Conjunctivitis is sometime called red eye or pink eye. It is an infection of the surface of the eyeball and of
the inside of the eyelid. Usually, it is an infection from a virus or bacteria, but it can also be caused by an
allergy, by air pollution, or by rubbing the eye too much. In this study, we are interested in Conjunctivitis caused
by virus known as Hemorrhagic Conjunctivitis (HC). It is highly communicable disease typical of tropical,
coastal cities. The onset of HC is sudden and the condition develops rapidly. They occur 12 to 48 hours after an
individual has been infected. Symptoms of the viral infection are: Itching and redness of the eye(s); this may
begin in one eye and slowly progress to the other. The conjunctiva is profusely covered with discharge from the
blood vessels (called hemorrhaging). Formation of crusts (usually seen in the morning, on waking-up); sticky
eyelids, which are difficult to keep open. Severe eye pain with eyelid inflammation occurs; with gritty feeling of
sand-like particles inside the eye. This is accompanied by continuous discharge of watery mucus from the eyes.
Blurred vision, light sensitivity also occurs. Mild fever develop in infants. Generally the signs and symptoms
start to improve in 5 to 7 days. The condition usually resolves completely in 2 weeks.
HC is caused by two main viruses: Enterovirus 70 and Coxsackievirus A24. The disorder is extremely
contagious and the infectious phase may last for 5-7 days, until the eye returns to normal color. The virus is
transmitted through direct contact with items used by the infected individual; by touch (hand-to-eye route), use
of shared spaces (like swimming pools), and through respiratory or nasal droplets. The virus can be transmitted
through the fecal-oral route; entering the human body through the mouth and nose. This mainly happens in
geographical locations with poor sanitary conditions, ill-maintained public restrooms. Deficient hygiene
conditions, crowded urban spaces, and a lack of quality healthcare, are factors that enhance the rapid spread of
HC.
Mathematical models have become an important tool for understanding the spread and control of disease.
Chowell et al (2003) proposed the simple model of Acute Hemorrhagic Conjuntivitis (AHC) that includes
susceptible, exposed, infectious, reported, and recovered classes. The model considers the impact of underreporting
and behavior changes on the transmission rate and is applied to an outbreak of AHC in Mexico. They
estimated that a primary infectious case generates approximately 3 secondary cases. Sangsawang et al [5]