Infectious Disease

Lyme Disease, West Nile Encephalitis, Tuberculosis, Fungal Infections

Older woman rubbing her head

Infectious diseases are often associated with symptoms like fever, malaise, and rashes. Many of these symptoms are actually instigated by your immune system as it rallies to fight off the effects of pathogenic microorganisms like bacteria, viruses, and fungi. Other symptoms result from the actions of the microorganisms themselves as they kill cells, disrupt cellular metabolism or secrete toxins.

Infectious diseases enter your body in a variety of different ways. Some are transmitted through direct contact with the bodily secretions of host humans, animals, or insects while others spread through aerosol dispersion of those secretions. Others contaminate environmental sources or are ingested through contaminated food.

Lyme Disease

Lyme disease is caused by a bacterium called Borrelia burgdorferi, which is transferred to humans through the bite of the blacklegged deer tick. Researchers at the Centers for Disease Control and Prevention (CDC) estimate that 300,000 cases of Lyme disease are diagnosed throughout the United States every year. Though the disease has been found in all 50 states, the majority of cases occur in the northeastern and north-central states.

Localized Stage (early)

Early symptoms of Lyme disease include fever, fatigue, and muscle and joint aches, which can also be associated with a variety of other illnesses. One symptom, however, is characteristic of this infection alone: a rash that surrounds the site of the initial tick bite and looks something like a red bull's eye. At this stage, if a patient is treated with an antibiotic like amoxicillin, cefuroxime, or doxycycline, typically he or she can expect a full and speedy recovery.

Not every patient with Lyme disease develops a characteristic rash; however, many patients who develop a rash may not realize the rash is indicative.

Disseminated Stage

If Lyme disease is not treated, patients may start experiencing symptoms as diverse as arrhythmias, severe fatigue, photosensitivity, and facial paralysis within two weeks to three months of the initial tick bite. As the illness progresses, patients often develop more serious symptoms such as arthritis, carditis, neuropathies and deficits in cognitive function.

Though over time, some people see a spontaneous resolution of Lyme disease symptoms even without treatment, complications like arthritis will turn out to be permanent in approximately 50 percent of all Lyme patients. Treatment is most effective when it is given early, and prevention is the best intervention of all. Use tick repellants, and wear long-sleeved shirts and long pants when you go outside during tick season.

West Nile Encephalitis

West Nile encephalitis is a complication that develops in some cases of West Nile fever infection. The causative organism is a virus that is spread by various mosquito species.

According to the CDC, approximately 80 percent of all individuals who are infected with the West Nile fever virus will exhibit no symptoms whatsoever. The remainder may develop symptoms that include fever, fatigue, muscle pain, headaches, and rash within 2 to 15 days after the initial mosquito bite. Senior citizens and people with suppressed immune systems are most likely to develop symptoms.

Fewer than one percent of patients infected with the West Nile fever virus will go on to develop encephalitis, which is a serious condition affecting the central nervous system. The brain, the spinal cord, and the meninges may become inflamed, causing severe headaches, convulsions, cognitive deficits, and coma. When the spinal cord is affected, paralysis may result.

There is no vaccine for West Nile encephalitis, and supportive measures like intravenous fluids and artificial ventilation are the only effective treatment in particularly severe cases. Prevention involves using insect repellents when you go outside during late spring to early autumn when mosquitoes that could be harboring the disease are most prevalent.

Tuberculosis

Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis, which spreads through contact with aerosol droplets. Although TB is still the leading infectious cause of death worldwide according to the World Health Organization (WHO), the disease had become increasingly rare in developing countries throughout a large part of the 20th century until the emergence of the HIV virus in the mid-1980s.

The definitive test for determining a TB infection is the tuberculin skin test, but many people who react positively to this test are asymptomatic and cannot spread the disease. However, without appropriate treatment, approximately 10 to 15 percent of individuals with latent TB infections will go on to develop the active variant of the disease at some point later in their lives.

A deep cough, fever, night sweats, fatigue, and eventually weight loss characterize an active TB infection. People with suppressed immune systems are particularly susceptible to this infection. Treatment for both latent and active TB involves antibiotic therapy for anywhere between six and nine months. TB medications such as such as Isoniazid and Rifampin can be toxic to your liver, so it is important to be monitored closely by your physician while you are taking them. TB has become resistant to some antibiotics and requires a newer stronger antibiotic regimen.

Fungal Infections

Of the more than 1.5 million species of fungi on the planet, only about 300 are implicated in human illness. Fungal contagions run the gamut from common health problems like tinea pedis (athlete's foot) and yeast infections (thrush) to serious pulmonary illnesses like histoplasmosis. Although fungal infections can be difficult to eradicate, they do not usually represent a serious health threat unless the person who develops the infection is immunosuppressed.

Fungal infections typically spread through contact with microscopic fungal spores. Spores can either be inhaled or come into contact with moist or broken skin. Anti-fungal medications tend to work by destroying the cell wall of the fungus. Topical treatments may be prescribed for infections that affect the skin and nails while fluconazole pills are the treatment of choice for thrush. Pulmonary and systemic fungal infections may require treatment with powerful intravenous drugs like amphotericin whose side effects can be so severe that it may need to be administered in a medical setting.