Bartonella spp. in human and animal populations in Gauteng, South Africa, from 2007 to 2009.

Bartonellae are highly adaptive organisms that have the ability to evade the host immune system and cause persistent bacteraemia by occupying the host's erythrocytes. Bartonella spp. is under-studied and health care professionals often misdiagnose Bartonella-related infections. The aim of this study was to investigate the carriage of Bartonella spp. circulating in human and animal populations in Gauteng using culturing and polymerase chain reaction (PCR) detection. A total of 424 human, 98 cat, 179 dog, and 124 wild rodent blood samples were plated onto specialised media and incubated for 7-21 days at 37 ºC in CO2. Culture isolates morphologically similar to Bartonella control strains were confirmed by PCR and sequenced to determine species. Deoxyribonucleic acid (DNA) was extracted from all blood samples and tested by nested PCR. Bartonella could only be cultured from the cat and rodent specimens. Cat isolates were > 99% similar to Bartonella henselae URBHLIE 9, previously isolated from an endocarditis patient, and rat isolates were > 98% similar to either RN24BJ (candidus 'Bartonella thailandensis') or RN28BJ, previously isolated from rodents in China. The PCR prevalences were 22.5% in HIV-positive patients, 9.5% in clinically healthy volunteers, 23.5% in cats, 9% in dogs and 25% in rodents. Findings of this study have important implications for HIV-positive patients.

Lessons learned about pneumonic plague diagnosis from two outbreaks, Democratic Republic of the Congo.

Pneumonic plague is a highly transmissible infectious disease for which fatality rates can be high if untreated; it is considered extremely lethal. Without prompt diagnosis and treatment, disease management can be problematic. In the Democratic Republic of the Congo, 2 outbreaks of pneumonic plague occurred during 2005 and 2006. In 2005, because of limitations in laboratory capabilities, etiology was confirmed only through retrospective serologic studies. This prompted modifications in diagnostic strategies, resulting in isolation of Yersinia pestis during the second outbreak. Results from these outbreaks demonstrate the utility of a rapid diagnostic test detecting F1 antigen for initial diagnosis and public health management, as well as the need for specialized sampling kits and trained personnel for quality specimen collection and appropriate specimen handling and preservation for plague confirmation and Y. pestis isolation. Efficient frontline management and a streamlined diagnostic strategy are essential for confirming plague, especially in remote areas.

Naturally acquired anthrax antibodies in a cheetah (Acinonyx jubatus) in Botswana.

An outbreak of anthrax in the Jwana Game Reserve in Jwaneng, Botswana, was first observed when three cheetahs (Acinonyx jubatus) died of the disease in November 2004. In the aftermath of this event, banked serum samples collected from 23 wild-caught cheetahs were examined, by the inhibition enzyme-linked immunoassay (ELISA), for antibodies to the protective antigen (PA) of Bacillus anthracis. Of the 23 cheetahs, 16 regularly accessed the reserve. Antibodies to PA were detected in one cheetah collected in May 2004, indicating the disease was occurring well before it was first noticed. This appears to be the first demonstration of naturally acquired anthrax antibodies in cheetahs. The finding of one antibody-positive animal amongst at least 16 potentially exposed individuals is consistent with existing reports that it is uncommon for cheetahs to develop natural immunity to anthrax.

Understanding and managing sanitary risks due to rodent zoonoses in an African city: beyond the Boston Model.

The Boston Model describes a successful rodent management plan that succeeded in a first-world city in the USA. In third-world cities, which often contain informal shack settlements, it is debatable whether the Boston Model would apply. In Durban, a major harbor city of three million people on the east coast of South Africa, we investigated the sanitary risks due to rodents in both formal (residential and commercial) and informal (shacks) sectors, and we evaluated the relative merits of different management interventions suggested by the Boston Model. Blood and tissue samples of six species (Rattus norvegicus, R. tanezumi, R. rattus, Mus musculus, Mastomys natalensis, Tatera brantsi) from 262 live-trapped rodents from 54 localities were tested for antibodies or DNA for plague (n= 193: antibody test), leptospirosis (n= 221 for antibody test; n= 69 for polymerase chain reaction test for DNA) and toxoplasmosis (n= 217: antibody test). We conducted a socioeconomic survey of 90 household to determine environmental and socioeconomic disease risk factors in the shack settlement of Cato Crest. No rodents were seropositive for plague, but nine Norway rats, R. norvegicus (4.1% of the sample tested) were seropositive for toxoplasmosis, and 22 R. norvegicus (10.0% of sample tested) were seropositive for leptospirosis. Disease endemic areas were concentrated in Cato Crest and the commercial district of Durban. Serology tests of humans living in Cato Crest (n= 219) showed 0% exposure to plague, 23% to leptospirosis and 35% to toxoplasmosis. Compared with shack-dwellers, the residents of brick houses had slightly lower levels of exposure to leptospirosis and toxoplasmosis. Based on our results, environmental hygiene and rodent-trapping campaigns were launched in Cato Crest. The initiative owes much of its current success to implementation of the principles inherent in the Boston Model, even though certain elements were lacking.

Fatal type A botulism in South Africa, 2002.

Although wildfowl and domestic livestock botulism has been recognized as a problem in southern Africa, very few human cases have ever been described in the region. In late February 2002, two siblings aged eight and 12 years developed acute flaccid paralysis and died. Mouse bioassays revealed the presence of type A botulinum toxin in the serum of both children, and in the retrieved remains of the implicated food. The implicated vehicle of the toxin was tinned fish in tomato sauce, commercially produced in South Africa. Type A Clostridium botulinum was cultured from the food. The most likely scenario was that corrosion damage had allowed entry of environmental organisms, including Clostridium botulinum, to the tinned food. This is the first outbreak of human type A botulism in southern Africa to be documented, and the first fatal outbreak described; previous human cases in this region have involved type B botulinum toxin, which tends to produce milder disease. A few other outbreaks elsewhere in Africa have been published, the most extensive being a type E epidemic in Egypt. Commercially tinned products were not involved in any of those outbreaks.

Susceptibility of Bacillus anthracis to eleven antimicrobial agents including novel fluoroquinolones and a ketolide.

OBJECTIVES: To determine the susceptibility of southern African strains of Bacillus anthracis to new, investigational agents as well as conventional antibiotics. MATERIALS AND METHODS: The MICs of 26 isolates of B. anthracis from South Africa and Zimbabwe, as well as the Sterne vaccine strain and a type culture strain, were determined by agar dilution. RESULTS: The most active antimicrobial agents were the novel ketolide ABT 773, new and conventional fluoroquinolones, and doxycycline; macrolides were intermediately active. The lack of activity of extended-spectrum cephalosporins against B. anthracis was confirmed. CONCLUSIONS: Susceptibility to conventional antibiotics was in keeping with previous studies. Two new fluoroquinolones and a ketolide showed promising in vitro activity that would support their further evaluation in animal models of anthrax.

Susceptibility of Yersinia pestis to novel and conventional antimicrobial agents.

OBJECTIVES: To determine the susceptibility of southern African strains of Yersinia pestis to novel as well as conventional antimicrobial agents. MATERIALS AND METHODS: The MICs of 28 strains of Yersinia pestis from a southern African plague focus were determined by agar dilution. RESULTS: The most active agents were cefditoren and the fluoroquinolones, both conventional and novel. The in vitro activity of macrolides was poor against this member of the Enterobacteriaceae. CONCLUSION: Further investigation of the novel quinolones olamufloxacin (HSR 903) and ABT 492 in animal models of plague would seem to be justified.

Factors Contributing to the Emergence of Escherichia coli O157 in Africa

In 1992; a large outbreak of bloody diarrhea caused by Escherichia coli O157 infections occurred in southern Africa. In Swaziland; 40;912 physician visits for diarrhea in persons ages 5 years were reported during October through November 1992. This was a sevenfold increase over the same period during 1990-91. The attack rate was 42