Entomology and Typhoid Fever Quiz

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Questions and Answers

What is the primary clinical manifestation associated with Chigger mites?

Scalp abnormalities

Intense dermatitis and pruritis (correct)

Blepharitis

Acne

Which type of louse is specifically known for causing infestations in school children?

Body louse

Head louse (correct)

Bed bug

Pubic louse

Where do body lice typically reside?

In bedding

In hair and on the scalp

On the skin surface

Within clothing (correct)

What type of louse can transmit rickettsial typhus?

Body louse Signup and view all the answers

What is a common characteristic of both head and body lice?

They have mouthpieces adapted for piercing flesh. Signup and view all the answers

What is the clinical manifestation observed during the second week of Typhoid Fever?

Severe prostration and rose spot rash Signup and view all the answers

Which complication is associated with Typhoid Fever during the third week?

Intestinal bleeding and perforation Signup and view all the answers

What diagnostic method can be used to confirm a case of Typhoid Fever?

Blood culture to detect S. Typhi Signup and view all the answers

Which symptom is likely to indicate the onset of complications in Typhoid Fever?

Dark, tarry stools (melena) Signup and view all the answers

What is the primary transmission route for B. quintana?

Pediculus humanus (body louse) Signup and view all the answers

Which of the following symptoms is most characteristic of trench fever caused by B. quintana?

Severe bone pain, especially in the shins Signup and view all the answers

During which week of Typhoid Fever is hyperplasia of ileal Peyer's patches observed?

Second week Signup and view all the answers

What is an important risk factor associated with B. quintana infection?

War and homelessness Signup and view all the answers

Which diagnostic method is considered ideal for confirming a B. quintana infection?

Blood culture or PCR Signup and view all the answers

What is the primary treatment for trench fever caused by B. quintana?

Doxycycline + Rifampin Signup and view all the answers

What type of pathogen is Salmonella typhi?

Gram-negative rod, non-coliform Signup and view all the answers

What is the main route of transmission for Typhoid Fever?

Fecal/oral route Signup and view all the answers

Which of these factors is a virulence factor for Salmonella typhi?

Vi antigen Signup and view all the answers

In which regions is Typhoid Fever most commonly found?

Africa, Latin America, and South East Asia Signup and view all the answers

What is a common predisposing factor for contracting Typhoid Fever?

Poor hygiene and sanitation Signup and view all the answers

Which characteristic of Salmonella typhi contributes to its pathogenicity?

Facultative intracellular organism Signup and view all the answers

What happens during the prolonged bacteremia phase of Typhoid Fever?

Seeding of the gallbladder occurs Signup and view all the answers

Who is classified as a potential carrier of Typhoid Fever, particularly in historical contexts?

Females over 50 Signup and view all the answers

What is the mortality rate of untreated Epidemic Typhus?

40% Signup and view all the answers

Which organism causes Epidemic Typhus?

Rickettsia prowazekii Signup and view all the answers

What is a key characteristic of the rash associated with Epidemic Typhus?

Evolves from blanching macular to maculopapular Signup and view all the answers

What is the vector for Epidemic Typhus?

Pediculus humanus (body louse) Signup and view all the answers

What type of disease is Brill-Zinsser Disease considered?

Recrudescent epidemic typhus Signup and view all the answers

What is the optimal time frame for administering Doxycycline to prevent severe illness in RMSF?

Within 5 days of symptom onset Signup and view all the answers

What are the systemic signs that appear 4-7 days after the onset of fever in Epidemic Typhus?

Rash and fever Signup and view all the answers

What is the typical epidemiological situation for Epidemic Typhus occurrence?

Associated with overcrowding, famine, and war Signup and view all the answers

What is the primary transmission route for Cat Scratch Fever?

Cat fleas Signup and view all the answers

Which age group is most affected by Cat Scratch Fever?

Children Signup and view all the answers

What type of environments do centipedes typically inhabit?

Dark and damp Signup and view all the answers

What is a common initial symptom of a black widow spider bite?

Pain and local edema Signup and view all the answers

Which of the following is a treatment option for centipede stings?

Ammonia paste Signup and view all the answers

What systemic symptoms can develop one hour after a black widow spider bite?

Muscle cramps and fasciculations Signup and view all the answers

Which of the following is NOT a method to prevent tick exposure?

Ignoring outdoor safety measures Signup and view all the answers

What is the main risk factor for Cat Scratch Fever?

Contact with cats, especially kittens Signup and view all the answers

What serious condition can occur due to envenomization from scorpions and spiders?

Seizures Signup and view all the answers

Which of the following is NOT an effect of arthropods on human health?

Myocardial infarction Signup and view all the answers

Study Notes

Infections of the Lymphoreticular System Study Notes

Study the facts for each disease.
For each disease, identify the epidemiology (where it's found, associated activities), symptoms/physical findings, and any unique aspects of the infection.
Understand the pathogen or vector associated with the disease, the pathogen type, gram stain, and shape (if applicable).
Learn about virulence factors and whether a vaccine is available.
Note predisposing factors for illness and how the pathogen is acquired (e.g., fecal-oral, tick bite).
Detail the pathogenesis of the disease.
Study specific examples like typhoid fever, anthrax, and Yersinia pestis.

Typhoid Fever Study Notes

Etiologic Agent: Salmonella typhi: Gram-negative rod, non-coliform bacteria (doesn't ferment lactose).
Virulence Factor: Vi antigen (anti-phagocytic for neutrophils). Also used as an immunogen in a vaccine.
Epidemiology: Reportable disease; 21 million cases globally (rare in the US), mostly in Africa, Latin America, and Asia (especially SEA).
Transmission: Fecal/oral (high dose organism). Hygiene/sanitation, oral/anal sex.
Reservoir: Humans.
Control: Carriers (>50 years old and female).
Pathogenesis: Ingestion via M cells in small intestine → phagocytes → hematogenous spread (liver, spleen, bone marrow, lymph nodes) → bacteremia (1-2 weeks) → gallbladder colonization → organism in bile and feces.

Anthrax Study Notes

Etiologic Agent: Bacillus anthracis: Gram-positive, boxcar-shaped, encapsulated spore-forming rod, grows well on most media. Facultative intracellular pathogen.
Virulence Factors: Capsule (poly-d-glutamic acid, anti-phagocytic), 3 toxin components (PA, LF, EF).
Epidemiology: Low incidence; excreted in feces, urine, and saliva. Spores found in soil, potentially from infected animals or animal products; cases occur from direct contact. Seasonality: Warmer months. Risk factors: Workers handling livestock products (veterinarians, abattoir workers, etc). Not spread person to person.
Pathogenesis: Ingestion of spores → germinate → vegetative cells → multiplies in macrophages and epithelial cells (then → circulation) → bacteremia → seeding in gallbladder and multiplication there → release into bile and feces.

Yersinia pestis Study Notes

Characteristics: Gram-negative, bi-polar staining (safety pin appearance). Encapsulated coccobacillus. Facultative intracellular pathogen (proliferates in macrophages).
Virulence Factors: Yops (inhibit phagocytosis, induce apoptosis, complement activation). LcrV (inducing Yops expression). Pla (enzyme that degrades factors in clotting/immune pathways: antiphagocytic and uptake by inhibition of adhesion). F-1.
Epidemiology: Worldwide distribution, high endemicity in Asia, Brazil, and some US states (West Coast, Rocky Mountain areas, and American Indian reservations).
Transmission: Typically through flea bites or droplet aerosols.
Reservoirs: Rodents (urban/domestic and rural/sylvatic).
Human-to-human Transmission: Rare but happens during epidemics of pneumonic plague and occurs mainly through droplet nuclei secondary pneumonia → primary pneumonia)
Pathogenesis: Organism multiplication in monocytes and spread to regional lymph nodes (lymphangitis and lymphadenopathy: bubonic plague) → blood spread to spleen, liver, lungs → lesions (pyogenic, necrotic, edematous).

Rickettsia Overview Study Notes

Etiologic Agent: Pleomorphic bacteria with Gram-negative cell wall (not seen on standard gram stain). Obligate intracellular pathogen (targets endothelial cells).
Epidemiology: Incidence/prevalence depends on vector number/activity. Arthropod borne transmission. Vertebrate hosts. Old age, Male gender associated with poor outcome.
Hosts: vertebrates, mites, ticks. Mites/ticks have transovarial transmission; fleas/mice no transovarial transmission. Infectious dose is low: 6-10 hours for spread.

Rocky Mountain Spotted Fever (RMSF) Study Notes

Etiologic Agent: Rickettsia rickettsii.
Southeast US Epidemiology*:
Vectors: Dermacentor variabilis (American dog tick), Dermacentor andersoni (Rocky Mountain wood tick), Amblyomma spp.
Seasonality: Spring and summer.
Risk Factors: Outdoor activity.
Prodrome (3–5 Days): High fever, chills, head & muscle aches, conjunctivitis.
Rash (3–5 Days after fever onset): Wrist & ankles, palms & soles → spreading to the trunk (centripetal) → petechial/purpuric.
Clinical Manifestations: -Empiric antibiotics ASAP - High mortality if untreated (within 7–9 days of illness)

Epidemic Typhus Study Notes

Etiologic Agent: Rickettsia prowazekii.
Epidemiology: Overcrowding & poor sanitation (war, famine, refugee camps). Humans are the reservoir. Pediculus humanus (body louse)
Seasonality: Highest in colder months.
Presentation
- Abrupt onset fever followed by head
- 4 - 7 days later — skin manifestations
- Rash begins on the upper trunk & axillary areas, spreads centrifugally
- Palms & soles are spared.
Mortality: 40% without treatment

Brill-Zinsser Disease Study Notes

Description: Recurrence of epidemic typhus years after initial infection.
Epidemiology: Occurs over 50 years of age and in endemic areas.
Presentation: Milder disease symptoms compared to initial epidemic typhus

Bartonella sp. Overview Study Notes

Etiologic Agent: Fastdious Gram-negative rods (facultative intracellular pathogens targeting endothelial cells and RBCs).
Diseases: Trench fever, Bacillary angiomatosis, Cat scratch disease.

B. quintana: Trench Fever Study Notes

Etiologic Agent: B. quintana
Epidemiology: Occurs in urban homeless populations and associated with poor sanitation & malnutrition. Pediculus humanus (body louse) is the vector.
Transmission: Pediculus humanus (body louse).
Presentation: 5 days, relapsing fever (quinan fever); insidious to sudden onset of fever (continuous for 5-7 days then recurrent every 4–5 days, potentially a 1-year cycle), malaise, night sweats, splenomegaly, headache, bony pain (especially the shin), & a maculopapular rash.

Bacillary Angiomatosis Study Notes

Etiology: Caused by Bartonella henselae or Bartonella quintana.
Epidemiology: Often seen in immunocompromised (particularly AIDS patients).
Transmission: By cat contact; fleas or ticks.
Vasoproliferation
Enlarging red papules
May ulcerate.
May affect the skin or viscera (especially the liver & spleen)
Multiple cystic blood-filled tumors, in internal organs (B. angiomatosis).
Bacillary Peliosis (visceral parenchymal organs)
Systemic (hepatitis, splenic peliosis, bacillary angiomatosis

Cat Scratch Fever Study Notes

Etiologic Agent: Bartonella henselae.
Epidemiology: Through contact with cats, especially kittens.
Clinical Manifestations: Regional lymphadenitis, fever, 2–3 weeks after a tick bite.

Lyme Disease Study Notes

Etiologic Agent: Borrelia burgdorferi (Gram-negative extracellular spirochete: cork-screw shaped).
Epidemiology: Enzootic in 19 US states, common in N.E. & Wisconsin in the summer. Small mammals (white-footed mouse mainly) are the reservoirs; ticks are the vector.
Transmission: Tick-borne; Ixodes scapularis (blacklegged tick) mainly, Dermacentor spp.
Life Cycle: Ticks are the vector of transmission, and nymphs and adults are primary transmitters to humans. They require a 48-hour feeding period for transmission to occur.
Stage 1: Localized (Early) Disease
- Erythema migrans (bulls-eye rash), beginning at the bite site ~ 3 days to a month after it; may have flu-like symptoms, but typically not severe.
Stage 2: Disseminated Disease
- Disseminated erythema migrans lesions, weeks to months after stage one.
- Lymphadenopathy - Possible neurological symptom (facial paralysis, Guillain-Barré, meningitis, etc.)
  - Arthritis (Especially the knee)
  - Cardiac (atrioventricular block)
Stage 3: Chronic Disease - Occurs 2–3 years after acute infection. - Persistent arthritis - Subacute encephalopathy (cognitive or mood issues).

Study Notes about Arthropods of Medical Importance

General Introduction: Arthropods impact human health directly through serving as vehicles & agents of disease.
General Mechanism: -Envenomization (eg., spider, bee stings, scorpion stings, etc.). -Anaphylactic reaction (e.g., bee stings). -Infestation (e.g., lice). -Invasion by larvae (e.g., myiasis). -Injury to organs (e.g., beetles in the eye/ear).
Classification/Specific Examples:
- Centipedes
- Spiders & Scorpions (black widow spider, brown recluse)
- Tarantulas
- Bees, wasps, ants, hornets
- Mites — scabies, chiggers
- Lice
- Bed bugs

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Description

Test your knowledge on the clinical manifestations of lice infestations and Typhoid Fever. This quiz covers key symptoms, transmission routes, and diagnostic methods associated with these health issues. Perfect for students in medical and health-related fields.