Co-Infection Epidemiology Flashcards
How heavy are gut bacteria typically in healthy humans?
> 1 kg
What can infection overlap result in?
- Clinical interactions
- Immunological consequences
- Therapeutic interactions
- Difficulty in diagnosis from overlapping symptoms
What core processes affect likelihood of an infection?
Exposure and susceptibility
What is the genetic influence on co-infection?
- Innate immunity (e.g. haemoglobinopathies, distribution of while tends to follow malaria, conveyed advantage)
- Balance of Th1 (pro) and Th2 (anti) immune mediators affecting the success of an infection
How does behaviour influence contraction of co-infection?
Host behaviour influences exposure quantitatively (parasite load) and qualitatively (which parasite)
- outdoor exposure
- water contact
- sexual promiscuity
- agricultural activities
- war/civil unrest
How does diet influence co-infection?
Increase and decrease exposure (food-borne parasites) and susceptibility (resource limitation can influence host immune response, degree of competition between co-infection parasites)
How does geography influence co-infection?
Both parasites need to share same biome
Influenced by abiotic requirements (temperature and humidity) and biotic requirements (abundance of food sources)
Give an example of syngergism
HIV and Malaria. HIV copy number higher in malaria pt (Hoffman et al), malaria load higher in HIV pt (Chavele et al)
An example of synergism and anatgonism
Actue schisto causes Th1 resoponse (ctyokines such as IFN-γ, IL-12 and TNF-α) controlling early malaria parasitaemia. Over expression of IFN-γ and TNF-α predisposes a subject to severe complications (anaemia, cerebral malaria).
Chronic schisto causes Th2 response (IL-4,5,10 etc) allowing long term survival in host. Hyporesponsiveness allows malaria parasite growth. Studies show anti-inflammatory role of IL-10, and in particular the IL-10/TNF-α ratio can have a protective effect against severe complications
Hartgers and Yazdanbakhsh
