The field of infectious disease is vast and this chapter is by no means an exhaustive review of all possible serious infections one may encounter while rendering care in the wilderness. It is possible that nearly any infection that one could see in traditional EMS could also occur in the wilderness. Out-of-hospital
medicine is inherently limited by, and in essence defined by, a lack of advanced diagnostic equipment, support, and resources. Wilderness EMS relies on physical exam, clinical history, and knowledge of epidemiology to guide treatment. This leads to quite a bit more uncertainty, and differentiating similar infections may not be possible without bacterial cultures, gram stains, and the support of a microbiology lab that one would have in a hospital emergency department. Although similar diseases may be indistinguishable to the wilderness EMS provider, by using a systematic approach it is possible to initiate appropriate treatment early and prevent patient deterioration. This chapter will cover recognition and treatment of the most common and life-threatening infections of the skin and soft tissue, gastrointestinal (GI) system, genitourinary (GU) system, central nervous system (CNS), and pulmonary system. Finally, this chapter covers sepsis and its management in the wilderness.

Infections of the pulmonary system are common and range in severity from very mild to life-threatening. Although travelers to wilderness areas are at risk of a variety of diseases uncommon in the frontcountry, they are still much more likely to suffer from the same infections that are common in the frontcountry. Infections of the pulmonary system are classified by the anatomic location of the infection, and have characteristic physical exam findings and symptoms.

Bronchitis is one of the most common ailments seen in clinical medicine. It is the infection of the bronchi, or large airways of the lungs. It is usually caused by viruses, and by definition, is self-limited in course. Patients present with at least 5 days of dry cough, sometimes with sputum production, wheezing, and can have mild dyspnea with exertion. Bronchitis has an indolent course and usually has a gradual onset, worsening over days. Patients with bronchitis may also have cough productive of rust-colored or blood-tinged sputum, which is a result of inflammation and irritation of the bronchioles by persistent coughing. During the first few days of illness it is not possible to distinguish acute bronchitis from other viral upper respiratory infections caused by the common cold or related viruses. Patients who are smokers or have underlying lung disease such as chronic obstructive pulmonary disease (COPD) or asthma are more likely to have severe symptoms, and can have acute exacerbations of their disease triggered by the inflammation caused by infection.

Pneumonia is the acute infection of the lung parenchyma, the portions of the lung involved in gas transfer—the alveoli and small bronchioles. It is distinct from bronchitis in both presentation and significance. While bronchitis may cause annoying symptoms by irritating the large airways and causing cough, pneumonia can cause difficulty with gas exchange leading to severe shortness of breath and even hypoxia. Pneumonia is characterized by relatively rapid onset of fever, chills, cough, malaise, and shortness of breath. Approximately 30% of patients will experience chest
pain. Pneumonia often follows a viral illness in otherwise healthy adults. Sudden shortness of breath (or worsening of earlier mild shortness of breath), high fever, and rapid respiratory rate in a patient who has been suffering from cold symptoms for several days should be an alert that a patient is developing pneumonia. In contrast to bronchitis, pneumonia is typically a bacterial infection, although viruses can cause pneumonia as well.

Pneumonia is classified as either community-acquired pneumonia (CAP) or health care-associated pneumonia (HAP) depending on the clinical context. Patients with significant contact with the health care system are classified as health care-associated, including³:

Wilderness EMS providers are unlikely to encounter HAP patients in remote areas, but it is important to note that they are more likely to be infected with different organisms than patients with CAP, and will need different antibiotics.

Pneumonia is a common, potentially life-threatening condition that is usually of little concern in otherwise healthy patients in the traditional EMS context. Standard practice in hospital-based medicine is to obtain chest x-ray to confirm the diagnosis of pneumonia. Wilderness EMS providers will need to rely on history and physical exam findings to make the diagnosis and begin treatment; however, there are no specific sets of clinical symptoms that can reliably distinguish pneumonia with complete certainty. Additionally, exposure to common wilderness factors, such as mold and mat, produce conditions that mimic pneumonia. While the vast majority of patients with pneumonia are febrile (80% according to some studies), accurate measurement of the patient’s temperature in the wilderness is difficult, and can be affected by the environment. Exposure to a cold environment can lower the patient’s core temperature and mask a fever, just as exertion and exposure to heat can raise the core temperature. Portable pulse oximetry is relatively inexpensive and units are available that are small and lightweight (Figure 20.2.1). These units measure pulse oximetry (SpO₂,) a surrogate but usually accurate reflection of arterial oxygen saturation (SaO₂). A significant drop in the patient’s pulse oximetry reading during ambulation or lower than expected readings accompanied by fever, rapid respirations, and cough are also strongly suggestive of a severe pneumonia warranting intervention. On examination, most patients will also have audible crackles on lung auscultation. Despite much investigation, no constellation of symptoms has ever been shown to reliably predict whether a patient has pneumonia.⁴ An assessment of the overall risk of treatment versus that potentially leaving a bacterial pneumonia untreated should accompany the decision to begin therapy. While bronchitis is self-limited and unlikely to incapacitate a patient, pneumonia can progress to a life-threatening and incapacitating illness fairly quickly without treatment. Prior to antibiotics, this was a leading cause of death in human populations.

Treatment of respiratory illness can be thought of in three parts: support of the patient’s breathing and respiratory function, treatment of underlying organism causing illness (if possible), and relief of symptoms. Not all patients suffering from respiratory illness and infections will require rapid evacuation or even antibiotics. In general, treatment by wilderness EMS providers should start with careful risk-assessment considering:

If in doubt, rapid evacuation should be initiated for patients at high risk of deterioration or with rapidly progressive illness. When the situation allows, beginning treatment and evacuating early is preferable when the patient is still able to assist in his or her own rescue.

Complaints of painful urination (dysuria), urinary urgency, flank pain, vaginal or penile discharge, and lower pelvic/suprapubic pain are suggestive of GU infections. Depending on the severity of the illness, patients may also have fever, chills, tachycardia, or rapid respirations. As with all infections, signs of poor perfusion, altered mental status, and low blood pressure are signs of very severe infection and portend a poor outcome in the wilderness.

Lower UTIs, also known as cystitis, are quite common in females, but relatively uncommon in men. Approximately 5 to 8 otherwise healthy men per 10,000 will experience a UTI yearly, compared to 1 in every 2 or 3 otherwise healthy women.^12,13 Young women who complain of a combination of dysuria, suprapubic pain, urgency, and hematuria are likely to have UTIs. Women of childbearing age should be screened for pregnancy. The diagnosis is usually confirmed by urinalysis—in the wilderness, necessarily, by urine pregnancy dipstick rather than serum testing. With regard to UTI, the presence of leukocyte esterase with or without nitrites, microscopic evaluation of the urine for bacteria and white blood cells, and urine culture combined with symptoms of UTI is the gold standard for diagnosis. Urine smell is often associated with UTIs by both patients and clinicians; however, it is reflective of hydration status and is of no utility in determining whether a patient has a UTI.¹⁴ Dipsticks are small and easy to carry; however, it is not necessary to confirm the UTI diagnosis with urine dipstick to begin treatment in nonpregnant, otherwise healthy females without vaginal complaints. The likelihood of a UTI in these patients is 90% and with vaginal complaints is still 50%.¹⁵ The only utility of urine dipstick in this case would be that if negative, it may suggest investigating other causes, or potentially conserve limited supplies of antibiotics.

Patients presenting with the symptoms of UTI who also have flank pain and/or fever may be suffering from an upper UTI, also known as pyelonephritis. Bacteria can travel from the bladder to the kidneys via the ureter and infect one or both kidneys. On exam, patients may have pain with percussion of the costovertebral angle (Figure 20.2.2), fever, and tachycardia. Although most otherwise healthy patients do very well if treated early for pyelonephritis, long delays in initiation of antimicrobials can lead to patient decompensation. Given the relatively low incidence of UTIs in men, one should strongly consider other diagnoses before settling on pyelonephritis in an otherwise healthy male. Intermittent sharp pain in flank, which may radiate to the groin, accompanied by blood in the urine should raise the suspicion for a kidney stone. If this patient also has a fever, this does constitute an emergency, as infected kidney stones can lead to serious complications and patients can quickly become very sick.

Complaints of vaginal pain, discomfort, foul-smelling discharge, and suprapubic discomfort indicate that the patient may be suffering from gynecologic infections. Risk factors include being sexually active, and not using barrier protection. Mild infections are limited to the cervix, and generally do not produce severe symptoms. Chlamydia and gonorrhea are common sexually transmitted infections in developed countries. These infections can ascend to infect the uterus, fallopian tubes, ovaries, and surrounding pelvic structures. This is known as pelvic inflammatory disease (PID). Patients with risk factors who complain of symptoms of gynecologic infections, and who have significant lower abdominal pain, tenderness, and or fever should be treated as though they have PID. The diagnosis is typically made by a speculum examination of the cervix and digital examination of the internal reproductive organs. This is very uncomfortable for the patient, is beyond the scope of practice of most wilderness EMS providers, would add little useful information in the wilderness EMS context, and is not routinely recommended for the diagnosis of gynecologic infections in wilderness EMS.

It is critically important to consider ectopic pregnancy when evaluating any female of childbearing age complaining of pelvic pain. This is a potentially immediately life-threatening condition that should warrant emergent evacuation. A negative urine pregnancy test makes the diagnosis of ectopic pregnancy highly unlikely.

Treatment of GU infections is relatively less complex than pulmonary infections, and in general, they are less likely to be the primary reason for wilderness EMS calls.