John W. Cutting, M.D., M.P.H.2
Construction of the Pan American Highway in eastern Pana- ma is producing marked environmental changes. Future assessment of the impact these changes have upon health in the area will need to draw on baseline data about previous health conditions. This article, which reports the results of a survey on intestinal parasitism in one community where the highway had not yet arrived, is designed to provide that type of information.
Introduction
The eastern region of Panama is now being subjected to a degree of outside influence not seen since the Spanish first explored its jungles. Construction to complete the only remaining gap in the Pan American Highway is underway in this area. Marked changes are expected as farmers from the crowded areas of western Panama move into the eastern sector’s sparsely settled, undeveloped lands.
Our current knowledge of this region’s health status is limited. Some surveys were done in connection with sea-level canal studies (Z-.5), and there have been other reports dealing with viral diseases (6-10). However, only a few reports have been published on intestinal para- sitism in this area (11-14), and none has appeared since 1955. To help obtain current information on this latter subject, a survey was carried out at the community of Yaviza in October 1972.
Yaviza is located in Darien Province, about 220 km southeast of Panama City, at the
‘Also appearing in Spanish in the Boletin de la
Oficina Sanitaria Panamericana.
%Deputy Director, Division of Preventive Medicine, Walter Reed Army Institute of Research, Washington, D.C., U.S.A.; and Coordinator, U.S. Army Tropical Health Training Program, Gorgas Memorial Labora- tory, Panama City, Republic of Panama.
juncture of the Chico and Chucunaque rivers (see Figure 1). It has a population of approxi- mately 1,800 (15) and is the largest town in the province. Nearly all of the permanent residents are Negroes, many of them immigrants from Colombia. The major economic pursuits are cultivation of plantains, bananas, and other subsistence crops on plots of land cleared from the jungle by slash-and-burn methods.
Buildings are generally of wood, with corru- gated metal or thatched roofs. Floors are primarily of wood planking raised above the ground, though dirt floors in part of the living space are common. Nearly all residents have ready access to a pit privy, which they say is the customary place for defecation. However, young children often go without clothing, and promiscuous defecation may be more common than generally admitted. No waste disposal facilities are available in the fields; and the Choco Indians, represented in Yaviza by small numbers of transient inhabitants, habitually defecate directly into the rivers.
The standard diet consists of rice, plantains, beans, small amounts of chicken and beef, and, infrequently, other vegetables. Night soil is not used for fertilization of crops in this area.
Rainwater is preferred, when available, for cooking and drinking. Water for other uses is taken from the rivers. During the dry season, from late December through April, the rivers
14 PAHO BULLETIN . Vol. IX, No. I, 1975
FIGURE 1-A map of eastern Panama showing the projected route of the Pan American Highway and the
location of Yaviza. Da&n.
serve as the only source of water. Examination of the river water has shown it to be heavily contaminated with coliform bacteria (16). Only a few people purify their water by boiling, the great majority using it without any treatment.
Methods
Selection of Sample
Using a sketch map of the community, 30 per cent of the town’s structures were selected at random for the investigation. Each structure was visited, and after eliminating commercial establishments and unoccupied houses, 434 individuals were identified and asked to parti- cipate in the study.
Of these persons, 202 cooperated by submit- ting fecal specimens for examination. The 202 participants, who came to constitute the study group, represented 11 per cent of the sample area’s population.
Collection, Preservation, and Examination of Specimens
fecal specimen. Participants were told to bring the specimen to a central collection point as soon as possible after passage.
Upon receipt of each specimen, a sample of about half a gram was placed in a plastic vial bearing the individual’s study number and containing 3 ml of freshly prepared merthio- late-iodine-formalin (MIF) preservative-staining solution (17). These samples were thoroughly emulsified and then stored at ambient tempera- ture until they could be transported to Panama City for further processing and examination.
All specimens were examined with a com- pound microscope after ether concentration (18). All observed helminth eggs and larvae were qualitatively identified and recorded. No quantitative estimates were made, nor were hookworm eggs cultured to determine the species present. Of the protozoa seen, only
Entamoeba histolytica and Giardia lamblia are dealt with in this report.
Results
Table 1 shows the age and sex distribution of the study group’s 202 members, together with the proportion of the total population (adjusted for age and sex) which they repre-
sented. It is evident that adults were somewhat underrepresented in this group.
Examination of the single fecal specimens showed that 18 1 individuals (90 per cent of the total) had one or more potentially pathogenic parasites. Of these persons, 32 were found to have one type of parasite, while each of the remaining 149 were found to have from two to five different types of potential pathogens.
Table 2 shows the prevalence of infection for each of the seven parasite species observed.
TABLE l-Distribution of study participants by age and sex, showing the
percentage of the town’s total population in each sex and age group which they
represented as of October 1972.
Males Females
Age of Total
subject No % of total
(years) . male age group No . female age group % of total No. % of total age group
<I 6 16 1 4 7 11
l-4 17 13 25 20 42 16
5-14 37 14 49 15 86 15
15-49 26 7 29 9 55 8
50+ 6 7 6 8 12 7
Total 92 10 110 13 202 11
TABLE 2-Prevalence of intestinal parasites in male and female subjects at
Yaviza (October 1972).
Parasites
Males Females Total
% % %
No. positive No. positive No. positive
T. trichiura . _ . . . . 68 i4 94 85 162 80
A. lumbricoides . . . . . . 52 57 73 66 125 62
Hookworm . . . 40 43 43 39 83 41
E. histolytica . . . 17 18 15 14 32 16
S. stercoralis . _ . . . 10 11 5 5 15 7
G. lamblia _ . . . . . . . 2 2 8 7 10 5
H. diminuta _ _ _ _ . . . 0 - 1 1 1 1
Persons with one
16 PAHO BULLETIN . Vol. IX, No. 1, 1975
TABLE 3-Distribution of Trichuris trichiura, Ascark Iumbricoides, hookworm, and Entamoeba
hkkolytica infections by age at Yaviza (October 1972).
e of
‘75
T. trichiura A. lumbricoides Hookworm E. histolytica
su Ject
(years) No. of qo of No. of % of No. of % of No. of % of infections subjects infections subjects infections subjects infections subjects
1 1 14 0 0 - 0
l-4 28 61 28 65 4 10 3 ?
5-14 83 97 68 79 35 41 14 16
15-49 42 76 25 45 36 65 11 20
50+ 8 67 4 33 8 67 4 33
Total 162 80 125 62 83 41 32 16
The most common parasite encountered was Trichuris trichiura, which was found in 80 per cent of the subjects. Ascaris lumbricoides was found in 62 per cent, hookworm in 41 per cent, E. histolytica in 16 per cent, Strongyloides stercoralis in 7 per cent, G. lamblia in 5 per cent, and Hymenolepis diminuta in 0.5 per cent. Table 3 shows the distribution by age of persons infected with the four most prevalent parasites.
The single infection with H. diminuta, in a three-year-old girl, may represent a spurious infection; eggs of this species were not seen in any other specimens, not even in those from eight other members of the same household.
Only one of seven children under the age of one year were found to have parasites, in this case Trichuris. But over 80 per cent of those one to four years old, and about 90 per cent of those five and older, had positive findings. The prevalence ratios for males and females were very similar.
Discussion
It is apparent that intestinal parasitism is prevalent in this population. Of males between the ages of 15 and 50, 96 per cent had positive stools; for females in the same age group the figure was 86 per cent. Together, 91 per cent of both sexes in this most productive period of life were found to have one or more pathogens. These data of course represent minimal esti- mates of true prevalence values, since they are based on single stool examination.
The most recent study of this kind for the Darien region is that of Jung, et al. (Id),
published in 1955. The parasite prevalences which it reported are remarkably similar to those reported here: Trichuris, 7 1.5 per cent; Ascaris, 69.7 per cent; hookworm, 46.8 per cent; E. histolytica, 2 1 .O per cent; and Strongy- loides, 9.4 per cent.
Hegner, et al. (I3), reporting on a study of E. histolytica in the same area, cited, a prev- alence of 15 per cent based on a sample of 20 individuals. Faust (II, 12) found E. histolytica infections in as many as 73 per cent of his subjects in the Darien, but he performed multiple examinations on all individuals.
Cort, et al. (19), working in western Panama, found the following prevalences: hookworm, 83 per cent; Trichuris, 54 per cent; and Ascaris, 51 per cent. The differences between these figures and those reported here from the Darien are a reflection of differing environmental conditions and also probably of less apparent differences in cultural practices. Results from studies in other areas similarly reflect differing conditions and methods and cannot be directly compared.
anticipated that the pace of these improve- permit a more accurate assessment of the ments will be greatly accelerated. The accom- impact that environmental changes will have on panying effects on the health of the area may the health of this population as the area be remarkable. Baseline data developed now, undergoes rapid development.
such as those reported in this article, may
ACKNOWLEDGMENTS
The author wishes to express his apprecia- Bocanegra for their assistance during the field tion to Mr. Dan Hammack and Mr. Ignacio portion of this study.
SUMMARY
A survey of intestinal parasitism was con- ducted at Yaviza, a town in eastern Panama’s Province of Darien.
Single stool specimens from 202 persons, representing 11 per cent of the town’s total population, were examined. In all, 181 (90 per cent) of the specimens examined were found positive for one or more potentially pathogenic parasites. The most common parasite found was
Trichuris trichiura, which was observed in 80
per cent of the samples. Others were Ascaris
lumbricoides, in 62 per cent of the samples;
hookworm, in 41 per cent; Entamoeba histo-
lytica, in 16 per cent; Strongyloides stercoralis,
in 7 per cent; Giardia lamblia, in 5 per cent; and
Hymenolepis diminuta, in 0.5 per cent.
The aim of the survey was to gather baseline data on parasite prevalence before the Pan American Highway passes through this area. Construction of the highway is producing marked environmental change in eastern Panama, and it is anticipated that the data from the survey will prove useful in later efforts to assess the health impact of that change.
REFERENCES (I) Stacy, H. G., M. D. Young, and G. El. Fairchild.
A survey to assess potential human disease hazards along proposed sea level canal routes in Panama and Colombia: I. Introduction.
Milit Med 138: 269-270, 1973.
(2) Eldridge, B. F., D. G. Young, and R. R. Gerhardt. A survey to assess potential human disease hazards along proposed sea level canal routes in Panama aid Colombia: III. Survey methods. Milit Med 138: 340-344. 1973. (3) Srihongse, S., H. G. Stacy, and J. k. Gauld. A
survey to assess potential human disease hazards along proposed sea level canal routes in Panama and Colombia: IV. Arbovirus sur- veillance in man. Milit Med 138: 422426.
1973.
(4) Kourany, M., and M. A. Vbsquez. A survey to assess potential disease hazards along proposed sea level canal routes in Panama and Colom- bia: VI. Enterobacterial pathogens in man.
MilitMed 139: 625-629,1974.
(5) Kourany, M., and M. A. Visquez. A survey to assess potential disease hazards along proposed sea level canal routes in Panama and Colom- bia: VII. Survey for salmonella antibodies in man. Milit Med 139: 696698, 1974.
(6) Galindo, P., E. C. de Rodaniche, and C. M. Johnson. St. Louis encephalitis in Panama: I. Isolation of the virus from forest mosquitoes
and human blood. Am J Trop Med Hyg 8:
557-560, 1959.
(7) Galindo, P., P. H. Peralta, R. B. Mackenzie, and H. K. Beye. St. Louis encephalitis in Panama: A review and progress report. Am J Trop Med Hyg 13: 455,1964.
(8) Galindo, P., and E. C. de Rodaniche. Surveillance for sylvan yellow fever activity in Panama (1957-1961). Am J Trop Med Hyg 13: 844-
850,1964.
(9) Gaiindo, P., and S. Srihongse. Evidence of recent jungle yellow fever activity in eastern Panama.
BUN WHO 36: 151-161, 1967.
(10) Srihongse, S., and C. M. Johnson. Human infec- tions with Chagres virus in Panama. Am J Trap Med Hyg 23: 690-693,1974.
(II) Faust, E. C. Investigations in Panama during the Summer of 1930. Science 73: 4345,193l.
(1.2) Faust, E.-C. The incidence and significance of infestation with Endamoeba histolyticu in
New Orleans and the American tropics. Am J
7kopMed 11: 231-237,1931.
(13) Hegner, R., C. M. Johnson, and R. M. Stabler. Host parasite relations in experimental amoe- biasis in monkeys in Panama. Am J Hyg 15:
394443,1932.
18 PAHO BULLETIN . Vol. IX, No. I, 197.5
of amebiasis. Am J Trop Med Hyg 4: 989-997,
1955.
(1.5) Warren, D., and R. Chloupek. Unpublished report, 1973.
(16) Gaydos, J., and D. Balaban. Unpublished report,
1973.
(17) Sapero, J. J., and D. K. Lawless. The “MIF” stain-preservative technic for the identification of intestinal protozoa. Am J Trop Med Hyg 2:
613-619,1953.
(18) Blagg, W., E. L. Schloegel, N. S. Mansour, and G. I. Khalaf. A new concentration technic for the demonstration of protozoa and helminth eggs in feces. Am J Trop Pled Hyg4: 23-28, 1955. (19) Cort, W. W., N. R. Stall, W. C. Sweet, W. A. Riley, and L. Shapiro. Studies on hookworm,
Ascaris and Trichuris in Panama. Am J Hyg,
