Tick transmission of Babesia microti to rhesus monkeys (Macaca mulatta)

To determine whether Ixodes dammini is capable of transmitting Babesia microti to primates, infected nymphal ticks were allowed to feed on five Macaca mulatta. The monkeys were then followed for at least 60 days with daily thick blood smears for evidence of infection. Patent B. microti parasitemia developed in four of the five animals. Prepatent periods were 13, 18, 20, and 28 days. Maximum parasitemia ranged from 83 to 7,068 organisms/mm3 blood. Splenectomy 15-17 months after exposure to ticks results in recurrences of parasitemia in three of the four infected monkeys.

Reservoir hosts of human babesiosis on Nantucket Island

The host range of Babesia microti was studied on Nantucket Island in order to identify the enzootic reservoir of this human pathogen. White-footed mice (Peromyscus leucopus) were more frequently parasitized than were other indigenous animals. Infection was ubiquitous in locations where deer were abundant. Mice were most frequently parasitemic during spring and summer and adults more frequently than juveniles. Parasitemia, which was rarely intense, was sustained for as long as 4 months. Mice lived as long as 10 months, and juveniles were most abundant during early summer. Prevalence of zoonotic infection, in certain locations, appeared to be inversely correlated with abundance of mice. B. microti was present solely in regions harboring deer.

Human babesiosis on Nantucket Island: prevalence of Babesia microti in ticks

In order to derive direct evidence implicating Ixodes dammini as a vector of human babesiosis, we determined the prevalence of Babesia microti infection in nymphal I. dammini collected on Nantucket Island. In experiments in the laboratory we found that nymphs remained attached to hamsters for about 3 days. Babesial infection was transmitted more often during 54 hours of attachment then during 36 or 48 hours. Since parasites were demonstrable in salivary glands solely after 48 hours, we derived an engorgement index for identifying ticks attached for 2 days or more. Of 156 nymphal I. dammini, collected from white-footed mice in 1979, 86 were engorged sufficiently to satisfy this index of attachment, and the salivary glands of four contained B. microti parasites. This demonstrates that about 5% of nymphal I. dammini are infected in nature. Risk of human infection can be reduced by prompt removal of attached ticks.

Studies on feline babesiosis. 2. Clinical observations

Clinical observations were made on 20 experimentally infected and 70 clinical cases of feline babesiosis. The experimental cats showed a remarkable ability to adapt to the disease. Lethargy, anorexia and anaemia were recorded in both groups. Icterus was only occasionally seen. Elevated body temperature was not a feature of the disease. All untreated animals eventually died. Blood smears revealed increased polychromatophils, Howell-Jolly bodies, nucleated erythrocytes and anisocytosis indicative of a regenerative anaemia. Erythrophagocytosis by monocytic type leucocytes was also observed.

The transmission of Babesia canis to the wild dog Lycaon pictus (Temminck) and black-backed jackal Canis mesomelas Schreber

Babesia canis was successfully transmitted from the domestic dog to 3 wild dogs Lycaon pictus and 4 black-backed jackals Canis mesomelas. Both wild dogs and black-backed jackals showed no clinical signs or clinical pathological evidence of disease. Trophozoites of Babesia canis were found in peripheral blood smears from all experimental animals. The disease was also successfully transmitted from both black-backed jackals and wild dogs to the domestic dog.

Exposure of cattle immunised against redwater to tick-induced challenge in the field: challenge by a heterologous strain of Babesia divergens

Eighteen, one-and-a-half-year-old Friesian heifers and a three-year-old Friesian bull were immunised against bovine redwater by inoculation with blood infected with a known strain of Babesia divergens which had been irradiated at 30 kilorads. Three weeks later these cattle plus 10 Friesian bullocks of the same age which served as controls were introduced to a grazing area infested with ticks able to transmit infections of a heterologous strain of B divergens. The control cattle all became infected with the heterologous strain, two severely. None of the inoculated cattle became clinically affected.

Serosurvey for human babesiosis in New York

Healthy individuals at high risk of exposure to ticks were surveyed to determine the prevalence and incidence of asymptomatic babesiosis on Shelter Island, New York, during a single transmission season. Paired sera obtained in June and October 1978 were tested for antibodies to Babesia microti by indirect immunofluorescence. Point prevalence values of 4.4% in June and 6.9% in October were obtained. Six of 102 persons tested in both months showed at least a fourfold rise in titer of antibodies to B. microti (an incidence of 5.9% for the season). None of 300 serum specimens obtained from the New York City metropolitan area had significant titers to B. microti. Of the six persons who seroconverted, four gave a history of tick bite during the transmission season; three of the four persons claimed to recognize the tick as an Ixodes dammini, the vector for B. microti.

[The brown dog tick Rhipicephalus sanguineus Latreille 1806 in the Netherlands, an analysis of imported cases, including their veterinary and medical significance (author's transl)]

Eighteen cases of infestation with Rhipicephalus sanguineus were reported during the past five years. Of the cases, six were observed during the first seven months of 1979. Of all infestations, four originated from sources within the territory of the Netherlands. Several cases of infestation with canine babesiosis were reported. There could have been a relationship between some of these cases and infestation with R. sanguineus. Populations of this tick can survive and develop in Dutch homes. Forming reservoirs of boutonneuse fever and canine babesiosis would appear to be possible.

Blood parasites of sheep in the Netherlands. II. Babesia motasi (Sporozoa, Babesiidae)

A large Babesia species occurs in sheep on the North Sea islands of the Netherlands. The tick Haemaphysalis punctata is a vector. Its pathogenicity appears to be low. It is morphologically similar to a Turkish strain, considered to be B. motasi, which is also transmitted by Haemaphysalis ticks. It differs from the Turkish parasite serologically as well as in cross-immunity tests and in not being effective to goats. There may be a group of morphologically similar parasites with serological differences and different infectivity for sheep and goats. As it is impossible to know which one is to be considered as the original B. motasi, we designate the Dutch parasite as B. motase (Netherlands). Anaplasma mesaeterum was found to occur on the island of Texel as well as on Ameland, where it had been found initially.

Some aspects of the epidemiology and control of bovine babesiosis in Australia

A short account of the epidemiology and control of babesiosis in Australia is presented. Epidemiological topics discussed include differences in the transmission of Babesia bovis and B. bigemina by the cattle tick, Boophilus microplus and the relative prevalence, disease incidence and pathogenicity of B. bovis and B. bigemina. Circumstances under which babesiosis occurs in Australia are described. In the Section on control, only vaccination is discussed. Changes in the preparation of babesial vaccines, particularly those resulting in a highly infective vaccine containing relatively avirulent B. bovis are described. Fluctuations in demand, such as the increase from about 100,000 to over 1,000,000 doses in 4 years in the mid-1960s are shown. An unexpected increase in the use of A. centrale in 1973 is discussed, and the supply of B. bigemina for cattle exported from Australia reported.

Canine Babesia new to North America

A domestic dog residing in New England suffered a fatal febrile illness caused by a Babesia infection. The morphology of these intraerythrocytic protozoa and the range of hosts that could be infected experimentally suggested that the parasite was B. gibsoni. Although this tick-bourne disease is enzootic in wild and domestic Canidae in Africa and Asia, it appears to be new to the Americas.

Babesia infections in man

Only recently has it been recognized that hemotropic animal parasites of the genus babesia are also human pathogens. Similar to malaria in both symptoms and laboratory findings, acute babesiosis generally results in self-limited illness, but it can be fatal in the asplenic patient. The widely disseminated vector tick, Ixodes dammini, can transmit infection at each stage of its development, larva and nymph as well as adult.