Diseases

Killer B’s

In a fit of homonym frustration, I have finally decided to write down every “B” infection on one page so I can hopefully stop confusing them.

Borreliosis: tick and louse-borne relapsing fever

Tick-borne:
- Vector: Ornithodoros (soft tick)
- 14d incubation
- 3-6 attacks of sudden onset headache and fever lasting 2-3 days
- Hepatosplenomegaly 30%
- CNS involvement w facial nerve palsy and lymphocytic meningitis
Louse-borne
- Vector: Pediculus humanus
- Wide clinical variety: self-limiting to 70% fatal
- Incubation 4-8 days
- Abrupt onset febrile illness
- Myalgia, headache, cough, jaundice
- Rash
- Hepatosplenomegaly is typical
- Complications: hepatic +/- cardiac +/- DIC
- Relapse 1 week later 60-70% of the time
Treatment: doxycycline
- Jarisch-Herxheimer reactions common

Brucellosis: bacterial infection associated with livestock

Babesiosis: tick-bonre intra-erythrocytic infection

Ixodes (hard tick)

Burkholderia pseudomallei: causitive agent of melioidosis

Bartonella:

Honorable mention:Burkitt’s lymphoma, buruli ulcer

Malaria Treatment

Treatment of non-falciparum (P. vivax/ovale/malariae)- chloroquine, followed by primaquine (gametocide) for P. vivax

Falciparum: quinine or ACT

– iv treatment required for hyperparasetemia or e/o schizonts (need blood film) and/or complications (anemia (kids), coma/stupor, liver/renal failure, ARDS, hypoglycemia, bleeding, DIC)

– in UK, quinine po followed w second agent (doxy or fansidar)

Influenza

Clinical: sudden onset fevers, sore throat, cough, myalgia

Type A, B, C

But only Type A (esp. subtypes H1-H3) associated with epidemics

Details:

Incubation: 1-3d
Symptomatic: 2-7d
Infectious: 3-5d after clinical onset adults, up to 7 in children
Transmission: via resp secretions (airborne and droplet), contaminated surfaces
Ages most affected: very young and very old
Duration of activity: usu. 8-10 weeks during winter
Complications: secondary bacterial, exacerbate underlying comorbidities
Mortality:3,000-4,000/annum up to 20,000+ in epidemics

Antigenic drift: small change in structure vs. Antigenic shift: producing new “subtype”

Unclear efficacy of Tamiflu for treatment or prevention

Pandemic Trends

Young children (under 5’s) have highest attack rates
Seasonal flu features/activity change with pandemic shifts

Avian influenza

Migratory wild fowl harbor all strains of Influenza Type A and are reservoir for disease -> mix w/ domestic fowl
H5N1 causes severe illness in poultry -> transmits disease (often severe) to humans
- Limited human-to-human spread
H7N9 is mostly asymptomatic in poultry->transmitted to humans (often very severe disease)
- Almost zero human-to-human spread

Currently only in China