Erastus K. Kang'ethe

Preliminary findings from an experimental study of caprine besnoitiosis in Kenya

Inoculation of cystozoites obtained from natural, chronic cases of caprine besnoitiosis produced clinical disease in goats but not in rabbits, mice, guinea pigs, hamsters, rats or cattle. Histological examination of tissue sections from the experimental animals showedBesnoitia cysts only in goats. This, together with field observations that cattle reared together with goats having besnoitiosis do not contract the disease, suggests that theBesnoitia species that infects goats in Kenya is host-specific and is notBesnoitia besnoiti. We suggest that the nameBesnoitia caprae be adopted for the caprine pathogen.

Participatory risk assessment: a new approach for safer food in vulnerable African communities

Women play the major role in food supply in developing countries, but too often their ability to feed their families properly is compromised; the result is high levels of food-borne disease and consequent limited access to higher-value markets. We argue that risk-based approaches – current best practice for managing food safety in developed countries – require adaptation to the difficult context of informal markets. We suggest participatory research and gender analysis as boundary-spanning mechanisms, bringing communities and food-safety implementers together to analyse food-safety problems and develop workable solutions. Examples show how these methodologies can contribute to operationalising risk-based approaches in urban settings and to the development of a new approach to assessing and managing food safety in poor countries, which we call ‘participatory risk analysis’.

Isolation and characterization of group B streptococci from human and bovine sources within and around Nairobi.

Group B streptococci (GBS) were isolated from bovine milk and from vaginas and throats of antenatal and postnatal women using TKT and rapid GBS media. Sixty-three of 529 (12%) bovine bulk milk samples, 9 of 48 (19%) vaginal and 3 of 48 (6%) throat samples were positive. Both bovine and human beta haemolytic isolates were characterized biochemically and serologically. Pigment production was a characteristic of both human and bovine beta haemolytic isolates. The majority (88%) of human isolates fermented salicin and not lactose and most bovine isolates were either lactose positive/salicin positive (41%) or lactose positive/salicin negative (38%). Human and bovine isolates were 100% and 85% typable respectively. Serotype distribution was similar in the bovine and human populations with serotype la, lc and lll being most common in both. Fermentation of sugars showed major differences between bovine and human isolates but similarity in serotype distribution suggests some genetic relationship.

Comparative ultrastructural studies onBesnoitia besnoiti andBesnoitia caprae

Comparative transmission electron microscopy onBesnoitia besnoiti and on a strain ofBesnoitia derived from goats in Kenya revealed that the two organisms differ in their pellicle, micropore, microtubules, nucleus, wall-forming body 1 (W1), amount of lipids and amylopectin. Thus the caprine besnoitia is probably a different organism and the termBesnoitia caprae should continue to be used.

Caseous Lymphadenitis in Goats: The Pathogenesis, Incubation Period and Serological Response after Experimental Infection

Twenty goats, in two groups of 10, were injected intradermally with Corynebacterium pseudotuberculosis. The doses of infection were 1×105 and 5×104 colony-forming units (cfu) for groups 1 and 2, respectively. Thereafter, a goat from each group was killed every 2–3 days and examined for gross and microscopic caseous lesions in the draining lymph nodes. Bands or zones of macrophages and polymorphonuclear granulocytes were observed microscopically on the second day of infection in both groups. Gross caseous lesions were observed from days 8 and 9 of infection, respectively. Positive bacterial agglutination test and haemolysis inhibition test titres were detected after 15–17 days and 20–25 days of infection, respectively. These results indicated that caseous lymphadenitis is a subacute disease with an incubation period of 8–9 days, but that it is not detectable serologically until after 15 days of infection.

Risk Assessment for Escherichia coli O157:H7 in Marketed Unpasteurized Milk in Selected East African Countries

We carried out a study to assess the risk associated with the presence of Shiga toxigenic Escherichia coli (STEC) in informally marketed unpasteurized milk in urban East Africa. Data for the risk models were obtained from on-going and recently completed studies in Kenya and Uganda. Inputs for the model were complemented with data from published literature in similar populations. A fault-tree scenario pathway and modular process risk model approach were used for exposure assessment. Hazard characterization was based on a socioeconomic study with dose-responses derived from the literature. We used a probabilistic approach with Monte Carlo simulation and inputs from farm and household surveys. The qualitative analysis suggested a low to moderate risk of infection from consuming milk and that the widespread consumer practice of boiling milk before consumption was an important risk mitigator. Quantitative analysis revealed that two to three symptomatic STEC infections could be expected for every 10,000 unpasteurized milk portions consumed, with a possible range of 0 to 22 symptomatic cases. Sensitivity analyses to assess the uncertainty and variability associated with the model revealed that the factor with the greatest influence on disease incidence was the prevalence of STEC in dairy cattle. Risk assessment is a potentially useful method for managing food safety in informal markets.

The Developing World Urgently Needs Phages to Combat Pathogenic Bacteria

With the growing global antimicrobial resistance crisis, there is a critical need for alternatives to conventional antibiotics, especially in developing countries. Virulent bacteriophages (phages) represent a viable antibacterial technology that could be particularly beneficial, since phages are active against antimicrobial-resistant bacteria, easy to isolate from contaminated environments, and relatively inexpensive to produce. We discuss here examples of infectious diseases that significantly affect developing countries, phage applications that could be especially impactful in those settings, and special considerations for implementing phages in the developing world.

Gender Roles and Food Safety in 20 Informal Livestock and Fish Value Chains

Food-borne disease remains a major public health challenge in Africa and Asia. Most of the foods that carry the highest pathogen risk are produced by smallholder farmers, marketed through the informal sector, and sold in wet markets. Given the significant role of informal markets in African and Asian food systems, attention is invested in understanding (1) how the people that participate in informal markets are exposed to risk, and (2) how they manage risk. We conduct a participatory risk analysis with a gender lens in 20 livestock and fish value chains to study whether gender-based differences influence risk of food-borne disease. We find that socially constructed gender roles are more important determinants of health risk than biological differences between men and women. Variations in risk exposure between men and women are mainly due to gender-based differences in occupational exposure, and secondarily to differences in consumption patterns. Women are important but under-recognized risk managers in the realms of food production, processing, selling, preparation, and consumption. Understanding the influence of gender on risk exposure and management is essential for improving food safety in informal markets.