Communities of practice
Plasmodium vivax and Mixed Infections Are Associated with Severe Malaria in Children: A Prospective Cohort Study from Papua New Guinea
3 Jul 2008
Maria Victoria Valero
Source: PLoS Medicine
(see original article
)
Citation: Genton B, D’Acremont V, Rare L, Baea K, Reeder JC, et al. (2008). Plasmodium vivax and Mixed Infections Are Associated with Severe Malaria in Children: A Prospective Cohort Study from Papua New Guinea . PLoS Med 5(6): e127 doi:10.1371/journal.pmed.0050127
Plasmodium vivax malaria is endemic in the tropical and subtropical areas of Asia (including Papua New Guinea), North and South America, the Middle East, North Africa, and the South Pacific. It is the most common of the four human malaria species (P. falciparum, malariae, ovale, and vivax). In Latin America for instance, 75% of malaria cases are due to Plasmodium vivax, 23% to P. falciparum and the rest are due to P. malariae (Dr Keith Carter, PAHO Advisor, Personal communication).
Most research and published literature on malaria focuses on P. falciparum, due to its high mortality rates, and much less has been done on P. vivax (1). P. vivax differs from P. falciparum in several respects. The parasite preferentially invades younger, smaller red blood cells. It can ‘lie dormant’ in the liver for months or even years and then recur, causing disease. It cannot infect people (including 95% of West Africans) with a certain blood type (Duffy+) (2,3). The organ dysfunction seen in P. falciparum malaria is not seen in P. vivax infections.
Luxemburger et al. (4) observed that severe malaria is 4.2 times less common in patients with mixed P. falciparum and P. vivax infections than in those with P. falciparum alone.
The present clinico-epidemiological study from Papua New Guinea was designed to: assess the proportion of cases with severe manifestations of malaria and associated P. vivax parasitaemia; compare this proportion to that of P. falciparum cases in the same setting; and to investigate the potential of mixed P. falciparum and P. vivax infection to protect against severe malaria (SM).
Of 73,220 patients 6.2% (7,759) fulfilled the case definition for SM. P. vivax was responsible for 21% of SM cases, P. falciparum for 71%, and mixed P. vivax and P. falciparum infections for 5%. The risk of severe disease is age-related. It decreases linearly for P. falciparum, P. vivax or mixed infections. The proportion of patients with severe disease was greatest among children below the age of five years.
The considerable frequency of SM attributed to non-falciparum malaria in this study, and also found in Amazon studies (5), demonstrates that there is a need for integrated intervention, for which the most prevalent form of Plasmodium in the region must be determined.
For a long time P.vivax has been regarded as ‘benign malaria’. However, clinical and epidemiological data from recent studies suggests the emergence of a new form of vivax malaria (for example, in South America, Korea and India). Biological changes in the vector and parasite have been recorded. This has already given rise to concern, as has the discovery of P. vivax hypnozoites in the liver. This new study – together with another from Papua, Indonesia (6) published in the same issue of PLoS Medicine – adds to these concerns. We can no longer accept the view that the risk of death in P. vivax cases is very low. Malaria control programmes must now take P. vivax seriously into consideration.
Sentinel surveillance systems intended to record cases of SM and to evaluate drug resistance must now consider all forms of malaria and seek to characterise new strains. Clinicians and researchers must also take note of these new developments. Public health authorities need to educate the public about the risks of vivax malaria. In vivax-endemic regions it is important to improve the early identification of SM cases.
References
1. Sina B. Focus on Plasmodium vivax. Trends Parasitol. 2002;18:287–9.
2. World Health Organization, Meetings on Plasmodium vivax and Schistosoma japonicum in Asia. TDR News, 1999. Available on http://www.who.int/tdr/publications/tdrnews/news60/vac cine.htm
3. Malaria Vaccine Initiative, Fact sheet: Plasmodium vivax malaria. Available on http://www.malariavaccine.org/files/vivax-factsheet.pdf. Accessed on June 24, 2008.
4. Luxemburger C, Ricci F, Raimond D, Bathet S, White NJ. The epidemiology of severe malaria in an area of low transmission in Thailand. 1997. Trans R Soc Trop Med Hyg;91:256–62.
5. Características de la malaria por Plasmodium falciparum y P. vivax en la Amazonía brasileña. Rev Panam Salud Publica. 2008;23(1):69-72. Available onhttp://journal.paho.org/index.php?a_ID=1068. Accessed on June 26, 2008.
6. Tjitra E, Anstey NM, Sugiarto P, Warikar N, Kenangalem E, et al. (2008) Multidrug-Resistant Plasmodium vivax Associated with Severe and Fatal Malaria: A Prospective Study in Papua, Indonesia. PLoS Med 5(6): e128.
© 2008 Genton et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Source
Related Articles
Comments
In many countries concern is rising that some recent fatal cases of malaria may have been due to P vivax. In India a team from the National Institute of Malaria Research is investigating some possible cases of this sort in Goa.
Dr A P Dash, who is heading the team, said, “We want to know whether P vivax has actually started to kill people. We want to be prepared for its changing clinical profile.” Members of the team have stressed that P vivax fatalities are usually rare.
Read more on: http://timesofindia.indiatimes.com/Goa/Alarmed_Centre_rushes_malaria_experts_to_Goa/articleshow/3247933.cms
Featured Meetings:
Is your organisation working against the infectious diseases of poverty?
There is 1 comment about this article: Please login if you want to submit a comment.