Serologic Surveillance of Anthrax in the Serengeti Ecosystem, Tanzania, 1996–2009

Abstract

Bacillus anthracis, the bacterium that causes anthrax, is responsible for varying death rates among animal species. Difficulties in case detection, hazardous or inaccessible carcasses, and misdiagnosis hinder surveillance. Using case reports and a new serologic assay that enables multispecies comparisons, we examined exposure to and illness caused by B. anthracis in different species in the Serengeti ecosystem in Tanzania during 1996–2009 and the utility of serosurveillance. High seroprevalence among carnivores suggested regular nonfatal exposure. Seropositive wildebeest and buffalo showed that infection was not invariably fatal among herbivores, whereas absence of seropositivity in zebras and frequent detection of fatal cases indicated high susceptibility. Exposure patterns in dogs reflected known patterns of endemicity and provided new information about anthrax in the ecosystem, which indicated the potential of dogs as indicator species. Serosurveillance is a valuable tool for monitoring and detecting anthrax and may shed light on mechanisms responsible for species-specific variability in exposure, susceptibility, and mortality rates.

Anthrax in a Backyard Domestic Dog in Ukraine: A Case Report

“…The disease is identified primarily in herbivorous livestock with secondary human infections, although there is a growing recognition of the impacts of infection on wildlife. Domestic and wild canids are most likely infected through ingestion of bacteremic carcass meat (Lembo et al 2011). Dogs (Canis lupus familiaris) are generally considered at low risk for developing anthrax following exposure.…”

“…The presumptive low mortality and high seroconversion rate in dogs observed in Tanzania led to the suggestion that they may serve as sentinels in cross-sectional serological surveys for livestock anthrax in areas where anthrax surveillance is otherwise challenging (Lembo et al 2011). To better understand the ecology of anthrax in Ukraine, passive surveillance among domestic livestock has been used for the past century.…”

Prevention, detection, and response to anthrax outbreak in Northern Tanzania using one health approach: A case study of Selela ward in Monduli district

“…It may also represent a significant burden which is both poorly reported and misdiagnosed [4]. The soil is the primary reservoir of B. anthracis [5].…”

“…In humans, hospital records show that 7,538 cases were suspected for anthrax and 8 cases were confirmed for gastrointestinal form with four deaths (case fatality rate 50%) during 1999-2006 [5]. Recent reports indicate the occurrence of the anthrax outbreak in Rombo district of Northern Tanzania affecting four people leaving one died after acquiring infection from infected cattle in 2016 [20].…”

Gastrointestinal helminths may affect host susceptibility to anthrax through seasonal immune trade-offs

“…While multiple factors are likely involved in the timing of anthrax outbreaks, we hypothesize that seasonal changes in host coinfection and immune factors may influence host susceptibility to this environmental pathogen. Anthrax can cause death within hours to days [33], though there is evidence that even very susceptible host species can experience a sublethal dose of anthrax and survive, in part, due to a humoral immune response against the anthrax protective antigen (PA) toxin [32,34]. These anti-PA antibodies have been shown to be essential for adaptive protection against anthrax and can mature through memory responses with multiple infections, though otherwise tend to last less than six months [32,35,36].…”