Correspondence

Malaria in a Trinidadian Man

N Engl J Med 2000; 343:1046-1047October 5, 2000

Article

To the Editor:

Chadee et al. (June 22 issue)1 describe a 70-year-old Trinidadian man with symptomatic reactivation of Plasmodium malariae infection seven days after neurosurgery. Their conclusion is that the infection was reactivated “after decades of latency,” given that malaria was officially eradicated in Trinidad in 1965 and that the patient denied having traveled to a country where malaria was endemic.

Yet a recent report by the same lead author of reemergence of P. malariae infection in Trinidad suggests a more logical explanation for this case.2 From 1994 to 1996, 22 people from 12 different areas of Trinidad had blood smears that were positive for P. malariae. Seven of these 22 people were less than 25 years old and thus had been born after the official eradication of malaria in 1965. All of them denied having traveled outside Trinidad. In addition, a number of other people, half of whom had been born after 1965, were found to have negative blood smears and high-titer seropositivity for P. malariae. Mosquito vectors of the parasite were abundant in the geographic areas associated with the detected cases.

Given all these facts, the current patient may very well have been infected with the parasite during the recent outbreak and thus have had a latent infection for only a few years, and not for decades. Only with the great stress and the high level of immunosuppression associated with a major operation did the infection become reactivated. Even though the possibility that the patient became infected before 1965 cannot be ruled out entirely, there is no evidence to reach a conclusion about when and how long this patient had the disease.

Wanla Kulwichit, M.D.
Chulalongkorn University, Bangkok 10330, Thailand

2 References

1. 1

   Chadee DD, Tilluckdharry CC, Maharaj P, Sinanan C. Reactivation of Plasmodium malariae in a Trinidadian man after neurosurgery. N Engl J Med 2000;342:1924-1924
   Full Text | Web of Science | Medline

2. 2

   Chadee DD, Beier JC, Doon R. Re-emergence of Plasmodium malariae in Trinidad, West Indies. Ann Trop Med Parasitol 1999;93:467-475
   CrossRef | Web of Science | Medline

To the Editor:

Chadee et al. report a case of P. malariae infection that was diagnosed long after the exposure to malaria. The authors state that their patient was treated with “the standard regimen of chloroquine phosphate and primaquine phosphate.” However, primaquine phosphate is inappropriate for the treatment of P. malariae infection. This drug is used to eradicate dormant hypnozoites in the liver and thus prevent relapses of malaria caused by P. vivax or P. ovale. Since P. malariae has no hypnozoite stage, the appropriate therapy is chloroquine phosphate alone. Primaquine phosphate is often given inappropriately for P. malariae or P. falciparum infection. Although this drug is usually well tolerated, it can cause serious complications, including fatal hemolysis in persons with a deficiency of glucose-6-phosphate dehydrogenase.1 The use of primaquine phosphate should be reserved for the treatment, in conjunction with chloroquine phosphate, of P. vivax and P. ovale infections.

Philip J. Rosenthal, M.D.
University of California, San Francisco, San Francisco, CA 94143-0811

1 References

1. 1

   Luzzi GA, Peto TEA. Adverse effects of antimalarials: an update. Drug Saf 1993;8:295-311
   CrossRef | Web of Science | Medline

Author/Editor Response

Dr. Chadee replies:

To the Editor: Our recent report on the reactivation of P. malariae in a Trinidadian man after neurosurgery has generated some debate on the exact time the patient contracted the infection and on the drug regimen used for treatment. Kulwichit points out that the patient could have become infected during the small outbreak of malaria that occurred during the period from 1994 to 1996, when infection with P. malariae was diagnosed and treated in 22 people in Trinidad. However, our patient denied having traveled to the area where the outbreak had occurred, and no Anopheles bellator or A. homunculus mosquitoes were found through extensive collections within his home and the surrounding areas. These anopheline mosquitoes have been reported to have a limited flight range within the forest and the outer fringes of the forest.1 Therefore, the available data do not support the argument that the infection was acquired during the outbreak of P. malariae infection from 1994 to 1996.

Kulwichit agrees that the patient could have been infected before 1965 (the year malaria was eradicated in Trinidad). As with most diseases with a long latency period, determination of the exact date of infection is impossible. Consequently, we stated that our patient could have had this infection for “more than 30 years and perhaps, given his clinical history, about 65 years.” Similar cases of P. malariae infection with long latency periods have been reported elsewhere.2,3

Rosenthal suggests that the treatment of P. malariae infection with primaquine phosphate was inappropriate. I agree that primaquine phosphate is not recommended for the treatment of quartan malaria, but in Trinidad the use of chloroquine phosphate and primaquine phosphate is the standard treatment for malaria caused by P. vivax, P. malariae, or P. ovale. The rationale for the use of primaquine phosphate is the frequency of malaria with mixed infections in persons coming from outside the country (especially since P. vivax is submicroscopical) and the presence of efficient vectors that are potential risk factors for renewed transmission from persons with relapse. Primaquine phosphate is administered in Trinidad and Tobago only after the appropriate tests for glucose-6-phosphate dehydrogenase have been conducted. This test was conducted in our patient before treatment, and thus there was no risk of complications (such as hemolysis) as a result of the treatment.

Dave D. Chadee, Ph.D., D.Sc.
Insect Vector Control Division, St. Joseph, Trinidad, West Indies

3 References

1. 1

   Pittendrigh CS. The ecoclimatic divergence of Anopheles bellator and Anopheles homunculus. Evolution 1950;4:58-89
   

2. 2

   Diagnosis of malaria. Pan American Health Organization scientific publication no. 512. Washington, D.C.: Pan American Health Organization, 1965.
   

3. 3

   Vinetz JM, Li J, McCutchan TF, Kaslow DC. Plasmodium malariae infection in an asymptomatic 74-year-old Greek woman with splenomegaly. N Engl J Med 1998;338:367-371
   Full Text | Web of Science | Medline