4years ago, a heated debate concerning malaria prophylaxis had been triggered on. It concerned the very promising results obtained by Patrick Ogwang, with an herbal product called Artavol; he had developed with the Ministry of Health in Uganda. Peer reviewed papers and press releases concerning these findings are easily found on internet. Merlin Willcox, UK, Honorary Secretary of RITAM, questioned the validity of the therapeutic and prophylactic results obtained by the research team from Uganda; that like many other studies they were poorly designed with fundamental flaws. And that it would be unethical to promote Artemisia teas at the expense of ACTs in young children. ACT is the acronym for Artemisinin Combined Therapy, the first line drug recommended by WHO. It combines artemisinin derivatives with lumefantrine or amodiaquine. So far, no prophylactic effect could be evidenced for these drugs. Willcox is right in stating that no large scale, randomized, double blind clinical trials confirming the efficiency of Artemisia plants against malaria are available. Indeed, they are forbidden by WHO. Only clinical trials with ACTs have been run in high numbers. OXFAM and others even claim that Africans are guinea pigs for pills or vaccines from Bigpharma WHO. Fortunately, some African medical doctors have decided not to obey the ludicrous veto of WHO Geneva and obtained the authorization of their health authorities to run clinical trials, small or large scale, with Artemisia annua or Artemisia afra: in Cameroon, in Mali, in Kenya, in RDCongo, in Senegal, in The Gambia, in Benin, in Ethiopia, in Tanzania, in Uganda, in Mozambique. They all assess a cure rate of >95% for uncomplicated malaria, much higher than for ACTs. This all was confirmed by a large-scale trial in the province of Maniema, RDCongo of Artemisia annua and Artemisia afra vs ASAQ: 1000 patients, randomized, double blind. The herbal treatment was in all aspects superior: for fever clearance, parasitemia clearance, gametocytemia clearance, with no adverse effects and a virtual absence of recurrence on day 28. The trial included 465 children from 2-5 years of age. But these were all symptomatic patients and the question of the efficacy of Artemisia tea infusions on asymptomatic carriers remained open. Dr. Jerome Munyangi has now completed a first randomized trial with 2x100 primary school children in the province of Maniema. The objective was to study the impact of a prophylactic treatment of 3 cups/week Artemisia annua infusion. The results are overwhelming. In the second and third month of the treatment parasitemia and gametocytemia have completely disappeared in the Artemisia arm, but in the control arm the parasite carriage remains constant over the 3months. The seminal discovery in this small trial, which will be repeated in more schools, is of course that the prophylactic effect is evident, but more important: that the treated children will not transmit gametocytes to mosquitoes biting them. Based on these results it may be concluded that only Artemia tea infusion or powdered leaves have a lasting gametocytocidal effect. ACT’s do not, and dihydroartemisinin-piperaquine may even prolong the gametocyte carriage.¹

The question needs to be asked. Are afebrile malaria infections truly asymptomatic, benign, or even beneficial to the individual? The evidence suggests the contrary. A recent review paper financed by the Bill&Melinda Gates Foundation and by the European Community’s 7^th Framework Program addresses this critical issue.² So-called asymptomatic malaria infections are associated with recurrent episodes of symptomatic parasitemia, chronic anemia, maternal and neonatal mortality, co-infection with invasive bacterial disease, cognitive impairment, and ongoing transmission of the parasite. They have significant health and societal consequences. A prophylactic effect as Artemisia annua infusions had been noticed in 2012 in a study of the Ministry of Health in Uganda.³ Patrick Ogwang (personal communication) found that when asymptomatic carriers started taking Artemisia infusion, the parasites are kind of forced to progress quickly, to cause fever and disease, and once persons are treated and continue taking Artemisia they don’t catch malaria easily. A similar positive effect of Artemisia annua powdered leaves in the form of capsules had been noticed by a study in Bangui. During surgical interventions, asymptomatic children often suffer a severe malaria crisis and don’t survive. For the 11 patients treated during 36hours, the parasitemia decreased from 395 to 142, i.e. a 64% (23%-100%) improvement. For the 14 patients treated during 60hours, parasitemia decreased from 461 to 183, i.e. a 60% (<14%-85%) improvement. The prevention of malaria during the surgical intervention was effective in all cases and an antinociceptive effect was even noticed.⁴ Adults contribute significantly to the infectious reservoir, particularly in areas of intense seasonal transmission.^5,6 The concept to reduce the parasite load in asymptomatic carriers is not new. Intermittent preventive treatment (IPT) with antimalarials has repeatedly been tried. But it has often been hampered by serious side effects. Let’s just mention the increased gametocyte load after sulfadoxine-pyrrimethamine treatment⁷ and the severe haemolysis in G6PD patients after primaquine or artesunate treatment.^8,9 A paper reviewing IPT studies involving 5 antimalarial finds that the highest protective effect against symptomatic parasitaemia was obtained with dihydroartemisinin-piperaquine (95%). Sulfadoxine-pyrimethamine did not provide any protection.¹⁰

The average protective effect was 55% which is much lower than in the trial run by Jerome Munyangi¹¹ with Artemisia annua infusion in Maniema. The gametocyte carriage is of much longer duration than generally believed. Several cases of infection of naïve patients after blood transfusion indicate that the parasite carriage lasts up to 3years.¹² In fact, not many studies have addressed the longevity of gametocytes. A very recent in vitro study shows alarming data. The longevity was assessed on three different strains by microscopy, flow cytometry and RT-qPCR and find similar results: 50 days with peak concentrations at 22days.¹³ Previous studies have shown that if gametocytes remain viable, a small number of gametocytes (sub-microscopic level) is sufficient for transmission.¹⁴ Artemisinin and its derivatives do not explain the prophylactic efficiency of Artemisia annua. A traveler returning from Nigeria to Canada suffered severe malaria after taking artesunate prophylactically.¹⁵ Endothelial dysfunction in malaria is nearly universal in malaria disease, symptomatic and/or asymptomatic. It is reversible with arginine. Furthermore, arginine produces NO which inhibits the development of gametocytes.^16,17 A working hypothesis which has been advanced is that the high content of saponins in Artemisia infusion releases parasites in dormancy in the late trophozoite stage from erythrocytes by saponin lysis. Inulin is a dietetic fiber, a polysaccharide and some Artemisia species may contain up to 9% polysaccharides of their dry weight. Capsules of Chinese origin containing Artemisia annua leaf powder also contain inulin. The main reason may be reduction of iron absorption in the intestine.^18,19 Pentacyclic triterpenes (amyrin, asiatic acid, maslinic acid, betulinic acid) also have a long lasting effect on the reduction of symptomatic and asymptomatic malaria.²⁰ Immunity to malaria is hard won, and yet it is imperfect. CD4⁺ helper T cells are critical orchestrators of immune responses.²¹ In Nigeria a significantly lower CD4⁺ count was observed among Plasmodium falciparum-infected truck drivers compared to those uninfected. Malaria seems to have a negative impact on the CD4⁺ lymphocyte count.

This is in line with our findings in Katanga where we confirmed that administration of capsules containing Artemisia leaf powder raised the CD4⁺.²² 44 volunteers carrying trophozoites were treated with capsules containing Artemisia afra. The total dose of Artemisia powder administered over 10 days was 20 gr. It was found that on day 10 the CD4⁺ count had on the average increased by 20% and the trophozoite count was reduced to zero except in a few cases. A low CD4⁺ T cell count is indicative of a weak immune system. In Guinea-Bissau it was found that the CD4⁺ cell percentage was inversely correlated with the density of malaria parasites.^23,24 Another study group finds that with age there is a significant decline in the percentage of naïve T cells and CD8⁺ T cells, and an increase in the percentage of CD4⁺ and NK cells.²⁵ In Nigeria a significantly lower CD4⁺ count was observed among Plasmodium falciparum infected truck drivers compared to those uninfected. Malaria seems to have a negative impact on the CD4⁺ lymphocyte count.²⁶ The role T lymphocytes are complex. Loss and dysfunction of proinflammatory Vδ2+ γδ T cells was associated with a reduced likelihood of symptoms upon subsequent P. falciparum infection. Together, these results suggest that repeated malaria infection during childhood results in progressive loss and dysfunction of Vδ2 (+) γδ T cells that may facilitate immunological tolerance of the parasite.²⁷ The humoral response is also important for malaria protection because passive transfer of IgG from immune African adults to children and nonimmune adults with acute malaria rapidly reduces parasitaemia and abrogates fever.²⁸ Typhoid fever and salmonellosis kill more than 100000 people per year in Sub-Saharan Africa. These diseases are directly linked to a weakened immune system, by symptomatic and asymptomatic malaria.^29‒31 A recent paper from Saudi-Arabia opens new doors. Trophozoites where gametocytes are born and developed accumulate hemozoin and trophozoites where the asexual cycle continues are void of hemozoin, like it is absent in merozoites and ring forms.³²

If the trophozoite containing the gametocyte carries its load of hemozoin it is because heme is essential in the mosquito and liver stages. The sporozoite even generates its own heme in the liver stage, but parasites in erythrocytes do not.^33,34 ACTs are not able to eliminate gametocytes, nor do antibiotics, nor does chloroquine, nor do quinolines. They may even enhance transmission of more resistant parasites. Quinine had a strong reputation to be a prophylactic against malaria. But it is imposible to find a single scientific paper confirming this statement. The only clinical trial retrievable is from 1918 and finds the same number of infections in two arms; in the control arm (n=252) and in the treatment arm where 140 patients received 10gr of quinine per day. The reputation of quinine as prophylactic rests probably on the fact that the continuous intake of the drug was suppressive and curative in case of infection.³⁵ In fact gametocytes in the stages I-IV hide in bonemark as it was found recently. This may explain why gametocytes can survive for a much longer period than the asexual stages. It is only in stage V that they become vulnerable.³⁶ The hemozoin carried by the gametocytes is not carried inside, but on the outside in Granham bodies.³⁷ Some proteasome and protein synthesis inhibitors seem to be effective against gametocytes.³⁸ Iron chelators also have an effect. Results of the double-blind, placebo controlled trial of desferrioxamine in humans with asymptomatic parasitemia provided unequivocal evidence that this iron-chelating agent has antimalarial activity. Depriving the parasite of a metabolically important source of iron may represent a novel approach to antimalarial drug development. Desferrioxamine has no effect on the early intra-erythrcytic stages of the parasite. Iron supplementation annihilates the effect of this chelator on gametocytes in asymptomatic malaria. The efficiency of the treatment with chelators is not immediate. It requires several days of administration. This appears logical and recommendable as the gametocytogenesis and gametocyte circulation spread over several weeks after the asexual stage.³⁹ In fact the efficiency of these chelators is known since 25years.⁴⁰ It is likely that the Artemisia plants contain some molecules which interfer with the storage of hemozoin in the Granham bodies of the gametocytes. Proanthocyanidins and other tannins for example are well known for their chelating effect. Comparison with the gametocytocidal effect of other plants may be useful. Extracts of Azadirachta indica although they have little therapeutic effect during the asexual stage have a strong gametocydocidal effect, at 50 ppm. But here again the molecules responsible for this effect have not been identified.⁴¹

None.

Author déclares that there is no conflict of interest.

1. Sawa P, Shekalaghe S, Drakeley CJ, et al. Malaria transmission after artemether-lumefantrine and dihydroartemisinin-piperaquine: A randomized trial. J Infect Dis. 2013;207(11):1637‒1645.
2. Chen I, Clarke SE, Gosling R, et al. Asymptomatic Malaria: A Chronic and Debilitating Infection That Should Be Treated. PLoS Med. 2016;13(1):e1001942.
3. Ogwang PE, Ogwal JO, Simon K, et al. Artemisia Annua L. Infusion Consumed Once a Week Reduces Risk of Multiple Episodes of Malaria: A Randomised Trial in a Ugandan Community. Tropical Journal of Pharmaceutical Research. 2012;11(3):445‒453.
4. Onimus M, Carteron S, Lutgen P. The Surprising Efficiency of Artemisia annua Powder Capsules. Med Aromat Plants. 2013;2:125.
5. Drakeley CJ, Akim NI, Sauerwein RW, et al. Estimates of the infectious reservoir of Plasmodium falciparum malaria in the Gambia and in Tanzania. Trans R Soc Trop Med Hyg. 2000;94(5):472‒476.
6. Drakeley CJ, Bousema JT, Akim NI, et al. Transmission-reducing immunity is inversely related to age in Plasmodium falciparum gametocyte carriers. Parasite Immunol. 2006;28(5):185‒190.
7. Barnes KI, Little F, Mabuza A, et al. Increased gametocytemia after treatment: an early parasitological indicator of emerging sulfadoxine-pyrimethamine resistance in falciparum malaria. J Infect Dis. 2008;197(11):1605‒1613.
8. Rehman K, Lorsch F, Kresmner PG, et al. Hemolysis associated with the treatment of malaria with artemisinin derivatives : a systematic review of current evidence. Int J Infect Dis. 2014;29:268‒273.
9. Watson J, Taylor WR, Menard D, et al. Modelling primaquine-induced haemolysis in G6PD deficiency. Elife. 2017;6:e23061.
10. Matangila JR, Mitashi P, Raquel A, et al. Efficacy and safety of intermittent preventive treatment for malaria in schoolchildren: a systematic review. Malaria Journal. 2015;14:450.
11. Munyangi J, Vernet LC, Pierre Lutgen. Artemisia plants: a deadly weapon against tropical diseases. J Pharm Drug Deliv Res. 2016;5(Suppl 4):29.  
12. Jacques Verdrager. L’OMS et le Paludisme. L’Harmattan.
13. Gebru T, Held J, Albert L, et al. Life-span of in vitro differentiated Plasmodium falciparum gametocytes. Malaria Journal 2017;16:330.
14. Churcher TS, Bousema T, Walker M, et al. Predicting mosquito infection from Plasmodium falciparum gametocyte density and estimating the reservoir of infection. Elife. 2013;2:e00626.
15. Shabinas D, Leu R, Khairnar K, et al. Artesunate misuse and Plasmodium falciparum malaria in traveler returning from Africa. Emerg Infect Dis. 2010;16(10):1608‒1610.
16. Ya-Ming Cao, Takafumi T, Motomi T. Nitric oxide inhibits the development of Plasmodium yoelii gametocytes into gametes. Parasitology International. 1998;47(2):157‒166.
17. Yeo TW, Lampah D, Gitwati R, et al. Impaired nitric oxide bioavailability and L-arginine-reversible endothelial dysfunction in adults with falciparum malaria. J Exp Med. 2007;204(11):2693‒2704.
18. Laparra Llopis JM, Elad Tako, Glahn R, et al. Inulins and mucins in the intestine can reduce iron uptake. The FASEB Journal. 2008;22(2):S745.
19. Zimmermann MB. Effect of Inulin on iron absorption in humans. Clinical trials. Switzerland; 2011.
20. Mavondo GA, Mkhwananzi BN, Mabandia V, et al. Asiatic acid influences parasitemia reduction and ameliorates anaemia in P berghei infected rats. BMC Complement Altern Med. 2016;16:357.
21. Schmidt NW, Podyminogin RL, Butler NS, et al. Memory CD8 T cell responses exceeding a large but definable threshold provide long-term immunity to malaria. Proc Natl Acad Sci U S A. 2008;105(37):14017‒14022.
22. Constant Kansongo Tchandema, Lubumbashi, Rdcongo, et al. In vivo Trials on The Therapeutic Effects of Encapsulated Artemisia annua and Artemisia afra. GJRA. 2016;5(6):228‒234.
23. Lisse IM, Aaaby P, Whittle H, et al. A community study of T lymphocyte subsets in malaria parasitaemia. Trans R Soc Trop Med Hyg. 1994;88(6):709‒710.
24. Xu H, Wipasa J, Yan H, et al. The mechanism and significance of deletion of parasite-specific CD4 T celles in malaria infection. J Exp Med. 2002;195(7):881‒892.
25. Yan J, Greer JM, Hull R, et al. The effect of ageing on human lymphocyte subsets: comparison of males and females. Immun Ageing. 2010;7:4.
26. Erhabor O, Azuonwu O, Frank-Peterside N. Malaria parasitaemia among long distance truck drivers in the Niger delta of Nigeria. Afr Health Sci. 2012;12(2):98‒103.
27. Jagannathan P, Kim CC, Greenhouse B, et al. Loss and dysfunction of Vδ2+ γδ T cells is associated with clinical tolerance to malaria. Sci Transl Med. 2014;6(251):251ra117.
28. Cohen S, Mc Gregor IA, Carrington S. Gamma-globulin and acquired immunity to human malaria. Nature. 1961;192:733‒737.
29. Cunnington AJ, De Souza JB, Walther M, et al. Malaria impairs resistance to Salmonella through heme-and heme oxygenase-dependent dysfunctional granulocyte mobilization. Nat Med. 2011;18(1):120‒127.
30. Takem EN, Roca A, Cunnington A. The association between malaria and nontyphoid Salmonella bacteraemia in children in sub-Saharan Africa: a literature review. Malar J. 2014;13:400.
31. Roux CM, Butler B, Chau J, et al. Both hemolytic and malaria parsite-specific factors increase susceptibility to nontyphoidal Salmonella enterica Servar Typhimurium infection in mice. Infect Immun. 2010;78(4):1520‒1527.
32. Ghazi A Jamjoom. Evidence for a role of hemozoin in metabolism and gametocytogenesis. MWJ. 2017;8:10.
33. Nagaraj V, Sundaram B, Varadarajan NM, et al. Malaria parasite-synthesized heme is essential in the mosquito and liver stages. PLoS Pathog. 2013;9(8):e1003522.
34. Rizopoulos Z, Matuschewski K, Haussig JM. Distinct prominent roles for enzymes of Plasmodium berghei heme biosynthesis in sporozoite and liver stage maturation. Infect Immun. 2016;84(11):3252‒3262.
35. Waugh Scott G. Quinine prophylaxis in malaria. Br Med J. 1918;2(3017):463.
36. Alano P. The emerging role of the human bone marrow as a a privileged development niche for the transmission stages of the malaria parasite Polasmodium falciparum. Ann 1st Super Sanita. 2017;53(2):96‒99.
37. Orjih AU. Hemozoin accumulation in Granham bodies of Plasmodium falciparum gametocytes. Parasitol Res. 2012;111(6):2353‒2359.
38. Tanaka TQ, Guiguemde WA, Barnett DS, et al. Potent Plasmodium falciparum gametocidal activity of diaminonaphtoquinones. Antimicrob Agents Chemother. 2014;59(3):1389‒1397.
39. Ferrer P, Vega-Rodriguez J, Tripathi AK, et al. Antimalarial iron chelator FBS0701 blocks transmission by Plasmodium falciparum gametocyte activation inhibition. Antimicrob Agents Chemother. 2015;59(3):1418‒1426.
40. Hershko C, Gordeuk VR, Thuma PE, et al. The antimalarial effect of iron chelators: studies in animal models and in humans with mild falciparum malaria. J Inorg Biochem. 1992;47(3‒4):267‒277.
41. Yerbanga RS, Lucantoni L, Yao FA, et al. Transmission blocking activity of Azadirachta indica on the sporogonic development of Plasmodium Falciparim field isolates in Anpheles coluzii mosquitoes. Parasit Vectors. 2014;7:185.