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In vitro confirmation of clinical resistance of Plasmodium falciparum to chloroquine in Kenya
ROYAL.S~CJETY OF TROPKALMEDICIKEAND HYGIENE, VOL. 77, No. 3 (1983).CORRESPONDENCE Lanotte, G. (1975). Le fqer de leishmaniore vis&ale des Ct!wmes. Limites et Structures. Essai MCthodologique. Th&e. Montpellier. Rioux, J.-A., Albaret, J.-L., Houin, R., Dedet, J.-P. & Lanotte, G. (1968). Ecoloaie des leislunanioses dam le sud de ia France. 2. Les &servo& selvariques. Infestation spontanCedu renard (Vulpes vulpes L.). Annales de Parasitologic humaine et comparke, 43, 421-428. Rioux, J.-A., Lanotte, G., Destombes, P., Vollhardt, Y. & Croset, H. (1971). Leishrnaniose ex&rimentale du Renard Vulpes vulpes L. Recueil de Mtdecine VtUrinaire de I’Ecole d’Alfmt,
147, 489-498.
Accepted for publication
10th January,
In vitro confirmation
1983
of clinical resistance of Plasmoin Kenya to chloroquine has often been reported from East Africa, but in most of the earlier observations parasite sensitivity has been assessed only by the in vivo method (standard or extended field test). Since this investigation can be influenced by host factors such as immune status, reinfections, malabsorption and the concomitant use of other drugs, it is now recognized that clinical records require, before being considered proved, analysis of serum chloroquine concentration or evaluation of in vitro techniques (CAMPBELL et al., 1979; ARONSSON et al., 198i; B~~NCTSSON et al., 1981; FAEHLMANN et al.. 1981: PETTERSON et al.. 1981). We describe here ‘a cask of P. falciparum ‘malaria acquired in Kenya; the strain showed in vivo a RI response to chloroquine, and was highly resistant in the in vitro sensitivity assay. A 36-year-old man, who had not previously been to other endemic areas, visited Kenya during the autumn of 1982: he suent 10 davs in Malindi and then made a five-iay saiari in Easi Tsavo and Amboseli National Parks: He took no anti-malarial prophylactics. Two davs after his return to Italv. he fell ill with high fever, Headache and joint pains:‘Six days later, without blood examinations or consulting a physician, he started a treatment with chloroquine phosphate (1050 mg of chloroquine base in 24 hours). On the next day he was referred to our hospital, where his blood s&ear was found positive for trophozoites of P. falcibarum (45OO/ul). Chloroauine administration was contnued &th 4% ma dail; for five davs, total dose 3300 mg (32 mgikg body-weight). Neichher vomiting nor diarrhoea was recorded durine therauv. The patient improved quickly and becaGe afebiie after three days of treatment; asexual parasitaemia decreased to nil in the same period.. Five davs after discontinuing chloroquine therapv, symptoms- of malaria reappeared and blood fil& again showed P. falciparum trophozoites (1 lSOO/~l). The patient was readmitted, and an in vitro chloroquine sensitivity test was carried out with the macrotechnique (WHO test kit). The strain proved to be markedly resistant to chloroquine, schizont maturation being still observed at the highest concentrations of the drug (schizonts/300 leucocytes: at 2 nmol/ml = 15; at 3 nmol/ml = 3; mean of the dium falciparum to chloroquine Resistance of Plasmodium falciparum
421
controls = 162). Resistance appears particularly striking, the more so considering the certain residual presence of chloroquine in the patient’s serum. Treatment with pyrimethamine/sulphadoxine and quinine sulphate was therefore instituted; parasitaemia cleared three days later, and clinical conditions returned to normal without further relapses. Such a pattern of in vitro response contrasts with the data reported by SPENCER et al. (1982), who did not detect - chloroqbine resistance in P. ‘falciparum isolates from the Malindi and Kisumu areas of Kenva. But peculiar to our case is the difference between fhe results of in vivo and in vitro sensitivity tests. Clinically, the patient seemed to have chloroquineresistant P. falciparum malaria type RI (early recrudescence), even though he received more than the 25 mg/kg chloroquine base recommended for the WHO field test. The in vitro method. on the contrarv. showed a higher degree of resistahce, as schizoi; growth at 2.5 or more nmol chloroquine per ml is usually a sign of RI1 or RI11 resistance (WERNSDORFER & KOUZNETSOV, 1980). This discrepancy stresses the need for careful in vitro study of all the cases of chloroquine-resistant malaria, in order to obtain objective indications on the sensitivity of P. falciparum strains from the different endemic zones. ROBERTO ESPOSITO GIOVANNA ORLANDO
PAOLO CROCCHIOLO Diseases,
of Infectious University of Milan,
Institute
‘Ospedale
L. Sacco,
201.57 Milan,
Ztaly References
Aronsson, P., Bengtsson, E., Bjarkman, A., Peherson, P. O., Rombo, L. & Wahlgren, M. (1981). Chloroquineresistant falciparum malaria m Madagascar and Kenya. Annals of Tropical Medicine and Parasitology,
75, 367-
373. Bengtsson, E., BjGrkman, A., Brohult, J., Hedman, P., Persson, P., Rombo, L. & Wahlgren, M. (1981). Malaria prophylaxis when visiting areas of East Africa with chloroquine resistance. Lancer, ii, 249. Campbell, C. C., Collins, W. E., Chm, W., Teutsch, S. & Moss, D. M. (1979). Chloroquine-resistant Plasmodium falciparum from East Africa: cultivation and drug sensitivity of the Tanzanian UCDC strain from an American tourist. Lancet, ii, 1151-1154. Faehlmann, M., Rombo, L. & Hedman, P. (1981). Serum concentrations of chloroquine in a patient with a late recrudescenceof Kenyan Plasmodium falcipanrm malaria. Transactions of the Royal Society of Tropical Medicine and Hygiene, 75, 362-364.
Petrerson, T,., Kyrtinseppl, H. & Pitklnen, T. (1981). Chloroqume-resistant falciparum malaria from East Africa. Transactions of the Royal Society of Tropical Medicine and Hygiene, 75, 112-113.
Spencer, H. C., Chemengay Masaba, S. & Kiaraho, D. (1982). Sensitivity of Plasmodium falciparum isolates to chloroquine in Kisumu and Malindi, Kenya. American Journal of Tropical Medicine and Hygiene, 31, 902-906. Wernsdorfer, W. H. & Kouznetsov, R. L. (1980). Drugresistant malaria-occurrence, control, and surveillance. Bulletin of the World Health Organization, 58, 341-352.
Accepted for publication
12th January,
1983.
147, 489-498.
Accepted for publication
10th January,
In vitro confirmation
1983
of clinical resistance of Plasmoin Kenya to chloroquine has often been reported from East Africa, but in most of the earlier observations parasite sensitivity has been assessed only by the in vivo method (standard or extended field test). Since this investigation can be influenced by host factors such as immune status, reinfections, malabsorption and the concomitant use of other drugs, it is now recognized that clinical records require, before being considered proved, analysis of serum chloroquine concentration or evaluation of in vitro techniques (CAMPBELL et al., 1979; ARONSSON et al., 198i; B~~NCTSSON et al., 1981; FAEHLMANN et al.. 1981: PETTERSON et al.. 1981). We describe here ‘a cask of P. falciparum ‘malaria acquired in Kenya; the strain showed in vivo a RI response to chloroquine, and was highly resistant in the in vitro sensitivity assay. A 36-year-old man, who had not previously been to other endemic areas, visited Kenya during the autumn of 1982: he suent 10 davs in Malindi and then made a five-iay saiari in Easi Tsavo and Amboseli National Parks: He took no anti-malarial prophylactics. Two davs after his return to Italv. he fell ill with high fever, Headache and joint pains:‘Six days later, without blood examinations or consulting a physician, he started a treatment with chloroquine phosphate (1050 mg of chloroquine base in 24 hours). On the next day he was referred to our hospital, where his blood s&ear was found positive for trophozoites of P. falcibarum (45OO/ul). Chloroauine administration was contnued &th 4% ma dail; for five davs, total dose 3300 mg (32 mgikg body-weight). Neichher vomiting nor diarrhoea was recorded durine therauv. The patient improved quickly and becaGe afebiie after three days of treatment; asexual parasitaemia decreased to nil in the same period.. Five davs after discontinuing chloroquine therapv, symptoms- of malaria reappeared and blood fil& again showed P. falciparum trophozoites (1 lSOO/~l). The patient was readmitted, and an in vitro chloroquine sensitivity test was carried out with the macrotechnique (WHO test kit). The strain proved to be markedly resistant to chloroquine, schizont maturation being still observed at the highest concentrations of the drug (schizonts/300 leucocytes: at 2 nmol/ml = 15; at 3 nmol/ml = 3; mean of the dium falciparum to chloroquine Resistance of Plasmodium falciparum
421
controls = 162). Resistance appears particularly striking, the more so considering the certain residual presence of chloroquine in the patient’s serum. Treatment with pyrimethamine/sulphadoxine and quinine sulphate was therefore instituted; parasitaemia cleared three days later, and clinical conditions returned to normal without further relapses. Such a pattern of in vitro response contrasts with the data reported by SPENCER et al. (1982), who did not detect - chloroqbine resistance in P. ‘falciparum isolates from the Malindi and Kisumu areas of Kenva. But peculiar to our case is the difference between fhe results of in vivo and in vitro sensitivity tests. Clinically, the patient seemed to have chloroquineresistant P. falciparum malaria type RI (early recrudescence), even though he received more than the 25 mg/kg chloroquine base recommended for the WHO field test. The in vitro method. on the contrarv. showed a higher degree of resistahce, as schizoi; growth at 2.5 or more nmol chloroquine per ml is usually a sign of RI1 or RI11 resistance (WERNSDORFER & KOUZNETSOV, 1980). This discrepancy stresses the need for careful in vitro study of all the cases of chloroquine-resistant malaria, in order to obtain objective indications on the sensitivity of P. falciparum strains from the different endemic zones. ROBERTO ESPOSITO GIOVANNA ORLANDO
PAOLO CROCCHIOLO Diseases,
of Infectious University of Milan,
Institute
‘Ospedale
L. Sacco,
201.57 Milan,
Ztaly References
Aronsson, P., Bengtsson, E., Bjarkman, A., Peherson, P. O., Rombo, L. & Wahlgren, M. (1981). Chloroquineresistant falciparum malaria m Madagascar and Kenya. Annals of Tropical Medicine and Parasitology,
75, 367-
373. Bengtsson, E., BjGrkman, A., Brohult, J., Hedman, P., Persson, P., Rombo, L. & Wahlgren, M. (1981). Malaria prophylaxis when visiting areas of East Africa with chloroquine resistance. Lancer, ii, 249. Campbell, C. C., Collins, W. E., Chm, W., Teutsch, S. & Moss, D. M. (1979). Chloroquine-resistant Plasmodium falciparum from East Africa: cultivation and drug sensitivity of the Tanzanian UCDC strain from an American tourist. Lancet, ii, 1151-1154. Faehlmann, M., Rombo, L. & Hedman, P. (1981). Serum concentrations of chloroquine in a patient with a late recrudescenceof Kenyan Plasmodium falcipanrm malaria. Transactions of the Royal Society of Tropical Medicine and Hygiene, 75, 362-364.
Petrerson, T,., Kyrtinseppl, H. & Pitklnen, T. (1981). Chloroqume-resistant falciparum malaria from East Africa. Transactions of the Royal Society of Tropical Medicine and Hygiene, 75, 112-113.
Spencer, H. C., Chemengay Masaba, S. & Kiaraho, D. (1982). Sensitivity of Plasmodium falciparum isolates to chloroquine in Kisumu and Malindi, Kenya. American Journal of Tropical Medicine and Hygiene, 31, 902-906. Wernsdorfer, W. H. & Kouznetsov, R. L. (1980). Drugresistant malaria-occurrence, control, and surveillance. Bulletin of the World Health Organization, 58, 341-352.
Accepted for publication
12th January,
1983.