Microbiology Hot topics from the tropics Flashcards Preview

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Flashcards in Microbiology Hot topics from the tropics Deck (42):
1

Parasites infecting man can be subdividided as follows:

o Single cell parasites – Protozoa e.g. malaria, giardia
o Multicellular parasites – Metazoa e.g. helminths
o Ectoparasites e.g. fleas and lice

2

Malaria: A disease caused by

The malaria parasite – a protozoan

3

Malaria: Incidence

>300 million people infected with malaria per year

4

Malaria: Mortality

>1 million deaths from malaria per year – mainly affects children <5 years of age

5

Malaria: Geographical locations

equator

6

Malaria: Human forms of Malaria

There are 4 types of malaria that affect humans:
• Plasmodium vivax
• Plasmodium falciparum – severe malaria (cerebral/anaemia etc)
• Plasmodium ovale
• Plasmodium malariae

7

Malaria: Onset

7-30 days after mosquito bite depending on the species (pre-patent period (life cycle takes awhile)

8

Malaria: P. vivax incubation

May rarely take up to 1 year

9

Malaria: P.vovax and P.ovale can also exist

As dormant forms (hyponozoites) that produce relapses months or years later

10

Malaria: Life cycle (see more)

1. Mosquito bites host (female for eggs to mature)
2. Injects anticoagulant to prevent blood clotting + saliva (and if she is
3. Sporozoytes (15-20 min) travel to liver
4. Undergo life cycle (1 week) – infect RBC (multiplied by binary fission)
5. Once RBC infected = brittle/ less malleable in capillaries + surface changes causing sticking to blood vessels.
6. Burse and release exponential increase in infected RBC’s

11

Malaria: Presenting Features/ Complication of Malaria

Flu-like symptoms
Respiratory symptoms
GI symptoms
CNS symptoms
Other

12

Malaria:Flu-like symptoms

Fever
Rigors
Sweats
Malaise
Myalgia

13

Malaria: Respiratory symptoms

Cough
Respiratory distress
Pulmonary oedema

14

Malaria: GI symptoms

Nausea
Vomiting
Diarrhoea
Jaundice
Liver failure

15

Malaria:CNS symptoms

Headaches
Confusion
Coma – cerebral malaria

16

Malaria: Other

Shock
Acidosis
Renal impairment
“Blackwater fever”
Anaemia
DIC
Hypoglycaemia
Splenic rupture

17

Malaria: Management of Malaria

1. Antimalarials e.g. quinine*, doxycycline, fansidar, primaquine (See BNF, HTD)
2. Supportive therapy – correct shock, anaemia, bleeding abnormality, treat or prevent convulsions, hypoglycaemia, (incurrent infections)
3. Avoid over hydration
4. Consider exchange transfusions

18

Malaria: Methods of preventing Malaria

Protection against bites
• Bed nets
• Insect repellants
• Clothing to avoid bites at dusk and dawn
• Screens on doors and windowns
Protection against infections
• Prophylaxis
• Future role of immunisation
Prevent parasite life cycle:
• Prompt effective treatment in endemic areas
• Local measure e.g. pesticides, avoid pooling of water
Potential role for Altruistic vaccine

19

Investigations


• If you suspect VHF, do a malaria film only
• Thick and thin malaria films
→ Thick – looking at structure of RBC’s
• Malaria antigen test
• FBC – decreased platelets
• Clotting screen
• U and Es, LFTs
• Blood cultures
• Serology – e.g. dengue fever
• pH
• Lactate

20

Results

WCC – depressed in malaria
Clotting screen – disseminated vascular
Blood cultures – intercurrent infections
Serology – other

21

Viral Haemorrhagic Fevers → Types

Lassa
Marburg
Ebola
CCHf

22

Viral Haemorrhagic Fevers → Risk Factors

• Travel to high risk area in the last 21 days
• Contact with human or animal with suspected VHF (body fluids/tissues)
• Injestion of bush meat

23

Viral Haemorrhagic Fevers → Description

Febrile disease caused in a variety of ways

24

Leishmaniasis

Several types of leishmaniasis broadly categorised info:
Visceral leishmaniasis
Cutaneous leishmaniasis

25

Visceral leishmaniasis is characterised by

Hepatosplenomegaly

26

Cutaneous leishmaniasis

Tropical sores

27

Transmission

Sandflies

28

Diagnosis

Biopsy

29

Treatment

Antimonials
Pentamidine
Amphotericin

30

Prevention

Impregnanted bed nets
Elimination of animal vector e.g. dog control

31

Description (2 types)

Sleeping sickness (Africa)
Chagas disease (S. America)

32

Transmission of Sleeping sickness

Tsetse fly transmit from wild animals to man

33

Chagas disease transmission causes

Rejuvid blood transmits to man causing (if it gets to this stage its irreversible):
1. megaoesophagus
2. Megacolon
3. Cardiomyopathy

34

Treatment

Arsenicals

35

Transmission of helminths:

ingestion
Inoculation

36

ingestion


• Of eggs ir larvae from the faeces of an infected host e.g. threadworm
• Of soil or food contaminared by soil in which larvae have developed from eggs passed in the faeces have developed from eggs passed in the faeces of an infected host e.g. ascaris
• Ingestino of larvae in the tissue of an intermediate host e.g. taenia so.

37

Inoculation

• By a blood sucking insect e..g. filariasis
• By active penetrationof the larvae e.g. schistosomias, hookworls

38

Schistosomiasis (bilharzia) Description

A trematode that infects man

39

Schistosomiasis (bilharzia) 3 forms

S. haematobium – bladder (haematuria)
S, mansonii (blood vessels around gut eggs released in faeces
S. japonisum

40

Schistosomiasis (bilharzia) Presentation

• None- “swam in lake malawi”
• “swimmer’s itch”
• “katayama fever” – a seroconversion illness characterised by fever, arthralgia, uticarial rash, death
• Haematuria
• Portal hypertension e.g. haematemesis
• Malignancy
• Paraparesis

41

Schistosomiasis (bilharzia)Diagnosis

• Ova in urine, stool or biopsy
• Immunodiagnosis
• Eosinophila

42

Schistosomiasis (bilharzia) Treatment

Praziquantel

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