Prevalence, Etiology, and Risk Factors Associated with Occurrence of Canine Cutaneous Myiasis in Kitui County, Kenya

Abstract

Myiasis is the infestation of living tissues of animals with dipterous larvae. In Africa, Cordylobia species (C. anthropophaga, C. rodhaini, and C. ruandae) and Dermatobia hominis are reported as the principal cause of nonmigratory cutaneous myiasis of domestic animals. None of these have been reported in dogs in Kenya. A cross-sectional study was conducted in eight subcounties of Kitui County, Kenya, from March to August 2021 to estimate the prevalence, risk factors, and etiological agents associated with canine cutaneous myiasis (CCM). A questionnaire was administered to dog owners to collect information on CCM risk factors. A total of 400 dogs were physically examined and larvae collected from myiasis skin lesions and preserved in 70% ethanol, taken to the laboratory, processed and identified using parasitological morphological features. Live larvae were incubated and emerging adults were captured and identified. The overall prevalence of CCM was 45% (180/400) (95% confidence interval: 40.0-50.0%). A total of 434 larvae were collected from 180 dogs infested with cutaneous myiasis. All larvae (100%) were identified as C. anthropophaga and hatched adults were "tumbu" flies. There were no significant differences in the prevalence of CCM at 95% confidence interval among different age and sex groups (p > 0.05), although puppies (<6 months) appeared more affected. The highest prevalence of myiasis was in Kitui Central at 65% (95% confidence interval: 51.6-76.9%), Mwingi North at 52.5% (95% confidence interval: 36.1-68.4%), Kitui South at 48.5% (95% confidence interval: 31.5-63.9%), Kitui Rural at 40% (95% confidence interval: 27.6-53.5%), Mwingi Central at 40% (95% confidence interval: 24.9-56.7%), Mwingi West at 40% (95% confidence interval: 24.9-56.7%), Kitui West at 38.3% (95% confidence interval: 26.1-51.8%), and Kitui East subcounty at 36.7% (95% confidence interval: 24.6-50.1%). Lack of housing, housing structures, and dog living area environmental hygiene were the main risk factors associated with the occurrence of CCM (p < 0.05). The CCM occurrence was significantly different among breeds (p < 0.05). Cordylobia anthropophaga larvae were the etiological agent of CCM in Kitui County. There is a need for improved dog housing and hygiene measures to prevent the occurrence of CCM, and affected dogs should be treated to prevent the spread of CCM among the dogs.

Figure 1

A map of Kenya (a) showing Kitui County (in brown, the study area) and eight subcounties of Kitui County (b) by Klisch and Atzberger [17].

Figure 2

(a) Length of Cordylobia anthropophaga larvae in millimeters (12 mm); (b) Cordylobia anthropophaga larvae with a barrel-shaped body with dorsal minute brown cuticular spines on the thoracic and abdominal body segments.

Figure 3

The anterior end of Cordylobia anthropophaga larvae showing pair of oral hooks (i) and short conical brown cuticular spines (ii) on the thoracic body segments (×40 magnification).

Figure 4

Thoracic and abdominal body segments' brown conical cuticular spines. (a) ×40 magnification; (b) ×100 magnification.

Figure 5

Posterior end of Cordylobia anthropophaga larvae with two posterior spiracles (PS) each with three sinuous spiracular slits (SS). (a) ×40 magnification; (b) ×100 magnification.

Figure 6

Pupae (a) (i) and adult tumbu fly (b) (ii) of Cordylobia anthropophaga after culturing of larvae at ambient temperature and exposure to direct sunlight in the field.