Etiology of Respiratory Tract Infections in Children in Cali, Colombia

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Etiology

of Respiratory

Tract

Infections

in Children

in

Cali,

Colombia

Jorge A. Escobar, M.D., M.P.H., TM., Arthur S. Dover, M.D., Alvaro Due#{241}as,M.D.,

M.P.H., T.M., Ermilson Leal, M.D., Pablo Medina, M.D., M.P.H., Antonio Arguello,

M.D., Mercedes de Gaiter, M.D., Donald 1. Greer, Ph.D., Rupert Spillman, M.D., and

Marco A. Reyes, M.D.

From the Departments of Pediatrics and Microbiology, Universidad del Valle, and the International Center for Medical Research, Tulane University-Universidad del Valle, ali, Jolombia

ABSTRACT. One hundred eighty children hospitalized for

acute respiratory disease were studied in Cali, Colombia. In

the majority of patients, pneumonia was the reason for

hospitalization and remained the final diagnosis. Fifty-one

cases of pneumonia of indeterminate etiology comprised the

largest single diagnostic category, followed by 38 cases of

pneumonia associated with measles, and 22 cases associated

with serologic evidence of infection with other viral agents

or Mycoplasma pneumoniae.

Etiologic diagnosis could be assigned with a reasonable

degree of confidence in 1 16 of the 180 patients (64%). The

laboratory procedure found most likely to provide the

etiologic diagnosis in this series was paired sera specimens

for demonstration of rise in antibody titer against the

common viral respiratory pathogens. Those most frequently

implicated serologically as etiologic agents in the cases

studied were, in order of decreasing frequency, measles,

influenza, parainfluenza, and adenoviruses. Pediatrics,

57: 123-130, 1976, RESPIRATORY DISEASE, PNEUMONIA, MEASLES, LUNG PUNCTURE.

Acute respiratory tract infections constitute

one of the major causes of significant morbidity

and mortality in children throughout the world.’

The mortality attributed to respiratory illnesses in

various communities surveyed within the

West-em Hemisphere differs considerably.2 In order to

determine what etiologic agents or combinations

of agents are involved in our own particular

ecological niche, the present study was

under-taken as part of a larger in-depth investigation of

both inpatient and outpatient respiratory

infec-tions.

Cali, Colombia, is a rapidly growing

metropol-itan area of more than 1 million persons, located

in the fertile valley of the Cauca River of

Colom-bia. This agricultural area, important for its

production of sugar cane, soybean, and cotton,

lies at 1,000 meters altitude between two ranges

of the northern Andean chain. The mean annual

temperature is 24 C with little year-round

varia-tion, although there are two wet and two dry

seasons each year. The Hospital Universitario del

Valle (H.U.V.) is a large, semipublic medical

center affiliated with Universidad del Valle

School of Medicine and serving the population of

the entire Valle region, but most of the patients

are from the working classes living within the

metropolitan area of Cali.

MATERIALS AND METHODS

Chosen for study were 180 patients between

the ages of 1 month and 14 years who had been

admitted to the H.U.V. for treatment of an acute

respiratory tract infection between January 1,

1972,

and April 1, 1973. These patients had

respiratory symptoms and clinical findings

refer-able to disorders at any level of the respiratory

tract, but in practice the only upper respiratory

problem for which children were hospitalized

was diphtheria. Patients chosen had been

hospi-talized shortly before or during the regular

working hours of the study team. The following

tests were performed on each patient admitted to

the study: complete blood count and

erythrosedi-(Received August 8, 1974; revision accepted for publication

February 5, 1975.)

Supported by Tulane University-Universidad del Valle

ICMR grant AI-10050 from the Institute of Allergy and

Infectious Diseases, National Institutes of Health, Public

Health Service.

ADDRESS FOR REPRINTS: (A.S.D.) ICMB, Apartado

Aereo 5390, Cali, Colombia, South America.

at Viet Nam:AAP Sponsored on September 8, 2020 www.aappublications.org/news

(2)

TABLE I

AGE DImIBt.rrIoN AND MORTALITY

Age No. Deaths %

itoilmo 52 5 9.6

lto4yr 89 11 12.4

5to9yr 27 1 3.7

lOtol4yr 12 0 0.0

Total 180 17 9.4

mentation rate, urinalysis, chest X-ray, stool

examination for evidence of parasites, PPD skin

test, and standard bacteriologic cultures of nasal

and pharyngeal swabbings and of blood. Serum

immunoglobulins were determined by a radial

plate diffusion method.3 After being approved by

the medical school committee on human

investi-gation, lung and tracheal aspirates were

perform-ed by an experienced operator using standard

techniques on the last 102 patients studied, regardless of presumptive diagnosis. Aspirated material was subjected to standard bacteriologic

and mycologic examination. In addition,

histo-logic examination of lung puncture and autopsy

material was performed with methenamine-Comori silver stain to identify Pneumocystis

carinii.

Viral Isolation

Pharyngeal swabs were collected in vials with

2 ml of Hank’s solution supplemented with 1%

fetal bovine serum; tracheal and pulmonary

punc-ture aspirates in 5 and 2 ml respectively of saline

solution. These specimens were received cool in

the laboratory and subsequently processed. The

solutions were centrifuged at 2,000 rpm, and after

treatment with antibiotics each supernatant was

inoculated in four tubes of primary human

embryonic kidney and Hep-2 cells. The tubes

were divided into two sets and incubated at

35

C

and 37 C for 12 days. A small piece from each

pulmonary lobe collected at autopsy was ground,

suspended at 20% in Hank’s solution, treated, and

inoculated as described for the other specimens.

Viral isolation was determined by the detection of

cytopathic effect on the inoculated cells at any

time during the period of incubation.

Serologic Studies

Each set of acute and convalescent serum was

studied for antibody titer by complement fixation

test for adenovirus, parainfluenza viruses 1, 2, and

3,

respiratory syncytial virus, and Mycoplasma

pneumoniae antigens, and by hemagglutination

inhibition for measles#{176} as well as influenza viruses

A, B, and C. In the cases from which a virus was

isolated, a neutralization test was performed for

antibody titer in the patient’s serum against the

isolated virus.

RESULTS

A total of 105 male and 75 female patients were

studied with clinical diagnoses of diphtheria or

lower respiratory tract infection. Seventeen of the

180 patients (9.4%) died during hospitalization.

Their age distribution is shown in Table I along

with corresponding mortality rates. It is evident

that a disproportionate number of infants and

preschool children is present. The majority of the

patients (78.4%) were of mixed racial

on-gin-11.1% were black, 7.8% were white, and

1.7%

were Indian. All of the patients came from

neighborhoods (barrios) of very low

socio-economic standing in Cali. The low

socioecon-omic status of the patients was reflected by their

parents’ reported job statuses and level of

educa-lion. Sixty-eight percent of the patients routinely

shared their beds with one or more other family

members (for those who shared, the average

reported number of co-occupants of the bed was

4.0). Crowded housing conditions were also

mdi-cated by an average packing index of 4.3 persons

per room of the family residence (range, 1.3 to

14.0).

Treatment of the current illness with

antibio-tics within one week prior to admission was

received by 57 of the patients, and nearly one half

of these received penicillin.

Nutritional status for the patients was

deter-mined according to the patients’ age and weight

using a growth curve appropriate for the patients’

racial background.4 Table II shows the

distribu-lion of the patients according to this classification

and the corresponding mortality rates. The

average patient in this series was mildly

malnour-ished. Tables I and II demonstrate the

dispropor-tionately higher mortality rates among the 1- to

4-year-old group and the malnourished patients.

The average nutritional status for the fatal cases

was that of moderate malnutrition, i.e., these

patients were more malnourished than the

survi-vors.

Diagnoses were assigned in the following

manner: oil-aspiration pneumonia, croup, asthma,

bronchiolitis, pertussis syndrome, diphtheria, and

tuberculosis were diagnosed on the basis of

#{176}Antigenfor this test was kindly provided by the Laboratory

Program, Center for Disease Control, Atlanta, Georgia.

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TABLE II

NUTRITIONAL STATUS AND MORTALITY

Status % of Normal W eight for Age No. % Deaths %

Normal 85 to 100 94 52.2 3 3.2

Mild malnutrition 75 to 84 39 21.7 5 12.8

Moderate malnutrition 60 to 74 38 21.1 8 21.1

Severe malnutrition 50 to 59 9 5.0 1

#{176}

#{176}Percentage not calculated for fewer than ten cases.

typical history, physical findings, and laboratory

results. The term pertussis syndrome is used

rather than pertussis because it is known that

several viruses such as adenovirus and

cytomega-lovirus can cause a clinical picture

indistinguish-able from that caused by Bordatella pertussis. Of

the nine patients studied with this syndrome,

three had adenovirus isolated from pharyngeal

washings but none had serologic evidence of viral

infection. Culture isolates of Gorynebacterium

diphtheriae or Mycobacterium tuberculosis were

considered confirmatory of diphtheria and

tuber-culosis but not mandatory for their diagnosis. The

diagnosis of measles was made only if a four-fold

or greater rise in titer was found with acute and

convalescent sera, or in the presence of typical

clinical syndrome combined with history of

contact with a measles case. Several cases were

confirmed with the finding of giant cell

pneu-monia at autopsy. Pneumonia was considered to

be associated with a bacteriologic agent other

than those mentioned above if potentially

patho-genic organisms were isolated from cultures of

lung puncture aspirates or blood. Cases of

pneu-monia associated with four-fold or greater rise in

antibody titer to 1 or more of the viral antigens

tested or to M. pneumoniae were considered to be

associated with viral infection. Cases meeting

criteria of the two latter classifications were

termed “mixed.” All cases not meeting one of the

above criterion were considered to be pneumonia

of indeterminate etiology. The distribution of

diagnoses thus assigned is represented graphically

in Figure 1.

Diagnoses established and their respective

number of fatal cases are listed in Table III. No

cases were found in which either parasites or

fungi could be implicated as the cause of illness.

No cases of Loeffier’s syndrome were

docu-mented in spite of the fact that many patients had

Ascaris infection demonstrated during

hospitali-zation. Of the four cases considered due to the

aspiration of oil, bacterial isolation was positive in only one case, in this instance Staphylococcus.

Two of the patients with diphtheria presented

with croup; they are not included in the croup

classification. No etiologic agent was associated

with any of the cases of bronchiolitis or croup.

We attempted to relate the group of patients

considered to have pneumonia of indeterminate

etiology to those with bacterial-associated or viral-associated pneumonia. Characteristics such

as age, sex, nutritional status, hemoglobin, white

count, and percentage of neutrophils in

differen-tial count were compared. Patients with

pneu-monia of indeterminate etiology had higher

average white cell counts (19,562/cu mm) than

those cases associated with viral or mycoplasmal

infection (16,184/cu mm) or bacterial infection

(14,157/cu

mm), but no other distinguishing

features could be found among the three

groups.

The most common pattern of pathology found

on the chest roentgenogram taken at admission

was termed bronchopneumonia (55%), followed

by a diffuse interstitial process considered

compa-tible with viral pneumonia (14%) and lobar

pneu-monia (11%). Admission X-ray diagnoses were not

found to correlate significantly with final

diag-noses when compared to the cases of pneumonia

defined as bacterial- or viral-associated or

inde-terminate.

Several interesting primary conditions which

may have predisposed the patients to acquisition

of pneumonia were discovered during the study.

There were three cases of congenital heart

disease, and one each of cystic fibrosis, laryngeal

papillomatosis, and tracheomalacia. None of

these patients died.

Results of serologic studies for virus and

myco-plasma antibodies are shown in Table IV. Paired

sera were available for 155 of the 165 surviving

patients and were considered to show conversion

if a four-fold or greater titer was observed. In 66

of the 155 patients (43%), four-fold or greater rises

in titer were found against one or more antigens.

In 21 patients, significant rises were found to two

or more agents, while in 89 of the 155, no change

(4)

DIPHTHERIA CRJP

BROtH-TOUTIS

FIG. 1. Distribution of diagnoses in 180 children with acute respiratory tract illness.

was recorded. The randomness of the

combina-lions of serologic findings was demonstrated by

lack of goodness-of-fit using the method

employed by Still et al. for testing for the

significance of possible association of etiologic

agents. Attempted isolation of virus yielded

scanty results: there were 7 isolates of adenovirus

and 29 of virus which was not identifiable,

accompanied by corresponding serologic titer rise

in one and five cases, respectively.

Thirty-eight patients were ultimately

diag-nosed as having pneumonia associated with

measles infection. Thirty of these had a typical

clinical syndrome plus history of recent exposure

to measles and/or serologic confirmation with the

hemagglutination inhibition test. An additional

eight patients were diagnosed as having

pneu-monia associated with measles based on serologic

results. The latter had compatible clinical

syndromes in every respect except they did not

have a rash either before or during their

hospital-ization. An additional four patients were

diag-nosed as having measles on clinical grounds but

were subsequently shown to have adenovirus

(three cases) or cytomegalovirus (one case)

infec-tions.

Both lung puncture and tracheal aspirations

were performed on 102 patients. The material

aspirated from lungs was cultured and resulted in

19 bacterial and 2 viral isolates. Pneumothorax,

the major complication of lung puncture, was

observed on post-puncture chest X-ray in 16% of

patients on whom this procedure was practiced.

In five of 16 instances, the pneumothorax was of

minimal size, disappeared quickly after the

procedure, and did not seem to adversely affect

the patient’s respiratory symptoms and signs. Its

occurrence was not -related to patient’s age,

diagnosis, nutritional status, or the isolation of

Staphylococcus on lung puncture. The clinical

importance of pneumothorax for these patients is

difficult to evaluate, but it is of interest to note

that the case-fatality rate was 7.8% in those

patients subjected to lung puncture, compared to

11.6% among those not undergoing the diagnostic

procedure. For patients with positive bacterial

isolates from lung puncture, there were only

seven with simultaneous pathogenic bacterial

isolates from pharyngeal cultures, four of which

were in agreement. In only three patients were

potentially pathogenic organisms isolated from

both nasal and lung punctures, and two of these

paired specimens were in agreement. No case of

Pneumocystis carinii infection was suspected

(5)

TABLE III

DIAGNOSES AND CASE FATALITY RATES

!)iagnoses No. % Deaths Fatality Rate (%)

Bronchopneumonia

Associated with bacterial infection 15 8.3 1 5.7

Associated with viral infection (other than measles) 22 12.2 0 0.0

Associated with bacterial and viral infection 5 2.7 0 0.0

Associated with oil aspiration 4 2.2 0 0.0

Indeterminate 51 28.3 4 7.8

Measles 38 21.1 4 10.5

Diphtheria 7 3.9 2 NC#{176}

Tuberculosis 13 7.2 4 30.8

Asthma 10 5.6 0 0.0

Pertussis syndrome 9 5.0 2 NC

Bronchiolitis 4 2.2 0 0.0

Croup 2 1.1 0 0.0

Total 180 100.0 17 9.4

#{176}Ratesnot calculated for fewer than ten cases.

ically nor found on histologic examination of aspirated material or at autopsy.

Administration of antibiotics prior to

hospitali-zation was found to have slight influence upon

the type of organism isolated from lung puncture

aspirates. Bacterial organisms were more

com-monly recovered from patients who had not

received prior antibiotic therapy, and these

patients were found to have a relatively wider

variety of organisms (Table V). Prior antibiotic

therapy was associated with a relative but not absolute increase in the isolation of Staph

yb-coccus from the lung but was not found to correlate significantly with the patients’ initial leukocyte count, percentage of neutrophils, or survival.

Table VI summarizes the results of the

immu-noglobulin determinations for 172 of the patients. Results were categorized as normal, “high,” or

“low” according to whether they were within,

above, or below the age-specific mean values ± 1

SD of normal values established by Steihm and

Fudenberg in their survey of healthy North

Amer-ican children.t Many of the patients were found

to have immunoglobulins higher than those

expected with this method, and elevated levels of

1gM were found to correlate with survival. Two

patients with low 1gM died; a 6-month-old child

with pneumonia of indeterminate etiology, and

an 8-month-old child with staphylococcal

pneu-monia. Both of these patients had grade II

malnu-trition.

DISCUSSION

Infection of the respiratory tract is a major

health problem during childhood. Frequent,

minor upper respiratory tract infections are quite

common in childhood7 and, due to the ubiquity

and antigenic variety of the more common

etiologic agents, these infections are not only

inescapable but presently are beyond the control

of practical and effective immunization

tech-niques.’ In developing countries, however,

immu-nization practices are not widespread and

nutri-tional and other factors may aggravate what

otherwise would be a mild, self-limited

respira-tory syndrome. Furthermore, it is important that

the infectious agents prevalent within a particular

community be identified, since it may be

expected that there are regional differences in the

variety and pathogenicity of the etiologic agents

to be encountered. Nevertheless, in this study

(6)

TABLE IV TABLE VI SEROLOGIC RESULTS Agent No. With Semlogic Conversion0

% of Samples

(No. = 155)

Measles 27 17.4

Influenza virus

A, (Hong Kong)

A, (Japanese) B (Singapore) C (Taylor) 22 12 4 4 2 14.2 -Parainfluenza virus 1 2 3 15 5 2 8 9.7

-Adenovirus 11 7.1

Mycoplasma pneumo-niae 7 4.5 Respiratory syncytial virus 6 3.9

Neutralization of

un-identifiable virus

5 3.2

Total 93

#{176}Four-foldor greater increase.

certain important observations should be made.

First, we must recognize that the patients

included in this series are, for the most part,

among the most disadvantaged members of the

community in terms of nutrition, economic

resources, educational background and social

standing of their parents, and access to medical

care. Large families living in crowded conditions

and the sharing of the child’s bed with a parent or

TABLE V

BACTERIAL ISOLATES FROM LUNG PUNCTURE ASPIRATES

AND PRIOR ArIBIoTIc THERAPY

Prior Bacterial Isolates Antibiotic Th Yes erapy

.,

No

Staphylococcus aureus 3 5

Diplococcus pneumoniae 1 4

Hemophilus influenzae 0 4

Gram-negative bacteria 0 1

Mycobacterium tuberculosis 0 1

Negative 27 56

Total 31 71

IMMUNOGLOBULIN LEVELS

Immuno-globulin Normal High Low Total

IgG

Live 70 67 24 161

Dead 5 4 2 11

Total 75 71 26 172

IgA

Live 89 56 15 160

Dead 4 6 1 11

Total 93 62 16 171

1gM

Live 12 145 2 159

Dead 1 8 2 11

Total 13 153 4 170

with other children are characteristics of this

group of patients which also are likely to

influence their general health status and, in

particular, their acquisition of air-borne

patho-gens. Similarly, we must be aware that among

these patients’ parents, it is common to delay

seeking medical advice until what initially may

have been a mild illness has complicated or

advanced to become serious. Simultaneously,

limited facilities usually restrict H.U.V.

admis-sions to the most seriously ill among those

patients seeking medical attention.

A greater-than expected number of male

patients was found in the study group (P < .02), a

phenomenon which has been observed by other

authors.9-’#{176} However, excess mortality was

observed among the female patients

(x2

= 4.78,

P

<

.05),

an observation without any apparent

explanation.

No definite seasonal variation in identification

of specific etiologic agents was observed,

although there was an apparent clustering in

admissions of measles cases and of patients with

serologic evidence of influenza A2 (Hong Kong)

during the summer of 1972. This lack of expected

variation in part may be due to sampling

tech-niques, i.e., the small number of patients studied

per month and the fact that only the most

seriously ill are admitted to the hospital.

Lung puncture recently has become an

accepted and useful method for the study of

pneumonia in patients with unusual susceptibility

due to deficient host defenses or with pulmonary

infections which do not respond to usual

thera-py.”-” We found lung puncture to be a relatively

benign and moderately valuable tool for

(7)

lishing specific etiologic diagnoses. The

oc-currence of complications was not related to

diagnosis. We would concur with the

recom-mendations of Eichenwald” that this technique should be reserved for pneumonia cases of ques-tionable etiology unless there is evidence of acute

emphysema or the patient shows clinical or historical evidence of coagulopathy.

The rate of determination of etiology in this

series compares favorably with the results

reported by others. Attempts at isolation of

viruses were disappointing in terms of useful

information gained. The low yield may be

ex-plainable partly by the likelihood that many

patients ceased shedding virus before their

illnesses progressed to the point of requiring

hospitalization. Serologic conversions, in contrast,

provided one of the most reliable indicators of

infection among the patients and accounted for

more etiologic diagnoses than any other single

measure. In assigning etiologic diagnoses, we

disregarded bacterial findings from nasal and

pharyngeal swabs as well as tracheal aspirates.

Results from these techniques are generally

considered to be unreliable,’ and we found very

little correlation of bacteria isolated from these

sites compared to blood and lung puncture

cultures results.

It is estimated that 80% of acute primary

respiratory illnesses in man are caused by viruses.’

The absence of documented four-fold titer rise in

the many patients whose pneumonia was

consid-ered to be of bacterial or undetermined etiology

again may be due to the delay from time of onset

of illness to time of entry into the study, i.e., the

patients may have already progressed to the

convalescent stage of a viral infection, yet have

bacterial complications at the time of

hospitaliza-tion which were not demonstrable with blood or

lung aspirate cultures. Another possibility is that

patients with no evidence of serologic conversion

may have had purely bacterial processes which

were not initiated by any viral insult to the

respiratory apparatus, but not diagnosable

etiologically even with the added technique of

lung puncture.

Simultaneous mixed infections of

bacterial-viral or viral-viral combinations were common in

this series. Several previous studies have shown that such combined infections are frequent and

may cause more severe illness than infections

with relatively benign individual agents.’57

Older patients were not found to have more

frequent serologic evidence of multiple viral

infections than younger patients, as reported

elsewhere.hui Not only did we encounter patients

with simultaneous serologic conversion and

isola-tion of bacterial pathogens from blood or lung

puncture. We also found patients with serologic

conversions to two or more viral agents, and to M.

pneumoniae plus the isolation of one or more

bacterial agents. One patient with pneumonia, for

example, demonstrated serologic conversion

against influenza A, (Hong Kong) and isolation of

Hemophilus influenzae from lung puncture

mate-rial, while Dipbococcus pneumoniae was

simulta-neously isolated from the blood culture.

The higher-than-expected immunoglobulins

found in many of our patients are not readily

explainable. In part, these values may not be

significantly high but are between 1 and 2 SD

above the mean. Also, preliminary results of a

survey of healthy children from a socioeconomic

background in Cali similar to that of our patients

show elevated immunoglobulins according to age

during the first year of life. (L. Cassaza and D.

McMurray, unpublished data). These combined

results suggest that children living in this

environ-ment are subjected to greater or more frequent

antigenic stimulation than their North American

counterparts.

The data clearly indicate the increased

mortality of respiratory infections among those

who are malnourished and among those under 5

years of age, especially the 1- to 4-year-old group.

Also, it is clear that the majority of the fatalities

were due to diseases which can be readily

prevented or controlled by simple,

well-estab-lished public health measures, namely

immuniza-lion against measles, diphtheria, and pertussis,

and epidemiologic control in the instance of

tuberculosis. (Since the completion of this study, a

mass immunization campaign was undertaken in

Cali during 1974 in which live, attenuated

vaccine was given to all children from 3 months

to 7 years of age. It is expected that nearly

100,000 individuals will be immunized in this

program.)

SUMMARY

In any community with distinct population,

climate, and environmental factors, the etiologic

agents causing common disease patterns can not

be assumed to be the same as those for other

communities. A rational approach to prevention,

prophylaxis, and treatment requires first that

those agents be defined and their relative roles of

importance be assessed. We studied 180 children

hospitalized for moderate-to-severe acute

respira-tory disease in order to establish this background

and the most appropriate diagnostic methods for

our community. Our results indicate that largely

(8)

preventable diseases predominate, and that

chil-dren in the 1- to 4-year-old group and children

with compromised nutritional status are those at

greatest risk of acquiring severe, often fatal

respi-ratory infections. The challenge of rectifying

these apparent deficits in child care within our

community now lies ahead.

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ACKNOWLEDGMENT

We gratefully acknowledge the technical assistance of

Beatrice Selwyn, Marshall Schreeder, and Jane

Trow-bridge.

(9)

1976;57;123

Pediatrics

Arguello, Mercedes de Gaiter, Donald L. Greer, Rupert Spillman and Marco A. Reyes

Jorge A. Escobar, Arthur S. Dover, Alvaro Dueñas, Ermilson Leal, Pablo Medina, Antonio