Microbiology Hot topics from the tropics Flashcards
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
Malaria: A disease caused by
The malaria parasite – a protozoan
Malaria: Incidence
> 300 million people infected with malaria per year
Malaria: Mortality
> 1 million deaths from malaria per year – mainly affects children <5 years of age
Malaria: Geographical locations
equator
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
Malaria: Onset
7-30 days after mosquito bite depending on the species (pre-patent period (life cycle takes awhile)
Malaria: P. vivax incubation
May rarely take up to 1 year
Malaria: P.vovax and P.ovale can also exist
As dormant forms (hyponozoites) that produce relapses months or years later
Malaria: Life cycle (see more)
- Mosquito bites host (female for eggs to mature)
- Injects anticoagulant to prevent blood clotting + saliva (and if she is
- Sporozoytes (15-20 min) travel to liver
- Undergo life cycle (1 week) – infect RBC (multiplied by binary fission)
- Once RBC infected = brittle/ less malleable in capillaries + surface changes causing sticking to blood vessels.
- Burse and release exponential increase in infected RBC’s
Malaria: Presenting Features/ Complication of Malaria
Flu-like symptoms Respiratory symptoms GI symptoms CNS symptoms Other
Malaria:Flu-like symptoms
Fever Rigors Sweats Malaise Myalgia
Malaria: Respiratory symptoms
Cough
Respiratory distress
Pulmonary oedema
Malaria: GI symptoms
Nausea Vomiting Diarrhoea Jaundice Liver failure
Malaria:CNS symptoms
Headaches
Confusion
Coma – cerebral malaria
Malaria: Other
Shock Acidosis Renal impairment “Blackwater fever” Anaemia DIC Hypoglycaemia Splenic rupture
Malaria: Management of Malaria
- Antimalarials e.g. quinine*, doxycycline, fansidar, primaquine (See BNF, HTD)
- Supportive therapy – correct shock, anaemia, bleeding abnormality, treat or prevent convulsions, hypoglycaemia, (incurrent infections)
- Avoid over hydration
- Consider exchange transfusions
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
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
Results
WCC – depressed in malaria
Clotting screen – disseminated vascular
Blood cultures – intercurrent infections
Serology – other
Viral Haemorrhagic Fevers → Types
Lassa
Marburg
Ebola
CCHf
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
Viral Haemorrhagic Fevers → Description
Febrile disease caused in a variety of ways
Leishmaniasis
Several types of leishmaniasis broadly categorised info:
Visceral leishmaniasis
Cutaneous leishmaniasis
