I am trying to understand the risk of malaria in Kenya and I am wondering which method could be better between modelling the incidence or parasite prevalence. Considering studies recommend countries with
I mean that, in the particular context of malaria, the "risk" must be defined by the power of "transmission". So, one good indice is the prevalence of gametocytes in the population!!
I would go for prevalence. However the method of detection matters. PCR will give an higher value than blood smears. And even using a very sensitive PCR will give you much higher prevalence data. Described for example there:
PLoS Med. 2015 Mar 3;12(3):e1001788. doi: 10.1371/journal.pmed.1001788. eCollection 2015. Ultra-sensitive detection of Plasmodium falciparum by amplification of multi-copy subtelomeric targets. Hofmann et al.
I agree with Thomas parasite prevalence is better and addition the risk of transmission can be identified by parasite density in local vectors i.e anopheles mosquitoes density in the area.
Dear Sir,
See these links may be useful for you.
1) Epidemiological Measures of Risk of Malaria - Springer
www.springer.com/.../9780896038233-c2.pdf?...
Traduire cette page measures of risk of malaria and define their utility in the context of local parameters of endemicity ..... The ACS may be the best approach to assessing risk of.
2) CDC - Malaria - Malaria Worldwide - How Can Malaria ...
www.cdc.gov/malaria/malaria_worldwide/reduction/
Traduire cette page 22 sept. 2015 - Information on various methods and interventions used to reduce malaria's impact in malaria-endemic regions. ... Risk Assessment · How to Choose a Drug to Prevent Malaria ... These terms can be defined differently for different illnesses. ... Malaria control is carried out through the following recommended ...
3) Estimating Trends in the Burden of Malaria at Country Level ...
www.ncbi.nlm.nih.gov › ... › Literature › Bookshelf
Traduire cette page de JG Breman - 2007 - Autres articles
Defining and Defeating the Intolerable Burden of Malaria III: Progress and ... Information on the population at risk of malaria and incidence of disease is critical .... In practice, it is best to use both methods because they complement each other.
Dear colleague Ouma,
I think all answers have been very interesting. In my opinion, we have to take into account several considerations: One, both incidence and prevalence measure morbidity, the first for new cases, the latter both for new and former cases. Two, risk is an epidemiological issue. This means than we need to see the scenario we are working with, in a comprehensive way. I agree with Mr. Bouare that both measures complement with each other. However, when we face the need of monitoring size and extension of risk in areas where malaria declines, seroprevalence more than other will be the best option, even if we do surveillance of feverish people with thick/thin smears (most will be negative, and many will be, and probably we will need to increase fields examination, due to low parasitaemia). Additionally, seroprevalence will give us an image of endemicity. The best way to apply this in places where malaria is dropping, is with repeated cross-sectional surveys (a mixed design), according to the local seasonality. This cares about centinel agegroups...
On the other hand, when we face situations of intense transmission, the best tool for us to approach risk is parasite incidence, Due to costs for public health, the thick/thin smear remains the first option. Also, we have RDTs and PCR. What we have to define regarding the techniques to be used is our final purpose: if regarding research interest or regarding the need of reinforce our public health strategies, or both.
Thus, I allow myself to add that transmission intensity defines reaches for one or another measurement. When we need to measure risk, it is important bear in mind the whole malaria landscape, and this image under our view will be more reliable in so far as we know and understand the local dynamics human-parasite-Anopheles-natural and socio-economic environment. How is the focus and about how is the case. We learned malaria is focal and local. But, also. we have to consider human mobility, situations where susceptible populations go to endemic areas or infected people return to areas with anophelism...
Dear Paul,
If you can obtain the parasite Incidence it is a much better measure of malaria risk than parasite prevalence. Take for instance one measure of risk called Relative Risk (RR) of coming down with malaria if one was exposed to to the vector ( female anopheles mosquito). In this case the RR can be obtained directly and accurately using the formula: incidence of malaria among those exposed to the vector divided by incidence of malaria among those not exposed to the vector. On the other hand, the parasite prevalence can only give you an estimate of risk of malaria using the concept of Odd's Ratio (OR). This is a mere estimate of risk and can not be as accurate as a direct measure as exemplified by RR. Hope this is useful?
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