Vol. 4, Issue 1, Part A (2022)

Microsporidia are a diverse group of obligate intracellular, spore-forming parasites that infect invertebrates including mosquitoes. A few studies showed that microsporidia infection of mosquitoes is associated with larval mortality or reduced adult fecundity and lifespan. This phenomenon might be used to protect against vector-borne disease transmission. This study aimed to determine microsporidia infection in field-collected Anopheles larvae and reared adults.
Anopheles larvae were collected from the field and analyzed from February to April 2022. After determining the species identity of the 4th stage larvae, they were dissected to extract their midgut while the early-stage larvae were transported to an entomological laboratory for rearing the adult in the insectary room. Similarly, after determining the species identity of adult female Anopheles mosquitoes, they were dissected to extract their midgut. Then, two thin smears for each dissected larvae and/ adults were made. Fixed preparations were stained with Giemsa and modified Ziehl-Neelsen staining techniques to detect the microsporidia. Descriptive statistics and an independent t-test were used to analyze the data. Anopheles gambiae complex was identified as the most predominant species from field-collected larvae and insectary reared adults. From the total 258 larvae and 258 adults An.gambiae complexes tissue smears examined, microsporidia were detected in 2.7% [7/258, (95%, CI: 0.8-5)] and 1.2% [3/258, (95%, CI: 0.01-2.7)] of larvae and adults respectively. The mean density of microsporidia in larvae and adults was 64.9 (± 23.4 SD) and 36 (± 8.5SD) respectively. The difference in microsporidia density between infected larvae and adults was statistically significant (F=1.77, P= 0.02).
Conclusion: Significant level of microsporidia infection was detected using light microscopy. Further microsporidia identification in the genus and species level is needed.