An eight-year-old boy who has been in good health attends a summer camp for two weeks. When he returns home, his mother notices that he has a mild runny nose and a very slight fever. The boy mentions that "something was going around" during the last few days of his stay at the camp, so his mother assumes that this is just a typical "summer cold." However, the boy's runny nose is more pronounced the next day, and he develops a mild sore throat and nonproductive cough. When he awakens the following morning, his left eye is swollen, and he says that it feels like there is "something stuck" in the eye. By lunchtime, the boy's right eye is also noticeably swollen and there is a little more discomfort in the left eye. His mother examines him and notices that the insides of both the upper and lower eyelids look bloody, especially in the left eye. Moreover, his tears appear to contain a small quantity of blood. At this point, the boy's mother becomes very concerned and takes him to the family pediatrician, where they have to wait for almost three hours because they don't have an appointment and there are many other walk-in patients ahead of them.

On examination (late in the afternoon), the boy's vital signs are normal, except for the low-grade fever (38.2ºC). He now has blurred vision in his left eye, and there is a tender, palpable lymph node just in front of his left ear. Vision in the boy's right eye is still normal. The bulbar and palpebral conjunctivae in each eye have a granular or pebbled appearance, and they are both quite inflamed. Aside from a runny nose and somewhat irritated throat, the only other remarkable finding is mild cervical adenopathy. The physician asks about the boy's recent activities and learns that he recently attended a summer camp.

Question 1.1: What is your diagnosis?

The primary ophthalmic symptom-inflammation of both conjunctivae is characteristic of conjunctivitis (sometimes known as "pinkeye"). However, there are some additional symptoms that probably would not be seen with many forms of conjunctivitis. The blurred vision in the left eye indicates that the infection there has progressed to a keratoconjunctivitis (an inflammation of the cornea and conjunctiva). There are also cold- or flu-like symptoms (sore throat, runny nose) and mild fever. These symptoms might be caused by a separate infection. Given the boy's recent history, however, the most likely diagnosis is pharyngoconjunctival fever, a characteristic febrile illness of children that typically occurs in outbreaks, most often in summer camps.

Question 1.2: What is the likely causative agent?

A variety of bacteria and viruses can cause conjunctivitis, but "hemorrhagic conjunctivitis" is almost exclusively an adenovirus disease. In about 75% of cases, adenoviral conjunctivitis is also accompanied by a diffuse, comparatively superficial keratitis (keratoconjunctivitis) that causes a transient blurring of vision. (In the present case, the infection happened to develop a littler faster in the left eye than in the right eye. Keratoconjunctivitis will probably develop in the boy's right eye quite soon.) Pharyngoconjunctival fever is associated specifically with adenoviruses and is most often caused by adenovirus types 3 and 7.

Adenoviruses are double-stranded DNA viruses. They have non enveloped virions with icosahedral capsids. Approximately 100 different serotypes have been described thus far, at least 47 of which can infect humans. They cause both lytic infections (in mucoepithelial cells) and latent infections (in lymphoid and adenoid cells.) When conjunctivitis occurs alone (i.e., without keratoconjunctivitis or other symptoms), the most frequent causative agents are: Haemophilus influenzae (42% of cases), adenovirus (22%), Streptococcus pneumoniae (12%), Moraxella catarrhalis (3%), and Staphylococcus spp. (2%). Other (less frequently noted) causative agents include group B and viridans streptococci, Haemophilus aegypticus, Neisseria gonorrhoeae, Francisella tularensis, Pseudomonas aeruginosa, Chlamydia trachomatis, Corynebacterium spp., measles virus, and rubella virus.

Question 1.3: What other diseases does this causative agent produce?

Adenoviruses most frequently cause respiratory infections. Typical symptoms include nasal congestion, rhinorrhea, cough, sore throat, laryngitis, fever, malaise, and/or myalgias. The severity of the symptoms varies from one case to another. Adenoviruses are also a major cause of acute viral gastroenteritis, accounting for 15% of cases in hospitalized patients. Adenovirus types 40, 41, and 42 are known to produce epidemics of diarrhea in children but apparently do not produce respiratory disease. In immunocompromised patients, adenoviruses sometimes cause dangerous systemic infections.

Question 1.4: What age groups are most affected by this agent?

Adenoviruses primarily affect children; adult infections are less common. Adenoviruses account for 3-5% of acute respiratory diseases in children, but < 2% of such illnesses in adults. Infection during childhood is exceedingly common, as evidenced by the presence of antibodies to multiple serotypes of adenoviruses in almost all adults. Adenovirus outbreaks do occur among adults, but they usually do so only under certain circumstances. Adult respiratory epidemics, for example, occur mostly in military barracks. Epidemic keratoconjunctivitis sometimes occurs as an occupational hazard for industrial workers. (More than 10,000 people working in the naval shipyards of Pearl Harbor were affected by an outbreak that occurred during World War II.)

Question 1.5: How is this disease transmitted?

Adenovirus infections can be transmitted by inhalation of aerosolized virus, by inoculation of the virus into conjunctival sacs (for example, by rubbing eyes with contaminated fingers), and, most likely, by the fecal-oral route (especially in the case of serotypes that cause gastroenteritis).

Question 1.6: How can you treat this case?

There are no effective anti-adenoviral drugs. Supportive therapy for keratoconjunctivitis consists of removal of exudate (if it is matted) with saline-moist cotton and application of an eye patch to relieve pain. With reasonable supportive therapy, keratoconjunctivitis is self limiting and almost never results in permanent damage to the eye or permanent loss of visual acuity. In this case, the boy's signs and symptoms disappeared within three days. The patches were removed and no further treatment was required.