Help me please, y'all math whiz people (re: malaria & Dar es Salaam, Tanzania)

[MomTo2Boys]

Hello, everyone who is smarter than I am.

In researching malaria rates and whether folks in urban Dar es Salaam should use chemoprophylaxis or not... and these sorts of fun topics relating to traveling/living there (anyone been there? Anyone like it or hate it? Or anything?)... I ran across a quote regarding the odds one has of becoming infected with malaria in downtown/urban Dar es Salaam, and since I'm not a math whiz I'm not sure I can interpret it correctly and so I am asking for help.

Here is the quote (from here: http://www.malariajournal.com/content/6/1/126):

_________

"Despite the very low vectors densities (Annual estimate of about 170 An gambiae s.l bites per person per year), CB-ITT was the only entomological predictor of parasite infection risk (Odds Ratio [95% CI] = 4.43[3.027,7. 454] per An. gambiae or Anopheles funestus caught per night, P =0.0373)."

_________

I'm trying to work out what that odds ratio really means in English. When it says that P =0.0373, does that translate to there being a 3.73% risk that a person in urban Dar could end up with malaria? Or just that there is a 3.73% chance that that particular mosquito that was caught in the sample could infect someone?

Malaria. Ugh.

And also, I think 170 mosquito bites per year is A LOT. But that has nothing to do with my question. I'm just saying. 

[WiseOne]

What does "CB-ITT" mean?

"p" is a measurement of statistical significance.  0.03 is within the accepted range (less than 0.05) for accepting that the hypothesis, that CB-ITT is related to malaria risk, is true.

Without knowing what CB-ITT is, I can't tell you in plain English what the odds ratio means, but it says that <something> is 4 times as likely to happen as whatever it (presumably CB-ITT) is being compared to, according to the data measured.  The 95% confidence interval says that random sampling error in the data set could throw that number off, and there is a 95% chance that the actual number is somewhere in 3 - 7.4 range. 

One problem with odds ratios is that even a high number can still mean something is very unlikely.  For example, if you go sky diving your risk of dying is 3 times the chance of being killed by a lightning bolt.  Sounds terrible until you realize that the chances of the latter are 1 in several million.  For what you're looking for, I think you want the incidence of malaria among visitors to that city or region.

I suggest that you visit a travel medicine specialist.  They'll know the current recommendations for that particular area, including the type and resistance of malaria bugs - very important for picking the medication.  You may also need vaccinations for things like yellow fever and hepatitis B, if you don't have those already.

[Reub]

Malaria as a variable portfolio play?

I like it!

[MomTo2Boys]

What does "CB-ITT" mean?

"p" is a measurement of statistical significance.  0.03 is within the accepted range (less than 0.05) for accepting that the hypothesis, that CB-ITT is related to malaria risk, is true.

Without knowing what CB-ITT is, I can't tell you in plain English what the odds ratio means, but it says that <something> is 4 times as likely to happen as whatever it (presumably CB-ITT) is being compared to, according to the data measured.  The 95% confidence interval says that random sampling error in the data set could throw that number off, and there is a 95% chance that the actual number is somewhere in 3 - 7.4 range. 

One problem with odds ratios is that even a high number can still mean something is very unlikely.  For example, if you go sky diving your risk of dying is 3 times the chance of being killed by a lightning bolt.  Sounds terrible until you realize that the chances of the latter are 1 in several million.  For what you're looking for, I think you want the incidence of malaria among visitors to that city or region.

I suggest that you visit a travel medicine specialist.  They'll know the current recommendations for that particular area, including the type and resistance of malaria bugs - very important for picking the medication.  You may also need vaccinations for things like yellow fever and hepatitis B, if you don't have those already.

Thank you, WiseOne!

CB-ITT is a type of machine that is used in capturing and sampling mosquitoes.

Thank you for helping me understand the mathematics! I hope you and yours are well.

[MomTo2Boys]

By the way, SORRY to everyone! I had meant to post this under "Other Discussions" and now I see that somehow I mangled where it was supposed to go and inadvertently stuck it under "Variable Portfolio Discussion!" 

I'm a moron. Well, and my horrible internet is no help. Sorry! Carry on!