Thanks for that David - I have two questions:
1. I read on the insert of the malaria tabs I took that one can still get malaria if you take the tabs...how does this happen and if that is the case, why take the tabs? In other words, how does taking anti-malaria medication actually help/prevent?
2. If one is infected by a bite does the malaria show up in a blood test immediatly? If one has a blood test that is neg does that mean that there is no way you could have malaria until you are at risk again?
DB, I will not give myself out as knowledgeable on malaria parasites as my focus was previously on worm parasites. But regarding to your first question it must be remembered that as with so many other parasites and bacteria, these organisms have developed a certain measure of resistance to the drugs normally used to kill them. What you read on the insert of the tablets meant that depending on the malaria parasite present in the mosquito that bites you, that parasite might be resistant against the drug you took and therefore the drug will be ineffective in protecting against the parasite. Your doctor or travel clinic should have the latest information on drug resistance available to them to help you choose the most effective prophylaxis to use.
Here is some information taken from the website of the CDC Division of Parasitic Diseases
that might help to answer your other questions.
Malaria Incubation Period
Following the infective bite by the Anopheles
mosquito, a period of time (the "incubation period") goes by before the first symptoms appear. The incubation period in most cases varies from 7 to 30 days. The shorter periods are observed most frequently with P. falciparum
and the longer ones with P. malariae
Antimalarial drugs taken for prophylaxis by travellers can delay the appearance of malaria symptoms by weeks or months, long after the traveller has left the malaria-endemic area. (This can happen particularly with P. vivax
and P. ovale
, both of which can produce dormant liver stage parasites; the liver stages may reactivate and cause disease months after the infective mosquito bite.)
Such long delays between exposure and development of symptoms can result in misdiagnosis or delayed diagnosis because of reduced clinical suspicion by the health-care provider. Returned travellers should always remind their health-care providers of any travel in malaria-risk areas during the past 12 months.
The following CDC links may also answer questions or give more info for those interested
Frequently Asked Questions about Malaria
Schema of the Life Cycle of Malaria
Follow this link
to more CDC information on Malaria
Malaria Department of the World Health Organization
SAA Netcare Travel Clinics: Malaria