Rickettsial Diseases ,ROCKY MOUNTAIN SPOTTED FEVER ,MEDITERRANEAN SPOTTED FEVER

A genus of bacteria of the family Rickettsiaceae, order Rickettsiales. Their vectors are arthropods such as fleas, ticks, mites, and lice. They are obligate intracellular parasites (must be in living cells to reproduce) and are the causative agents of many diseases.

ROCKY MOUNTAIN SPOTTED FEVER

• These are Gram negative coccobacilli that grow in­tracellularly.
• They are transmitted by insects or ticks. Humans are incidental hosts.
• Out of these, Coxiella burnetii causes Q fever and is extremely infectious. It can also cause pneumonia.

ROCKY MOUNTAIN SPOTTED FEVER

ROCKY MOUNTAIN SPOTTED FEVER

• · Caused by Rickettsia rickettsii
• · Vector is Dermacentor andersoni
• · Found in US

MEDITERRANEAN SPOTTED FEVER

Types of  Rickettsial Diseases —

Rickettsia africae:

• The causative agent of African tick bite fever, usually found only in sub-Saharan Africa.

Rickettsia honei:

• It is found only in Australia and neighboring islands.
• The causative agent of a spotted fever that clinically resembles Rocky Mountain spotted fever.

Rickettsia rickettsii:

• The causative agent of Rocky Mountain spotted fever.
• The animal reservoirs are rodents and dogs and the vectors are ticks of several genera.

Rickettsia akari:

• The animal reservoir is the house mouse and the vector is a mite.
• The causative agent of rickettsialpox.

Rickettsia prowazekii:

• The causative agent of epidemic typhus, spread by the human body louse.
• It was once thought to be a strictly human pathogen.
• Flying squirrels may be animal reservoirs, and humans acquire infection from their lice or fleas.

Rickettsia conorii:

• The animal reservoirs are rodents and dogs and the vectors are ticks of several genera.
• The causative agent of boutonneuse fever found in the Mediterranean, parts of Africa, and India.

MEDITERRANEAN SPOTTED FEVER

• · Caused by R. conorii
• · Found in Asia and Africa

AFRICAN TICK BITE FEVER

AFRICAN TICK BITE FEVER

AFRICAN TICK BITE FEVER

• · Caused by R. africae
• · Found in Africa

RICKETTSIAL POX

RICKETTSIAL POX

RICKETTSIAL POX

• • Found in US

EPIDEMIC TYPHUS

EPIDEMIC TYPHUS

• · Caused by R. prowazekii
• · Found worldwide
• · Vector is pediculus humanus corporis

MURINE TYPHUS

MURINE TYPHUS

MURINE TYPHUS

• · Caused by R. typhi
• · Vector is Xenopsylla cheopis
• · Found worldwide

SCRUB TYPHUS

SCRUB TYPHUS

SCRUB TYPHUS

• · Caused by Orientia tsutsugamushi
• · Found in Asia and Australia

Treatment —

• The rickettsial diseases respond to DoX’ cine 100 mg BID orally for _5 days and even ciprofloxacin or ofloxacin.

Q– FEVER

Q– FEVER

Q – FEVER

• Q fever results from infection with C. burnetti. It is a Gram negative microorganism.
• Man gets the infection from cattle, goats and dogs by handling, and drinking contaminated milk.

Incubation period is

• 3 – 30 days.

Clinical presentation

• · Fever, flu, pneumonia, hepatitis, pericarditis, myocarditis, meningoencephalitis, extra pyrami­dal disease, GB syndrome.
• · Chronic Q fever can present with infective en­docarditis, hepatomegaly, splenomegaly, chronic bone infection.

Treatment

• Doxycycline 100 mg BD for 14 days
• Ciprofloxacin 750 mg BD.