Polio

Polio is a severe acute infectious disease caused by the poliovirus, which can spread from person to person, damaging the central nervous system and motor neurons, resulting in flaccid paralysis, the inability to move limbs, difficulty breathing, and eventually leading to paralysis and death, particularly in unvaccinated children. In Thailand, from July 1, 2023, a new polio vaccine regimen is instituted to help boost immunity while reducing the risk of paralysis. Parents should bring their children who have reached the vaccination age to receive the new polio vaccinations available at all hospitals.

What causes polio?

Polio, or poliomyelitis, is due to one of the three strains of poliovirus in the same family of enteroviruses that cause hand, foot, and mouth disease  and meningitis, which enters the mouth through eating contaminated food or water. Once inside the body, the virus travels to the tonsils, multiplies in the throat, moves to the stomach and the colon, serving as the disease's reservoir, and multiplies in the lymph nodes, liver, and spleen. Only 1-2% of the virus will spread to the bloodstream, spinal cord neurons, and brainstem, damaging the central nervous system (CNS) and motor neurons that control muscle function, resulting in muscular atrophy, muscle weakness, and paralysis.

How does polio spread?

Polio is a contagious disease that can readily spread from person to person via the secretion or excretion of an infected person through the following routes:

1. Oral-oral route: The virus accumulating in the throat (Oropharynx) and upper GI tract of an infected person spreads through pharyngeal secretion, such as mucus or droplets from coughing and sneezing spilling onto food or drinking water that enters the mouth of another person.
2. Fecal-oral route: In areas with poor sanitation or underdeveloped public health infrastructures, the polio virus can be transmitted from person to person by feces. The virus in the intestinal reservoir excreted with feces can contaminate food through the dirtied, unclean hands of the infected person which then enter another person's mouth.

What are the polio symptoms?

People infected with the polio virus have varying symptoms but can spread the disease to others while asymptomatic. The vast majority of infected people exhibit no symptoms. Only 1-2 percent of infected persons develop severe forms of the disease, with muscle weakness and flaccid paralysis. Polio symptoms are of the following four groups:

1. Asymptotic: 70-90% of those infected with the polio virus are asymptomatic but can infect others.
2. Abortive poliomyelitis (a minor illness) in 5% of patients presenting with flu-like symptoms, such as fatigue, low-grade fever, sore throat, headache, loss of appetite, and gastrointestinal symptoms of vomiting, abdominal pain, diarrhea, or constipation. After 2-3 days, the symptoms resolve without paralysis.
3. Non-paralytic poliomyelitis in 1% of cases, which begin with symptoms of abortive poliomyelitis, followed by symptoms due to aseptic meningitis with neck pain, stiff neck, severe headache, pain, or pins-and-needles sensation in the arms and legs, sensitivity to light (photophobia), muscle pain, decreased muscle reflexes, and muscle weakness. After 1–2 weeks, the symptoms return to normal without paralysis.
4. Paralytic poliomyelitis is the most disabling form of polio when the poliovirus infects the brain and spinal cord, occurring in only 1-2% of cases, with symptoms divided into two stages as follows:
   • 4.1 Stage 1 paralytic poliomyelitis starts with symptoms similar to abortive poliomyelitis, preceded by a non-paralytic poliomyelitis phase, 3–4-day of fevers that waxes and wanes and then return, followed by generalized, intense muscle ache, acute or gradual muscle weakness, muscle spasms, and then paralysis in various body parts. The reflexes (automatic muscle response) gradually weaken before total paralysis sets in within 48 hours, along with the following symptoms: flaccid paralysis (the most common symptom of paralytic polio) involving the arms, legs, trunk muscles, chest, abdomen, more commonly in the legs than in the arms, particularly in the thighs or upper arms rather than the distal limbs, and usually affect one leg rather than both (asymmetry), but does not affect the sensory system.
   • 4.2 Stage 2 paralytic poliomyelitis is acute poliomyelitis in which the virus infects the neurons and nerve fibers in the medulla oblongata that control breathing, the circulatory system, eating, swallowing, and speaking, causing breathing, swallowing, resulting in speech difficulties, as well as respiratory muscle paralysis, which eventually leads to death.

How is polio diagnosed?

The doctor will arrive at a polio diagnosis by taking your medical history, performing a physical examination, and ordering laboratory tests to rule out or confirm the disease, particularly for unvaccinated persons, travelers to an endemic area, or persons presenting with acute flaccid paralysis (AFP). The doctor will perform the following diagnostic steps:

1. Physical examination: test for abnormal reflexes by tapping with a rubber mallet to gauge the knee and ankle reflexes, checking for stiff neck, muscle weakness, urinary incontinence, constipation, difficulty swallowing, or difficulty speaking.
2. Lab testing for enteroviruses
   • Oropharyngeal swab to collect a secretion sample and run tests in a laboratory to check for enterovirus material during the first week of suspected infection.
   • Stool examination: collecting stool samples to test for poliovirus. Throat secretions are usable only during the first week of illness. The virus is thus more likely detectable with a fecal examination.
   • Cerebrospinal fluid examination is beneficial in ruling out poliovirus and other neurological diseases.
   • Neuroimaging/Electrodiagnostic testing is a diagnostic test for peripheral nervous system disorders and muscle weakness.
   • The antibody test checks for specific antibodies against the virus following an infection.
   • Polymerase chain reaction (PCR) is a test to detect poliovirus genetic material in the body.
   • Culture: taking bodily secretions to incubate in a culture medium to confirm or rule out the disease.

How is polio treated?

Polio is a disease for which there is no cure. Polio treatment, therefore, focuses on symptomatic care and physical therapy to speed up muscle rehabilitation and avoid complications that may occur with the following measures:

• Getting enough rest and providing intimate care
• Using pain relievers such as ibuprofen to alleviate pain.
• Using portable ventilators to help with breathing.
• Using warm compresses to help relieve muscle pain and spasms.
• Swallowing exercises of the oral and tongue muscles; practice drinking water or a liquid diet.
• Using a splint or body brace to help align the spine and limbs in a proper position.
• Physical therapy to prevent bone deformity and loss of muscle mass.

What are the complications of polio?

The most frightful complication of polio is respiratory muscle paralysis, which causes difficulty in breathing and may result in death. Other polio complications include:

• Permanent paralysis, immobility, muscle weakness, and fatigue
• Severe chronic muscle pain in the legs, waist, wrists, and head
• Swallowing and speaking difficulties, which may cause choking
• Respiratory muscle weakness and atrophy causing breathing difficulty, shortness of breath, or sleep apnea.
• Muscle contraction that causes bone or joint deformity
• The flat-back syndrome causes the body to bend forward, unable to stand upright due to muscle weakness.

How to prevent polio?

The best prevention for polio is with a series of five scheduled vaccinations, as well as the following hygienic practices:

• Polio vaccination (IPV and OPV): Doctors recommend a series of five vaccinations at 2, 4, 6, and 18 months, with the final booster dose at age 4.
• Proper hygiene measures include washing your hands before meals and adhering to hygienic bowel elimination practices.

New polio vaccine formulation

Thailand has earmarked the polio vaccine in the national immunization program for all Thai children. Starting July 1, 2023, a new polio vaccine formulation is 2 IPV + 3 OPV, or two injections + 3 oral drops, to boost immunity and reduce the risk of disability. The new polio vaccine formulation is as below:

1. Injected Poliomyelitis Vaccine (IPV) is a live, attenuated viral vaccine administered in two doses, the first at age two months and the second at four months.
2. Oral polio vaccine (OPV) is an inactivated virus vaccine administered by oral drops three times at six months, 18 months, and four years.
   
   

Polio, a vaccine-preventable viral infection

Polio is a highly contagious disease that causes disability and death and is currently incurable. Thailand has not encountered a Polio case since 1997, but the Ministry of Public Health and the Department of Disease Control continue to keep watch with the polio surveillance program. During the past three years, there has been a rising trend of outbreaks with growing numbers of infected people, particularly in Asian countries.

However, polio is eminently preventable through vaccination. Parents or guardians of children two months and older can take their children to any hospital to receive the first and second injected polio vaccine doses and the three subsequent oral drops boosters when coming due, following proper hygiene principles, including eating freshly cooked, clean, and safe foods, using serving spoons, regularly washing hands, which can keep you safe from polio.