Rabies elimination in rural Kenya:Need for improved availability of human vaccines, awareness and knowledge on rabies and its management among healthcare workers

BACKGROUND: In Africa, rabies causes an estimated 24,000 human deaths annually. Mass dog vaccinations coupled with timely post-exposure prophylaxis (PEP) for dog-bite patients are the main interventions to eliminate human rabies deaths. A well-informed healthcare workforce and the availability and accessibility of rabies biologicals at health facilities are critical in reducing rabies deaths. We assessed awareness and knowledge regarding rabies and the management of rabies among healthcare workers, and PEP availability in rural eastern Kenya. METHODOLOGY: We interviewed 73 healthcare workers from 42 healthcare units in 13 wards in Makueni and Kibwezi West sub-counties, Makueni County, Kenya in November 2018. Data on demographics, years of work experience, knowledge of rabies, management of bite and rabies patients, and availability of rabies biologicals were collected and analyzed. RESULTS: Rabies PEP vaccines were available in only 5 (12%) of 42 health facilities. None of the health facilities had rabies immunoglobulins in stock at the time of the study. PEP was primarily administered intramuscularly, with only 11% (n = 8) of the healthcare workers and 17% (7/42) healthcare facilities aware of the dose-sparing intradermal route. Less than a quarter of the healthcare workers were aware of the World Health Organization categorization of bite wounds that guides the use of PEP. Eighteen percent (n = 13) of healthcare workers reported they would administer PEP for category I exposures even though PEP is not recommended for this category of exposure. Only one of six respondents with acute encephalitis consultation considered rabies as a differential diagnosis highlighting the low index of suspicion for rabies. CONCLUSION: The availability and use of PEP for rabies was sub-optimal. We identified two urgent needs to support rabies elimination programmes: improving availability and access to PEP; and targeted training of the healthcare workers to improve awareness on bite wound management, judicious use of PEP including appropriate risk assessment following bites and the use of the dose-sparing intradermal route in facilities seeing multiple bite patients. Global and domestic funding plan that address these gaps in the human health sector is needed for efficient rabies elimination in Africa

Utilising milk from pooling facilities as a novel approach for foot-and-mouth disease surveillance

This study investigated the potential of pooled milk as an alternative sample type for foot‐and‐mouth disease (FMD) surveillance. Real‐time RT‐PCR (rRT‐PCR) results of pooled milk samples collected weekly from five pooling facilities in Nakuru County, Kenya, were compared with half‐month reports of household‐level incidence of FMD. These periodic cross‐sectional surveys of smallholder farmers were powered to detect a threshold household‐level FMD incidence of 2.5%, and collected information on trends in milk production and sales. FMDV RNA was detected in 9/219 milk samples, and using a type‐specific rRT‐PCR, serotype SAT 1 was identified in 3/9 of these positive samples, concurrent with confirmed outbreaks in the study area. Four milk samples were FMDV RNA positive during the half‐months when at least one farmer reported FMD, i.e. the household‐level clinical incidence was above a threshold of 2.5%. Additionally, some milk samples were FMDV RNA positive when there were no reports of FMD by farmers. These results indicate that the pooled milk surveillance system can detect FMD household‐level incidence at a 2.5% threshold when up to 26% of farmers contributed milk to pooling facilities, but perhaps even at lower levels of infection (i.e. below 2.5%), or when conventional disease reporting systems fail. Further studies are required to establish a more precise correlation with estimates of household‐level clinical incidence, to fully evaluate the reliability of this approach. However, this pilot study highlights the potential use of this non‐invasive, routinely‐collected, cost‐effective surveillance tool, to address some of the existing limitations of traditional surveillance methods

Modelling Vaccination Strategies against Rift Valley Fever in Livestock in Kenya

The impacts of vaccination on the transmission of Rift Valley fever virus (RVFV) have not been evaluated. We have developed a RVFV transmission model comprising two hosts-cattle as a separate host and sheep and goats as one combined host (herein after referred to as sheep)-and two vectors-Aedes species (spp) and Culex spp-and used it to predict the impacts of: (1) reactive vaccination implemented at various levels of coverage at pre-determined time points, (2) targeted vaccination involving either of the two host species, and (3) a periodic vaccination implemented biannually or annually before an outbreak. The model comprises coupled vector and host modules where the dynamics of vectors and hosts are described using a system of difference equations. Vector populations are structured into egg, larva, pupa and adult stages and the latter stage is further categorized into three infection categories: susceptible, exposed and infectious mosquitoes. The survival rates of the immature stages (egg, larva and pupa) are dependent on rainfall densities extracted from the Tropical Rainfall Measuring Mission (TRMM) for a Rift Valley fever (RVF) endemic site in Kenya over a period of 1827 days. The host populations are structured into four age classes comprising young, weaners, yearlings and adults and four infection categories including susceptible, exposed, infectious, and immune categories. The model reproduces the 2006/2007 RVF outbreak reported in empirical surveys in the target area and other seasonal transmission events that are perceived to occur during the wet seasons. Mass reactive vaccination strategies greatly reduce the potential for a major outbreak. The results also suggest that the effectiveness of vaccination can be enhanced by increasing the vaccination coverage, targeting vaccination on cattle given that this species plays a major role in the transmission of the virus, and using both periodic and reactive vaccination strategies. Reactive vaccination can be effective in mitigating the impacts of RVF outbreaks but practically, it is not always possible to have this measure implemented satisfactorily due to the rapid onset and evolution of RVF epidemics. This analysis demonstrates that both periodic and reactive vaccination ought to be used strategically to effectively control the disease

Parameters table.

<p>Parameters table.</p

Estimated proportion of cases averted for different vaccination coverages and at different times to the outbreak in cattle (top panel) and sheep (bottom panel).

<p>Estimated proportion of cases averted for different vaccination coverages and at different times to the outbreak in cattle (top panel) and sheep (bottom panel).</p

Summary flow diagram of the model structure demonstrating the bidirectional RVFV transmission between domestic livestock and the two mosquito species.

<p>The structure also shows the infection states of livestock and mosquitoes and the parameters that describe transition pathways. <i>Aedes</i> spp population growth is governed by a fuzzy distribution model that leads to development, through explicitly modelled aquatic stages (Ϫ), of either susceptible or infectious adults. <i>Culex</i> spp population growth is governed by a logistic distribution model that leads to development, through explicitly modelled aquatic stages (Ϫ), of susceptible adults. See vector aquatic stages modelling in the text.</p

Simulated incidence of RVFV in hosts over 1200 days.

<p>The inset graph is a magnification of the full-blown outbreak period.</p

Predicted temporal relationship between fuzzy (panel A) and logistic probability functions (panel B) and vector: host ratios.

<p>Predicted temporal relationship between fuzzy (panel A) and logistic probability functions (panel B) and vector: host ratios.</p