Communicable Diseases : Measles

Epidemiology
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Background
Measles is in the elimination status in the US, but there are still cases of highly contagious diseases. Therefore, preventing and controlling measles transmission is a public health concern, with vaccination and isolation the most common preventive measures. The paper focuses on the epidemiology of measles and provides insights into the most affected demographic groups, risk factors, and how the epidemiologic triangle explains measles transmission. There is also a focus on the role of the community health nurse and the role of the CDC in preventing and monitoring the disease.  
Description and Demographic of Interest
Measles (Rubeola) is a viral infection of the Morbillivirus genus and the Paramyxoviridae family (ECDC). The disease begins with fever, and there may be a persistent cough, runny nose, sneezing, sore throat, and watery or inflamed eyes. Over time, there are Koplik spots and rash, red spots. Measles mostly affects unvaccinated children, unvaccinated pregnant women, and other susceptible populations with a high burden of morbidity and mortality. However, even vaccinated in the past but failed to develop immunity are also at high risk of measles. People born before the 1950s tend to have natural immunity against measles since it is likely they were exposed to the disease.
According to the CDC (Centers for Disease Control and Prevention) (2021), roughly one in five people who are not vaccinated in the US and get measles are hospitalized. One in 20 children with measles gets pneumonia. The CDC (2019) further highlights that in the hospitalization in one out of four of those infected, there is encephalitis (inflammation of the brain) in one out of 1,000 of those infected and mortality of 1-2 per 1,000 cases. The severity of the symptoms is mostly in children under five years and adults above 20 years. There is also a high risk of complications in immunocompromised individuals. Besides pneumonia and encephalitis, children and immunosuppressed (immunocompromised) individuals and groups are at risk of otitis media (ear infection or inflammation), obstructive laryngitis, and occasionally acute diarrhea.
Determinants of Health 
Measles is a highly contagious acute viral disease that is preventable through the measles-mumps-rubella (MMR) vaccine. Early vaccination provides long-term protection, and susceptibility in a community decreases when there are high vaccination rates. Measles prevention measures focused on vaccination have led to a dramatic worldwide decline in the number of cases reported globally, but the virus is still infectious. The measles virus is spread through coughing and sneezing, intimate personal contact, or direct contact with nasal or throat secretions from infected people. The incubation period is around 11 to 12 days from exposure to the onset of fever or other nonspecific symptoms (CDC). The transmission period varies from four days before the appearance of the rash to four days after the appearance of the Maculopapular rash.
The seasonality of respiratory viral infections such as influenza and measles tend to affect unvaccinated communities when there are outbreaks disproportionately. Measles is more common in densely populated areas, can promote transmission, and mostly affects poor tropical countries. Since measles is highly contagious when infected people are, being in contact or close increases the risk of being infected with measles. In temperate climates, measles appears mainly in late winter and early spring. In tropical climates, the risk of measles outbreaks increases during rainy seasons (Yang et al., 2014). Having Vitamin A deficiency is also a risk factor that determines susceptibility to measles.
 In evaluating the risk of a measles outbreak, epidemiologists often consider the interaction of demographics, the environment, and even religious affiliations as religious groups tend to have unusually high rates of unvaccinated children. For instance, the close-knit New York Orthodox Jewish community has low children vaccination rates in the US and is most affected by measles outbreaks in the past (Patel et al., 2019). This is especially true when there are inadequate hygiene measures and exposure to the virus causing measles. Adequate ventilation and clean surfaces are secondary measures against measles.
Epidemiologic Triangle 
Host factors
Diseases caused by biological agents, such as communicable ones, occur in the environment where the agent and the host interact. The host factors are the risk factors influencing susceptibility after exposure. Additionally, the host factors include personal characteristics and demographics. The risk factors for measles are low socioeconomic status, low vaccination rates, immunosuppression, and those below 12 years of age. In particular, unvaccinated children less than five years and at times pregnant mothers tend to be the most vulnerable, and in times of outbreaks, there are high mortality rates for such children.  
Hygiene levels are often prioritized to reduce measles vaccination rates since there is less risk of the virus spreading. Tracing people who have been in contact with measles-infected people helps reduce and prevent the spread of measles (Enanoria et al., 2019). Susceptibility also depends on the immunologic status such that individuals with weak immunity are at higher risk of measles during outbreaks. Unvaccinated who have been exposed, including infants, should be vaccinated within 72 hours of exposure in this way if the disease appears with milder symptoms and a shorter duration. People with weakened immunity, pregnant women, and some children may receive vaccination given within six weeks after exposure to help prevent measles or reduce symptoms.
The measles virus is transmitted through the respiratory route and close contact with infected persons or surfaces. Airborne transmission causes the spread by air to susceptible hosts depending on distance and environmental factors. The virus enters the host through the upper respiratory tract and infects the respiratory epithelium and immune cells.
 Agent factors
 The infectious agent is the measles virus (paramyxovirus). A high concentration of infected people in an area and various infected sources increases the risk of measles infections, related complications, and deaths. Exposure to infectious agents depends on interaction, contact with infected persons, the environment, and the environmental condition. The virus tends to spread fast among susceptible persons, with infections occurring four days before and after the onset of the rash. The virus has a short survival time and is inactivated by extreme heat, light, and acidic pH. If the virus is present in the air or surfaces, the more people are in contact, the more likely they will get infected. 
Environmental factors
Environmental factors include con...