Scrub typhus

Etiology : orientia tsutsugamushi
Transmission : mite ( larva )
Clinical features :
Fever
Myalgia
Petichiae
Presence of Eschar - at the site of bite of the mite

Complication
ARDS
Ascitis
Peritonitis
Acute renal failure

Laboratory diagnosis
 Total count - leukocytosis
Weil Felix test positive for OxK
IgM ELISA
Immunoflurescence - antigen detection

Cholera

Clinical features
Rice watery stool (painless)
Severe dehydration  with following features
Tready pulse
Sunken eyes
Skin turgor decreased
Low blood pressure
Causative agent: Vibrio cholerae

Laboratory diagnosis
Stool sample for culture

Stool sample inoculated into alkaline peptone water and hanging drop done after 6 hrs

Hanging drop showing darting motility is suggestive of Vibrio cholerae

Then the broth is plated onto TCBS and MacConkey
After overnight incubation
TCBS- yellow coloured colonies
MacConkey- non lactose fermenting colonies 
Further identification 
Gram stain - gram negative curved bacilli
Oxidase- positive 
Indole- positive
TSI- A/A no gas and no H2S 
Citrate - positive 
Urease- negative
Mannitol - fermented 

Cholera red reaction - innoculate peptone water with few colonies of Vibrio cholerae
After overnight  incubation add few drops of concentrated H2SO4 along the sides of the test tube a red colour ring is formed indicating nitrosoindole ring 

Confirmatory test
Agglutination with antisera
1. Polyvalent O
2. Ogawa
3. Inaba
4. Hikojima

Diagnosis of melioidosis

Melioidosis
The disease has a insidious onset, fever for more than 3 weeks, body pain and loss of appetite
Multiple abscess in the lungs, liver, kidney and soft tissue

Caused by - Burkholderia pseudomallei

Diagnosis
Mainly based on the culture of blood,urine or pus from abscess


Identification of the organism is based on the following
Grey moist colonies on blood agar with metallic sheen which has a crumbled paper appearance on 48 hrs of incubation
Gram stain reveals - safety pin appearance of the gram negative bacilli
Mac Conkey agar - non lactose fermenting colonies crumbled paper appearance 

Oxidase positive
Indole negative
TSI - k/k no gas,no H2S
Citrate positive
Urease negative
Mannitol motility- fermented, motile
OF glucose      Oxidatively utilised
OF mannitol              "
OF lactose                 "
OF maltose                "
Arginine de hydrolysed

Polymyxin B (300units) - resistant


Treatment
 Cotrimoxazole is the drug of choice given over a period of 6 months
In severe cases carbapenems are the drug of choice

Diagnosis of Malaria

Clinical features
Fever with chills and rigors
Type of fever: Intermittent---

quotidian fever as an intermittent fever that occurs each day,

Tertian (fever every third day) 

quadrant(fever every 4 days)

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Splenomegaly
Haematuria
Jaundice

Caused by

P. vivax, P. falciparum, P. ovale, P. malariae

Transmitted by the bite of culex mosquito

Laboratory diagnosis
Peripheral smear - leishman's stain for the detection of the parasite ( gametocytes/ring forms and schizonts)

Multiple ring forms are seen specifically only in P.falciparum.

ICT test for detection of the LDH or Histidine rich protein II from blood
Quantitative Buffy coat test