What is the risk of transmitting P. vivax malaria from a kidney donor who took Malarone (atovaquone-proguanil) prophylaxis and how long after exit from a malaria-endemic area can surgery be scheduled to minimize this risk?

Risk Assessment and Management for Potential Kidney Donors with P. vivax Malaria Exposure

Malarone (atovaquone-proguanil) prophylaxis is effective against P. vivax during exposure, but potential kidney donors should wait at least 4 weeks after leaving the malaria-endemic area before donation surgery to minimize transmission risk.

Risk of P. vivax Malaria in Potential Kidney Donors

• P. vivax can cause relapsing malaria due to persistent liver stages (hypnozoites) that can remain dormant for up to 4 years after leaving endemic areas, even with appropriate prophylaxis 1
• Malarone (atovaquone-proguanil) provides effective prophylaxis against the blood stages of P. vivax during exposure, with protective efficacy of 84% (95% CI, 44%-95%) 2
• Unlike P. falciparum prophylaxis, where Malarone can be stopped 7 days after leaving the endemic area, P. vivax poses additional risks due to potential liver-stage persistence 3, 4

Transmission Risk in Organ Donation

• Malaria parasites can be transmitted through organ donation, posing a significant risk to immunosuppressed transplant recipients 1
• Kidney transplant recipients are particularly vulnerable due to immunosuppressive medications that reduce their ability to control parasitic infections 1
• Post-transplant infections can lead to significant morbidity and mortality, with reported deaths in transplant recipients who develop malaria 1

Recommended Waiting Period

• Despite appropriate Malarone prophylaxis, potential kidney donors who have traveled to P. vivax endemic areas should wait at least 4 weeks after leaving the endemic area before donation 1, 3
• This waiting period allows time to:
  • Monitor for any breakthrough infection that might have occurred despite prophylaxis 1
  • Detect early blood-stage parasites that might not be symptomatic yet 1
  • Reduce the risk of transmitting parasites that may have survived prophylaxis 3

Additional Precautions

• Consider screening potential donors with thick and thin blood smears and/or malaria-specific PCR testing before donation, especially if they've been in high-risk areas 1
• For donors with any post-travel fever or symptoms suggestive of malaria, donation should be deferred until malaria is definitively ruled out 1
• If donation must proceed urgently, consider administering primaquine to the donor (after G6PD testing) to eliminate potential liver-stage parasites 1, 5

Special Considerations

• The risk of P. vivax transmission varies based on the endemic region visited, with higher risks in certain parts of Asia and South America 1
• Compliance with the full prophylactic regimen (starting 2 days before travel through 7 days after) significantly reduces but does not eliminate risk 3, 6
• Breakthrough infections can still occur despite proper prophylaxis, with documented cases of P. vivax malaria occurring after compliant use of atovaquone/proguanil 4

Risk Minimization Algorithm

1. Confirm complete compliance with Malarone prophylaxis (2 days before through 7 days after exposure) 3, 6
2. Wait minimum 4 weeks after leaving endemic area before donation 1
3. Perform malaria screening tests (blood smears and/or PCR) before donation 1
4. If any fever or symptoms develop during waiting period, defer donation and evaluate for malaria 1
5. Consider primaquine treatment (after G6PD testing) if donation timeframe cannot be extended 1, 5