Host pregnancy influences the establishment of Trichinella zimbabwensis in Balb C mice

Abstract

In order to determine the effect of host pregnancy in the establishment of , 120 female Balb C mice were divided into 4 groups of 30 mice each. Group 1 animals were orally infected with 50 larvae per gram (LPG) of body weight on day 0; group 2 were mated on day 0 and not infected; group 3 were mated at day 0 and infected with 50 LPG at day 7 post-mating and Group 4 were control animals which were neither mated nor infected. Six animals from each group were sacrificed and the number of adult parasites in the intestines as well as larvae in the muscles were determined at day 0, 7, 14, 21 and 28 post-infection for group 1; 0, 7, 14, 21 and 28 post-mating for group 2 and days 7, 14, 21, 28 and 35 post-mating for group 3. In addition, levels of progesterone and cortisol were measured in all groups at the same intervals. Our results showed that pregnancy reduced the number of larvae establishing in muscles with progesterone levels significantly higher in pregnant than in non-pregnant Balb C mice ( < 0.05). There were no significant differences in cortisol levels between pregnant and non-pregnant mice. High progesterone level in pregnant mice was assumed to have parasiticidal effect on the new-born larvae (NBL). Further research is needed to determine the direct effect of progesterone on NBL and how this can be exploited in designing remedies for preventing infection in susceptible domestic animals and humans.

Differential immune responses in mice infected with the tissue-dwelling nematode Trichinella zimbabwensis

“…Therefore, the enteric phase of T. zimbabwensis infection majorly favoured a mixed Th1- and Th2-type response, as opposed to T. spiralis and T. pseudospiralis infections which favoured a low-level Th1-type response with an earlier Th2-type response (Wakelin et al, 1994). The role of T cells in both parasites has been fully elucidated (V. Fabre et al, 2009) and the differences in immune responses observed between the encapsulating and the non-encapsulating Trichinella species may be attributed to the challenge dose, parasite antigenic diversity, animal-host sex and the rate of worm expulsion (Furze & Selkirk, 2005; Fu et al , 2009; Hlaka et al , 2015). The mixed Th1- and Th2-type responses elicited create a pro-inflammatory and anti-inflammatory environment that favours parasite immune evasion and establishment (Hewitson et al , 2009; Gruden-Movsesijan et al , 2011; Ilic et al , 2011; Sofronic-Milosavljevic et al , 2015).…”

Characterization of Membrane-Associated Progesterone Receptor Component-2 (MAPRC2) from Trichinella spiralis and Its Interaction with Progesterone and Mifepristone

“…Anzaldúa et al [ 16 ] studied the highest level of P4 that causes resistance against parasite invasion during pregnancy. Physiologically, the association between the increase in the P4 doses and induction of NBL mortality was observed in T. spiralis and Trichinella zimbabwensis [ 17 , 18 ].…”

Oral contraceptive pills: Risky or protective in case of Trichinella spiralis infection?

“…Although oestrogen was reported to have an effect on establishment of Trichinella infection and reduction of larval burden, these observations have been recorded during pregnancy . In vitro studies have also reported the death of newborn larvae on exposing them to the sera of human pregnant females, though the absence of anti‐NBL antibodies.…”

“…() supported such postulation when female rats started to develop more T. spiralis worms and larvae after ovariectomy . Hlaka et al . stressed this point even on another species of Trichinella , when female rats and pregnant mice infected with developed least T. zimbabwensi parasitic burden.…”

“…It was proved that some parasites affect the hormonal signalling within the host and disrupt the oestrus cycle . These observations have enlightened the potentiality of using progesterone as a helminthotoxic drug against T. spiralis infection that Hlaka et al . has recommended designing a new anti‐ Trichinella remedy that depends on the helminthotoxic effect of progestin to control infection in susceptible domestic animals and humans.…”