppl. I), 2003
321-1174-A3494 0/0/0 0/0/0 0/0/0 0/0/0 E
321-1174-B3494 0/0/0 0/0/0 0/0/0 0/0/0 E
429-3911 0/0/0 0/0/0 0/0/0 0/0/0 S
502-1671 —— —— 0/0/0 0/0/0 G
402-1219 —— —— 0/0/0 0/0/0 E
415-3364 0/0/0 0/0/0 0/0/0 0/0/0 G
615-1369 0/0/0 0/0/0 0/0/0 0/0/0 S
436-3941 0/0/0 0/0/0 0/0/0 0/0/0 S
718-2016 0/0/0 0/0/0 0/0/0 0/0/0 S
758-3274 0/0/0 0/0/0 0/0/0 0/0/0 S
702-1443 0/0/0 0/0/0 0/0/0 0/0/0 S
740-2705 0/0/0 0/0/0 0/0/0 0/0/0 G
704-1487 0/0/0 0/0/0 0/0/0 0/0/0 S
229-2314 3/5/1 0/0/0 0/0/0 0/0/0 S
10-147 34/12/16 1/1/1 1/2/1 0/0/0 E
1-60 —— —— 0/0/0 0/0/0 E
317-1173 14/26/15 9/13/2 —— —— G
11-222 0/0/0 0/0/0 0/0/0 0/0/0 S
308-1130 —— —— 0/0/0 0/0/0 E
804-1383 0/0/0 0/0/0 0/0/0 0/0/0 S
14-175 1/1/1 0/0/0 4/3/1 0/0/0 G
21-246 0/0/1 0/0/0 5/5/3 0/0/0 S
850-1391 1/0/1 0/0/0 3/4/3 0/0/0 E
1-120 0/0/0 0/0/0 0/0/0 0/0/0 S
30-316 0/0/0 0/0/0 0/0/0 0/0/0 E
3-93 1/1/1 0/0/0 0/0/0 0/0/0 E
17-319 0/0/0 0/0/0 1/1/1 0/0/0 G
809-1405 2/2/1 0/0/1 1/0/0 0/0/0 S
705-1502 1/3/1 0/0/0 1/1/1 0/0/0 E
407-1304 8/17/4 2/5/2 3/0/3 0/0/0 G
411-1354 0/0/0 0/0/0 0/0/0 0/0/0 E
706-1546 0/0/0 0/0/0 0/0/0 0/0/0 S
301-1000 0/0/0 0/0/0 0/0/0 0/0/0 E
309-1132 0/0/0 0/0/0 0/0/0 0/0/0 S
504-1700 0/0/0 0/0/0 3/1/0 0/0/0 G
1-1213 0/0/0 0/0/0 0/1/0 0/0/0 S
702-1443 0/0/0 0/0/0 0/0/0 0/0/0 S
806-1396 1/0/1 0/0/0 3/2/1 0/0/0 S
714-1766 0/0/0 0/0/0 0/0/0 0/0/0 S
712-1644 —— —— 0/0/0 0/0/0 S
704-1487 —— —— 0/0/0 0/0/0 S
412-1364/1365 —— —— 0/0/0 0/0/0 G
S: subadult; E: adult female; G: adult male
Provenience Scalp Max Scalp Min Hair Max Hair Min Sex
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7 8 9 101112131415161718192021
Fig. 1: the distribution of mummies by infection category for
Chiribaya Alta. The X-axis is the mean maximum egg/nit counts
from the scalp. The Y-axis shows the percentage of mummies that
occur in each category. As can be seen, the largest percentage of
mummies had no lice nits or eggs.
0
5
10
15
20
25
0123456789101112131415161718192021
Fig. 2: the percentage of louse observations by infection category
for Chiribaya Alta. The X-axis is the mean maximum egg/nit counts
from the scalp. The Y-axis shows the percentage of louse egg/nit
observations made for each category. As can be seen, the largest
percentage of louse observations came from the few mummies that
were heavily infected.

178 Chiribaya Louse Infestation  KJ Reinhard, J Buikstra
Second, males are more commonly infested than females
at all sites. At Chiribaya Alta, adult females are more
commonly infested than children. At El Yaral, children are
more often infested than women.
Lice are easily transmitted from person to person and
crowding results in higher prevalence. Therefore, Pedicu-
lus humanus tells us something of the nature of the life
conditions between the two villages of Chiribaya Alta
and El Yaral. The prevalence per site for P. humanus is
plotted in Fig. 3. The prevalence is markedly different
between Yaral and Chiribaya Alta. This indicates that the
inhabitants of Chiribaya Alta were more crowded and
therefore at greater risk of exposure and reexposure than
those of El Yaral.
The Chiribaya were certainly host to head lice. The
lice must have been a source of considerable discomfort.
P. humanus is a species of anopluran lice, commonly called
sucking lice. The common name refers to their mode of
feeding which is by ingesting blood. Their mode of ob-
taining a blood meal is termed solenophagia. Solenophagic
arthropods push their mouth parts directly into blood
vessels to obtain blood. The mouth parts are modified
into piercing stylets which work in a way analogous to a
hypodermic needle. The bites of the louse cause a local-
ized, pruritic response which in turn elicits scratching.
The scratching can lead to dermatitis. Secondary infesta-
tion could also be a problem. After years of exposure, the
scalp becomes thickened and discolored. This condition
is commonly known as vagabond’s disease. Further ex-
amination of Chiribaya crania may show that many indi-
viduals suffered from dermatitis.
Individual 802-1371 may reflect the extreme develop-
ment of pediculosis: plica polonica. In the case of plica
polonica, the hair becomes matted with exudate and fun-
gus grows in the mass. Individual 802-1371 exhibited hair
that was matted in scab-like material and perhaps was
badly effected by lice.
Unfortunately, the hair was so matted on this indi-
vidual that it was impossible to examine the scalp for the
proliferation of lice that accompany plica polonica with-
out destroying the integrity of the specimen.
Men had a higher infestation prevalence than women.
This is because men more commonly had elaborate hair
styles that covered the scalp in braids (Fig. 4). Shielded
by these hair styles, the lice might find more hospitable
hosts on men. The men’s braided hair was remarkably
clean. It is likely that Chiribaya men had more lice for the
same reasons as modern girls who are more commonly
infested because long, clean hair promotes louse infesta-
tion.
TABLE III
Prevalence of infestation between main study sites. Chiribaya Culture mummies, Peru
Prevalence in % Algodonal El Yaral Chiribaya Alta All sites
All mummies 71% 18% 36% 35%
Male mummies n.a. 60% 62% 56%
Female mummies n.a. 0% 42% 38%
Child mummies n.a. 14% 29% 24%
Fig. 4: braided hair styles typical of Chiribaya men, Chiribaya Cul-
ture, Peru. Women and children had simple, straight, unbraided
hair.
Considering the annoyance lice must have caused to
Chiribayans, they must have had some technological and
hygienic tools to minimize louse proliferation. It is pos-
sible that the lice were controlled by mutual grooming
0
10
20
30
40
50
60
70
80
Algodonal Chiribaya Alta El Yaral
Fig. 3: the percentage of mummies infected from the three main
sites, Chiribaya Culture, Peru. As can be seen by this gross compari-
son, the prevalence of infection varied markedly between the sites.

179Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 98(Suppl. I), 2003
accompanied by eating the lice, as is common among many
tribal peoples. Artifactual evidence bears on the ques-
tion. We noticed comb-like tools buried with some indi-
viduals (Fig. 5). These may have been used for weaving.
However, the presence of these artifacts shows that the
Chiribaya had the technology to make combs. A few indi-
viduals had a decreased density of scalp nits/eggs in com-
parison to hair measurements. This suggests that louse
infestation could be controlled and decreased by hygienic
measures. Individuals 901-2059, 14-175, 21-46, 850-1391,
and 4-1700 show decreasing louse density from the hair
to the scalp. This indicates that these individuals were
reducing their louse infestations. When louse infesta-
tion became extreme, a technique of last resort must have
been cutting off the hair. One male, 317-1173, had an amaz-
ing density of louse nits/eggs. He did not exhibit the
highest maximum density of lice, but he did exhibit a rela-
tively high minimum density. Every square centimeter of
scalp had louse nits or eggs. The range of maximum den-
sity was 7-13 nits/eggs/cm
2
with a mean of 9/cm
2
. The
range of minimum densities was 1-6.5 nits/eggs/cm
2
with
a mean of 4/cm
2
. This individual must have been suffer-
ing severely from louse infection and his hair was shorn
off between 1 and 2 inches from the scalp. This individual
also suffered from an infestation of the mucocutaneous
tissue of the nose and mouth, probably as a result of
leishmaniasis. The facial disfigurement of this individual
was profound and probably inspired avoidance by other
members of the village. Such avoidance and fear is com-
mon in areas with endemic leprosy which produces simi-
lar soft tissue lesions. In the case of individual 317-1173,
it appears that the lice proliferated in a weakened indi-
vidual who may not have been able to gain hygienic aid
from anyone else beyond a hair cut. Several individuals
show pronounced densities of lice at the scalp with lower
densities in the hair. This may indicate a similar prolifera-
tion of lice in sick and dying individuals (407-1304, 10-
147, and 211-2225). Therefore, declining individual health
status may have allowed lice to proliferate when individual
care could not be easily rendered.
The fact that children were least often infested is in-
teresting. In modern societies, children are most often
infested (Mellanby 1942, Ibarra 1989, Mumcuoglu et al.
1990, Ibarra & Hall 1996, Ibarra et al. 2000). Children from
large families are more likely to be infested than children
from small families. Child cares, schools, and preschools
in the modern world promote social interaction between
children and louse infestation. The low prevalence of
infestation among Chiribaya children suggest that chil-
dren were not associated in the same social settings as
modern children. The contrast between Chiribaya louse
prevalence between the Chiribaya children and modern
children highlights the importance of schools and other
child-centered social activities in promoting infestation.
Of all the areas of archaeoparasitology, we believe that
the study of lice has the greatest potential for providing
real epidemiological data regarding past populations.
When large numbers of mummies are examined, it is rela-
tively effortless to collect sufficient observations for in-
terpretation. In this study, only San Geronimo had such
poor preservation that it could not be used. The poor
preservation of mummies from the site of San Geronimo is
due to it beach location and association with moisture.
Of the remaining three sites, Chiribaya Alta and El Yaral
provide the best insights into louse paleoepidemiology
due to the relatively large numbers of mummies for which
age and sex was determined. The analysis of these mum-
mies shows how aspects of hairstyle and other behavior
effected louse distribution among the Chiribaya.
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Fig. 5: comb-like tool found in a tomb, Chiribaya Culture, Peru.