Nectar americanus - Laboratory Diagnosis, Epidemiology, Transmission, Treatment
Laboratory diagnosis of Nectar americanus
Infection by the hookworm parasite Nectar americanus is difficult to diagnose in the laboratory. Conditions associated with the infection such as eosinophilic leucocytosis and hypochromic microcytic anaemia are linked to the parasite infestation in endemic areas.
Sample
The samples collected for the diagnosis of Nectar americanus include:
stool
lung biopsy/autopsy
Microscopy
Microscopy of stool is done to demonstrate the Nectar americanus eggs. However, as the eggs of Ancylostoma duodenale and Necator americanus are similar in morphology, misidentification may occur.
Nectar americanus egg in an unstained wet mount (Source: ResearchGate)
Stool microscopy
Among numerous stool microscopy methods, direct wet mount microscopy is done for the diagnosis of Nectar americanus.
Direct wet mount microscopy
the wet mount for Nectar americanus is prepared by mixing stool sample with saline, iodine, or lactophenol cotton blue (LPCB)
necatoriasis is confirmed by the demonstration of the hookworm eggs which is identified by “falling leaf” motility
adequate for the detection of moderate or severe infections
Stool concentration
the formalin-ether method or salt flotation of stool is used for the concentration of the specimen for the detection of eggs of Nectar americanus
for quantitative diagnosis, egg counting technique such as the Kato-Katz method is used as a load of parasites is directly associated with the severity of infections
Adult Necator americanus - mouth parts with cutting plates (Source: ResearchGate)
Culture
The stool specimen is cultured by Harada Mori method to demonstrate the infective filariform larva (third-stage larva) which has hatched out of hookworm eggs present in the stool. It is done by smearing stool on moist filter paper and incubating it for 5 days to 7 days at room temperature.
This method has more advantages to stool microscopy as Ancylostoma duodenale and Necator americanus can be distinguished by the presence of infective filariform larva of Ancylostoma duodenale.
However, the stool specimen should be processed as soon as possible. If allowed to stand for several hours, the rhadbitiform larva that has hatched may be confused with Strongyloides.
rhadbitiform larva of Nectar americanus (Source: ResearGate)
Other methods
X-ray of the chest for diagnosis of respiratory manifestation of the hookworm infections
Epidemiology of Nectar americanus
Infection by hookworm, both Ancylostoma duodenale and Necator americanus, are the second most common helminthic parasitic infection – ascariasis being the first.
Although the parasite is found to be worldwide, they are most common in areas with warm and moist climates – throughout the tropics and subtropics. The thin, smooth eggshell of the parasite makes it delicate for harsh environment survival.
Incidence is high in places where people defecate in the open ground, in rural areas, and in children.
Geographically, the parasite is found in Central Africa, South Africa, South America, Central America, South Asia, and Far East Asia.
Transmission of Nectar americanus
Nectar americanus is transmitted by the following methods:
cutaneous route – penetration of host skin by filariform larvae. Common sites include feet, hands, buttocks or areas frequently exposed to soil
oral route – ingestion of filariform larvae. A less common route of infection
transmammary route – from breast milk. Rare route of infection
transplacental transmission
Treatment of Nectar americanus
Treatment of Nectar americanus infection is done by administration of anthelmintics (eg. mebendazole, albendazole) as well as iron replacement therapy in cases of iron deficiency anaemia (severe anaemia).