Diseases Associated with Water/Environmental Contact Flashcards
Cutaneous Larva Migrans Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Most cases are reported in travelers to the Caribbean, Africa, Asia, and South America. Beaches are a common source of infection.
Prevention: Reduce contact with contaminated soil by wearing shoes and protective clothing and using barriers such as towels when seated on the ground.
Transmission: Skin contact with contaminated soil or sand.
Symptoms: Creeping eruption usually appears 1–5 days after skin penetration, but the incubation period may be ≥1 month. Typically, a serpiginous, erythematous track appears in the skin and is associated with intense itchiness and mild swelling. Usual locations are the foot and buttocks, although any skin surface coming in contact with contaminated soil can be affected.
Treatment: Albendazole is the treatment of choice. Ivermectin is effective but not approved for this indication.
Leptospirosis Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Leptospirosis has worldwide distribution, with a higher incidence in tropical climates, especially after heavy rainfall or flooding due to hurricanes. Outbreaks of leptospirosis have occurred in the United States after flooding in Hawaii and Puerto Rico. Travelers participating in recreational water activities are at increased risk, particularly after heavy rainfall or flooding.
Prevention: No vaccine is available in the United States. Travelers who might be at an increased risk for infection should be advised to consider preventive measures such as chemoprophylaxis, wearing protective clothing, especially footwear, and covering cuts and abrasions with occlusive dressings. Until further data become available, CDC recommends chemoprophylaxis with doxycycline (200 mg orally, weekly), begun 1–2 days before and continuing through the period of exposure for people at high risk of leptospirosis. Doxycycline is not recommended for pregnant women or children aged < 8 years
Transmission:
Infection occurs through abrasions or cuts in the skin, or through the conjunctiva and mucous membranes. Humans may be infected by direct contact with urine or reproductive fluids from infected animals, or with water or soil contaminated with those fluids. Prolonged immersion in contaminated water increases the risk for infection. Infection rarely occurs through animal bites or human-to-human contact.
Symptoms:
The incubation period is 2 days to 3 weeks. The acute phase (approximately 7 days) presents as an acute febrile illness with symptoms including headache (can be severe and include retroorbital pain and photophobia), fever, chills, myalgia, nausea, diarrhea, abdominal pain, uveitis, conjunctival suffusion, and occasionally, a skin rash. The second or immune phase is characterized by antibody production and the presence of leptospires in the urine. The icteric or severe form of the disease (Weil disease) occurs in 5%–10% of patients with leptospirosis. Symptoms include jaundice, renal failure, hemorrhage (especially pulmonary), cardiac arrhythmias, pneumonitis, and hemodynamic collapse.
Treatment:
Doxycycline is effective in decreasing the severity and duration of leptospirosis and should be initiated early in the course of the disease if leptospirosis is suspected. Intravenous penicillin is a drug of choice for patients with severe leptospirosis. Patients with severe leptospirosis may require hospitalization, supportive therapy, and close monitoring.
Schistosomiasis Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
An estimated 85% of the world’s cases of schistosomiasis are in Africa, where prevalence rates can exceed 50% in local populations. Schistosoma mansoni and S. haematobium are distributed throughout Africa; only S. haematobium is found in areas of the Middle East, and S. japonicum is found in Indonesia and parts of China and Southeast Asia (Map 3-12). Two other species can infect humans: S. mekongi, found in Cambodia and Laos, and S. intercalatum, found in parts of Central and West Africa. These 2 species are rarely reported causes of infection. Many countries endemic for schistosomiasis have established control programs, but others have not. Countries where development has led to widespread improvements in sanitation and water safety, as well as successful schistosomiasis control programs, may have eliminated this disease. However, there are currently no international guidelines for certification of elimination. All ages are at risk for infection with freshwater exposure in endemic areas. Swimming, bathing, and wading in contaminated freshwater can result in infection. Human schistosomiasis is not acquired by contact with saltwater (oceans or seas). The distribution of schistosomiasis is very focal and determined by the presence of competent snail vectors, inadequate sanitation, and infected humans. The geographic distribution of cases of schistosomiasis acquired by travelers reflects travel and immigration patterns. Most travel-associated cases of schistosomiasis are acquired in sub-Saharan Africa. Sites in Africa frequently visited by travelers are common sites of infection. These sites include rivers and water sources in the Banfora region (Burkina Faso) and areas populated by the Dogon people (Mali); Lake Malawi; Lake Tanganyika; Lake Victoria; the Omo River (Ethiopia); the Zambezi River; and the Nile River. However, as visitors travel to more uncommon sites, it is important to remember that most freshwater surface water sources in Africa are potentially contaminated and can be sources of infection. A local claim that there is no schistosomiasis in a body of freshwater is not necessarily reliable. The specific snail vectors can be difficult to identify, and infection of snails with human schistosome species must be determined in the laboratory. The types of travelers and expatriates potentially at increased risk for infection include adventure travelers, Peace Corps volunteers, missionaries, soldiers, and ecotourists. Outbreaks of schistosomiasis have occurred among adventure travelers on river trips in Africa.
Prevention: No vaccine is available. No drugs for preventing infection are available. Preventive measures are primarily avoiding wading, swimming, or other contact with freshwater in disease-endemic countries. Untreated piped water coming directly from freshwater sources may contain cercariae, but filtering with fine-mesh filters, heating bathing water to 122°F (50°C) for 5 minutes, or allowing water to stand for ≥24 hours before exposure can eliminate risk for infection. Swimming in adequately chlorinated swimming pools is virtually always safe, even in disease-endemic countries. Vigorous towel-drying after accidental exposure to water has been suggested as a way to remove cercariae before they can penetrate, but this may only prevent some infections and should not be recommended as a preventive measure. Topical applications of insect repellents such as DEET can block penetrating cercariae, but the effect depends on the repellent formulation, may be short-lived, and cannot reliably prevent infection
Transmission: Waterborne transmission occurs when larval cercariae, found in contaminated bodies of freshwater, penetrate the skin.
Symptoms: The incubation period is typically 14–84 days for acute schistosomiasis (Katayama syndrome), but chronic infection can remain asymptomatic for years. Penetration of cercariae can be associated with a rash that develops within hours or up to a week after contaminated water exposures. Acute schistosomiasis is characterized by fever, headache, myalgia, diarrhea, and respiratory symptoms. Eosinophilia is present, as well as often painful hepatomegaly or splenomegaly. The clinical manifestations of chronic schistosomiasis are the result of host immune responses to schistosome eggs. Eggs secreted by adult worm pairs enter the circulation and lodge in organs and cause granulomatous reactions. Eosinophilia may be present. S. mansoni and S. japonicum eggs most commonly lodge in the blood vessels of the liver or intestine and can cause diarrhea, constipation, and blood in the stool. Chronic inflammation can lead to bowel wall ulceration, hyperplasia, and polyposis and, with heavy infections, to periportal liver fibrosis. S. haematobium eggs typically lodge in the urinary tract and can cause dysuria and hematuria. Calcifications in the bladder may appear late in the disease. S. haematobium infection can also cause genital symptoms and has been associated with increased risk of bladder cancer. Rarely, central nervous system schistosomiasis may develop; this form is thought to result from aberrant migration of adult worms or eggs depositing in the spinal cord or brain. Signs and symptoms are related to ectopic granulomas in the central nervous system and can present as transverse myelitis.
Treatment: Schistosomiasis is uncommon in the United States, and the inexperienced physician should consult an infectious disease or tropical medicine specialist for diagnosis and treatment. Praziquantel is used to treat schistosomiasis. Praziquantel is most effective against adult forms of the parasite and requires an immune response to the adult worm to be fully effective.
Tetanus Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Distributed worldwide; more common in agricultural regions, areas where contact with soil or animal excreta is likely, and areas where immunization is inadequate.
Prevention: Vaccine
Transmission: Contact with nonintact skin, usually via injuries from contaminated objects. “Tetanus-prone” wounds include those contaminated with dirt, feces, or saliva; punctures; burns; crush injuries; or injuries with necrotic tissue.
Symptoms: Incubation period is 10 days (range, 3–21 days). Acute symptoms typically include muscle rigidity and spasms, often in the jaw and neck. Symptoms of less common forms of tetanus (localized or cephalic) can include muscle spasms confined to the injury site, head or face lesions, and flaccid cranial nerve palsies. Progression from these forms to generalized tetanus may occur. Severe tetanus can lead to respiratory failure and death. Treatment: Incubation period is 10 days (range, 3–21 days). Acute symptoms typically include muscle rigidity and spasms, often in the jaw and neck. Symptoms of less common forms of tetanus (localized or cephalic) can include muscle spasms confined to the injury site, head or face lesions, and flaccid cranial nerve palsies. Progression from these forms to generalized tetanus may occur. Severe tetanus can lead to respiratory failure and death.
Treatment:
Tetanus requires hospitalization, treatment with human tetanus immune globulin (TIG), a tetanus toxoid booster, agents to control muscle spasm, and aggressive wound care and antibiotics. Metronidazole is the most appropriate antibiotic. The wound should be debrided widely and excised if possible.
Legionella Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Disease occurs after exposure to aquatic settings that promote bacterial growth—the aquatic environment is somewhat stagnant, the water is warm (77°F–108°F [25°C–42°C]), and the water must be aerosolized so that the bacteria can be inhaled into the lungs. These 3 conditions are met almost exclusively in developed or industrialized settings. Disease does not occur in association with natural freshwater settings such as waterfalls, lakes, or streams. Despite the presence of Legionella bacteria in many aquatic environments, the risk of developing legionellosis for most people is low. Travelers who are exposed to aerosolized, warm water containing Legionella are at risk for infection. Travelers who are aged >50 years, are current or former smokers, have chronic lung conditions, or are immunocompromised are at higher risk of developing illness after exposure. Many outbreaks have been associated with exposure to cruise ships, hotels, and resorts. Exposures can occur during recreation in or near a whirlpool spa, while showering in a hotel, or touring in cities with buildings that have cooling towers. Patients often do not recall specific water exposures, as they frequently occur during normal activities.
Prevention: There is no vaccine for legionellosis, and antibiotic prophylaxis is not effective. Travelers at increased risk for infection, such as the elderly or those with immunocompromising conditions such as cancer or diabetes, may choose to avoid high-risk areas, such as whirlpool spas
Symptoms Legionnaires’ disease typically presents with pneumonia, which usually requires hospitalization and can be fatal in 10%–15% of cases. Symptom onset occurs 2–14 days after exposure. pontiac fever is milder than Legionnaires’ disease and presents as an influenzalike illness, with fever, headache, and muscle aches, but no signs of pneumonia. Pontiac fever can affect healthy people, as well as those with underlying illnesses, and symptoms occur within 72 hours of exposure. Most patients fully recover. Up to 95% of people exposed in outbreak settings can develop symptoms of Pontiac fever.
Treatment For travelers with suspected Legionnaires’ disease, specific antibiotic treatment is necessary and should be administered promptly while diagnostic tests are being processed. Appropriate antibiotics include fluoroquinolones and macrolides. Treatment may be necessary for up to 3 weeks. In severe cases, patients may have prolonged stays in intensive care units
