Serosurvey for Brucella spp. and Coxiella burnetii in animals on Caribbean islands.

To determine the prevalence of antibodies to Brucella melitensis, Brucella abortus and Coxiella burnetii in animals on Caribbean islands we obtained sera from convenience samples of cattle (C), sheep (S), goats (G) and cats (F) from Dominica (C, S, G), Grenada (C, S, G), Montserrat (C, S, G), Puerto Rico (C), Nevis (C, S, G), St Kitts (C, S, G, F) and St Lucia (C, G). The sera were tested for antibodies against the Brucella spp. using commercial ELISA kits. Some sera were also tested at 1/80 for antibodies to C. burnetii using an indirect fluorescent antibody test. Positive sera were also tested at 1/640. None of 599 cattle, 462 sheep or 434 goats were positive in the Brucella ELISAs. None of 230 cattle had antibodies against C. burnetii, but one of 299 sheep was positive at 1/80 (Dominica - 1/54, 2%, 95% CI (0%-5.6%)), as were two of 314 goats, at 1/80 (Grenada - 1/53, 2%, 95% CI (0%-7.5%)) and 1/640 (St Kitts - 1/18, 5.6%, 95% CI (0%-16.7%)), and one of 34 cats, at 1/80 (St Kitts - 1/34; 3%, 95% CI (0%-8.8%)). Our data suggests that there is a very low prevalence or absence of B. melitensis and B. abortus on Caribbean islands. Coxiella burnetii, however, is present but it appears to be present on only some islands and then only at low levels. Overall, there appears to be a low threat to human and animal health from these organisms in the Caribbean.

Efficacy of slow-release tags impregnated with aggregation-attachment pheromone and deltamethrin for control of Amblyomma variegatum on St. Kitts, West Indies.

BACKGROUND: Amblyomma variegatum is an important cause of morbidity, mortality and economic losses in Africa and the West Indies. Attempts to control and/or eradicate the tick from the Caribbean have largely been unsuccessful because of difficulties relating to the biology of the three-host tick and problems with applying acaricides on a regular basis to free-ranging domestic ruminants. While plastic collars impregnated with insecticides are widely and effectively used in companion animals to control external parasites there is little information on this technology in ruminants. METHODS: Over 21 months we tested the efficacy of slow-release plastic tags impregnated with deltamethrin (7%) and aggregation-attachment pheromones (DPITs) in controlling A. variegatum on free-ranging cattle on two farms on St. Kitts. The tags were replaced every three months or when found to be lost. RESULTS: On sentinel animals fitted with tags containing only aggregation-attachment pheromones there were an average of 23.1 ticks per semi-monthly visit although this number varied considerably, peaking in the dry season around May and being lowest in August to October during the wet season. Significantly fewer ticks (3.5 on average) were found on cattle with DPITs at each visit (P < 0.001). Although the DIPTs provided good control (92% on average), they did not significantly reduce A. variegatum in the environment with tick numbers on sentinels being higher in the second year of the study, despite up to 44% of animals being fitted with DPITs. The tags were economical, costing 0.2% of the 1% flumethrin pour-on treatment widely recommended for A. variegatum control in the Caribbean. The major problem encountered was that 38% of tail tags were lost before they were due for replacement every three months. CONCLUSIONS: Our study has shown that DPITs are cheap to produce, easy to place, only require handling of animals every three months, and are very effective in protecting cattle from A. variegatum. Before DPITs can be considered for eradication programs the problems needing to be addressed include loss of tail tags, particularly in thick vegetation, and the optimum number of animals that must be treated to reduce numbers of ticks in the environment.

Ehrlichiosis, babesiosis, anaplasmosis and hepatozoonosis in dogs from St. Kitts, West Indies.

BACKGROUND: Although tick-borne diseases are important causes of morbidity and mortality in dogs in tropical areas, there is little information on the agents causing these infections in the Caribbean. METHODOLOGY: We used PCRs to test blood from a cross-section of dogs on St Kitts for Ehrlichia (E.) canis, Babesia (B.) spp., Anaplasma (A.) spp. and Hepatozoon (H.) spp. Antibodies against E. canis and A. phagocytophilum/platys were detected using commercial immunochromatography tests. Records of the dogs were examined retrospectively to obtain clinical and laboratory data. PRINCIPAL FINDINGS: There was serological and/or PCR evidence of infections of dogs with E. canis (27%; 46/170), Babesia spp. (24%; 90/372) including B. canis vogeli (12%; 43/372) and B. gibsoni (10%; 36/372), A. platys (11%; 17/157) and H. canis (6%; 15/266). We could not identify the Babesia sp. detected in nine dogs. There was evidence of multiple infections with dual infections with E. canis and B. canis vogeli (8%; 14/179) or B. gibsoni (7%; 11/170) being the most common. There was agreement between immunochromatography and PCR test results for E. canis for 87% of dogs. Only 13% of exposed dogs had signs of a tick-borne disease and 38% had laboratory abnormalities. All 10 dogs presenting for a recheck after treatment of E. canis with doxycycline were apparently healthy although all remained seropositive and six still had laboratory abnormalities despite an average of two treatments with the most recent being around 12 months previously. Infections with Babesia spp. were also mainly subclinical with only 6% (4/67) showing clinical signs and 13% (9/67) having laboratory abnormalities. Similarly, animals with evidence of infections with A. platys and H. canis were largely apparently healthy with only occasional laboratory abnormalities. CONCLUSIONS: Dogs are commonly infected with tick-borne pathogens in the Caribbean with most having no clinical signs or laboratory abnormalities.

Rickettsia africae in Amblyomma variegatum and domestic ruminants on eight Caribbean islands.

We used PCRs with omp A primers to determine if spotted fever group rickettsiae occurred in Amblyomma variegatum from 6 Caribbean islands. Positive amplicons were obtained from ticks from the U.S. Virgin Islands (9/18; 50%), Dominica (39/171; 30%), Montserrat (2/5; 40%), Nevis (17/34; 50%), St. Kitts (46/227; 20%), and St. Lucia (1/14; 7%). Sequences for a convenience sample of reaction products obtained from A. variegatum on St. Kitts (7), American Virgin Islands (4), Montserrat (2), and St. Lucia (1) were 100% homologous with that of Rickettsia africae , the agent of African tick-bite fever. To determine if transmission of R. africae occurred, we used Rickettsia rickettsii antigen in IFA tests and found positive titers (≥ 1/80) with sera from cattle, goats, and sheep from Dominica (24/95 [25%], 2/136 [2%], 0/58 [0%]), Nevis (12/45 [27%], 5/157 [3%], 0/90 [0%]), St. Kitts (2/43 [5%], 1/25 [4%), 1/35 [3%]), and St. Lucia (6/184 [3%] cattle), respectively. No seropositive animals were found in Grenada (0/4, 0/98/, 0/86), Montserrat (0/12, 0/26, 0/52), or Puerto Rico (0/80 cattle). Our study indicates that R. africae and African tick-bite fever are widespread in the Caribbean.

Feline immunodeficiency virus, feline leukemia virus and Bartonella species in stray cats on St Kitts, West Indies.

Stray cats trapped in various areas of Basseterre, the capital of St Kitts in the West Indies, were tested for infection with feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) using commercial kits. Of 99 (51 male and 48 female) cats trapped in 2006/7, 15% (12 males and three females) were positive for FIV while none were positive for FeLV. Of 72 (41 males and 31 females) cats trapped in 2009, 14% (nine males and one female) were positive for FIV while none were positive for FeLV. Polymerase chain reaction analysis revealed DNA of Bartonella species in whole blood collected from 60/95 (63%) cats trapped in 2006/7. Sequencing of the 16S-23S rRNA gene intergenic transcribed spacer (ITS) region of a convenience sample of nine amplicons and the 11 isolates made from 43 blood samples which were cultured using Bartonella alpha Proteobacteria (BAPGM) enrichment medium revealed B henselae (14) and B clarridgeiae (six).

Failure to demonstrate Babesia, Anaplasma or Ehrlichia in thrombocytopenic dogs from St Kitts.

BACKGROUND: Thrombocytopenia is common in dogs on St Kitts but there is no data on the possible etiological role played by infections with Anaplasma, Babesia and Ehrlichia, other than E. canis, which are known to occur in the Caribbean. METHODOLOGY: Blood from 13 thrombocytopenic but apparently healthy dogs seronegative (Snap 3Dx) for E. canis were tested by PCR for Ehrlichia, Anaplasma and Babesia. RESULTS: All PCRs were negative. CONCLUSIONS: The results confirm the high sensitivity of SNAP testing for E. canis and indicate Anaplasma and Babesia are not important causes of thrombocytopenia in dogs on St Kitts.