Point-of-Care Ultrasound Assessment of Tropical Infectious Diseases--A Review of Applications and Perspectives

Abstract

The development of good quality and affordable ultrasound machines has led to the establishment and implementation of numerous point-of-care ultrasound (POCUS) protocols in various medical disciplines. POCUS for major infectious diseases endemic in tropical regions has received less attention, despite its likely even more pronounced benefit for populations with limited access to imaging infrastructure. Focused assessment with sonography for HIV-associated TB (FASH) and echinococcosis (FASE) are the only two POCUS protocols for tropical infectious diseases, which have been formally investigated and which have been implemented in routine patient care today. This review collates the available evidence for FASH and FASE, and discusses sonographic experiences reported for urinary and intestinal schistosomiasis, lymphatic filariasis, viral hemorrhagic fevers, amebic liver abscess, and visceral leishmaniasis. Potential POCUS protocols are suggested and technical as well as training aspects in the context of resource-limited settings are reviewed. Using the focused approach for tropical infectious diseases will make ultrasound diagnosis available to patients who would otherwise have very limited or no access to medical imaging.

Figure 1.

(A) Epigastric transverse view: enlarged round hypoechoic tuberculous lymph nodes behind the liver in the area of the celiac trunk. (B) Left longitudinal flank view: enlarged spleen with small hypoechoic lesions (arrow) due to tuberculous microabscesses.

Figure 2.

Ultrasound (US) probe positions used in focused assessment with sonography for human immunodeficiency virus–associated tuberculosis (FASH) protocol. (1) Epigastric/subxiphoidal transverse view, (2) longitudinal pleural view right, (3) longitudinal right flank/upper quadrant view, (4) longitudinal pleural view left, (5) longitudinal left flank/upper quadrant view, and (6) transverse pelvic view (adapted from Heller et al. 201211).

Figure 3.

Suggested cystic echinococcosis (CE) stage-specific clinical management options according to World Health Organization Informal Working Group on Echinococcosis (WHO-IWGE) Expert consensus. PAIR = puncture, aspiration, injection of a scolicidal agent, and re-aspiration. Non-PAIR percutaneous treatments include several percutaneous techniques using cutting instruments and large bore catheters to evacuate the entire cyst content.

Figure 4.

(A) Right longitudinal upper quadrant view: amebic liver abscess posteriorly in the right lobe of the liver, presenting as a round hypoechoic lesion with hyperechoic debris and without a clearly discernable wall. (B) Right longitudinal upper quadrant view: pyogenic liver abscess presenting as an irregularly shaped, hypo- to anechoic lesion, containing hyperechoic gas bubbles with posterior acoustic shadowing.

Figure 5.

(A) Longitudinal pelvic view: thickened and irregular wall of the urinary bladder secondary to Schistosoma haematobium infection. (B) Right longitudinal flank view: dilatation of the renal collecting system, secondary to fibrosis and obstruction in S. haematobium infection.

Figure 6.

Epigastric transverse view: liver with bright hyperechoic fibrosis surrounding the intrahepatic portal vessels, due to Schistosoma mansoni.

Figure 7.

(A) Longitudinal scan of hemiscrotum showing anechoic fluid hydrocele. (B) Longitudinal scan of hemiscrotum showing low-intensity echoes in hydrocele fluid and thickened scrotal skin.