Malaria vaccines: looking back and lessons learnt

Malaria vaccines: the 60-year journey of hope and final success-lessons learned and future prospects

BACKGROUND

The world has made great strides towards beating malaria, although about half of the world population is still exposed to the risk of contracting malaria. Developing an effective malaria vaccine was a huge challenge for medical science. In 2021 the World Health Organization (WHO) approved the first malaria vaccine, RTS,S/AS01 vaccine (Mosquirix™), for widespread use. This review highlights the history of development, and the different approaches and types of malaria vaccines, and the literature to date. It covers the developmental stages of RTS,S/AS01 and recommends steps for its deployment. The review explores other potential vaccine candidates and their status, and suggests options for their further development. It also recommends future roles for vaccines in eradicating malaria. Questions remain on how RTS,S vaccine will work in widespread use and how it can best be utilized to benefit vulnerable communities.

CONCLUSION

Malaria vaccines have been in development for almost 60 years. The RTS,S/AS01 vaccine has now been approved, but cannot be a stand-alone solution. Development should continue on promising candidates such as R21, PfSPZ and P. vivax vaccines. Multi-component vaccines may be a useful addition to other malaria control techniques in achieving eradication of malaria.

Malaria vaccine development and how external forces shape it: an overview

The aim of this paper is to analyse the current status and scientific value of malaria vaccine approaches and to provide a realistic prognosis for future developments. We systematically review previous approaches to malaria vaccination, address how vaccine efforts have developed, how this issue may be fixed, and how external forces shape vaccine development. Our analysis provides significant information on the various aspects and on the external factors that shape malaria vaccine development and reveal the importance of vaccine development in our society.

Malaria helminth co-infections and their contribution for aneamia in febrile patients attending Azzezo health center, Gondar, Northwest Ethiopia: a cross sectional study

OBJECTIVE

To assess the prevalence of malaria helminth co-infections and their contribution for aneamia in febrile patients attending Azzezo health center, Gondar, Northwest Ethiopia.

METHODS

A cross section study was conducted among febrile patients attending Azezo health center from February-March 30, 2011. Convenient sampling technique was used to select 384 individuals. Both capillary blood and stool were collected. Giemsa stained thick and thin blood film were prepared for identification of Plasmodium species and stool sample was examined by direct wet mount and formalin-ether concentration technique for detection of intestinal helminthes parasites. Haemoglobin concentration was determined using a portable haemoglobin spectrophotometer, Hemocue Hb 201 analyzer.

RESULTS

Out of 384 febrile patients examined for malaria parasites, 44 (11.5%) individuals were positive for malaria parasites, of which Plasmodium vivax accounted for 75.0% (33), Plasmodium falciparum for 20.5% (9) infectious, whereas two person (4.5%) had mixed species infection. Prevalence of malaria was higher in males (28) when compared with prevalence in females (16). More than half (207, 53.9%) of study participants had one or more infection. Prevalence was slightly higher in females (109, 52.7%) than in males (98, 47.3%). About helminths, Ascaris lumbricoides was the predominant isolate (62.1%) followed by hookworms (18.4%). Only 22 participants were co-infected with malaria parasite and helminths and co-infection with Ascaris lumbricoides was predominant (45.0%). The prevalence of anemia was 10.9% and co-infection with Plasmodium and helminth parasites was significantly associated with (P< 0.000 1) higher anemia prevalence compared to individuals without any infection.

CONCLUSIONS

Prevalence of malaria and soil transmitted helminths is high and the disease is still major health problem in the study area. Hence, simultaneous combat against the two parasitic infections is very crucial to improve health of the affected communities in economically developing countries.

Irritability of malaria vector, Anopheles sacharovi to different insecticides in a malaria-prone area

OBJECTIVE

To determine the susceptibility and irritability level of malaria vector Anopheles sacharovi (An. sachrovi) to different insecticides in a malaria-prone area.

METHODS

Susceptibility and irritability levels of field collected strain of An. sacharovi to WHO standard papers of DDT 4%, dieldrin 0.4%, malathion 5%, fenitrothion 1%, permethrin 0.75%, and deltamethrin 0.05% were determined in East Azerbaijan of Iran during reemerging of malaria as described by WHO.

RESULTS

Results showed that at the diagnostic dose of insecticides this species exhibited resistance to DDT, tolerant to dieldrin and but somehow susceptible to fenitrothion, malathion, permethrin and deltamethrin. The results of irritability of this species to DDT, lambdacyhalothrin, permethrin cyfluthrin and deltamethrin revealed that DDT had had the most and deltamethrin the least irritancy effect. The average number of take offs/fly/minutes for DDT was 0.8±0.2. The order of irritability for permethrin, lambdacyhalothrin, cyfluthrin and deltamethrin were 0.7±0.2, 0.5±0.2, 0.5±0.3, and 0.2±0.1, respectively.

CONCLUSIONS

Results of this study reveals the responsiveness of the main malaria vector to different insecticides. This phenomenon is depending on several factors such as type and background of insecticide used previously, insecticide properties, and physiology of the species. Careful monitoring of insecticide resistance and irritability level of species could provide a clue for appropriate selection of insecticide for malaria control.

Malaria parasite status and cholesterol level of malaria patients in parts of the IMO River Basin of Nigeria

OBJECTIVE

To investigate the relationship between malaria parasite status and cholesterol level of 110 consenting subjects (55 patients and 55 controls) in parts of the Imo River Basin of Nigeria.

METHODS

Giemsa staining was used for malaria parasite examination while Randox cholesterol kit was used for cholesterol level estimation.

RESULTS

About 49 persons (90%) with malaria had low cholesterol (<180 mg/dL). Highest mean cholesterol levels were 274 mg/dL for study patients and 220 mg/dL for controls respectively; Lowest mean cholesterol levels were 168 mg/dL (patients) and 138 mg/dL (controls) respectively. Low cholesterol levels (<180 mg/dL) were found in patients (84%) and controls (6%) respectively. However, 16.4% of controls and 6% of patients had borderline cholesterol level (200-239 mg/dL). This study establishes a significant correlation (12.9%, P<0.01) between malaria parasite status and cholesterol level.

CONCLUSIONS

These findings imply that cholesterol level estimation may be a potential concurrent and valuable diagnosis for malaria status.

Chemoprophylaxis in malaria: drugs, evidence of efficacy and costs

This review concentrates on different aspects of malaria chemoprophylaxis, namely drug combinations, resistance, impact of malaria prevention in pregnancy and cost effectiveness. A MEDLINE search was performed for all articles with the key word 'Malaria' in the title field and 'Prophylaxis' in any field. The search was restricted to articles published in English within the last decade (1999-2009). Data sources included review articles published in core clinical journals, cohort studies, interventional studies, case control studies and cross sectional analyses. The mechanism of action, trial evidence of efficacy, side effects and geographical distribution of resistance is discussed for each prophylactic drug regimen. Impact of prophylaxis in pregnancy and the cost considerations are discussed under two separate sub topics.

Prevalence of Plasmodia and hepatitis B virus co-infection in blood donors at Bishop Murray Medical Centre, Makurdi, Benue State, Nigeria

OBJECTIVE

To evaluate the prevalence of co-infection of hepatitis B and Plasmodia among potential blood donors in Benue State, and Nigeria at large and offer suggestions and containment methods.

METHODS

Three hundred and thirty seven (337) potential blood donors, comprising 229(67.95%) Males and 108(32.05%) Females were screened for co-infection with hepatitis B virus (HBV) and Plasmodia between the months of July and December, 2009 using standard laboratory methods.

RESULTS

An overall co-infection rate of 137(40.67%) was observed among the donors. The month of December showed highest co-infection rates 59(17.51%). Highest rates of infection was observed in males at 129(38.30%) to 8(2.37%) in females. Statistical analysis showed significant difference in infection rates between males and females (P<0.05). The more youthful age groups 18-22, 23-27 and 28-32 had higher prevalence of infection at 11.90%, 13.05% and 6.53%, respectively. Irrespective of age group, males showed higher rates of infections than females in corresponding age groups.

CONCLUSIONS

The high rates of co-infection imply that these infections are threats the health of citizens and should be adequately addressed by adoption of strategies to combat and control them. Further, blood should be rigorously screened before transfusion to safeguard the health of recipients.