For Brazil, the current recommendations are that you need prophylaxis if you
are going to be travelling through the Amazon Basin (which includes the
cities of Manaus and Belém) or will be in Mato Grosso State (in the West of
Brazil, bordering Bolivia) or Maranhao State (in the North-East of the
country, bordering the sea).
The options for what you can take are five as all these areas have malaria
that is resistant to a drug called "chloroquine".
When I went to Thailand in 1996 I chose to take one 100mg tablet of
Doxycycline daily as I felt it would have the least amount of side-effects.
It did cause - after a few weeks - fairly severe stomach inflammation in me,
but Iwas able to sort this out with some local stomach acid suppressing
tablets that I bought. If you choose to go this route then I suggest that
you start taking such tablets - for example, "LOSEC" - at the same time as
you start the Doxycycline. I would take two 20 mg tablets. I would be very
surprised if you had stomach troubles if you were to do that.
There are several cousins of "Losec" that will do the same thing - "somac",
"pariet", etc., and none of them have any side-effects to speak of.
The only other things to be aware of if you are taking doxycycline is that
you will burn easier in the sun, and that you need to take it for 4 weeks
after you leave the malarial area.
The other tablet options are:
1. Mefloquine ("Lariam" is the other name you may hear). One tablet a week.
Needs to be taken for four weeks after you leave the malarial area.
This is the one that CAN (but not necessarily will) cause the bad dreams,
concentration difficulties and anxiety. My gut feeling from the reading that
I've done is that the standard line about "these effects being uncommon at
preventative doses but common at treatment doses" is not correct. I think
that the chance of developing some such effect is "moderate".
2. Malarone ("Atovoquone-Proguanil" is the other name you may hear). One
tablet a day. Needs to be taken for only a week after leaving malarial
areas. I can't remember it being around back in 1996. It's said to be
"generally well tolerated" with the commonest effects being tummy pain. I
think this will probably also be due to inflammation of the stomach caused
by the contact of the chemicals with the stomach lining. Hence, should be
preventable with those anti-acid drugs I mentioned.
It's also said to be able to cause headaches- I think that this is part of
those brain group of symptoms that any drug with "-quine/quone" can cause
(chloroQUINE, mefloQUINE, atovaQUONE), which really means that it could also
cause all those bad dreams, etc., that are mentioned for Lariam and
Chloroquine (though this seems to be unusual with atovaquone).
3. Primaquine is not felt to be as effective at prevention as the other two
mentioned (i.e. greater incidence of break-through malaria).
4. Tafenoquine is, as far as I'm aware, not available on the PBS. It's main
advantage is the long time that a single tablet produces effective blood
levels, which means that it only needs to be taken once a week. It's said to
be "well tolerated" and "effective" but I'm sure that as soon as it starts
being widely used, a truer picture of adverse effects will emerge.
Here's a reference:
TI Efficacy of monthly tafenoquine for prophylaxis of Plasmodium vivax and
multidrug-resistant P. falciparum malaria.
AU Walsh DS; Eamsila C; Sasiprapha T; Sangkharomya S; Khaewsathien P;
Supakalin P; Tang DB; Jarasrumgsichol P; Cherdchu C; Edstein MD; Rieckmann
KH; Brewer TG
SO J Infect Dis 2004 Oct 15;190(8):1456-63. Epub 2004 Sep 20.
We assessed monthly doses of tafenoquine for preventing Plasmodium vivax and
multidrug-resistant P. falciparum malaria. In a randomized, double-blind,
placebo-controlled study, 205 Thai soldiers received either a loading dose
of tafenoquine 400 mg (base) daily for 3 days, followed by single monthly
400-mg doses (n = 104), or placebo (n = 101), for up to 5 consecutive
months. In volunteers completing follow-up (96 tafenoquine and 91 placebo
recipients), there were 22 P. vivax, 8 P. falciparum, and 1 mixed infection.
All infections except 1 P. vivax occurred in placebo recipients, giving
tafenoquine a protective efficacy of 97% for all malaria (95% confidence
interval [CI], 82%-99%), 96% for P. vivax malaria (95% CI, 76%-99%), and
100% for P. falciparum malaria (95% CI, 60%-100%). Monthly tafenoquine was
safe, well tolerated, and highly effective in preventing P. vivax and
multidrug-resistant P. falciparum malaria in Thai soldiers during 6 months
of prophylaxis.
All up, were I to travel to Brazil, visit those areas where there is risk
and stay in them for a while, I would either take Doxycycline with a stomach
acid suppressing drug, or Malarone with a stomach acid suppressing drug.
If I was only going to be there a short time then I would seriously consider
using Lariam/Mefloquine, and think about switching to Primaquine for a week
after I'd left. The reason is that you only need to take it for a week after
you leave the malarial area (as opposed to 4 weeks for Lariam/Mefloquine)
and it kills the liver form of the disease. I think the blood levels would
be high enough to have done their thing after a week because it takes "three
to five half-lives" for blood levels to get up to where they want to be, and
the half-life of primaquine has to be less than 24 hours because it's given
as a daily dose. So, you should have reached necessary blood levels by 3-5
days. If you then wanted to be really sure, you would take it for a week
after that. All in all, 12 days at the most (i.e. 5 + 7).
It would need to be taken with stomach-acid suppressing drugs based on the
findings of this report:
TI Primaquine prophylaxis against malaria in nonimmune Colombian soldiers:
efficacy and toxicity. A randomized, double-blind, placebo-controlled trial.
AU Soto J; Toledo J; Rodriquez M; Sanchez J; Herrera R; Padilla J; Berman J
SO Ann Intern Med 1998 Aug 1;129(3):241-4.
BACKGROUND: Primaquine had a prophylactic efficacy of 90% to 95% against
infection with Plasmodium falciparum and P. vivax in Indonesian settlers.
OBJECTIVE: To evaluate the efficacy of primaquine prophylaxis for protecting
nonimmune persons from malaria. DESIGN: Randomized, double-blind,
placebo-controlled field study. SETTING: A malaria-endemic area in Colombia.
PATIENTS: 176 healthy, young, nonimmune adult male soldiers. INTERVENTION:
Primaquine, 30 mg/d, or matching placebo during 15 weeks of patrol in the
endemic area and 1 week afterward. MEASUREMENTS: Symptomatic parasitemia was
determined over the 16-week intervention period and for 3 weeks in base
camp. RESULTS: Protective efficacy in the primaquine group (122
participants) was 89% (95% CI, 75% to 96%) against all types of malaria, 94%
(CI, 78% to 99%) against P. falciparum malaria, and 85% (CI, 57% to 95%)
against P. vivax malaria. Six primaquine recipients had mild to moderate
gastrointestinal distress, and three had severe distress. CONCLUSIONS: For
prophylaxis against P. falciparum malaria, primaquine has an efficacy and
toxicity competitive with those of standard agents. A potential advantage of
primaquine is that prophylaxis may be discontinued 1 week after the
recipient has left the endemic area.
AD Universidad Militar Nueva Granada, Consorcio de Investigaciones
Bioclinicas, Direccion de Sanidad Ejercito, Bogota, Columbia.
PMID 9696733
Here's another one which is very interesting and was published in the most
prestigious/important medical journal in the world ("New England Journal of
Medicine").
TI Delayed onset of malaria--implications for chemoprophylaxis in travelers.
AU Schwartz E; Parise M; Kozarsky P; Cetron M
SO N Engl J Med 2003 Oct 16;349(16):1510-6.
BACKGROUND: Most antimalarial agents used by travelers act on the
parasite's blood stage and therefore do not prevent late-onset illness,
particularly that due to species that cause relapsing malaria. We examined
the magnitude of this problem among Israeli and American travelers. METHODS:
We examined malaria surveillance data from Israel and the United States to
determine the traveler's destination, the infecting species, the type of
chemoprophylaxis used, and the incubation period. RESULTS: In Israel, from
1994 through 1999, there were 300 cases of malaria among returning travelers
in which one species of plasmodium could be identified. In 134 of these
cases (44.7 percent), the illness developed more than two months after the
traveler's return; nearly all of these cases were due to infection with
Plasmodium vivax or P. ovale. In 108 of the 134 cases (80.6 percent), the
patient had used an antimalarial regimen according to national guidelines.
In the United States, from 1992 through 1998, there were 2822 cases of
malaria among travelers in which the cause could be evaluated. Late illness
developed in 987 (35.0 percent) of these travelers. The infection was due to
P. vivax in 811 travelers, P. ovale in 66, P. falciparum in 59, and P.
malariae in 51; 614 (62.2 percent) of those with late-onset illness had
appropriately taken an effective antimalarial agent. CONCLUSIONS: In more
than one third of malaria-infected travelers, the illness developed more
than two months after their return. Most of these late-onset illnesses are
not prevented by the commonly used and effective blood schizonticides.
Agents that act on the liver phase of malaria parasites are needed for more
effective prevention of malaria in travelers.
AD Center for Geographical Medicine and the Department of Medicine, C. Chaim
Sheba Medical Center, Tel Hashomer, Israel. elischwa@post.tau.ac.il
PMID 14561793
I'd discuss this option with a travel doctor. You'd need to have a blood
test to make sure you were not "glucose-6-phosphate dehydrogenase deficient"
before you left Australia, as Primaquine causes destruction of red blood
cells in people who are born with this enzyme deficiency.
