Dynamics of malaria parasites in areas of high transmission

• Research unit: TPH
• Project number: 6.03

Key words (English)

Malaria, sequestration, transmission, Anopheles gambiae, models, statistics,

Short description (English)

The project is studying the dynamics of host and/or parasite products released during schizogony and schizont rupture to estimate the extent of sequestration and synchronisation of P. falciparum. Statistical modelling of longitudinal parasite dynamics using Markov Chain Monte Carlo approaches is also being used to provide alternative estimates and validate biochemical sequestration markers. The project aims to use estimates of the extent of sequestration to test whether this can account for age distributions neither in apparent malaria tolerance nor in the multiplicity of infection in areas of high malaria endemicity.A subsidiary objective is the development and calibration of two field methods for quantifying human infectivity to mosquitoes

Project aims (English)

(a) To develop a method for routine assessment of the sequestered load of malaria parasites.

(b) To determine if apparent acquired tolerance in P. falciparum could be an effect of sequestration.

(c) To validate and calibrate two field methods for quantifying human infectivity to mosquitoes.

Abstract (English)

The project is studying the dynamics of host and/or parasite products released during schizogony and schizont rupture to estimate the extent of sequestration and synchronisation of P. falciparum.

Statistical modelling of longitudinal parasite dynamics using Markov Chain Monte Carlo approaches is also being used to provide alternative estimates and validate biochemical sequestration markers.

The project aims to use estimates of the extent of sequestration to test whether this can account for age distributions neither in apparent malaria tolerance nor in the multiplicity of infection in areas of high malaria endemicity.

A subsidiary objective is the development and calibration of two field methods for quantifying human infectivity to mosquitoes

Publications / Results (English)

Mathenge, EM, Omweri, G, Irungu, LW, Ndegwa, PN, Walczak, E, Smith, T, Killeen GF, Knols BGJ. Comparative field evaluation of the Mbita trap, CDC light trap and the human landing catch for sampling of malaria vectors in western Kenya. American Journal of Tropical Medicine & Hygiene 70(1), 33-37, 2004.

Owusu-Agyei S, Smith T, Beck HP, Amenga-Etego L, Felger I: Molecular epidemiology of Plasmodium falciparum infections among asymptomatic inhabitants of a holoendemic malarious area in northern Ghana. Trop Med Int Health 7:421-428 (2002).

Smith, T, Vounatsou P. Estimation of infection and recovery rates for highly polymorphic parasites when detectability is imperfect, using hidden Markov models. Statistics in Medicine 22:1709-1724, 2003.

Smith, T., Dietz K.,Vounatsou P., Müller I., English M., Marsh K.. Bayesian age-stage modelling of P. falciparum sequestered parasite loads in severe malaria patients. Parasitology 129(3), 289-299, 2004.

Ochola L B, Marsh K, Lowe B, Gal S, Pluschke G, Smith T. Estimation of the sequestered parasite load in severe malaria patients using both host and parasite markers. Parasitology (131): 449-458, 2005.

Ochola L, Vounatsou P, Smith T, Mabaso M, Newton C. The reliability of diagnostic techniques in the diagnosis and management of malaria in the absence of a gold standard. Lancet Infect Dis;6(9):582-8, 2006.