This article elucidates the clinical diagnosis of measles along with its clinical manifestations, clinical variants, complications and treatment.

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More than 100,000 children die each year from the measles virus, making it one of the most dangerous human pathogens. Fever, malaise, cough, coryza, and conjunctivitis are among the symptoms of the illness, which is followed by exanthem.

Around 90% of vulnerable persons will get measles after exposure. Based on monthly data reported to WHO (Geneva) as of early April 2022, India ranks 3rd position with approximately 4178 cases in the list of Top 10 Countries with Global Measles Outbreaks.

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Clinical manifestation

Stages of infection - The clinical phases of classic measles virus infection are as follows:

• Incubation
• Prodrome
• Exanthem
• Recovery

Incubation period  

1. After viral entrance through the respiratory mucosa or conjunctivae, the incubation period for measles is 6 to 21 days (median of 13 days). The virus replicates locally, travels to regional lymphatic tissues, and then is assumed to move through the circulation to additional reticuloendothelial locations, which is referred to as the initial viremia.
2. The infectious period is anticipated to last five days before the rash appears and four days thereafter.
3. During the incubation phase, infected persons are often asymptomatic, but some may have temporary respiratory symptoms, fever, or rash.

Prodrome 

1. The prodrome typically lasts two to four days but may last up to eight days.
2. It is characterised by the onset of symptoms such as fever, malaise, and anorexia, followed by conjunctivitis, coryza, and cough.
3. Conjunctivitis has a varying intensity and may be accompanied by lacrimation or photophobia.
4. Respiratory symptoms are caused by inflammation of the mucosa as a consequence of viral infection of epithelial cells.

Enanthem 

1. Around 48 hours previous to the commencement of the exanthem, individuals may develop an enanthem characterised by Koplik spots; these are 1–3 mm white, greyish, or blue elevations with an erythematous base that commonly appears on the buccal mucosa opposite the molar teeth, but they may extend to encompass the buccal and labial mucosa, as well as the hard and soft palate. These are characterised as "grains of salt on the red background."
2. Koplik spots may agglomerate and last between 12 and 72 hours. When the exanthem emerges, Koplik spots often begin to slough.
3.  It is critical to conduct a thorough search for Koplik spots in individuals with suspected measles, as they may help enhance clinical diagnostic accuracy. However, this enanthem may not be present in all measles cases.

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Exanthem 

1. The exanthem of measles appears two to four days after the beginning of fever and consists of an erythematous, maculopapular, blanching rash that begins on the face and extends cephalocaudally and centrifugally to cover the neck, upper trunk, lower trunk, and limbs.
2. Early on, the lesions are blanching; in the later stages, they are not.
3. Petechiae may be present; in extreme instances, the rash may seem hemorrhagic.
4. In general, the size of the rash and the degree of confluence correspond with the severity of the sickness in youngsters. Rarely are the palms and soles affected.
5. Although the spread of the rash from cranial to caudal is indicative of measles, it is not pathognomonic.

Other characteristic findings during the exanthematous phase are lymphadenopathy, high fever, pharyngitis, and nonpurulent conjunctivitis. Uncommonly, generalized lymphadenopathy and splenomegaly.

Recovery and immunity 

1. Coughing may last one to two weeks after measles. Fever persisting beyond the third or fourth day of rash is suggestive of a measles-related complication.
2. Immunity against measles virus infection is believed to be permanent, however rare cases of measles reinfection have been reported.

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Clinical variants

Modified measles - Modified measles is an attenuated form of the disease that develops in persons who already have immunity against measles. Generally, the clinical signs are milder.

Atypical measles - Atypical measles is an illness caused by the measles virus in persons who have been inoculated with the killed-virus vaccine; atypical measles is now uncommon. Atypical measles is defined by a greater and longer fever.

Laboratory findings - Thrombocytopenia, leukopenia, and T cell cytopenia may be observed during measles infection. Interstitial pneumonitis may be seen on chest radiography.

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Complications

Around 30% of measles cases result in one or more complications. While diarrhoea is the most prevalent consequence, the majority of fatalities are caused by problems of the respiratory tract or encephalitis. Otitis media occurs in between 5% and 10% of cases and is more prevalent in children and adolescents.

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Diagnosis

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Treatment

Measles is treated supportively. There is no authorised antiviral medication for measles. Vitamin A has a function to play in some circumstances. Antipyretics, fluids, and treatment of bacterial superinfections such as bacterial pneumonia and otitis media are all examples of supportive therapy. Other consequences, such as seizures or respiratory failure, may also need treatment. Antibiotic prophylaxis may help avoid complications during measles outbreaks.

Vitamin A

Vitamin A deficiency prolongs healing and increases the risk of complications associated with measles infection. Additionally, vitamin A levels decrease during measles; measles may result in xerophthalmia in children who already have a vitamin A deficit.

Vitamin A supplementation may help reduce the severity and risk of complications associated with measles. Certain findings imply that administering vitamin A to measles-infected children under the age of two years may result in a reduction in mortality.

Vitamin A is administered orally once a day for two days :

• Infants <6 months of age − 50,000 international units
• Infants 6 to 11 months of age − 100,000 international units
• Children ≥12 months − 200,000 international units

Ribavirin

Given the danger of measles-related mortality in specific risk categories, certain experts recommend using ribavirin to treat measles pneumonia in children under the age of 12 months, children under the age of 12 months with pneumonia needing ventilatory support, and immunocompromised patients.

Ribavirin is administered orally in two separate dosages of 15 to 20 mg/kg each day. Although the ideal length of treatment is unknown, a five- to seven-day course may be suitable.

Investigational therapies include Isoprinosine (inosine pranobex), Interferon-alpha or beta.

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Prevention

Measles, mumps, and rubella vaccination - Vaccination has resulted in the cessation of measles virus transmission in the industrialised world and provides herd immunity protection to unvaccinated persons. The measles, mumps and rubella (MMR) vaccination is a combination of live virus immunisations against measles, mumps, and rubella; it is critical for avoiding severe sickness caused by these illnesses.

Vaccination against measles often results in long-term protection. India has established the National Strategic Plan for Achieving and Sustaining Measles and Rubella Elimination in India and has vaccinated approximately 324 million children in the MR immunisation campaign between 2017 and 2020.

The government is progressing toward the MR eradication target of obtaining and maintaining a national and subnational immunisation coverage of 95% with two doses of a measles-rubella vaccine.

Infection control - Airborne transmission precautions are recommended in the hospital environment for four days after the development of rash in otherwise healthy patients and the length of disease in immunocompromised patients. Susceptible persons should avoid entering the room of suspected or confirmed measles patients. Susceptible persons should be kept out of work on days 5 through 21 after exposure.

If a case is verified, everyone should be excluded, including those who were vaccinated within 72 hours. MMR is administered in a 0.5 mL dosage. MMR is injected subcutaneously using a 5/8 inch (1.6 cm) 23- to 25-gauge needle. Individuals >12 months of age should generally get the injection in the upper outer triceps.

Individuals who are not fully vaccinated against measles should get two doses of MMR separated by at least 28 days in a measles epidemic scenario; the first immunisation should be delivered within 72 hours of exposure.

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Disclaimer- The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of M3 India.

Images used are for illustrative purposes only and do not represent a true or accurate depiction of the report.

The author is a practising super specialist from New Delhi.