Área Clínica Médica - 5º año: Zoonosis

Endemic Zoonoses Overview

Introduction to Endemic Zoonoses

• The session is led by Dr. Sandra Guill, an infectious disease specialist and adjunct professor at the National University of Rosario.

• Today's topics include ornithosis, anthrax (carbunco), trichinosis, and datidcosis, focusing on epidemiological reports from 2018.

Epidemiological Reports

• In Entre Ríos province, three outbreaks of trichinosis were reported with eight cases and six hospitalizations.

• Mendoza experienced a brucellosis outbreak with ten cases but no hospitalizations; trichinosis outbreaks were noted in San Luis (101 cases), Córdoba (484 cases), and others across various provinces.

Ornithosis: Understanding the Disease

• Ornithosis affects over 120 bird species; it is often referred to as chlamydiosis due to its causative agent being Chlamydia psittaci.

• Between 2002 and 2009, approximately 60,000 ornithosis cases were reported; the bacteria are obligate intracellular parasites that do not produce ATP.

Clinical Presentation of Ornithosis

• The disease enters through inhalation of aerosols from bird droppings; symptoms typically appear within 6 to 12 days.

• Initial symptoms include fever, joint pain, conjunctival injection, headache, fatigue, diarrhea; hepatosplenomegaly may develop by day five.

Complications and Diagnosis

• If untreated within the first week, complications such as hypersomnia or delirium can occur; mortality rates remain below 1% with treatment.

• Diagnosis relies heavily on epidemiological context rather than laboratory results which may often be normal.

Treatment Options for Ornithosis

• Control measures include community monitoring and clinical vigilance; suspected cases require clinical evaluation alongside serological tests.

• Treatment options involve tetracyclines like doxycycline or clarithromycin for adults; erythromycin is recommended for children at a dosage of 50 mg/kg/day.

Brucellosis: Patterns and Etiology

Epidemiology of Brucellosis

• Brucellosis has distinct urban patterns linked to dairy consumption and rural patterns associated with occupational exposure affecting over 500,000 people annually worldwide.

Causative Agent

Brucelosis: Understanding Transmission and Epidemiology

Overview of Brucelosis in Animals

• Brucelosis is primarily transmitted through infected animals, which serve as reservoirs for the disease. Key species include:

• Brucella abortus: Infects cattle and can transmit to humans.

• Brucella suis: Affects pigs and also infects humans.

• Brucella melitensis: Found in sheep and goats, capable of human infection.

• Brucella canis: Primarily affects dogs but can infect humans.

Prevalence and Species Characteristics

• Each species has different biovars; for instance:

• B. abortus has one biovar.

• B. melitensis has two biovars (1 & 3).

• B. suis has three biovars (1, 3 & cco).

• Canine brucellosis shows high prevalence in stray dogs compared to domesticated ones.

Case Statistics and Trends

• From 2008 to 2016, there were a total of 5,099 reported cases of brucelosis, indicating an upward trend in infections.

• Breakdown of cases from 2015 to 2016:

• 31% suspected cases

• 15% discarded cases

• 35% probable cases

• 18% confirmed cases, with specific counts for each Brucella type identified.

Age Distribution of Cases

• The majority of brucelosis cases occur between ages 24 to nearly 60, highlighting its classification as a professional disease due to occupational exposure.

Environmental Survival of Brucella

• Brucella's survival rates vary significantly based on environmental conditions:

• Survives up to 80 days in soil.

• In milk at room temperature, it lasts about 2 to 4 days.

• Can persist for several months under optimal conditions (e.g., fetuses maintained in shade).

Clinical Presentation and Occupational Risks

• Patients often present with symptoms like undulant fever and night sweats; common among those working in slaughterhouses or handling animal products.

• Workers exposed to contaminated materials must take precautions such as wearing gloves and boots due to the risk associated with handling infected tissues.

Vaccination Practices Among Livestock Producers

• Producers tend to vaccinate female livestock (which produce milk), neglecting males, leading to higher contamination levels within certain areas.

Pathogenesis and Transmission Routes

• In animals, brucellosis manifests mainly as a sexually transmitted infection causing abortions, mastitis, sterility, etc.

• Human transmission occurs via direct contact or consumption of contaminated food products like dairy; inhalation is also a risk factor.

Intracellular Nature of Brucella

Brucelosis: Clinical Manifestations and Diagnosis

Pathophysiology of Brucelosis

• The immune response involves phagocytosis by polymorphonuclear cells and macrophages; those not eliminated are transported to regional lymph nodes where they multiply.

• Intracellular brucellae survive in macrophages by inhibiting phagolysosomal function, leading to a slow multiplication rate compared to extracellular populations.

Clinical Presentation

• Brucelosis has been historically referred to as Malta fever or undulant fever, named due to its periodic occurrence observed during the Crimean War.

• Symptoms vary based on species, inoculation method, and patient condition; it can lead to chronic forms with localized symptoms affecting various tissues.

Acute vs. Chronic Forms

• The acute phase presents abruptly with fever, chills, profuse sweating (characteristic "wet dog" smell), severe headaches, and joint pain.

• Chronic cases may exhibit depression and psychasthenia alongside recurrent acute episodes; localized forms can affect bones, meninges, respiratory system, heart, or liver.

Complications of Brucelosis

• Localized complications include osteoarticular issues like arthritis and spondylitis; neurological complications may involve clear cerebrospinal fluid in meningitis cases.

• Endocarditis can compromise the aortic valve; hepatitis without jaundice is also possible along with skin manifestations or interstitial nephritis.

Diagnostic Approaches

• Laboratory diagnostics in the acute phase include serological tests such as Hudson's reaction and ELISA for antibody detection.

• Hemocultures using Ruiz-Castaneda medium require incubation for at least 30 days unless using rapid methods that detect over 95% positivity within 7 days.

Serological Testing Insights

• Sensitivity of PCR in peripheral blood is 100%, while indirect agglutination tests can yield false negatives if excess antibodies are present.

Brucellosis and Anthrax: Key Insights

Brucellosis Diagnosis and Treatment

• The fixation of complement is a highly specific international reference method, while the ELISA technique allows for sensitive discrimination between different immunoglobulins (IgM, IgA, IgG).

• Treatment typically involves a combination of antimicrobials effective intracellularly over three cycles of 42 days each year, with standard doses including doxycycline and rifampicin.

• For endocarditis, a triple antibiotic regimen (doxycycline, rifampicin, gentamicin) is recommended for at least 8 weeks; gentamicin should be extended for 3 weeks.

• In pediatric cases over 7 years old, treatment follows adult protocols; younger children may receive rifampicin or trimethoprim-sulfamethoxazole for 4 to 6 weeks.

• Doxycycline is advised for conjunctival exposure to brucella during laboratory accidents.

Prevention and Epidemiology of Brucellosis

• Vaccination against brucellosis in cattle uses strain 19b abortus; however, often only female cattle are vaccinated due to cost considerations.

• Anthrax is described as a worldwide zoonotic disease caused by Bacillus anthracis; it can also be used as a biological weapon.

Clinical Manifestations of Anthrax

• The bacterium has both vegetative and spore forms; infection sources include contaminated soil and animal carcasses.

• Cutaneous anthrax presents as necrotic lesions starting from papules that evolve into vesicles before forming black eschars within 36 hours.

Case Studies on Cutaneous Anthrax

• The most common form in the region is cutaneous anthrax which can lead to painless necrotic ulcers without general symptoms.

• A case study illustrates how spores spread through environmental factors after burning infected animals led to multiple human infections in exposed areas.

Visual Documentation of Cases

• Images document the progression of cutaneous anthrax lesions showing perilesional edema and necrotic ulcers on various patients' skin.

Complications and Diagnosis of Cutaneous Anthrax

Understanding Cutaneous Anthrax Complications

• The papular stage of cutaneous anthrax lesions can lead to complications such as malignant edema of the neck, which may compromise the airway, resembling cellulitis.

• Symptoms include fever (38-39°C), electrolyte disturbances, hemoconcentration, and potential renal failure in severe cases.

Diagnostic Approaches

• Diagnosis begins with a history of exposure to spores; direct Gram staining and culturing on common media are essential diagnostic tools.

• Differential diagnosis includes conditions like furunculosis, ecthyma, erysipelas, and insect bites.

Treatment and Prevention Strategies

• For cutaneous anthrax treatment, penicillin G is preferred; it is administered intravenously for 3-4 days followed by oral treatment for an additional 10 days.

• Alternative medications include erythromycin, tetracycline, and chloramphenicol. Local wound care is also crucial.

Trichinosis: Transmission and Lifecycle

Overview of Trichinosis

• Trichinosis is caused by a nematode transmitted through the consumption of undercooked or raw meat containing cysts from infected animals like pigs.

Lifecycle Stages

• After ingestion, larvae are released in the stomach within three days; they mature into adults in the intestines where females produce live larvae that penetrate intestinal mucosa.

Clinical Manifestations

• Symptoms typically appear 10 to 15 days post-infection; gastrointestinal issues may arise alongside hypersensitivity reactions or muscle encystment.

Diagnosis and Treatment of Trichinosis

Laboratory Findings

• Laboratory tests may show leukocytosis with eosinophilia (up to 40%), elevated muscle enzyme levels (CPK, LDH), indicating poor prognosis if present.

Treatment Protocol

• Specific treatments include albendazole or thiabendazole; dosages range from 10 to 15 mg/kg/day over several doses for up to five days while monitoring liver function.

Preventive Measures

Epidemiology and Clinical Presentation of Echinococcosis

Initial Cases and Symptoms

• A report of edema bipalpebral in patients who consumed pork products from a local butcher, with two additional cases noted on July 30 and August 2.

• A total of 29 patients consulted with varied symptoms including fever, myalgias, palpebral edema, diarrhea, dry cough, lack of appetite, or ocular effusion. An alert was issued on August 10.

Understanding Hydatidosis

• Discussion on hydatidosis as a zoonosis caused by the larva of the cestode genus Echinococcus, particularly Echinococcus granulosus prevalent in the region.

• Humans and herbivorous animals serve as intermediate hosts while dogs are definitive hosts where the parasite matures into an adult form.

Transmission and Infection Mechanism

• Dogs excrete eggs into the environment; herbivores become infected by consuming contaminated grass. The eggs develop into embryos in the intestines leading to hydatid cyst formation in tissues.

• Humans typically ingest these eggs through fecal contamination during play with dogs. The ingested eggs transform into embryos that migrate to various tissues forming cysts.

Clinical Manifestations

• The parasite primarily affects the liver and lungs but can impact any organ. Symptoms are often asymptomatic or depend on the affected organ.

• In South America, approximately 2000 cases are reported annually across five countries. Diagnosis is mainly through imaging techniques like ultrasound or CT scans.

Diagnostic Techniques

• Serological tests such as ELISA have high specificity (99%) but low sensitivity; negative results do not rule out hydatidosis.

• In endemic areas, systematic screenings via scheduled ultrasounds help detect hydatid cysts especially in primary filter organs.

Case Studies: Imaging Findings

• Example case of a 70-year-old patient with pulmonary hydatidosis showing slow-evolving asymptomatic cyst development respecting organ integrity.

• Another case presented a hepatic cyst located at segment 5 observed through radiographic imaging.

Complications from Mismanagement

• A case involving a 7-year-old girl with asymptomatic hepatic hydatidosis led to complications after inappropriate puncture without prior surgical formalization.

• This mismanagement resulted in dissemination to flat bones causing significant lumbar pain and weakness in lower limbs.

Uncommon Presentations

• Rare instances where daughter cells were observed macroscopically following external drainage; only about 2% of patients may present such atypical manifestations without affecting primary organs.

Hidatidosis: Clinical Insights and Management

Overview of Hidatidosis Cases

• The discussion begins with a case study of a female patient presenting with cardiac localization of hidatidosis, highlighting the importance of epidemiological history in diagnosis.

• MRI findings reveal an interventricular septum lesion measuring 55 mm by 25 mm, emphasizing the rarity of such atypical presentations (0.2% to 2% frequency).

• While atypical cases exist, primary locations for hidatidosis are predominantly the liver and lungs.

Complications and Treatment Options

• A significant complication is cyst rupture, which can lead to anaphylaxis or dissemination of the hydatid cyst; images illustrate these clinical scenarios.

• The external adventitial layer response to the parasite is noted, along with treatment options including albendazole at 800 mg/day for 45 days in cycles.

Control Measures and Surgical Considerations

• Effective control measures include interrupting transmission cycles, avoiding raw organ consumption by dogs, and regular deworming every 45 days.