Epidemiology

Question 1

What red-flag infections are associated with Guinea?

Answer 1

Ebola

Question 2

What red-flag infections are associated with Nigeria?

Answer 2

Lassa virus

Question 3

What red-flag infections are associated with the Demogratic Republic of Congo?

Answer 3

Ebola (and measles)

Question 4

What time of year is S.pneumoniae most common?

Answer 4

Winter/early spring

Question 5

What time of year is N.meningitidis most common?

Answer 5

Winter (here), dry season in the tropics.

Question 6

What is the epidemiology of Malassezia furfur?

Answer 6

Worldwide. Most prevalent in tropical/subtropical areas. Colonizes the outer (keratinised) layers of skin, hair, and nails.

Question 7

Epidemiology of Sporothrix schenckii?

Answer 7

Found in soil and decaying vegetation. Introduced into the subcutaneous tissue via a puncture wound. Causes Lymphocutaneous Sporotrichosis. Most commonly in warmer climates. Endemic in Japan, Mexico, North/South America. Infection is most prevalent amongst forest workers, miners,gardeners.

Question 8

What is the epidemiology of Entamoeba histolytica?

Answer 8

Worldwide; more common in tropical/subtropical regions (ie. South East Asia) and in areas of poor sanitation and contaminated water.

Infections are particularly common in:

• Military & refugee camps
• Prisons
• Crowed day care centres.

Question 9

Epidemiology of Trypansoma brucei gambiense and T. brucei rhodesiense?

Answer 9

• Trypansoma brucei gambiense (West Africa). - T. brucei rhodesiense (East Africa).

Question 10

What is the epidemiology of Trypanosoma cruzi?

Answer 10

North, Central, and South America. The infective trypomastigote of T. cruzi is present in the feces of the reduviid (triatomine) bug.Bites usually occur around the eyes (conjunctiva), mouth, and other facial sites.

Question 11

What is the epidemiology of Ancylostoma braziliense and A. caninum?

Answer 11

Soil, sandpits, or beaches with animal feces, in tropical/subtropical areas. The filariform larvae penetrate the skin and migrate no further; they remain trapped in the skin (weeks to months) and create serpentine tunnels.

Question 12

Epidemiology of Wuchereria bancrofti and Brugia malayi?

Answer 12

Endemic in Central Africa, many parts of Asia, Mediterranean coast, Haiti, Costa Rica, Brazil. Larvae migrate from initial bite to the lymphatic system (in arms, legs, groin) and grow into adults. 3 to 12 months after initial infection, males fertilise the females, which produce the microfilariae that spread to the bloodstream.

Question 13

Epidemiology of Sarcoptes scabiei?

Answer 13

Epidemic occurrence in confined populations: - Daycare centres - Nursing homes - Military bases - Prisons

Question 14

What are the risk factors for developing P. aeruginosa skin infections?

Answer 14

• in health care - immunocompromised

Question 15

Blastomyces geographical distribution

Answer 15

Around Wisconsin, Michigan, Illinois, Indiana, Ohio, Kansas, Tenessee, N+S Carolinas, Mississipi, + Louisiana. Especially the Ohio + Mississippi River Valleys, Great Lakes, + St. Lawrence River + MN + ON (SW) + QC (SE) + NB

Question 16

Coccidioides geographical distribution

Answer 16

Around California, Nevada, Utah, Arizona, New Mexico, Texas. Not in Canada.

Question 17

Histoplasma geographical distribution

Answer 17

Around Missouri, Illinois, Indiana, Kansas, Tenessee, Missouris, Arkansas + all surrounding states (but less so). Especially the Ohio + Mississippi River Valleys. (Suspected around SoCal, Arizona, New Mexico)

Question 18

What isthe most effective way to monitor treatment adherence for TB?

Answer 18

Directly Observed Therapy (DOT). A designated individual (e.g. HCW) provides the prescribed drugs + watches the patient swallow every dose. In Alberta, all active cases receive DOT.

Question 19

What is the rate of TB in Alberta? Canada? Worldwide?

Answer 19

Alberta is at ~4.7. In Canada, we have one of the lowest rates at ~4.8 (but Nunavut is ~20). Globally, the rate of TB is about 140 cases per 100,000 (c. 2008).

Question 20

What is the incubation period of TB before a TST will read positive?

Answer 20

8 weeks

Question 21

What is an “epidemic”?

What is an “outbreak”?

Answer 21

Epidemic:An occurrence of localized cases of an illness above what’s normally expected(…relative to usual frequency of the disease in the same area, among the specified population, at the same season of the year).

Outbreak:An epidemic limited to localized increase in the incidence of a disease.