BIOL334- Leptospirosis

Question 1

What bacteria causes Leptospirosis?

Answer 1

Leptospira- gram negative, obligate anaerobe, spiral shaped (spirochete)

Question 2

What is Leptospirosis also known as ?

Answer 2

Weils disease

Question 3

How is Leptospira motile?

Answer 3

• dependent on the presence of 2 endoflagella (one at each end).
• Flagella motor threads through the cell and drives locomotion/chemotaxis.
• The basal body functions as a rotary motor that enables flagellar filament to rotate

Question 4

How many species and serovars of Leptospira have been observed?

Answer 4

• 13 species

- > 250 serovars

Question 5

Determinants of pathogenicity of Leptospira

Answer 5

• Soluble hemolysin (burst RBCs)
• Lipoprotein Loa22 (function unknown)
• Endotoxin- LPS
• Cell mediated sensitivity reactions
• Target renal tubular Na, K and H, K ATPases (disrupts kidney function).

Question 6

What type of disease is Leptospirosis

Answer 6

Zoonotic disease

Question 7

What is the source of Leptospirosis disease

Answer 7

• Wide range of host reservoirs- dogs, rodents, wild animals
• Humans at risk are those in contact with animals or animal products
• Major indirect contact with urine with virulent Leptosira from a carrier/affected animal.
• Also from soil, food, and water
• Through a break in skin

Question 8

Which species of Leptospira genus causes Leptospirosis?

Answer 8

Leptospira interrogans

Question 9

Clinical infection (Leptospirosis/ Wells Disease)

Answer 9

Renal injuries:

• Intestinal nephritis
• Glomerular swelling
• Hyperplasia
• Thickening of basement membranes and tubules–> renal failure
• Meningitis
• Pretibial rash

Question 10

Clinical Manifestation of Leptospirosis

Answer 10

• Incubation period 10-12 days (sudden fever, chills, headache, GIT symptoms).
• First leptospiremic stage (day 7)
• Defervescence- no fever
• Second leptospiremic stage (<7 days) can be fatal

Question 11

Stages in Infections by Leptospires

Answer 11

• Breach in skin (cut)
• Rapid migration through the dermis (composed of connective tissues)
• Translocate across the endothelial barrier of blood cells (spread hematogenously- by the way of blood) and establish infection in target organs.
• Leptospiras produce adhesions for bindings to several cells or components of the cell e.g., ECM. These facilitate immune invasion and bacterial spread (dissemination).
• Leptospires can also secrete proteases which contributes to their ability to invade host cell tissues and host cells responses.
• Secrete hemolysin- degrade host cell membrane
• It has been shown that leptospires can survive, replicate and exit macrophages and induce macrophage apoptosis.

Question 12

Leptospira treatment and prevention

Answer 12

Treatment: Antibiotics within the first 2 days after onset (penicillin, streptomycin, tetracycline).

• Serovar specific vaccine
• Prophylaxis with short/long term tetracycline

Prevention:

• Avoid touching fresh water or soil that may be contaminated with animal urine.
• Avoid touching objects that may be contaminated with animal urine, such as animal bedding.
• Don’t wade, swim, or put your head in floodwaters or water from lakes, rivers, or swamps.