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Micro

Rocky Mountain Spotted Fever

-Caused by R. rickettsii carried by dog tick/ wood tick (arthropods)
<>incubation: One week
<>Initial Sxns: Fever, headache, maculopapular rash
<> Chronic sxns: splenomegaly and neurological involvement with spread of intravascular coagulation. Shock and death.
-Fatal cases are usually those with delayed diagnosis

Lyme Disease

<>Borrelia species
-Gram-negative coiled shaped
bacteria (spirochete)
<> Transmission: Hard ticks (genus Ixodes) on mice or deer
<>Sxns
1st degree: low-grade fever, aches, bulls-eye rash→ 'Erythema Chronicum Migrans' at bite site. Most treatable at this stage.
2nd degree: Arthritis, Bell's palsy, cardiac manifestations
3rd degree: Neurological damage, cardiac damage, mimics MS

Treatment of lyme disease

antibiotics (penicillin and tetracycline)

Malaria: vector

<>Protozoal infections → four types of plasmodium that cause malaria:
1) Plasmodium vivax
2) P. ovale
3) P. malariae
4) P. falciparum (most virulent)

<>Vector: Female Anopheles mosquito
<>Definitive host: Anopheles mosquito
<>Intermediate host: humans

Malaria can be transmitted by blood transfusion and needle accidents (very rarely mother to fetus)

Malaria: Life cycle

1)sporozoites (inside saliva of infected mosquito) injected into human bloodstream
2) they enter the liver. Mature → merozoites which are released into the bloodstream (some lie dormant in liver →hypnozoites)
3) the merozoites → RBCs,multiply, and release merozoites back into the bloodstream; this cycle may last for months or even years
4) some merozoites initiate the sexual stage in the RBCs. Form male and female gamaetocytes
5) the sexual cycle is completed when an Anopheles mosquito feeds on the gametocyte containing blood; they form a zygote that divides to give rise to sporozoites migrating to the salivary glands and initiating the cycle again

Malarial blood

Malarial blood smear

Blood smear showing ring forms in human red blood cells

Chagas Disease

South American trypanisomiasis
<>Transmission: bite of the Kissing Bug
Common to Central & South America
<>Caused by Trypanisoma cruzi
<>Acute & chronic forms
<>Initial Symptoms:fever, swelling of one eye, swelling of bite site
<>Chronic: infects heart and intestines, major cause of death = myocarditis

Chagas: treatment

treatment: it is one of the most difficult protozoal infections to cure

drugs of choice are arsenicals; prevention by vector control with insecticides and improving housing and living standards

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