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Assessment of malaria burden

Source: TropIKA

Title of the session: Assessment of malaria burden

Date: 03 November 2009

Agenda item: Scientific session 13

Session theme: Epidemiology

Meeting room: Tsavo Ballroom 2

Chair(s):

• David Schellenberg (London)
• John Lusingu (Tanga)

Presenters:

• Nafi ssatou Arame Diagne Institut de Recherche de Developpement (IRD)
• Taylor Sandison
• Makerere University-University of Carlifornia San Francisco Research Collaboration
• Philip Bejon
• Kenya Medical Research Institute
• Abdoulaye Diallo
• Institut de Recherche pour le Developpement (IRD)
• Chris Drakeley
• London School of Hygiene & Tropical Medicine
• Chris Drakeley London School of Hygiene and Tropical Medicine
• Daniel Minja
• National Institute for Medical Research, Tanga Medical Research Centre
• Denise Njama-Meya
• Makerere University-University of Carlifornia San Francisco Research Collaboration
• Erick Mibei
• Kenyatta University
• Bernadette Huho
• Ifakara Health Institute, Tanzania

TropIKA rapporteur: Daniel Kiboi

Major topics:

• One hundred malaria attacks since birth. A 18- year longitudinal study of malaria morbidity in Dielmo, Senegal [15083152]
• A randomized clinical trial of the protective efficacy of trimethoprim-sulfamethoxazole prophylaxis against malaria in HIV-exposed children [16209592]
• Immunity to febrile malaria in children: an analysis that distinguishes immunity from lack of exposure [16660540]
• Réalité du paludisme urbain, à dakar : paludisme infection et paludisme ressenti [16676037]
• Serological markers can detect heterogeneity in malaria exposure in an area of very low transmission intensity in Somaliland [16689209]
• Pregnancy associated malaria (PAM) follow-up in Benin: an epidemiological survey [16689806]
• Changing malaria epidemiology and susceptibility to pregnancy associated malaria among a cohort of pregnant women in Korogwe, northeastern Tanzania. [16691590]
• Declining incidence of malaria in a cohort of children living in Kampala Uganda [16697411]
• Distinct pattern of class and subclass antibodies in immune complexes of children with cerebral malaria and severe anaemia due to Plasmodium falciparum infection [16755079]
• Failure of ACTs to suppress human infectiousness in a malaria holo-endemic area, Rufiji-Tanzania [16757928]

Keywords:

Scope: The session covered on epidemiology of malaria, immunity and pregnancy associated malaria (PAM) prevalence in varying transmission setting of Africa. Effects of intervention strategies such a use of antimalarial drugs or use of Insecticides Treated Nets (ITNs) on the epidemiology of malaria was assessed.

REPORT ON ORIGINAL SESSION

Overview

The true burden of malaria in Diemo Senegal was higher that already recorded, Diagne shows that decreased susceptibility to malaria infection was associated with increasing age. Studies in KEMRI-Wellcome Trust also reflected the same scenario showing progression of febrile malaria to asymptomatic malaria with increasing age. A Trimethoprim-sulfamethoxazole (TS) prophylaxis study in Tororo, Uganda was associated with 40% increased protection against malaria in HIV exposed children under 5 years. This is the first reported study on prophylactic potential of TS in HIV exposed children. Report on increased risk of treatment failure on the use of amodiaquine-sulfadoxine-pyrimethamine (AQ-SP) in Kampala Uganda, The treatment failure was associated with low immunity as opposed to expected SP resistance.

CONTEXT AND ISSUE

Malaria burden in Diemo Senegal higher that reported, Diemo Senegal, to assess the prevalence of malaria in high transmission region Diemo Senegal, follow up study for 18 years, children under 5 years to 18 years old

Does TS prophylaxis protect HIV-infected children against malaria? Tororo Uganda, Observational studies suggest Trimethoprim-sulfamethoxazole protects HIV-infected children against malaria

Inconsistencies in febrile malaria in relation to immunity in children, Kenya,

Motivation of population to use antimalarial drugs, Dakar Senegal, high use of antimalarial drugs despite being low transmission areas

Efficacy of Amodiaquine—sulfadoxine/pyrimenthamine (AQ-SP) combination, Amodiaquine-artesunate (AQ-ASN) and Artemether-lumefantrine (AL), Kampla Uganda, to assess the efficacy of AQ-ASN, AQ-SP and AL combination therapies, children under 5 years

Key facts and figures

Malaria burden in Diemo Senegal is higher that currently estimated, all 86 enrolled children presented with at least 2 malaria attacks within the follow up period

A Trimethoprim-sulfamethoxazole (TS) prophylaxis protects HIV exposed children under 5 years against malaria by 40%

Over diagnosis of malaria in Dakar Senegal results to self medication and overuse of antimalarial drugs, documented prevalence rate in Dakar is below 10%

Treatment failure is associated with AQ-SP in Kampala Uganda, 14.1% treatment failure recorded for the combination,

Initiatives on the ground; experience/s derived

Cross-sectional and longitudinal studies were carried out, Report by Diagne from Senegal analyzed data of 81 children (20 months) and were followed at least ten years.

Taylor Sandison, conducted the first randomized clinical trial of Trimethoprim-sulfamethoxazole (TS) protective efficacy among HIV-exposed children.

Research Findings

Diemo Senegal daily surveillance of endemic populations shows that the malaria burden is much higher than previously believed and that the susceptibility to the disease varies considerably according to individuals (Diagne).

Antibodies to the infected red cell surface were associated with acquiring asymptomatic infection rather than febrile malaria or remaining uninfected (Philip Bejon)

Over use of antimalarial drugs in Dakar Senegal associated with self diagnosis (Diallo)

Risk of treatment failure of associated with AQ-SP in Kampala Uganda (Denise Njama-Meya)

Lessons learned

First report on prophylactic potential of Trimethoprim-sulfamethoxazole in HIV positive children

Decreased susceptibility to malaria episodes with increasing age associated with development of immunity due to exposure to malaria infections. Immunoglobulin G 4 associated with increased risk of developing severe malaria. Immunity against malaria varies between individual in high transmission due to variant antigens associated with Plasmodium falciparum.

Children in low transmission areas have higher malaria episodes than children in high transmission areas

Issues raised, obstacles, difficulties

Future plans

Effects of SP resistance on the efficacy of TS combination in HIV positive children under 5 years

Regulated use of antimalarial drugs to curb against self medication,

FINDINGS AND CONCLUSIONS

From formal presentations

Translational Research Impact

Implementation of TS in prophylaxis of malaria episodes in children under 5 years

Knowledge gap created

Relationship between Immunoglobulin G4 associated with increased risk of developing severe malaria.

From open discussions/debates

Reasons for increased malaria prevalence in Diemo Senegal, is it because of resistance or vector factors?

The effects of HIV on malaria episodes in HIV positive children in relation to increased protective effects of Trimethoprim-sulfamethoxazole

Identified conclusions

Main points of agreement

Potential of Trimethoprim-sulfamethoxazole in prophylaxis against malaria of HIV exposed children

Main points of divergence

Increased prevalence of malaria in Dakar Senegal could be due to changes in vector behavior.

Sulfadoxine-pyrimethamine resistance still varying in different areas

Recommendations

• Continued surveillance of prevalence of malaria in low and high transmission regions

• Control of drug use and prescription to avoid self medication

• Need for continued studies on immunology associated with malaria infections in different transmission settings

Comments

Personal observations from rapporteur

Effectiveness of antimalarial drugs depended on various reasons such as immunity, nutritional status of the patients and proper adherence of the prescription.

Comments