Diseases That Are Preventable by Vaccination

Polio, Tetanus, Measles, and Mumps

Mary E. Miller

• Editore: Momentum Press
• Anno: 2019
• ISBN:
  9781944749965
• Argomento: Scienze biologiche
• Categoria: Genetica e genomica

Vaccinations provide an effective way to prevent fatal diseases or reduce their symptoms. This book highlights four infectious diseases: polio, tetanus, measles, and mumps. These four diseases are very harmful to human health and are difficult to treat after the infection because they are caused by a toxin or pathogenic virus. In all four cases, the disease exhibits different modes of transmission and progression of symptoms, which require unique treatment regimens. However, all cases can be prevented by vaccinations administered prior to infection.

This book summarizes the symptoms and disease progression of all the four diseases and provides information about the toxin or virus that causes each disease. The ability to harness our immune system through vaccination is discussed in the context of disease prevention. Minor and infrequent risks associated with vaccination are also described, but the very dangerous misconception that vaccines cause autism or other major illnesses is strongly refuted.

CHAPTER 1

Symptoms and Diagnosis

Symptoms and Diagnosis of Polio

Polio, or poliomyelitis, is paralysis resulting from an infection by the poliovirus. Infection by the poliovirus could occur anywhere in the world, though aggressive vaccination efforts have eliminated the virus (as of 2019) from every country except three: Afghanistan, Pakistan, and
Nigeria. Poliovirus infection is very serious, with approximately 72 percent
of infected individuals showing symptoms of the infection. Early flulike symptoms include sore throat, fever, fatigue, nausea, headache, and stomach pain, which usually last for 2 to 5 days at which point they go away. A smaller percentage of infected individuals will develop more severe symptoms, such as paresthesia (pins and needles feeling in the legs). Approximately 25 percent of infected individuals will develop meningitis, which means that the infection of the virus will spread to the spinal cord and/or the brain. Only about 0.5 percent of infected individuals will get polio, paralysis of arms or legs or both, that can lead to permanent disability. The long-term effects of poliovirus infection vary, with some individuals showing symptoms 15 to 40 years after a full recovery from an infection. These long-lasting symptoms are called post-polio syndrome and usually include muscle pain, weakness, or paralysis. Of those individuals who experience polio (paralysis), between 2 and 10 percent will die from the infection, usually due to paralysis of the diaphragm, a muscle needed for breathing. Taken together, the overall risk of death is significant, with about 0.01 to 0.05 percent mortality of individuals who become infected with poliovirus. This mortality rate is high, since for every 10,000 individuals infected with the poliovirus, 1 to 5 will die. What makes poliovirus particularly concerning is its ability to spread very quickly with high rates of disability and death among infected individuals.

Diagnosis of poliovirus infection involves the identification of the virus in patient samples. Poliovirus can be isolated from cerebrospinal fluid, though this is rarely used for diagnosis. The most common source of specimen is from patient feces or throat swabs. The most sensitive way to determine whether or not poliovirus is present is to detect the presence of the viral genome in patient samples or by culturing virus (allowing the virus to replicate). Both of these sensitive tests are conducted only in controlled laboratory settings, due, in part, to the potential hazard of working with live and infectious poliovirus. The poliovirus genome is composed of RNA; so in order to detect viral RNA in patient samples, the poliovirus RNA genome is copied into a DNA version first so that it can be amplified through a molecular technique called polymerase chain reaction (PCR). PCR can detect the DNA copy of the viral RNA genome because it is specific to unique segments of the viral genome. PCR amplifies only a particular segment until this segment is abundant enough to detect. The presence of poliovirus can also be determined by quantifying IgG or IgM poliovirus antibodies circulating in the blood. However, antibody detection cannot be used for patients who have been vaccinated since they too would produce poliovirus antibodies regardless of their infection status. Currently, infection with the poliovirus and pathological development of poliomyelitis are both part of the National Notifiable Disease Surveillance System (NNDSS), meaning that they are among the 120 diseases that must be reported to the CDC that tracks especially harmful diseases within populations and develops appropriate responses to protect local communities.

Symptoms and Diagnosis of Tetanus

The disease tetanus is the contraction, or tightening, of muscles in the body resulting from toxins released during an infection with the bacteria Clostridium tetani. These muscle contractions can persist from minutes to weeks. Most cases of tetanus occur in adults, with very serious disease progression in those over 65, and in mothers/newborns if the mothers are not protected in advance by the tetanus vaccine. In the United States, 197 reported cases occurred from 2009 to 2015, and approximately 30 cases a year are reported. Tetanus symptoms usually occur 3 to 21 days after infection, with most cases showing symptoms on day 14. Occasionally, a delay in symptom onset can vary widely from 1 day to several months depending on the type and location of the site of infection that introduced the Clostridium into the body.

Muscle contractions caused by tetanus can cause jaw muscles to tighten and close (lockjaw), making speaking and swallowing difficult. Muscle contractions caused by tetanus may occur throughout the body and can take the form of reflex spasms, which are brief muscle contractions, sometimes triggered by muscle stretching or stimulation of the five senses. Painful contractions often begin with jaw and neck muscles, followed by muscles in the chest and abdomen. Occasionally, muscle rigidity is confined to the site of Clostridium infection. The involuntary tightening of muscles can be intense, causing broken bones and breathing difficulty. Other tetanus symptoms include staring, laryngospasm (spasms of the vocal cords), pulmonary embolism (blood clot that moves into the lungs and causes a blockage), aspiration pneumonia (pneumonia from breathing in foreign material into the lung), stomach pain, headache, and fever. If the secreted Clostridium toxin reaches the brainstem of the central nervous system, then symptoms can include autonomic dysfunction. Symptoms associated with autonomic dysfunction usually occur later in infections and can include changes in blood pressure, heart rate, sweating, bradyarrhythmia (irregular heartbeats), and cardiac arrest.

More than 80 percent of tetanus cases are described as generalized tetanus, with initial symptoms of muscle contractions of the jaw followed by painful contractions in the neck, trunk, or extremities of the body. These muscle responses can cause patients to bend backward with an arched back. Some patients might drool or lose control over urination and defecation. In severe cases, uncontrolled muscle contractions can progress to convulsions or seizures. Other neuronal dysfunction can vary greatly depending on prior immunity to Clostridium infection, amount of toxin present in the patient, and age of the patient. The closer the site of infection is to the nervous system, the faster disease progression occurs. Generalized tetanus is a serious complication and can cause death 10 to 20 percent of the time. Localized tetanus describes cases where symptoms are more confined to the area of infection. Localized tetanus cases are milder and usually occur in individuals with previous immunity to Clostridium infection, though localized tetanus can progress to generalized tetanus. Cephalic tetanus is very rare and is confined to muscles or nerves of the head and neck. This type of tetanus is more common when infections result from head laceration, skull fracture, eye injury, or dental injury so that Clostridium spores enter the body in these areas. Symptoms include neck stiffness, problems swallowing, lockjaw, retracted eyelids, abnormal eye movement (deviated gaze), and risus sardonicus, which translates from Latin as spasms of the facial muscles that cause the appearance of abnormal smiling. Cephalic tetanus can also progress to generalized tetanus. Neonatal tetanus can occur in newborns if tetanus arises within the first month of life and usually results from umbilical cord stump contamination. Neonatal tetanus can be lethal, and according to the WHO, 49,000 newborn children died worldwide for this reason in 2013. Although astonishing, these numbers are greatly reduced compared with 1988 when 787,000 newborns died from tetanus worldwide. Infants whose mothers were vaccinated usually do not get tetanus because of the babies exhibit immunity gained passively from their mothers. When tetanus occurs in the mother during pregnancy or after birth (up to 6 weeks), the infection is called maternal tetanus.

The diagnosis of tetanus is usually preceded by rapid onset of muscle contractions with no other observable cause. There is no specific laboratory test used for diagnosis. The identification of Clostridium bacteria is not necessary for diagnosis, since very few toxin-secreting cells are sufficient to cause disease. When the bacterium is present, it is detected as a spore-forming, motile, and swarming rod-shaped cell with distinct nutritional requirements and structural features (spores at one end creating a “tennis-racket” appearance, as shown in Figure 1.1). Some additional diseases have similar symptoms to tetanus and should be considered during diagnosis. Strychnine (rat poison) ingestion can show symptoms similar to tetanus. Lockjaw can also be caused by encephalitis, side effects from phenothiazine (antipsychotics used to treat schizophrenia and other psychotic disorders), as well as other diseases involving the jaw. Tetanus is part of the NNDSS, meaning that all diagnosed cases must be reported to the CDC.

Figure 1.1 The bacterium Clostridium tetani. Diagram on the left shows the overall structure of the bacteria and the position of the spore as it is formed within the bacteria. The image to the right is a micrograph of a group of C. tetani bacteria, the causative agent of tetanus. The diagram is by Kholmes16—Own work, CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], from Wikimedia: https://commons.wikimedia.org/w/index.php?curid=40504343. The micrograph is by the Center for Disease Control and Prevention’s Public Health Image Library, identification number #6372; PD-USGov-HHS-CDC; from Wikimedia: https://upload.wikimedia.org/wikipedia/commons/1/18/Clostridium_tetani.webp.

Symptoms and Diagnosis of Measles

Measles is a highly contagious respiratory illness resulting from infection by the measles virus. ...