Plasmodium vivax threatens nearly half the world’s population and is a significant impediment to achievement of the millennium development goals. It is an important, but incompletely understood, cause of anaemia. This review synthesizes current evidence on the epidemiology, pathogenesis, treatment and consequences of vivax-associated anaemia. Young children are at high risk of clinically significant and potentially severe vivax-associated anaemia, particularly in countries where transmission is intense and relapses are frequent. Despite reaching lower densities than Plasmodium falciparum, Plasmodium vivax causes similar absolute reduction in red blood cell mass because it results in proportionately greater removal of uninfected red blood cells. Severe vivax anaemia is associated with substantial indirect mortality and morbidity through impaired resilience to co-morbidities, obstetric complications and requirement for blood transfusion. Anaemia can be averted by early and effective anti-malarial treatment.

https://espace.cdu.edu.au/eserv/cdu:38333/Douglas_38333.pdf

The anaemia of Plasmodium vivax malaria

Possible role of a B-cell mitogen in hypergammaglobulinaemia in malaria and trypanosomiasis.

Publisher Summary This chapter focuses on the factors affecting immunity in both nonpregnant and pregnant women and on the chronicity of several infections that are carried through successive pregnancies with adverse consequences for mother and child. It considers risks to women of reproductive age to differ from men of equivalent years. Ensuring a reduction in the parasitic burden of women of reproductive age is the first step in reducing fetal infection and sensitization and in influencing the pathological pattern of parasitic disease in communities living in endemic areas. The practical and research implications of considering women as a special risk group for complications of parasitic infection are considerable and should lead to the development and implementation of improved control strategies. Health planners need to recognize that parasitic infection has serious consequences in pregnant women and primary health care services must be better equipped to detect and manage infections during pregnancy and between pregnancies. This chapter reviews those infections that are primarily identified by the Special Program for Research and Training in Tropical Diseases (World Health Organization) as being of particular public health concern (onchocerciasis, filariasis, schistosomiasis, malaria, African trypanosomiasis, and leishmaniases), although reference to other infections is made where relevant.

Parasitic infections in women and their consequences.

Purpose of reviewSplenomegaly is frequent in acute or chronic forms of Plasmodium falciparum malaria, and splenectomy is associated with more frequent fever and parasitaemia. A novel role for the spleen in malaria is indicated by recent epidemiological and experimental data, bringing about a novel p

Retention of erythrocytes in the spleen: a double-edged process in human malaria.

Significant variations in the prevalence of splenomegaly were found among members of the three main ethnic groups resident in North Bank Division, The Gambia Among young children splenomegaly and malaria were less prevalent in Mandinkas than in Wollofs or Fulas, suggesting that some genetic or environmental factors protect Mandinka children from this infection Among older children and adults splenomegaly was found most frequently in Fulas Six of 22 adults with very large spleens had a high serum IgM level and probably had the hyperreactive malarial splenomegaly (tropical splenomegaly) syndrome Four of these six subjects were Fulas This finding, together with the results of a previous study in Nigeria, suggest that Fulas have a predisposition to this condition

Ethnic differences in the prevalence of splenomegaly and malaria in The Gambia

The pattern of malarial parasitaemia and the incidence and degree of splenomegaly have been studied in the population of the Upper Watut Valley in New Guinea. Malaria is the only apparent cause of splenomegaly found in this area, and all cases of gross splenomegaly in adults conform to the descriptions of the tropical splenomegaly syndrome. Malaria is meso-endemic and moderately stable. The incidence of parasitaemia is similar in villages at 3300 feet and 5200 feet above sea level, although the incidence of splenomegaly in adults is lower at the higher altitude. Peak parasitaemia is recorded at 3 years of age and then declines slowly, and parasite rates are significantly lower in adult subjects with splenomegaly than in those without palpable spleens. No difference in distribution of species of plasmodia was found between individuals with different grades of splenomegaly or in different age groups or at different altitudes. P. vivax was the predominant species in all groups.

Malaria and the tropical splenomegaly syndrome in New Guinea

The course of the tropical splenomegaly syndrome has been observed for periods of up to 6 1 2 years in 75 adults living in the Upper Watut Valley of New Guinea. During this time there were 27 deaths, 2 from septicaemia and another 8 from similar fulminating febrile illnesses. The mortality rate in those with Grade V splenomegaly was 57%, almost 3 times that of the remainder. Serial hospital assessment of 26 subjects demonstrated progression of the disease, characterized by further enlargement of the spleen and a fall in haemoglobin concentration in 9; increases in splenic red cell pool, in plasma volume and in serum IgM concentration were sometimes, but not invariably, associated. In none of the total group of 75 subjects was a decrease in spleen size observed. Thus the natural history of the tropical splenomegaly syndrome is that of a progressive disease with a high mortality in the fully developed case. Periodic fluctuations in the clinical severity of the disorder are frequently seen and are largely related to the occurrence of episodes of acute haemolysis; however, spontaneous remission has not been observed.

Tropical splenomegaly syndrome in New Guinea I. Natural history

Serum concentrations of IgA, IgG and IgM were estimated for 2,000 inhabitants of 2 malarious areas of New Guinea—Kaiapit, where spleen rates are high in children but splenomegaly occurs infrequently in adults and is never gross, and the Upper Watut Valley, where the tropical splenomegaly syndrome is particularly common, and 80% of adults and children have palpable spleens. Kaiapit adults had significantly higher IgM levels than children: IgM levels tended to increase throughout life, were higher in women than in men and in adults with splenomegaly. IgG and IgA levels showed no significant relation to increasing age above 10 years, to sex or to the presence or absence of splenomegaly. The youngest Watut children had higher IgM levels than Kaiapit subjects. IgM concentrations rose more rapidly with age, particularly in the first 20 years of life, so that the mean Watut adult level was more than twice that of Kaiapit adults. In Watut children splenomegaly was associated with significantly higher levels of all 3 immunoglobulin fractions, whereas adults with splenomegaly showed markedly higher levels of IgM, but significantly lower IgA concentrations than did subjects with impalpable spleens. The change in the pattern of immunoglobulin levels in association with splenomegaly occurred between the ages of 6 and 20 years, indicating that the transition from simple malarious splenomegaly to tropical splenomegaly syndrome probably occurs at this age. Subjects living near the valley floor had higher spleen rates than those living in high villages; IgM concentrations were also affected by altitude. The reason for this remains obscure, but it is suggested that both observations may be related to differences in intensity of operation of the factors responsible for the development of the tropical splenomegaly syndrome.

Immunoglobulin levels in the Kaiapit and upper Watut areas of New Guinea: with special reference to the tropical splenomegaly syndrome

Between 1965 and 1967 splenectomy was performed on 21 Watuts and 5 other New Guineans to relieve persistent incapacitating symptoms of tropical splenomegaly syndrome. There were 3 operative deaths. Post-operatively abolition of the splenic red cell pool, correction of the shortened red cell survival time and reduction in plasma volume occurred, leading to a mean rise in haemoglobin concentration of 3·7 g./100 ml. Neutropenia and thrombocytopenia were also corrected. There was a rapid post-operative fall in serum IgG and IgM concentrations, and a prolonged reduction in intravascular pools of both immunoglobulin fractions. The 18 Watuts discharged from hospital and followed for from 41 to 74 months have had significant symptomatic relief, although 7 have died following short illnesses; this mortality rate (36%) is substantially less than that of a comparable group of Watuts not subjected to splenectomy.

G.G. Crane

Papers

Malaria and the tropical splenomegaly syndrome in New Guinea

Tropical splenomegaly syndrome in New Guinea I. Natural history

Immunoglobulin levels in the Kaiapit and upper Watut areas of New Guinea: with special reference to the tropical splenomegaly syndrome

Tropical splenomegaly syndrome in New Guinea II. Long term results of splenectomy