Measles: Transmission, Diagnosis and Complications

Introduction

An infectious disease that is caused by a very contagious virus. It is prevalent worldwide however, due to the presence of vaccine as part of MMR, the prevalence has dropped significantly compared to a century earlier. Though, a recent rise in incidence it attributed to a false link between MMR and Autism caused concerned parents to avoid taking this vaccine. The following article will summarize the mode of transmission, clinical manifestations, diagnosis and complications of measles.

Transmission

The virus is transmitted through air droplets, it can survive on surfaces for around 2 hours which means it doesn’t need a direct person to person interaction. Not only that, the percentage of infection upon contact is 90% making it very contagious.

Another major problem is what referred to as the incubation period. This virus is able to live in a host body for 6-21 days without showing signs or symptoms. This means that the patient is transmitting the infection to surrounding without knowing. However, the most contagious phase is when the person starts experiencing fever and fatigue. A stage referred to as Prodrome.

Presentation

Measles can manifest in several clinical variants, most commonly the classic measles infection of which this article will further elaborate on. Other forms include modified measles that occur for those with preexisting immunity either through a previous infection or vaccination.

The stages of class measles infection are:

1- Incubation: The duration of sign/symptom-free. However, the virus is in the process of replicating and spreading to the local lymphatic system and expanding to distant body tissues through blood. Usually, the person is infective 5 days before the appearance of the rash and four days after.

2- Prodrome: A duration of around 2 to 4 days with general viral symptoms of high-grade fever, up to 40c, cough, malaise, and loss of appetite. Then it is followed by those more specific like red eye, photosensitivity and coryza.

3- Enanthem: The appearance of distinctive white elevations with erythematous base name kolpik spots. Their presence is not always part of the clinical picture.

4- Exanthem: The classic maculopapular rash that starts on the face then moves down spreading to the trunk and lower body. Usually, the palms and soles are spared. The rash resolves in 6 days from head to toe as it appeared. If it is a severe infection, they might also experience generalized lymphadenopathy or enlarged spleen.

5- Recovery: It might take up to 2 weeks for the cough to completely resolve. However, if the fever lasts 5 days after the rash, the patient might be experiencing one of the measles complications.

Diagnosis:

• Should be suspected when a child/adult presents with fever, conjunctivitis and maculopapular rash.
• Positive measles IgM antibody
• A significant rise in measles IgG antibody
• Culturing the virus
• Detection of RNA by PCR

Treatment:

• It is mainly supportive care, which includes the management of fever using antipyretic, management of dehydration with lots of fluids.
• Sometimes, bacterial superinfection such as bacterial pneumonia can occur, so prophylactic antibiotics are suggested.
• Vitamin A has been used to prevent measles complications, especially on the nervous system.
• Antiviral treatment such as Ribavirin has been used mainly in high-risk groups such as those less than a year with pneumonia and those who are immunocompromised.

Complications

• Diarrhea is the most common complication. It can be significant enough to cause dehydration and malnourishment.
• The virus has the ability to infect T lymphocytes, causing immune system dysfunction. Patients are then liable to other infections such as lung and middle ear bacterial infections.
• Typical upper respiratory infections are common, however, measles can also lead to an immune-mediated inflammation of the lung tissue.
• The virus can transmit to the brain leading to encephalitis, it is diagnosed by high protein and lymphocytes content in CSF
• ADEM: an autoimmune-mediated disease where lymphocytes confuse the antigen of the virus with the antigen of the myelin sheath. This results in marked brain damage manifesting in several neurological symptoms such as loss of movement, balance, and sensation.
• Subacute sclerosing panencephalitis: a deadly disease that occurs 10 years after infection. It is a degenerative disease with several stages from strange behavior to myoclonus to eventually a vegetative stage and death. It has no cure.
• Inflammation of the cornea which can lead to scarring and blindness

Who is at risk for these complications?

- An immunocompromised patient such as those with leukemia and AIDS. They will not manifest the classic presentation such as fever and rash which make the diagnosis more challenging. Therefore, high suspicion should be present.

- Pregnant women: infection with measles in early pregnancy leads to abortion, maternal death, or baby born with mental retardation and several other abnormalities.

Prevention

1. MMR vaccine: apart from fever and mild rash, MMR is a safe vaccine to those who are immunocompetent.
2. Infection control: hand hygiene is extremely important. Isolation and use of special airborne masks are a must. This is particularly the case for those having fever with maculopapular rash suspicious of measles.

References

1. Cherry JD. Measles virus. In: Textbook of Pediatric Infectious Diseases, 6th ed, Feigin RD, Cherry JD, Demmler-Harrison GJ, et al (Eds), Saunders, Philadelphia 2009. p.2427
2. Adams RD, Victor M, Ropper AH. Multiple sclerosis and allied demyelinating diseases. In: Principles of Neurology, McGraw-Hill (Ed), New York City 1997. p.921.
3. Bernstein DI, Reuman PD, Schiff GM. Rubeola (measles) and subacute sclerosing panencephalitis virus. In: Infectious Diseases, Gorbach SL, Bartlett JG, Blacklow NR (Eds), WB Saunders, Philadelphia 1998. p.2135.
4. Darmstadt GL, Lane A. Disorders of the mucous membranes. In: Nelson Textbook of Pediatrics, 15th ed, WB Saunders, Philadelphia 1996. p.1888.