Clinical and pathological findings of Babesia infection in dogs

The clinical and pathological findings of Babesia infection in 32 dogs in northern Australia are presented. Eleven different breed types were represented from 6 localities in north Queensland and one locality in northern Western Australia. Twenty three (72%) were males. Babesia-infected dogs were grouped by the degree of haematological disturbance and clinical severity: Acute babesiosis (25/32), all pups with severe haemolytic anaemia; subclinical carriers (5/32) with non-specific malaise, characterised haematologically by a normal erythrogram but marked leucopenia; chronic anaemia, observed in 2 adult dogs. Pups were azotaemic (serum urea greater than 6.6 mmol/l) and had elevated serum bilirubin levels (20.8 to 48.5 mmol/l). Total serum protein was usually within the normal range. Pups that died were also hypoglycaemic and severely hyperkalaemic (K+ greater than 10 mmol/l). Low parasitaemias in routine blood smears complicated diagnosis but smears made from ear or toe capillaries, or after haematocrit concentration, greatly enhanced finding parasitised cells. At necropsy, pallor and jaundice were the most consistent observations. Haemoglobinuric nephrosis, an active reticulo-endothelial system and capillaries packed with large numbers of infected erythrocytes were the main histopathological findings. A combination of imidocarb dipropionate at 5 mg/kg body weight, given intramuscularly, with fluid therapy and blood transfusion was the most successful treatment.

Invasion of mature and immature erythrocytes of CBA/Ca mice by a cloned line of Plasmodium chabaudi chabaudi

During the early stages of the primary Plasmodium chabaudi chabaudi AS parasitaemia in CBA/Ca mice this parasite invaded normocytes, but as the parasitaemia developed increasing numbers of parasites were seen within reticulocytes. During and just after peak parasitaemia, as further parasite replication was controlled, the 'crisis' phase ensued, mice became increasingly anaemic and reticulocyte numbers were markedly increased. As the parasitaemia was resolved during crisis in excess of 25% of parasites had invaded reticulocytes. In phenylhydrazine-pretreated mice with artificially high reticulocyte levels and infected with P.c. chabaudi AS, normocyte/reticulocyte invasion occurred with equal frequency. No reduction in the infectivity of parasite populations developing in reticulocytes was observed.

Malaria and red cell genetic defects

The study of inherited RBC resistance to malaria has increased our knowledge of the biochemistry and physiology of the host-parasite interaction and suggested potential sites for therapeutic intervention. Discovery by Jensen and Trager of the in vitro culture system for P falciparum has facilitated research in this area. Known RBC defects may affect invasion, growth, or merozoite liberation (Fig 1). Significant advances made in understanding mechanisms underlying protection against malaria should not obscure the fact that the data are far from complete. More knowledge is needed about the influence of the erythrocyte cytoskeleton on invasion and growth of parasites as well as the potential role of phospholipids, erythrocyte enzymes other than G6PD, or other metabolic products. Application of DNA analysis and recombinant technology may have an increasing impact on study of the interaction of RBC defects with malarial parasites.

An intranuclear microsporidium associated with acute anemia in the chinook salmon, Oncorhynchus tshawytscha

An intranuclear microsporidium is described from hemoblastic cells of the chinook salmon, Oncorhynchus tshawytscha. The infection is associated with an acute anemia in the fish. Up to 47% of the hemoblast nuclei were infected in anemic fish. The organisms, found only in spleen and kidney tissues, were 1-2 microns in diameter and consisted of vegetative and early sporulation forms. This microsporidium differs from known species which parasitize fish in its tissue location; however, the absence of mature spores and other life cycle stages precludes determination of its precise taxonomic identity.

Severe anaemia and death due to the pharyngeal leech Myxobdella africana

Six cases of pharyngeal leech (identified as Myxobdella africana) are reported from a highland area of North Kenya. Three patients were severely anaemic and one died. There have been sporadic reports of leech infestation of man in East and Central Africa but these reports lack correct identification of the leech. This paper includes a detailed account of the systematics of the leech and of its habitat. The leeches were ingested accidentally by drinking water from two infested water sources. The major symptoms were a feeling of something in the throat, epistaxis and haemoptysis. On examination, pharyngeal blood was a consistent feature although the leech was rarely seen on initial inspection. Examination under anaesthesia was usually successful in locating and removing the leech. Prompt blood transfusion was life-saving in two cases. The water sources were used by both cattle and man; the cattle may also be parasitized by leeches. Methods of improving the water sources were discussed with community leaders.

Plasmodium berghei: the influence of blood volume changes on the malaria-induced anemia in Balb/C mice

Malaria-induced anemia exceeds that attributable to direct parasite destruction of erythrocytes. Since spleen and liver weights increase significantly, hemodilution may account for part of this excessive anemia. To determine the role of hemodilution in the etiology of anemia, vascular volumes were measured with Evans blue and isotope dilution techniques. The Evans blue dilution technique showed that blood volume increased 20%, in infected Balb/C mice. However, when blood volume was measured with Evans blue bound to protein prior to injection or with iodinated albumin and chromium-labelled red blood cells no significant change was detected. Evidently the permeability of the vasculature and/or erythrocytes of infected mice was increased so that injected Evans blue occupied a space larger than the vascular volume before becoming bound to plasma proteins. We conclude that hemodilution is not involved in the excessive anemia of Plasmodium berghei-infected Balb/C mice.

Studies of antigens in Plasmodium yoelii. I. Antigenic differences between parasite lines detected by crossed immunoelectrophoresis

Antigens of three lines of the rodent malaria parasite Plasmodium yoelii have been studied using crossed immunoelectrophoresis. P. y. yoelii line A1 is a mild line which is restricted to reticulocytes. P. y. yoelii line YM and P. y. nigeriensis line D1 are virulent infections which multiply in both immature and mature erythrocytes. One antigen, designated Py-1, was found to differ in its electrophoretic mobility between the lines, being fast (F) in lines A1 and YM and slow (S) in line D1. Antigen Py-1 also varied in quantity among the three lines; greater amounts were detected in parasites inhabiting mature erythrocytes than in those in reticulocytes. These characters were stable during blood and mosquito passage.

Hemoparasitism, humoral immunodeficiency, and an IgG1 fragment in a cow

An adult cow with nonregenerative anemia was found to be infected with Eperythrozoon wenyoni and Trypanosoma theileri. Further laboratory testing revealed hypoalbuminemia, hypogammaglobulinemia, decreased numbers of circulating B lymphocytes, and presence of a serum immunoglobulin G1 fragment. Reduced B-lymphocyte regions in lymphoid tissue, evidence of chronic nephritis, and infection with Fasciola hepatica and Sarcocystis spp were found at necropsy. The cause of the acquired humoral immunodeficiency and the serum immunoglobulin G1 fragment was undetermined.

Malaria: nutritional implications

Epidemiologic and immunologic factors determine the impact of malaria on the demography and economics of human communities. Where malaria is epidemiologically stable, its effects are most obvious in young children; adults, because of acquired immunity, are much less affected and remain an economically viable workforce. Where the disease is unstable, it affects all age groups and may incapacitate adults enough to impede food production seriously. Three areas are identified in which malaria may adversely affect host nutrition: low birth weight, the development of protein energy malnutrition, and the pathogenesis of anemia. The influence of host nutrition on malarial infections is considered. The view is expressed that, although deficiencies of some dietary factors may potentiate the resistance to malaria conferred by some genetic traits, there is as yet little convincing evidence that malnutritional states in humans materially enhance the severity or lethality of plasmodial infections.

Quantitative studies of ovine haemonchosis. 2. Relationship between total worm counts of Haemonchus contortus, haemoglobin values and bodyweight

The relationships between Haemonchus contortus burdens, haemoglobin levels and bodyweight, were examined in 50 commercial Merino sheep, 9-18 months of age, in south-east Queensland where haemonchosis was endemic. Worm counts and haemoglobin levels were predictable (P less than 0.001, r = 0.68) from the equations log worm count = B.wt. X 0.06942 + log worm count X (-2.18896) + 12.51557. Bodyweight was not predictable from either worm counts or haemoglobin levels. Although bodyweight was represented in both equations, it was only a small and insignificant contributor. When haemoglobin levels became moderately depressed (less than 10.5 g%) or severely depressed (less than 8.0 g%), then the number of worms associated with these haemoglobin levels varied with the bodyweight of the sheep. For sheep up to 20 kg, 10.5 g% Hb was associated with 112 worms and 8 g% with 355 worms. However, 355 worms caused only moderate depression of Hb levels in sheep over 50 kg, and 1259 worms were required to cause severe depression (less than 8.0 g%) in sheep over 50 kg. Three sheep were found to be severely anaemic in the presence of less than 100 worms. It was postulated that additional factors of time and nutrition may have affected these sheep. The sheep were of low bodyweight, in poor condition (low fat score) and were subject to high stocking rates on long grass pastures and high rainfall in autumn. Other internal parasite species present were Nematodirus spp. and Trichostrongylus spp. However, their numbers were low (57 and 218 worms, respectively) and did not contribute to anaemia. The correlation between H. contortus and Nematodirus spp. was found to be negative but non-significant (r = -0.26, P less than 0.01), while the correlation between H. contortus and Trichostrongylus spp. was positive and significant (r = 0.38, P less than 0.01).

Nutritional anemia in the English-speaking Caribbean and Suriname

Anemia is a problem in all countries of the English-speaking Caribbean where data are available. It affects mostly preschool age children and pregnant and lactating women. The most common cause is a deficiency of iron. This is probably due to an adequate intake with a low absorption. A deficiency of folate is also probably a responsible factor in the pathogenesis of some of the anemias. Anemias associated with parasitic infestations such as hookworm and whipworm and hemoglobinopathies such as sickle cell anemia are also noted.

Anaemia in mice with concomitant Schistosoma mansoni and Plasmodium berghei yoelii infection

1. The effect on anaemia in mice given Plasmodium berghei yoelii 3 and 5 weeks after exposure to Schistosoma mansoni cercariae, was investigated. 2. Haematological criteria (PCV and haemoglobin levels), reticulocytosis, parasitaemia and splenomegaly were used as indices. 3. Anaemia was severe in the animals given P. b. yoelii and in those with mixed infection (P. b: yoelii plus S. mansoni). Malaria was found to dominate the picture until the clearance of the parasitaemia. The effect of the interaction between the diseases on the anaemia was nil. 4. Toward the end of the experiment, moderate splenomegaly was observed in the mice with mixed infection.