Epidemiology is the
study the distribution patterns of diseases in human populations .
For most illnesses, in many health systems, the general practitioner is the
first point of contact in the health care system and he looks after a
population whose age and sex composition is known. So, family medicine is a
major source of information on health problems and their variation, and has
important epidemiological connotations, presenting a unique opportunity to
study outbreaks of diseases .
The essence of
family medicine is to assist individuals in families and communities, and this
implies, on the one hand a good continuity of care, and moreover a knowledge of
the nature of diseases in the community. The continuity of care is considered
as a defining characteristic of family medicine and primary health care [3-6].
The person is the center of
interest for the family doctor; but the importance of epidemiological research
at the family physician level is often forgotten. This epidemiological level
today is downplayed or underestimated; however, there have been family
physician pioneers who studied the epidemiologic problems of their community
with scientific rigor. Some of them have been recognized for their seminal work
in the last 125 years [7-12].
The most common eye
disease in the Western Hemisphere is conjunctivitis. Viral conjunctivitis is
relatively common. Viruses of the adenovirus group are responsible for
pharyngoconjunctival fever and epidemic keratoconjunctivitis. Epidemic Kerato Conjunctivitis
(EKC) is a highly contagious disease which may
be transmitted in the course of an ocular examination in a physician’s office.
The usual etiologic agents are adevirus types 8 and 17. The infection has an
acute onset and in 3-14 days, pain, photophobia, lacrimation, and blepharospasm
are predominant. As the acute follicular conjunctivitis subsides, a keratitis
In this context, we
present an example case of an outbreak of EKC
in a single large family and assess the epidemiologic role of family
doctor in to knowing the attack rate, patterns of transmission, control
measures and prevent future outbreaks in family and community, with
the aim of reflecting and conceptualizing the importance that, for
epidemiological knowledge have the data provide by family medicine
cohort study of an outbreak of EKC in a large
family attended a family medicine office was done, monitoring the family
members who were attended in the same consultation, and obtaining the rest of
the data through questioning of these patients and the review of the
computerized medical records of other relatives attended by other general
practitioners, and based on the genogram (Schematic Model Of The Structure And
Relationships Of A Family, Which Includes The Family Structure, The Life Cycle
Of That Family, And Family Relational Patterns) [14-17]. to know the individuals
exposed and the pattern of transmission. The
location was a family medicine office, in the Health Center Santa Maria de
Benquerencia, Toledo, Spain, which has a list of 2,000 patients.
case-control study was done to identify risk factors associated with
contracting EKC. The possible risk factors
studied for infection among family members were: cohabiting / non-cohabiting
with a patient with previous EKC, with / without close relationship with a
patient with previous EKC, with / without continued relationship with a patient
with previous EKC, medications, co-morbid conditions, visits to medical
specialists, and use of contact lenses or glasses of the persons with / without
EKC (Cases / Not Cases). No testing of
conjunctival specimens for virus isolation and / or serology was performed. No
ethical approval was required for the study as this was part of a normal
On May 5, 2017, the
patient S (Case number 2) was treated with a highly symptomatic conjunctivitis
clinic. On May 10, 2017, the D and O marriage (cases 3 and 4) was treated with
a conjunctivitis clinic. Patient D was sister of patient S. Preventive measures
were explained. On May 22, 2017, patient J (case 14) consulted for
conjunctivitis; he was brother of D. On May 25, 2017 patient Q (case 17)
consulted with conjunctivitis, who was the son of the D and
O marriage; when
attending this case, it was thought of an epidemic outbreak in the family.
Questioned the patient, Q, reported that also his brother P (case 13) had the
same symptoms, and added that other family members also had the same symptoms.
From there, the family members Q, S, and J were interrogated. It was an
extended family, with 9 siblings (Figure 1)
The next family
members, D, O, Q, S, G., T, U, and J provided the rest of the data when they
were questioned by family doctor. For obtain all medical data, the computerized
medical records of the rest of the patients/family members were revised.
The first case
occurred in the elderly mother, A (case 1), who presented the symptoms in the
last days of April 2017; this 86-year-old female patient had been visited at
the hospital's nephrology clinic on 18 of April 2017 (she has chronic renal
failure, high blood pressure and ischemic heart disease), and presumably it was
there that she contracted eye infection. This patient A, lives with her eldest
son B, who is separated, but all family members rota, according to the days,
especially daughters of the extended family, as well as some of the wives of
the male children, to caring to A. A sister of A, also an old woman, K, lives
with A, and is equally cared for by the various members of the family. K
presented EKC (case 6). C (case 5) and their children N (case 12) and M
(case10), E (case 11) and their son R (case 9), H (case 7) and their son V
(case8), and I (case 15) and their children Y (case 16) and Z (case 18),
presented in this period also Patient S (case 2) was the last to heal, on June
20; Patient Q (case 17) was the penultimate cure, taking the Discharge from
sick leave on June 15, 2017 (Figure 2).
Of the 18 cases, 8
were women (44%). The incubation time was estimated from a few days to a 2 week,
and the period of transmissibility from the end of the incubation period to 15
days following the onset of the disease. (Table 1)
shows the symptoms of EKC in cases.
sources and pathways of the infection, the illness was clearly related only
with family characteristics. In all 18 patients (100%) recalled that
a family member had also had conjunctivitis during a period
of 1-2 week before the onset of symptoms. Family member B, who lives with A and
K, however does not presented EKC; the rest of the family members explained to
the family doctor that B did not actually care for A or K, but the rest of the
family members, through the rotation scheme, performed this care.
Of 34 family
members, 18 (Attack rate = number of new cases x 100 persons exposed = 53%;
Secondary attack rate = number of new cases x 100 / persons exposed to a
primary case = 50%) had onset of eye symptoms consistent with EKC between April
20 and June 15, 2017. 10 (10/34=30%) of these had onset following the onset of
symptoms in a family member, despite habitual interventions and appropriate
preventive measures which were prescribed, but family cases were not isolated;
although the movement of relations was restricted in the family and in
community, including sick leave for workers, which may have prevented an
extensive viral transmission in the outbreak.
study was done to identify risk factors associated with contracting EKC. patients
with conjunctivitis were more likely than control patients to be coexisting
with another case, and especially maintain a close relationship with another
case; these results are reasonable, because in addition to living in his family
with a case, many members of the extended family maintained a relationship with
the index case when taking care of her (Table 2)
Relative Risk (RR)
was calculated as the ratio between disease rate in subjects "Closely
Related to A Case of EKC", by sex, with "Polypharmacy (> 3 Drugs Prescribed)", with "Multitimorbidity"
(>3 diseases), and aged> 50 years in cases and non-cases of EKC (Table 3).
The RR informs us
about the strength of the association between factor exposure and disease (EKC)
-the number of times it is more likely that subjects exposed to that factor
become ill, relative to the unexposed. The RR was only strong in the close
relationship with one case (RR = 3.2), and moderate in the presence of
polypharmacy RR = 1.5.
Although testing of
conjunctival specimens for virus isolation and / or serology were not
performed, but an adenovirus could be presumed to be the etiologic agent.
conjunctivitis and EKC
The blink reflex
protects the eye well against many potential injuries but cannot guard the
conjunctivae against atmospheric influences, nor against the entry of airborne
particles, some of which are inorganic dust, some are spores or pollen grains
and others are airborne pathogens transmitted from one person to another .
one of the most prevalent epidemic diseases in the community, and in the family
environment. Viral conjunctivitis affects all age groups equally and there are
frequent epidemics (widespread contagion) within the same family, school,
office and organizations, and can be extended to the community from these
groups. Viral conjunctivitis is usually produced by adenoviruses. The spectrum
of adenovirus ocular infection varies from mild to almost non-existent to
complete with significant morbidity. The two types of conjunctivitis caused by
adenovirus are: 1)
Pharyngoconjunctival fever, which is usually caused by adenoviruses types 3, 4,
and 7 and sometimes type 5, and that is transmitted through the droplets and
typically affects children who also have upper respiratory tract infection; And
2) The EKC.
EKC is an acute
infectious eye disease characterized by unilateral or bilateral inflammation of
the conjunctivae and eyelid edema and periorbital tissues. It suddenly begins
with eye pain, photophobia, blurred vision and sometimes low fever, headache,
general malaise and preauricular lymphadenopathy. Around 7 days after the onset
of the disease, about half of the cases exhibit petechial haemorrhages and / or
subepithelial infiltrates in the cornea. The latter can form punctiform ulcers
that stain with fluorescein. Acute conjunctivitis lasts for about 2 weeks,
persist and leave discrete epithelial opacities that can interfere with vision.
In severe cases, conjunctival membranes can be developed . Thus, EKC is a combination
of conjunctivitis and keratitis [20,21].
confirmed by isolating the virus in appropriate tissue culture, inoculated with
eye washings or conjunctival scrapings, and by increasing titre in serum
neutralization tests or inhibition of haemagglutination. The infectious agent
is adenovirus type 8, sometimes other types, especially 11, 19, and 29 [19,22,23]. The reservoir is man, and the mode of
transmission is by direct contact with the ocular secretions of an infected
person or indirectly with contaminated instruments or solutions. Outbreaks
originating from ophthalmological clinics or medical offices have long been
described . The spread of EKC in the family
is common. Immunity is usually complete following an adenovirus 8 infection;
with other adenoviruses, similar conjunctivitis may occur with minor keratitis .
In our study,
although testing for conjunctival specimens for virus isolation and / or
serology was not performed, because of the symptoms of our patients, an
adenovirus could be presumed to be the etiologic agent, and all EKC
characteristics recur in the family outbreak presented (Table 1, Figure 1). It is accepted that the incubation period is
probably 5-12 days , but has been reported
from 3 to 22 days [20,23,25,28]. We found an
incubation time that was estimated from a few days to 2 weeks, similar to what
It has been
reported in outbreak of EKC due to adenovirus type 37, in a chronic care
facility, an attack rate 49% , a figure
similar to that found by us. In our study, the secondary household attack rate
was 50%, higher than other reported (20%) .
Our initial case
(patient A) had been in a nephrology consultation in the hospital in the 2
weeks prior to beginning their symptoms, so we thought that the primary mode of
spread was nosocomial by contamination of the examiner's fingers, and in the
family epidemic the mode of spread was close personal contact . It has been reported that 30% of patients with
EKC had been visited in an ophthalmology office during a period of 2 weeks
before the onset of symptoms [20,26]. The
reported data from outbreaks illustrate the highly contagious nature of
adenovirus infection and the potential for transmission during routine office
between the task of family medicine and the epidemiological knowledge of the
outbreaks of diseases
The family doctor
occupies a relevant place in the health care of the population, its role as
health guardian, implies a performance fundamentally directed to the
observation and action on any phenomenon or event that undermines the welfare
of the community. The family doctor is the first element or fundamental
component of an epidemiological surveillance system, and can be located within
the clinical diagnosis subsystem, which is made up of the network of primary
and secondary health care services, outpatient consultations and emergencies .
Family medicine is in an ideal position to conduct
inquiries about outbreaks of diseases. The continuity of care is considered as a
defining characteristic of family medicine and primary health care [3-6]. The characteristics of family medicine imply:
A great accessibility of patients to their family
doctor, and their role of first contact with the patient: It allowing the
estimation of the probability of health problems of the population (Diagnoses:
Clinical Onset, Symptoms). From the epidemiological point of view, it is the
access to the "Numerator".
Working with a population as a "Denominator":
many health problems can only be identified within a population as a "Denominator"
(Attack Rate, Incidence and Prevalence) [32-36].
Family care: The family doctor knows the life cycle of
individual and family. The basics concepts of life cycle suggest an underground
order of lifetime, where the individual, family, or illness exists only within
a context that follows a basic sequence or not deployed. The family structure
is a generic concept by which we mean a pattern, design or underground
structure of the life of a person / family at a given point in her life cycle.
Its primary components include: occupation, relationships, marriage, family,
and roles in different social contexts .
The experience that
the family doctor must obtain from the family life cycle is not simply referred
to an individual member of the family, but in relation to the set of demands of
other members and from the external environment. The knowledge of family life
cycle allows us to understand: 1.-How in the stages of transition increases the
stress that can manifest as physical symptoms in some member; 2.-The strengths
and weaknesses of the time that elapses the lives of the members of a family;
3.- Possibilities of the family to face difficulties; and 4.- The family as a
space between society and the individual, in relation to behaviours, thoughts
and feelings which are expressed from the personal and group level .
In our outbreak of
EKC, all members of the extended family took turns, at varying degrees of time,
frequency and closeness, to care for the mother (case 1) day and night, which
involved different risks of contagion. On the other hand, these caregivers of
the elderly mother brought the EKC to their own families. We find that the
genogram is ideal document to register family structure, relationships and life
cycle [14-17, 39-42].
and other specialists working in the community, have the need to remember that
the experience of the family is a crucial part of the social environment of the
individual. The family provides the individual the most
influential relationships that will likely experience. However, these family
relationships can mean a resource but also a problem. In addition, many
problems that doctors initially identify as belonging to the individual level,
may be more appropriately understood as problems of the family system.
Moreover, the ill or incapacitated individual can often survive outside the
institutions with the support and care provided by their families.
All this can be
observed in our outbreak of EKC: the extended family means a resource for the
care of the mother (case 1), but at the same time carries the risk of
dissemination of the infectious disease to the whole family; Thus, an individual
case must be seen within their network of relationships, and individual medical
intervention becomes a family and community intervention. So, there is an area
where epidemiology and family medicine are found or merged. A good starting
point for epidemiological research is the critical analysis of individual
patients - a man and his small world . Box -1
purposes of epidemiological surveillance in family medicine, and BOX -2
the methods of
epidemiological control applied to EKC in family medicine. This leads to the
conceptualization and systematization of a series of specific epidemiological
implications of family medicine in the study of outbreaks of diseases (Table 4).
This outbreak illustrates
the potential for transmission of adenovirus infection during the provision of
eye care. Family physicians should be alert to cases of conjunctivitis, and
using their specific tools, diagnose ("Numerator"), characterize the
family (Genogram, Relationships, Pathways Of Transmission), monitor the course
of the disease and the outbreak (continuous care), and to know all the people
at risk or attended ("Denominator"), to obtain epidemiological
measurements, and implement measures to prevent such infection, which may
prevent extensive viral transmission in the outbreak.
This study has a
number of implications for household / family contacts of EKC, including the
potential to reduce the diagnostic delay for subsequent household cases and the
benefit of using certain tools specific to family medicine, such as clinical
interview for diagnosis, the genogram for family care, and continued care to
identify the source of contact, tracing the pathways of transmission outside
and inside the household.
The first priority
in the treatment of patients with definite or suspected EKC is the rigorous
application of hygienic measures, particularly because there is still no
effective drug treatment for this disease, and here the role of the family
doctor to interrupt family and community dissemination, as well as in medical
facilities, is a key factor.
Family medicine is a major source of information about
health problems and their outbreaks. For most illnesses the general practitioner
is the first point of contact in the health care system, he looks after a
population whose age and sex composition is known, and he take care of the
whole family and known their relationships. The ordinary general practitioners
can make a significant contribution to research in outbreaks of diseases on the
basis of patients seen in routine practice.
presents the unique opportunity to detect new cases of illness and study its
natural history, since it contemplates the family life cycle continuously. The
family doctor is an "Opportunistic Epidemiologist" or, in other
words, "A Fisherman with Hook, Instead of With Net" (as the formal
specialist in epidemiology does): he uses traditional small-scale techniques
-"The Hook"- instead of "Mass Fishing Or Industrial Fishing"
. For the sound practice of family medicine
not only traditional diagnostic and treatment skills are needed, but also the
application of the understanding of the frequency and distribution of the
disease in the family and community .
epidemiological strategies that use family medicine instruments as "Continuing
Care", “Family Care and Genograms”, Using Homogeneous Definitions Of
Diseases, And Working With A Population As A "Denominator” should be
enhanced in order to provide a basis for the development of health strategies,
prevention and treatment measures in outbreaks.