Was malaria resistant to chloroquine in Eritrea during the liberation war of the 1980s?

by Resoum Kidane, 2002

Abstract

This paper provides a summary of retrospective study conducted from 1982 to1991 during the liberation war in Eritrea. The overall aim of the research was to look at the effectiveness of the various anti-malaria drugs and to find out if there was any plasmodium as Vivax or Falciparum resistance to chloroquine.

To achieve this, data and other relevant information was gathered, mostly from the Orota Central Hospital's patient records, Eritrea and personal experience . Based on this, the author concludes that 73% of patients selected randomly were cured with chloroquine the conclusion was that in the 1980s, chloroquine was highly effective in curing malaria in Eritrea despite its less ineffectiveness, as being reported by other analysts in other parts of Africa and Asia.

Introduction

Malaria resistance to chloroquine was reported towards the end of the 1950s in Asia and in late 1970s in East Africa. The first documented case plasmodium falciparum of resistance to chloroquine in East Africa was reported in 1979 in American tourists who had contracted the disease in Kenya. Since then the case of plasmodium falciparmu's resistance to chloroquine has been found among non-immune persons visiting East Africa. In the 1980s reports from Ethiopia, Nigeria, Sudan and Zambia raised very strong suspicions that plasmodium falciparum's resistance to chloroquine had emerged in those countries. Homeida ( 1988) discovered that the response of malaria to chloroquine therapy was poor. According to him, despite two or more courses of chloroquine treatments, often blood films of patients remained positive after 10 days of therapy. There had not been any reports regarding the poor response of chloroquine in Eritrea before 1986,despite using it for prophylaxis. . However later from 1986 onwards reports on the poor effectiveness of chloroquine therapy in liberated and semi-liberated areas based on clinical data and observations from both medical assistants, health workers and hospitals.

In connection to this problem between 1986 and 1988/89 several studies were initiated in order to find out the reason for this. However, a multi-disciplinary scientific working group did not carry out a research and it was therefore limited to presenting the actual problem and did not address the issues. In addition, it was limited to a small population and specific geographical area in the NorthEast and West lowland areas). However, the information, which was gathered during this time, encouraged me to write this paper.

Aims of the report

Aim of this study was to lay down a foundation for further research with reference to the poor malaria response to chloroquine and to underline the reasons beyond this.

Data collection

The sample of data used in this paper is mainly focused on clinical malaria caused by plasmodium and its response to anti-malaria drug responses to the clinical. The information used in this paper was gathered from.:

• The central hospital patient records between 1987/88 and 1988/89.

• The report which was delivered to the 3rd Eritrea Medical Association in 1988,

• The annual report of the clinic located at Arag (between 1982 to 1987 by the author).

The information, which is presented in the table below, was obtained from the report of central laboratory unit, which was delivered to the 3rd Eritrea Medical Association in 1988. It shows the number of blood films positive for vivax and falciparum, which was gathered by the Central Laboratory Unit at Orota hospital. According to the report presented in table 3 below, 97.3 % were infected with vivax compared to 2.7% falcipurm,

Table 1

Laboratory finding from 81-87:

Source reported on EMA 3rd congress 25/7/88.

However, from 1985 onwards , there was equilibrium between the cases of vivax and falciprum infection .

To find out the choice of drug for vivax and falciparum the researcher also to collect data from medical records on three occasion of time in order to avoid any bias

As can be seen from table 1 the first collection was conducted within 1987 between June and July. The second collection was between 1988 and 1989

(November 1988 to June 1989). And the final data collection was accomplished within three months between December 1990 and March 1991.

Table 2 Response rate to anti-malaria drug (%)

From the above table the effectiveness of chloroquine becomes clear. Table 2 ; indicates that these patients, 73% in 1987, 74% in 1988/89 and 84% in 1990/91 were cured by chloroquine therapy.

Discussion and conclusion

Vivax was the dominant plasmodium infection in Eritrea before 1980s as is clear from table1. Further evidence of this had also proved from the results of the haematology studies, which were conducted in 1930 by the Italian Medical Association. In this study only 28 out of 77 blood smears were reported positive for vivax rather than falciparum. This is also supported by the findings of the small sample of 20 blood smears, which were sent from one small clinic in 1982 ( Arag) to the regional hospital. 80% of these were reported to be positive of vivax and 20 % were negative. Until 1985 chloroquin was considered to be the drug of choice for vivax and quinine for plasmodium falciparum which is similar to the experience of other countries such as Thailand. For instance, according to Hall (1975) chloroquin had 1 % cure rate of falciparum malaria in Thailand during 1973-1974.

However, from 1985 onwards , there was equilibrium between the cases of vivax and falciprum infection. Possible explanation for this might be related to military activities resulting in horizontal transmission from the western low land. Where plasmodium falciparum is endemic to the area where plasmodium vivax is predominant in the north -eastern lowlands. Further trends return that by the early 90s, the ratio of falciparum and : vivax was reversed and falciparum accounted for 90% of all malaria cases ( personal communication, Eyob, 1999).

In connection this, from 1986 onward poor response to chloroquine began to appear with most patients. This might be related with the increase in the number of falcipurm cases . Because of this report, at the beginning of the 1986s and before gaining adequate experience there was an assumption that, poor response to chloroquine occurred due to chloroquine resistance and then quinine started to be conceived as the drug of choice among medical professionals

.

Despite this and from my own experience, those who did not respond to the second course of chloroquine or other anti-malaria drugs were referred to the nearest regional hospital and between 74% and 81.5% were cured with chloroquine.as indicated in table2 . This suggests that plasmodium falcipurm is also cured with chloroquine

The other side of the situation is that 26% in 1987, 27% in 1988/1989 and 18% in 1990/91 were cured with a combination of Co-trimoxozole, Fansidar quinine and tetracycline. The possible reasons for this might be the following:

·Heavy parasitaemia has a large contribution to the poor malaria response to chloroquine. The Lancet highlighted that 10 out of 18 patients diagnosed with chloroquine-resistant malaria had persistent parasitaemia despite a high chloroquine serum level. However, in this study 6, out of 23 patients among the malaria patients of 1990/91 whom were twice positive for falcipurm were eventually cured with choloqine.

· Chloroquine is more active ( in merozotes stage of plasomodium) in the adult stage of plasmodium. In this case there might be failure in choloroquin in curing malaria especially on the gametocytes stage of falcipurm.

• Neequaye ( 1986 ) highlighted the contribution of prophylaxis to the cause of chloroquine resistance.

To conclude, despite the general uncertainty of chloroquine's effectiveness

in the treatment of malaria, my personal experience and data which was collected from the central hospital, indicates that the number of patients who were cured with other anti-malaria drugs were very small compared to those cured with chloroquine, as shown in this paper. Based on the results of my study, which was conducted between 1982 and 1985, chloroquine was the best anti-malaria drug of choice at Arag. Even between 1986 and 1991 chloroquine had the best results in curing malaria despite the findings of some professionals which were mainly based on small laboratory test in vitro tests or travelers from Europe and USA or within a small population resident in the main cities.in the 1980s reported on malaria resistance to chloroquine . The findings of these reported did not consider the possibilities of reinfection during the course of treatment, therefore making it impossible to conclusively assert the existence chloroquine resistance. Based on this paper , chloroquine was the first drug of choice; it is .a potential anti-malaria drug in the 1980s . There might be poor response to chloroquine due to the factors mentioned in this study or for unknown reasons, which are beyond the scope of this study.

Reference

Hall , A.P (1975) Falciparum Malaria Cured by Quinine Followed by Sulfadoxine-Pyrimethamine.

BMJ 2 : 15-17

Neequaye, Janet (1986) Vivo Chloroquine-Resistant Falcipurm Malria in Western Africa

Lancet Jan 18: 153

Homeida Mamoun(1988) Resistant Malaria and the Sudan Flood

Lancet Oct 15: p 912