Answer to the Parasite Case of the Week 815: Tungiasis, caused by the flea Tunga penetrans
The following excellent description is written by Dr. Rattin:
Tungiasis is endemic in Latin America, sub-Saharan Africa, and the Caribbean. As is sadly all too common, it predominantly affects resource-poor communities. There is no standard treatment, but recommendations include surgical removal, wound disinfection, and dimeticone-based topical therapy (NYDA – a mixture of two low-viscosity dimeticones).
Tunga penetrans is the chigoe flea (with myriad other names). Gravid females lay eggs which are shed in the environment. Here, the eggs hatch into larvae, which have two stages prior to forming pupae. The pupae are in cocoons, from which the adults hatch and search for a warm-blooded host. The males and females can feed on the host, but only the females will burrow into the skin. This answers the question in the case whether this is a male or female – it is a female since it has burrowed and because of the numerous eggs that are visible. Only the posterior ends will be exposed to the environment, with their anterior end burrowed into epidermis. They can shed about 100 large eggs over a two-week period. They will then die and be sloughed off by the host’s skin. The damage to the skin can cause secondary bacterial infections, even possibly leading to sepsis. If the patient tries to remove the embedded female by themselves without sterile tools, tetanus is also a possible complication.
The hematoxylin and eosin (H&E) stained sections showed hyperkeratosis of the overlying host skin and important features diagnostic of tungiasis. Identifiable features are the sclerotized cuticle (yellow) and tracheal rings (Figure 1), digestive tract (Figure 2), and numerous large eggs (Figure 3). The eggs are actually visible to the naked eye! These features, along with the large size of the embedded flea and the position within the epidermis help differentiate Tunga penetrans from other arthropods such as scabies and ticks that may be seen embedded within skin.
Figure 1, H&E, 100x magnification:
Figure 3, H&E, arrows pointing to two of many eggs. 100x magnification
Thanks again to Dr. Rattin for donating this great case!
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